74 CB360 cranks, backfires, but won't run

[dlogreen]

I have a Harbor Freight dynamic light. Works fine and didn't break the bank.

Ethanol can clog up little jets fast if the carbs are left with fuel in the bowls.

I don't *think* a leak at the headers would cause a hang, but improper timing, air leaks, or issues with the advancer could. Carb balance also, but you've not changed the carb synch since it was running good.

Yeah I don't run anything but 89 or 90 Ethanol-Free, so there shouldn't be any sludge in the bowls, but I suppose it could still dry up and create some blockages even without ethanol? I might throw some fuel treatment in there too just in case, while I look around the other stuff.

I have a HF right by me, like 2 miles, so i'll swing by tomorrow first thing and check. I didn't adjust anything else on the exhaust other than the elbow section and it welded right up earlier today. I'll go back over everything again... double check timing, valves, mixture screws (which I assume could be affected by new better seated exhaust valves), pilots and other carb circuits, throttle idle screw, etc.

Also, never used a dynamic timing light, so i'll be learning that tonight lol while I grill chicken and porkchops on the back porch

 

[stl360+450]

Also, never used a dynamic timing light, so i'll be learning that tonight lol while I grill chicken and porkchops on the back porch

It's pretty simple. I tend to use a spare battery to power it, but it can be powered by the battery on the bike.

Clip the pickup over one or the other spark plug wire and then point the light at the rotor and squeeze the trigger. The strobe light will help you see the point at which the corresponding cylinder is firing.

Mine has a dial on the back that allows you to adjust the the timing of the light itself. I suppose it could be used to determine the actual advance angle, but sometimes I accidentally bump that dial, which is annoying because it throws things off. Helps me understand why many performing guitarists put tape over pickup selectors, tone knobs, and volume knobs for shows!

 

[dlogreen]

It's pretty simple. I tend to use a spare battery to power it, but it can be powered by the battery on the bike.

Clip the pickup over one or the other spark plug wire and then point the light at the rotor and squeeze the trigger. The strobe light will help you see the point at which the corresponding cylinder is firing.

Mine has a dial on the back that allows you to adjust the the timing of the light itself. I suppose it could be used to determine the actual advance angle, but sometimes I accidentally bump that dial, which is annoying because it throws things off. Helps me understand why many performing guitarists put tape over pickup selectors, tone knobs, and volume knobs for shows!

it's funny you mention tape and stuff... I'm a performing guitarist, and instead of making them unchangeable on the fly (each room or song might need something different), I shove small grippy O-rings under the knobs to act as friction between the base and the body. Great for general settings retention, but i can still reach down or use my toe to spin em if I need to in a pinch. That and I use low profile small knobs on my tone and volume... or flip the control plate on teles to avoid he dreaded switch flip. big difference between a tele neck and bridge pickup.

to address the dynamic, I had one overnighted from amazon cuz by the time I get to that, chances are it'll be here, and i might not need it. but still useful to have. I watched a few vids and I understand now... I think i was thrown by some using the battery ON the vehicle while others went with a spare. induction coil to trigger makes sense, so should be cool to see even if everything is good. If that ended up being the fix...how neat to get a tool and truly use it to correct the issue.

 

[dlogreen]

I have a Harbor Freight dynamic light. Works fine and didn't break the bank.

Ethanol can clog up little jets fast if the carbs are left with fuel in the bowls.

I don't *think* a leak at the headers would cause a hang, but improper timing, air leaks, or issues with the advancer could. Carb balance also, but you've not changed the carb synch since it was running good

After some more thought, practically.... I changed the exhaust valves, but they are lapped, and should not be leaking. intake valves are sealing well.... no issues there. i did not replace the head gasket only because it did not tear or peel off with the head when I removed it....likely bc it had only been on there for a month and with minimal actual mileage.

high hanging intermittently has to be timing or a leak, and I'll triple check to make sure I didn't accidentally wiggle my pods and intake runners loose before i tear into anything else (though before when I had a whole pod pop off, it didn't hang, it just didn't wanna idle nicely). Since the bike is cold currently, I'm gonna recheck the valves and check the timing while I have the stator cover off.

I'm starting to think that protruding seal could be the issue, so again, while I'm checking the timing, I'll use my meter and light for audible and visual indication of points opening and closing in time, check the points plate to see if it rotated when I was tightening it, and then pop off the plate and the advance and see if it's dragging on the seal, at which point I'll loosen the valve cover and tap the seal into a better seated position.

I'll report back after I get thru this checklist. Shouldn't take more than an hour or so

 

[ancientdad]

i did not replace the head gasket only because it did not tear or peel off with the head when I removed it....likely bc it had only been on there for a month and with minimal actual mileage.

I realize you're on a budget, but a head gasket that had been fully torque-crushed and through heat cycles over the course of a month should have been replaced. It's obviously the fire ring that's most important.

 

[dlogreen]

I realize you're on a budget, but a head gasket that had been fully torque-crushed and through heat cycles over the course of a month should have been replaced. It's obviously the fire ring that's most important.

less on a budget and sick of replacing new parts due to silly or unfortunate events. I mean I bought a camshaft right away for $100 but repaired the first one because I didn't wanna sit here idly and wait just to figure out something else needed work.

I see head gaskets online and i don't mind the price, but shipping still takes longer than I'd expect when it can be thrown in a flat envelope and sent for $5 in two days. I'll go ahead and order one because if that's the culprit then I'll gladly replace it. My time is the biggest currency here, not my funds... i have plenty of both RIGHT now, but I would like to spend my time improving the ride not fixing it or diagnosing it.

thanks for the heads up, because I noticed this one has that ring where my FZR600 head gasket is just fiber and metal plates and no metal ring around each cylinder. New one ordered when I read your comment, and if I don't need it, no biggie until the next time.

I went for a walk to get some other stuff done digitally, so now I'm headed out to tear into the bike. fingers crossed I don't find any surprises lol

 

[ancientdad]

less on a budget and sick of replacing new parts due to silly or unfortunate events. I mean I bought a camshaft right away for $100 but repaired the first one because I didn't wanna sit here idly and wait just to figure out something else needed work.

I see head gaskets online and i don't mind the price, but shipping still takes longer than I'd expect when it can be thrown in a flat envelope and sent for $5 in two days. I'll go ahead and order one because if that's the culprit then I'll gladly replace it. My time is the biggest currency here, not my funds... i have plenty of both RIGHT now, but I would like to spend my time improving the ride not fixing it or diagnosing it.

thanks for the heads up, because I noticed this one has that ring where my FZR600 head gasket is just fiber and metal plates and no metal ring around each cylinder. New one ordered when I read your comment, and if I don't need it, no biggie until the next time.

I went for a walk to get some other stuff done digitally, so now I'm headed out to tear into the bike. fingers crossed I don't find any surprises lol

I hear you all around, I'm just thinking of you getting it truly long-term reliable and that doesn't usually happen through shortcuts.

 

[dlogreen]

I hear you all around, I'm just thinking of you getting it truly long-term reliable and that doesn't usually happen through shortcuts.

And we're back!!!

Timing light just got here but no time for that.. re set the cam shaft seal, flush and grease the face of it/rear of the advance. Timing reset, intakes were oddly both too tight after, so reset them and the exhausts were confirmed.

Points gap, mixture screws, manifolds all good.... Started right up.

Took a test ride or 5 and then when about to put her away, I noticed my headlight flickering and my right front turn signal was dead as well as my horn (rear signals both work so it's not the switch. I'll check wiring tomorrow cuz likely something wiggled loose in the bucket.

I also swapped in larger pods to see if it matters, but too soon to know. Next will be making an H-shaped plenum to possibly help intake be more consistent across the carbs.

I hafta run to the gym to lift and coach, so TBD.

Either way, at least we got a daytime rider lol

No hangs no sputtering and held low idle as well. N

 

[EzPete]

The flickering light is likely a ground.

 

[dlogreen]

The flickering light is likely a ground.

Oh yah shelf and not just flickering but it was just out after that....and it's possible the headlamp and front turn and horn share that ground.... I'd hafta look.

Since I have power going back and to the left switch but not the horn, right front blinker or headlight I prolly lost a ground routing to the leftt control.. Starter button and clutch switch work but the clutch ground was wired in afterwards so it's not routed into the bucket.

I'm not stressing it though bc typical wiring isn't that hard and bc I know what lights aren't working, I can literally trace back to them from the bulb and left switch and fork ears. 10 minute fix. And once I get that going I'll set out for a short ride while everybody else should be at work

 

[dlogreen]

Oh yah shelf and not just flickering but it was just out after that....and it's possible the headlamp and front turn and horn share that ground.... I'd hafta look.

Since I have power going back and to the left switch but not the horn, right front blinker or headlight I prolly lost a ground routing to the leftt control.. Starter button and clutch switch work but the clutch ground was wired in afterwards so it's not routed into the bucket.

I'm not stressing it though bc typical wiring isn't that hard and bc I know what lights aren't working, I can literally trace back to them from the bulb and left switch and fork ears. 10 minute fix. And once I get that going I'll set out for a short ride while everybody else should be at work

Hilariously all three issues were unrelated.... Headlight h4 connector came loose, horn positive lead was pulled while removing and replacing the head, and front right signal was just burnt out

 

[dlogreen]

Hilariously all three issues were unrelated.... Headlight h4 connector came loose, horn positive lead was pulled while removing and replacing the head, and front right signal was just burnt out

Now for the fun part with experimentation.... This is my plenum concept.... An "uninterrupted" chamber of air that feeds both carbs and thus technically would balance intake a bit more since they are pulling from the same sources. Using the small pods bc I don't wanna disrupt the other ones that are looking good and working well.

Thoughts?

 

[EzPete]

Even just the longer intake plenum does a lot to stabilize the airflow, paint that PVC black and nobody will know.

 

[dlogreen]

Even just the longer intake plenum does a lot to stabilize the airflow, paint that PVC black and nobody will know.

Kinda my thoughts too. Today it rode pretty well.... A little twitchy off throttle and when holding low rpms in 2nd n 3rd like cruising behind slow cars in residential traffic.

I'm thinking those adjustable cb160 needles might help but it's coming directly back to idle after cracking the throttle and roaming around so I think I got that part sorted. I'll try the needles this weekend, then maybe cut down the 65 primaries I got a few weeks back, and then try the plenum mod....

Or I'll throw the the plenum on there cuz I won't hafta take anything else apart and see whether it's a worthwhile adjustment before digging into the carbs.

Happy to report no hanging idles, electrical issues, overheating or oil leaks. And started right up without choke every time. It's 80 out right now, so I think that makes sense and when it gets cooler I could need a lil choke with the more dense air.

More updates tomorrow

 

[stl360+450]

@dlogreen works fast! You've been through a lot in a short amount of time. I'm glad you are rolling under power again.

 

[EzPete]

I’d go plenum mod first. No sense in trying to trick the carbs on the fuel side if you can solve for air.

 

[dlogreen]

@dlogreen works fast! You've been through a lot in a short amount of time. I'm glad you are rolling under power again.

Thanks! Yah I had a blast riding yesterday. I think before I do the plenum thing I'm gonna get a short ride in on some new plugs and do a chop to see how they're burning. Strong suspicion of some richness, but with this exhaust it's hard to tell by the sound.

I know the timing and valves are spot on, but I could prolly check the balancing and syncing this weekend since new valves could certainly affect how each cylinder is pulling.

It's also a little cooler today, so I'll also get to see what kind of impact that has on the starting and idling.

And then I have a few pinholes to close up on the exhaust that I'll can address tomorrow before cleaning, rust prevention spraying, and wrapping hopefully tame the sound a little as well.

All in all I'm stoked and glad I haven't had any truly catastrophic failures. I'll keep checking things to make sure they stay in place over the next week or so but I got an buddy I met as a mechanic at an old bike shop and he's been wanting to get it and ride the old bikes since he got his back up and running.

Thanks for all the encouragement and ideas as I've chased down these little demons lol

 

[dlogreen]

Small update on the bike. It's been a busy few weeks but I finally got some riding time in between the Florida rain and gigs.

I took it out last Sunday for a few hours and went thru a full tank with no major issues I could notice. I definitely need to add another layer of foam to the seat and swap the hard rubber grips for something a little softer to handle vibrations.

I went thru all the gears and need to check my speed with the GPS, but I feel like I maybe stuck around 70-73mph tops even though I'm certain 80 is doable. This might be where the secondary main and air factor in along with the exhaust which means more tuning.

But after I let it cool off and came back a few days ago, check out my plugs

To me that looks pretty decent. I am running a step hotter cuz I usually do it all my bikes. So these are 7s instead of 8s.

Overall it handled and played well and had plenty of thumbs up from riders and cars that pulled next to me.

Acceleration and stuff was good though, so once I sort out how to unlock more of that top end, we'll be in business.

When I finally made it home after two hours, I did notice some smoke from the exhaust and vent tube, but only when revving. Need for concern? I'm thinking I might have been burning a little oil or it was overfilled a little? Haven't been back out cuz I was dog sitting all week at my girl's house and the weather was spotty every day. But I'll get some rides in this week and check on a few things.

Hope you guys are enjoying some good rides!

 

[crazypj]

Plugs look pretty good to me as well, slightly warm but you said your running 7's.
Something very few seem to know, the ground electrode colour shows if you have correct heat range, there will be a well defined line across it when it's right, usually just before the bend where it's welded to body.
I can't tell if yours are 'perfect' for your riding style/carb set, etc, or it's shadow?

 

[dlogreen]

Plugs look pretty good to me as well, slightly warm but you said your running 7's.
Something very few seem to know, the ground electrode colour shows if you have correct heat range, there will be a well defined line across it when it's right, usually just before the bend where it's welded to body.
I can't tell if yours are 'perfect' for your riding style/carb set, etc, or it's shadow?

Here's a close up of another pic I took, and I was blocking the sun, so don't think there's a shadow.

I didn't know that about the bend reference, but that's helpful.

You think running 8s might be better? This ride was 80% US 1 and A1A up in Jax, so I wouldn't say WOT but I was over half for sure most of the time, and since I live close to the hwy, it didn't have a chance to really hang out in the low throttle range more than a few minutes out of two hours at the end.

I'm open to suggestions, and I hope to do some more tuning this week/weekend. Thanks!

 

[dlogreen]

Recently started re-using my 3D printer, and decided to have a go at the plenum design using my 3D printer and the AI prompter in the software. currently this is the design progress, but I'm trying to smooth out the connector tube to create a better airflow. The base diameter will attach to the carb body while the top will go inside the pod filters. I'll make it out of TPU, which is flexible and durable, AND is pretty heat resistance, though I don't see why they should be getting hot anyway lol

In addition, maybe @crazypj or @ancientdad @stl360+450 might know where to source the AIR jets under the diaphragm? I think I wanna do some experimenting.... but that'll be a little further down the road. I might hafta to source an entire set of carbs to access an extra set of the stock air jets. Remember I swapped the pilot and secondary air jets, but before I do anymore with that, I might go up to 115 on the secondary since I'm at 112 and maybe a touch hot/lean based on my plug.

Anyway, hope this catches an eye or two. Would love to know what you think or if you have tried anything similar

 

[ancientdad]

AND is pretty heat resistance, though I don't see why they should be getting hot anyway lol

Oh I don't know, maybe because the carbs and air cleaners are right behind an air-cooled engine running in Florida temps....

In addition, maybe @crazypj or @ancientdad @stl360+450 might know where to source the AIR jets under the diaphragm? I think I wanna do some experimenting.... but that'll be a little further down the road. I might hafta to source an entire set of carbs to access an extra set of the stock air jets. Remember I swapped the pilot and secondary air jets, but before I do anymore with that, I might go up to 115 on the secondary since I'm at 112 and maybe a touch hot/lean based on my plug.

Anyway, hope this catches an eye or two. Would love to know what you think or if you have tried anything similar

Did you look at CMSNL or other parts fiches? #29, 30 and 31 would seem to be them (and I'm surprised they were ever available)

Honda CB360TK0 1975 USA CARBURETOR - buy CARBURETOR spares online

✓ access the CARBURETOR schematic ✓ find Honda CARBURETOR spares easily ✓ CARBURETOR parts quickly delivered

www.cmsnl.com

 

[EzPete]

One major drawback to pods filters is losing the secondary "attachment" or anchor points the stock filters provide. With the weight of the carbs and the pods hanging off the intakes + vibration it's not the best. I'd look to add something to your plenum design to help bring that secondary anchor back.

 

[dlogreen]

Oh I don't know, maybe because the carbs and air cleaners are right behind an air-cooled engine running in Florida temps....

Did you look at CMSNL or other parts fiches? #29, 30 and 31 would seem to be them (and I'm surprised they were ever available)

Honda CB360TK0 1975 USA CARBURETOR - buy CARBURETOR spares online

✓ access the CARBURETOR schematic ✓ find Honda CARBURETOR spares easily ✓ CARBURETOR parts quickly delivered

www.cmsnl.com

haha! Yeah it was cooking last time I went out, and I'll definitely need to double check the heat rating of the material I have. Worst case is i can test print it, and see if the concept even works or will go without failing the print. Then I can get some higher rated stuff, but TPU is pretty resistance to stuff, which is nice, and the flexibility makes it great for this kind of thing.

I'll check out the fiche and see. It's the last thing I wanna change anyhow, cuz I already have fuel jets to play with. I don't THINK i'd need to mess with the air jets unless I decided to change my pilot again, but the bottom end and idling have zero issues, so I don't think I want to. It was just something I was thinking about when I almost had my hands on a second set of carbs for cheap.

I'm thinking the 115 secondary will do more for me at this point

 

[dlogreen]

One major drawback to pods filters is losing the secondary "attachment" or anchor points the stock filters provide. With the weight of the carbs and the pods hanging off the intakes + vibration it's not the best. I'd look to add something to your plenum design to help bring that secondary anchor back.

oh yeah I've noticed. What's currently on is some pretty heavy silicone intake tubing , and this stuff will be SIGNIFICANTLY lighter. I'm less concerned about the overall weight versus the weight of the pod relative to the TPU. I don't think it'll droop too much under its own weight, but I'll gladly attach some lightweight hangers to support the pod when I get to that point.

the PVC pipe rig I tried before was VERY heavy and why I started down this 3D printed route to begin with. I'll let ya know once I get my printer settings sorted. I'm gonna need a higher infill and temp so the layers fuse better, it'll take longer but it'll also be more sturdy

Wish me luck!

 

[stl360+450]

In addition, maybe @crazypj or @ancientdad @stl360+450 might know where to source the AIR jets under the diaphragm?

Maybe Jets R Us — look here. They may not be genuine Keihin even if they do carry the same jet, but I've used some of their fuel jets without major issues.

 

[EzPete]

Im curious how the 3D printing goes - really curious what tool you were using for the .stl files. I’ve been scuffling there to get a design right on a really similar project for the GL/CX series - nothing to date has held up

 

[dlogreen]

Im curious how the 3D printing goes - really curious what tool you were using for the .stl files. I’ve been scuffling there to get a design right on a really similar project for the GL/CX series - nothing to date has held up

Fusion360 has an AI prompter and I gotta admit it did the heavy lifting. Way easier than trying to click and drag each and every shape. Try it and then slice it with Ultimaker Cura. The first print failed cuz it shifted on the plate with poor adhesion. I changed the settings a little and added brim/feet to secure it and that added a few hours, but the resulting failed print was sturdy for what it was. I feel confident it'll hold up ONCE complete. I'll know at 730 in the am. 6.5 hour print turned to a 10 hour one with a different infill pattern and later height to get better overall squish and layer to layer cohesion.

 

[dlogreen]

Fusion360 has an AI prompter and I gotta admit it did the heavy lifting. Way easier than trying to click and drag each and every shape. Try it and then slice it with Ultimaker Cura. The first print failed cuz it shifted on the plate with poor adhesion. I changed the settings a little and added brim/feet to secure it and that added a few hours, but the resulting failed print was sturdy for what it was. I feel confident it'll hold up ONCE complete. I'll know at 730 in the am. 6.5 hour print turned to a 10 hour one with a different infill pattern and later height to get better overall squish and layer to layer cohesion.

First pic is the failed print. Second is about 5 hours into the reiteration with a better base for adhesion and tweaked settings.

The last is the Autodesk Fusion360 free software with a pretty good and responsive AI that literally will build what you want if you can give it the right prompting.

 

[dlogreen]

Argh.... so my 10.5 hr print was successful. BUTTTT because I didn't have the bracket in front of me to measure the distance between the carb bodies, I let google tell me. It said 87mm center to center multiple times, and then I went with that (again, why AI will never replace humans lol). Turns out they are 110mm center to center, so my figure is too narrow. I can address this by cutting it and placing a silicone sleeve across the junction to bridge the gap, ORRRR reprint. And I think I'll reprint only because I know it'll hold up with this design slightly modified. SO back to the drawing board LITERALLY, but I'll get it started up soon, and see how things fare. Good thing it I can do a side by side of the mockup with silicone tubing and PVC joints compared to my design, and I know where I'd like to tweak a few things. I'll add some pics once I upload and can edit via my phone to add them.

 

[RobMan]

That looks so cool. I did computer help desk for 25 years and to be honest I don't have the ambition to learn a new skill like that anymore but I definitely appreciate those that do!

 

[dlogreen]

That looks so cool. I did computer help desk for 25 years and to be honest I don't have the ambition to learn a new skill like that anymore but I definitely appreciate those that do!

honestly, before when I downloaded it, AI wasn't worth a crap and I spent hours manually designing things based off of photos I took and overlaid. This has been cake compared. And it'll do what you want as long as you're literate enough to know what you're trying to design. I told it I wanted two parallel columns joined by a cross tube with smooth transitions internally, a wall thickness of 3mm +/- .4 mm where necessary to keep the figure solid and flowing, and then I started playing with the dimensions to make it taller, shorter, the crosstube more elongated to create more stagnant space, and then I gave the center-to-center distances and just recently created an egg crate support under the overhanging part (now that the gap is much wider than before) to eliminate any misprinting on that area. Then the rest is just setting the printer up like we do our carbs..... finetuning and making sure it's level and sticky enough to hold the print. here's the latest design with corrected dimensions and some tuning.

 

[dlogreen]

Wish me luck. The new design is actually better and more closely resembles what I put together with the pvc pipe and silicone. I weighed that with the pods attached and it was nearly 700 g, that's well over a pound. This design uses 200g of filament roughly, will be flexible where necessary but still plenty rigid thanks to wall thickness and infill percentage. We're looking at about 11-12 hours of printing, so I'll be leaving this and going on with my day. It's started and looks good so far. I'll throw update photos in this post as it goes until I need to leave for my gig later at 6. We should know how things are going within a couple hours and then it should be done around midnight or 1am eastern time.

Here's the first stages with the anchors being laid out.

 

[crazypj]

Looked through a few more posts, you only need to smallest air jet (50) , either order from Honda or drill out the one you have with a 1mm~1.20mm drill.
The other two never need changing because there isn't enough restriction at low rpm from stock set up.
I made some years ago as I couldn't find any online plus had some carbs with pressed in air jets I wanted to convert to screw in air jets (only the 50)
Nice manifold, I think you may need flat plates at each side of cross tube with a smaller hole to create an Helmholtz resonator although having filters linked is a very good idea. ?
Took a look at plug picture, try the 8 and see if you get better defined line on ground electrode?
Handy to be close to A1~A1A, hope it's not too over policed?

 

[ancientdad]

Handy to be close to A1~A1A, hope it's not too over policed?

I've only ridden on A1A once, on the way home from Jacksonville on my first CB750 in 1973. Can't recall how far south I took it before cutting across toward Tampa, but riding only a few hundred feet from the ocean at times was pretty cool. Traffic was light to sparse, don't recall seeing a cop at all but I'm sure it's different now.

 

[crazypj]

When I first came to Florida I took it from St Augustine, 80~90+ for miles and miles., that was about 27 years ago.
Several months ago it was on Channel 13 news they were cracking down on speeders because some were doing 100+through the built up area's where people were crossing to get to beach.

 

[dlogreen]

Looked through a few more posts, you only need to smallest air jet (50) , either order from Honda or drill out the one you have with a 1mm~1.20mm drill.
The other two never need changing because there isn't enough restriction at low rpm from stock set up.
I made some years ago as I couldn't find any online plus had some carbs with pressed in air jets I wanted to convert to screw in air jets (only the 50)
Nice manifold, I think you may need flat plates at each side of cross tube with a smaller hole to create an Helmholtz resonator although having filters linked is a very good idea. ?
Took a look at plug picture, try the 8 and see if you get better defined line on ground electrode?
Handy to be close to A1~A1A, hope it's not too over policed?

Thanks for the suggestion. Is this assuming I put the air jets back where they belong originally? And I see what you mean with the Helmholz resonator. I wasn't aware how that would impact an intake bc I'm more familiar with that in regards to acoustic instruments and such but I do recognize the utility. I'd hafta take a shot in the dark to set it up with any kind of accuracy but I could add that into a design and print it out tomorrow to do a side by side of the two performance-wise.

I have some 8s I can swap in this weekend and test out before it gets too hot.

Also a few hours in... The faint strings are intentional because I'm overextruding without retraction and at elevated temp to promote better layer adhesion and smoothing. It's killing it so far

 

[dlogreen]

When I first came to Florida I took it from St Augustine, 80~90+ for miles and miles., that was about 27 years ago.
Several months ago it was on Channel 13 news they were cracking down on speeders because some were doing 100+through the built up area's where people were crossing to get to beach.

Yeah it's MORE policed than when I moved to Jax in 05, but only where it opens up most. Much of where I ride unless I'm headed all the way into St. Aug is two lane cruising and I felt like I was trying to urge others along. 202/JTB to the beach from town is way worse bc it dumps off to each major North south drag between downtown and A1A. Saying this as I exit onto it . Time to go play music

 

[crazypj]

Cool, most people have never heard of Helmholtz, forgot you said earlier your a musician so you may even have some better idea's than mine.
Yep, assuming air jets are in correct positions, there should be a few diagrams in different places, 150 is for pilot jet, 85 for primary main jet, you can follow casting to pretty much see where things are. I've been drilling out the 50 for secondary mains at least the last 15 years, tried various enlargements until I ended up at 120, with extended intake you may need smaller though?
'Tuning' a resonator could have a totally different meaning, if you get better than stock performance (and/or fuel economy) I want to know.

 

[dlogreen]

So got home around midnight and the print failed for no reason other than it disconnected from the print server that acts as a go between from my devices to the printer.... And I guess it couldn't recover. It failed like AS I was leaving the house. So extra lame. That was hours of time it could have been going.

Anyway, got home, adjusted some settings for time and material waste and started again on a freshly opened roll of black TPU filament that is printing very smoothly right now. It's an 11 hour print job and will be done around 1pm.

Here's the current one running
And here's the fail at 5:09pm WHEN I LEFT . Notice I removed the extra brim at the bottom. It wasn't necessary based on previous print versions.

 

[Jays100]

Liking your innovation!

 

[dlogreen]

Liking your innovation!

Thanks! I love tinkering and problem solving. So much that it was a career path for a while with Root Cause Analytics for ear, nose and throat medical devices and implants.

Engines, machines, and electronics have been a passion since I was a kid.

Also on my way home from the gym this morning. Crappy session but this gives me a little joy.... Fingers crossed
Update!


And on the bike after trimming the supports. I'm currently trying to design the resonant chamber but the AI struggles a bit. First test ride felt really strong thru 3rd but haven't been on the main road yet. I want to get the print started before I do that

 

[dlogreen]

Test run felt pretty decent but it felt a little rich with the short filters on. Gonna put the other filters on while the new print is going and then see how things feel. With the old setup I think going up to 118 deliberately secondary fuel jets will be worth it. But I'm holding off until I get the same feel with this 3D print setup. Good thing is I felt the engine area around the part and it's totally fine. Barely warm.

Bike started right up though, so at least I know we're gonna be ok in that regard. Just gotta get a little more time with it. Dimensions are perfect though.. I'm proud of that part.

 

[Jays100]

Bigger filters first, jetting next. Crazypj is our resident 360 (among others) expert for carbys.
Then a rear rain/debris shield from the rear wheel shedding at speed. Perfect 3D print project.

Not that you need help…

 

[dlogreen]

Bigger filters first, jetting next. Crazypj is our resident 360 (among others) expert for carbys.
Then a rear rain/debris shield from the rear wheel shedding at speed. Perfect 3D print project.

Not that you need help…

Oh yah. Def filters first since that can be done without disassembling anything AND I know they breathe well. I didn't get into WOT so what I presume was a little lean up top is likely still there with the 112 secondary. I'm also considering welding up a short exhaust can, about 5 inches to tame the exhaust note a little more too. That'll be a little further down the road.

I'm gonna finish designing the resonant chamber plenum and manifold and see if I can get it on the printer this afternoon.

As far as a carb shield, because of where they sit and the height of the tail and the design of the filters with the metal cap, there weren't any signs of splash or spray from the rear wheel. Apart from that, definitely a fair weather bike so I hope I never find out how bad it could get lol.

I can't think of anything else performance wise. I'll change the plugs after I'm done with this cuz the hotter plug might be perfect with slightly larger secondary. It certainly wasn't lean on the bottom end. But that's such an easy thing I don't even consider it work.

I will look into the air jet to drill out. Obviously with them rearranged they work well now but I can imagine having the secondary air being 120 instead of 150 and putting the 150 back where it originally belonged in the pilot circuit. Good thing is if anybody ever stole it I'd identify it very easily by those mods

Edit: photos. Took me several hours today to get this thing to do what I asked and eventually I just told it to stop once I could see it being closer to the right design. Then I manually finished it which was much faster. My advice if using the AI assistant on this particular software is to let it create the basic structures and then manually construct or modify the general design otherwise it'll try to redraw it from scratch repeatedly, messing up what you have RIGHT in an effort to correct what's WRONG. cost me a lot of design time but still a learning opportunity

Edit: as I drive I started thinking about turbulent air, and how the next iteration should have a singular block off plate separating a larger central chamber into top/bottom (as oriented in the photo and on the print bed but actually proximal separated from distal) and more sloped manifold shape into the mouth of the carb . This creates a clear distinction between the incoming air that rapidly fills the "box" while smoothly routing it to the carbs in similar fashion to the original angled boots from the OEM airbox and preserves the overall lesser restriction of the mesh pods versus paper filter
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