Purple People Eater Project 81 CM400T

I removed the cap for the balance chain adjustment.

The Good: looked like the full amount of travel was available on the adjuster...

The Bad: As soon as I loosened the bolt it sprung all the way to the other end.....

It was way out of adjustment, I still may need to remove the side cover to reset the adjuster gear. I'll start it up again and see if that helped the rattling sound.
 
Updates, ran the motor a couples times a day of the last two days. then this morning drainined and refilled the oil, re-set the valve lash, rechecked compression (up to about 125 now.) adjusted the mixture screw and synced the carbs. here is the result. still a little fluttery IMO and a slight stumble off idle. Maybe the accelerator pump is not working right. I will do another round of adjustments and see if it gets any better.

 
I am going to need a new rear tire eventually, a 120/90 16 is what is on it now, rim is a stock 2.50 There are so many more options for a 130/90 16 which seems to be better pricing too. It does not seem to be a problem with the 2.50 rim, but I dont know if there is a tire rub issue with this model bike. Does anyone out there have any real life experience with this situation?

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The 130/90/16 will fit BUT you'll need to make a couple mods. I've done over 60K running this size.
Look at the front attachment of the rear brake stay where it connects to the swing arm. The stay needs to be moved to the outboard side of the bracket. Washers should be inserted where the stay sat so the bracket won't collapse when the longer bolt is tightened.
The chain guard on the other side will probably need to the squeezed together some, typically they're spread out a bit instead of the sides being parallel.
 
I will have to get some photos later but I was out of town last week and had some other home project to complete but everything is back together except the tank. (still cleaning the tank) got the bike out of the basement and went for a short lap around the neighborhood. oh forgot to add clutch was stuck but freed up after rocking back and forth in gear. So a lap or two around the block runs good (on aux tank for now.) shifts all gears. brakes work, not great but do work. after a lap or 2 starts sputtering. I dug into that and found that the right carb is to slow to refill. I will need to open the bowl on that side and see if a minor adjustment can fix that before the carbs have to come off again. got a little front wheel hop which I kinda expected, I will need to balance the wheel.

Found a different (not new) compression tester today and compared my good running CB400T to the CM400t. both engines cold for comparison for now. CB was 152 and the CM was 145. So not too bad.

Thanks for the tips..... @LongDistanceRider new 130 tire is on, and looks like a beast next to the CB with the 110 on the rear.
 
That's great, it's alive! In one of my ratty carbs I noticed the gas feed lines clogged. I made tubing that would fit in a lot of passage ways to test by blowing and seeing if air would pass, I found it had and probably used some guitar wire and carb cleaner spray to clear it.
 
I’m late to the party, but following. The resiliency of these engines is uncanny considering some of the conditions (neglect) they’ve been subjected to. Great work!
 
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Wheel hop at low er speeds is unlikely wheel balance. Instead I suspect the tire isn't fully seated on the wheel. Look at the edge of the wheel on the tire and you'll see a thin raised line, that line has to be even all the way around the wheel. Check both sides.
 
LongDistanceRider said:
Wheel hop at low er speeds is unlikely wheel balance. Instead I suspect the tire isn't fully seated on the wheel. Look at the edge of the wheel on the tire and you'll see a thin raised line, that line has to be even all the way around the wheel. Check both sides.
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This wheel and tire has a tube in it. Sorry I did not provide this info earlier, but here is what I know as of now.

I noticed the wheel had a "bump" in it when I mounted it and spun the wheel. (non centered rim/tire) I adjusted the spokes to true up the rim, but the tire itself has a high spot. I tried rotating the tire to different spots on the rim referencing the paint dot on the tire. the location that has the smallest "HUMP" makes the wheel way out of balance. It does not seem right to adjust spokes to offset a high spot in the tire, so maybe I just need a new tire. the tire is not new so that is probably the best option long term. I was just trying to make it usable for some testing.
 
esmith250624 said:
This wheel and tire has a tube in it. Sorry I did not provide this info earlier, but here is what I know as of now.

I noticed the wheel had a "bump" in it when I mounted it and spun the wheel. (non centered rim/tire) I adjusted the spokes to true up the rim, but the tire itself has a high spot. I tried rotating the tire to different spots on the rim referencing the paint dot on the tire. the location that has the smallest "HUMP" makes the wheel way out of balance. It does not seem right to adjust spokes to offset a high spot in the tire, so maybe I just need a new tire. the tire is not new so that is probably the best option long term. I was just trying to make it usable for some testing.
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That paint dot is to align the stem for balancing. Sounds like a permanent warped tire.
 
after the float adjustment and putting the tank on and making sure no leaks, video quality is not great, just my cell phone in a waterproof holder around my neck, just trying to show you guy progress, maybe someday I will get a quality setup. mixture adjustment.... I will call it 7/8 turn out, not quite a full turn, so far good results with this setting I will recheck plugs after a few miles on it.

Tire hop is still there i got some wheel weights to add so I can keep tweeking on that but there is some issue with this wheel tire combo, it will need a new front wheel for sure.

Tachometer is screaming in the video so have not addressed that yet.


I can tell the oil is starting to help, shifting is starting to smooth out.

 
I have been around the block and around the neighborhood several times, (within a mile from my house) can't get above 30mph for very long with this front tire, (New tire is on it's way) starts right up, idles well, runs good, shifts ok, downshifting 2nd to 1st is just a little sticky, I have to use a bit more force than the others. Clutch feels better on this one than my CB. My CB has a much wider friction zone than this one, This one is shorter and more crisp transition. I don't know enough to know which is correct. I hope the shifting will smooth out with some more miles on it. I want to get it up to full speed to see how it does.

I have a couple small leaks, one is the Tachometer oil seal, the oil filter housing o-ring (still using the one already installed.) and the Fuel petcock is leaking in the reserve position. parts for the oil leaks are on order, I will order the fuel valve rebuild kit soon.

I had an extra set of gauges from my CB, so I put the innards of those in the CM gauge housings. Now I have both gauges working. Still plenty to do cosmetically, but maybe I can win ugliest bike contest at the local bike night.
 
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Still thinking about what to do about unobtainium side covers and found these snap on towing mirrors, the shape is really close to stock, they might make some fairly decent replacement side covers with a Few modifications. they are $37 on amazon

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esmith250624 said:
Still thinking about what to do about unobtainium side covers…
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Search Google/YouTube/Internet “diy motorcycle side covers”. Yes, I’ve done this myself, same covers fit 400/450. There’s a few nice ones out there. You’re definitely thinking out of the box, I’m interested in what you come up with.
 
tomeben said:
Search Google/YouTube/Internet “diy motorcycle side covers”. Yes, I’ve done this myself, same covers fit 400/450. There’s a few nice ones out there. You’re definitely thinking out of the box, I’m interested in what you come up with.
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Thanks, I have watched some of the videos about making side covers. none that I saw jumped out at me as awesome. If the OEM side covers on ebay were priced better I would just buy them. some of the pricing on that stuff is crazy. Plus I like to make stuff so I thought I would try something different. whatever I decide will probably get posted on here. 2 people locally are selling those first set of mirrors on marketplace, I will offer them a price and If I get them for cheap then problem solved.
 
I like the get creative part. It is just a plastic side cover. If nothing else it buys you time until you find a real one, or make a better one. Maybe something as simple as a plastic container that has a decent form, cut in half you have left and right panels. Add bailing wire, hot glue and paint.
 
esmith250624 said:
If the OEM side covers on ebay were priced better I would just buy them. some of the pricing on that stuff is crazy. Plus I like to make stuff so I thought I would try something different.
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Same here. I’m looking forward to seeing what you come up with.
 
We settled on $30 for the set of 2 side mirrors, they are 37 each on amazon i think. Holding them up to get an idea, this seems to fit the shape the best. I need to cut the mirror out so ot fits in there tighter, but just trying to get an idea if this might work. FYI. That is not the final seat. That is a cb400 seat pan and does not fit right, that is just temporary. There is plenty of extra plastic material that will get cut off.

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Here is the progress so far on the side covers. This is basically a couple of relief cuts and 2 main bends in the plastic. And of course, some trimming of the edges and ends to make it all fit. I try to keep it as simple as possible. I decided to start on the battery side since I felt there was more cuts on that side, and it would be easier to just duplicate the other 1000002802.jpgside once one side was done.

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Changed the oil last friday and was planning on riding the bike all week. But when I removed the oil filter housing there was no Spring and no thrust washer for the filter. The parts came in today, so I installed those.

I have still been working.
On the side covers when I have time, all the seams are welded and now i'm working on how to mount them. I added tabs at the top corner to use to fix to the frame holes up there. Now I need to add a piece of plastic from the leftover scraps to the bottom that will extend and line up with a bottom front mounting holes. You can see the scrap piece of plastic in the picture.

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Other things I'm working on.Is drilling out the holes for the exhaust heat shield mounts. I have the seat PAN stripped down to the getting.Ready to paint that and come up with a plan for the foam. I'm thinking about using A CB 400 seat cover and making a little bit of a low profile seat and just tuck the extra skirting material underneath and cut it off.

Kinda like this, but not brown
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Cool electric bike conversion. The one with 2 18V tool batteries, other with homemade battery?, same add on motor/gear. Never rode one but it could be nice. No carbs. Someone posted converting an old Honda bike to electric on the site.
 
They both have the same battery setup, just snap in two 18v tool batteries. Hard to see both in thephoto. The motor shaft has a freewheeling gear on it so you can pedal the bike normal with no motor resistance. this setup tops out at 15mph. But i dont use it that way. It is strictly a hill assist tool.
 
I like it. I found on ebay for $100 I could buy the kit with motor(350W, 36V, gear, controller). Alternative would be to just buy an electrified bicycle starting around $500. Add the batteries to the do it yourself thing and time putting it all together it's a tough choice. Not that I'm going to do this anytime soon, I've got my 2 motorcycles and a few bicycles, but it's interesting to investigate something in between. The cool thing about do it yourself is you can always undo it or fix it if you put the time into making it.

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kbongos said:
I like it. I found on ebay for $100 I could buy the kit with motor(350W, 36V, gear, controller). Alternative would be to just buy an electrified bicycle starting around $500. Add the batteries to the do it yourself thing and time putting it all together it's a tough choice. Not that I'm going to do this anytime soon, I've got my 2 motorcycles and a few bicycles, but it's interesting to investigate something in between. The cool thing about do it yourself is you can always undo it or fix it if you put the time into making it.

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If I had to do this over again the decider is the batteries. I got mine during christmas time when they have all the tool sales.
 
of the four screws that hold the heat shields on only one screw came out clean, the other 3 snapped off, so I got to drilling them out. three of them drilled out fine and I ran a tap to clean out the threads, the fourth was a little trouble but I drilled it out a bit larger so I will try to make this one a 6mm instead of a 5mm. If that does not work I can get someone to weld up the hole and then redrill it for 5mm again.

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Well I got the front tire bounce sorted out. and wouldn't ya know @LongDistanceRider was right, the tire bead was not seated quite right on the rim. now its good and no more wheel hop. now that is out of the way i could take it for a good run. went out for a 30 mile run yesterday, temp was warm 93-94. runs really good. slight gurgling on decel. May be running a bit lean. i did pull the plugs and they look to show slightly lean. I do have a pair of 75 jets that I could try, so that would be going from 72 to 75 on the primary main. I think LDR says he is running 75, 118 so that would match a known good setup. I may try that next and see if it works better or worse. I checked the temp on the oil sump with laser thermometer after the 30 mile run and it was 205 degrees, but it was a warm day. Same Test on my CB seems to stay 180-190
 
Well here I go again, I said erarlier that I had a set of 75 jets for my carbs, well I did not lie but the 75's are non OEM branded. I have this micro drill set sitting here so i found one that measures .75mm and the drill bit did not fit in either the already installed 72 jets or the non oem 75's. I drilled out the 75's so they are now a true .75 mm (hopefully)

I used a small hand drill shown in the pictures. I ran the bike with these drilled out jets and it did reduce the slight popping on decel. I will do a longer run soon and recheck the spark plugs.

I did not notice any adverse changes in the throttle during this last test.


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LongDistanceRider said:
I'm a bit a*al retentive. I check every jet, even originals, for sizing. Originals have always been good, aftermarket has always been over/under.
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haha, my little experiment here proves what most have said about the non OEM jets being off, I guess its just a matter of how off. I took the bowls off and removed the 72 jet and held it up to the light with the non-OEM right next to it, and had it passed the eye test I probably would have just installed it. But I looked at both at the same time and said... something is not right. that is when I started measuring. Good thing I did.
 
Well, it looks like I read the spark plugs wrong. With the Jet change, the spark plugs have a lot of carbon on them. I am going back to the 72 jets. Looking at the spark plug chart I may have missed these are too cold. I do have a set of D7EA spark plugs which I understand are A little bit hotter. I'm currently running the GM coil mod On this engine. I may swap the CDI from my CB 400 and see if I get a better spark. I'm also gonna go from one and a quarter. Turns out on the mixture screw to 3/4 of a turn.

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Its been a while since i posted on my own project. To get you up to speed, i ended up buying a set of side covers on ebay, but they re missing the clip inserts for the mounts next to the carburetors, i know some one on here was 3d printing them, but i am open to what some others have done for that.

I spent way too much time chasing down a ground issue in the front turn signals. If i put a alligator clip to the bolt on the turn signal housing and grounded the other end to the frame the light would work, so i knew i was missing the ground somewhere. I thought the ground would pass through the threads on the stem, but it seems now that a clean surface on the mounting bushing in the headlight housing and the inner stem nut is now working.

Solved an air leak in the airbox due to a missing lid screw and a bad seal.

The bike was dropped on the right side and bent the brake stop adjuster tab on the frame, so i took that all apart and straightened the tab and readjusted the brake, it works much better now


I have put 1000 miles on this hunkOJunk since i brought it home this past april. It runs pretty good just looks like it could be featured in the walking dead show.1000003058.jpg
 
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Recently the petcock valve started leaking and i was going to buy a rebuild kit for it but when i disassembled the valve i found that the only inner part that was replaceable was the inner rubber piece, so i decided to make one


i used the old gasket piece as a template and used spray pain to mark where the holes go
then i just punched the holes with my hole punch and reassembled. I will check it on the tank tomorrow to see if it leaks

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I had a piece of rubber mat that was the same thickness. my dad's old hole punch i think I used the 3/16 hole size inserts

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Ready for re-assembly

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for the thread tap i used the 4-40 tap from the carb rebuild (idle jet extractor) and i already had a bunch of small 4-40 screws.

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I've had to get creative with the side covers, getting broken knobs attached and so on. A little hot glue, silicone rubber, bailing wire, etc. Suggest to attach a string or wire to them and bike as loss prevention. If using a wire on battery side, use an insulated wire to prevent arc welding. And if you have two motorcycles and take the batteries out for winter, don't face them together as you walk them into the house. Don't ask me how I know these things.
 
Finally got some cool weather so i decided to install new fork seals in this bike. This one has the air assist shocks, and i never put air in them and they felt ok but i expected to find something. What i found was these plugs in between the top two springs. I took them out and installed everything per the parts diagram. But now i think i know why they were there. PO. Must have wanted to run the shocks without the air assist. These shock bottom out without any air in them. So either my springs are worn out or these are not to be ridden without air. Let me know your thoughts

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I greased the orings in the crossover hose. And i put about 10-15psi in there and it feels better. Sprayed with soapy water, dont see any leaks but i will see if it holds air overnight.
 
It's pretty common for spacers to be used to adjust the stiffness/preload/fit of the front shocks, especially when replacing the springs. I worked with a company to get new fork springs for my XL350 a few years ago and the recommended springs came with PVC tubes to be cut for spacers.

I also deleted the air assist from a 1982 CB750K that I once owned by obtaining longer springs from an earlier model that lacked air assist shocks. The spacers are another way to go and then you don't have to worry about leaks.
 
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