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CL350 Vintage racer project

Honda used the same steering bearings on 'everything' over 250cc until around 1978 so pretty much any Honda front end you get will fit.
You can grind off the weld or push out expander plug on 350 bottom yoke then just swap steering stem into whatever you get hold of.
I have pictures somewhere but it was at least 10 years ago so may not be too easy to find (maybe on DTT, I'll link if I find it)
A lot of the newer bikes also use same bearings, it's generally sport bikes and big cruisers that got larger bearing sizes
 
Thanks for that info, very helpful. Is there a source of data to compare the offset numbers for different models? I know that the 750F triples have slightly less offset which will increase trail slightly. Wondering what would be the difference with 450, etc. More homework to do.
 
IMG_6089.jpeg
Here’s the clutch basket. There are small serrations in the fingers but they only seem to be on the top edge. The face of the fingers looks smooth. What do you all think? Do I need to dress these edges smooth?
 
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Looks like it was in pieces andn bits not stored properly?
I would add some oiling holes to clutch hub while your in there, it helps wash out any residue and also helps cool plates, the middle of clutch pack can get overheated.
May have to do search on CB360 clutch hub mods as that's where I've posted most stuff in other peoples threads for the last 14~15 years
 
Found pic of clutch hub, it's common on modern bike.
I think I did my 550 in 1978 when I re-built it around 32,000 miles
Here's 360 mod, from around 2008, Photbucket rep was kind enough to put all my pictures in one folder for me to download, luckily there are only 'several hundred' so finding things isn't a total disaster
Clutchhub3.jpgdo same on 350.
 
Here’s the clutch basket. There are small serrations in the fingers but they only seem to be on the top edge. The face of the fingers looks smooth. What do you all think? Do I need to dress these edges smooth?
To be completely clear, these are the edges in question.

1726498832579.png

And they do look a bit rough, but in a way I'm not used to seeing (little choppy marks on the edges of the fingers). The marks being referred to are more like this

clutch basket wear.png
 
Looks like it was in pieces andn bits not stored properly?
I would add some oiling holes to clutch hub while your in there, it helps wash out any residue and also helps cool plates, the middle of clutch pack can get overheated.
May have to do search on CB360 clutch hub mods as that's where I've posted most stuff in other peoples threads for the last 14~15 years
This is how it came out of the engine a couple of days ago. I will certainly take a look at the oil mods for the clutch, as well.
 
To be completely clear, these are the edges in question.

View attachment 36910

And they do look a bit rough, but in a way I'm not used to seeing (little choppy marks on the edges of the fingers). The marks being referred to are more like this

View attachment 36912
Yeah, that’s what I expected to see, marks made across the face of the fingers by the edges of the clutch plates. They all seem to have those serrated edges, maybe manufactured that way? I will have to take a closer look later.
 
Are these holes made alongside each of the webs around the whole clutch hub? I see that you made 3 holes in the 12:00 position and 2 holes at 9:00. What size, number, and position should these holes be drilled? Thanks.
 
Looks a bit like someone was de-burring the edges with a die grinder but they didn't really know what they were doing.
I found a folder marked CB350, haven't looked at it yet though so no idea whats in there, it's from 2010~11
I drill the holes to line up with spaces between friction plates, don't want to risk weakening anything so it gets 2 and 3. Clutch hub turns counter clock so oil 'pools' agains rib then centrifuges through plates.
I think 1/8" is the largest hole you can drill, use ball end burr in die grinder or Dremel to 'countersink'
Only 2 sets of each at ribs
 
So, I would drive that plug out of the bottom of the steering head, correct? I’m assuming that I would use some sort of drift to knock that out?
After that, what is your method for removing the steering stem from my bottom yoke and installing in the donor yoke? I don’t have a shop full of tools so if it requires a press I will need the help of a professional.
 
To be clear, alternating 2 and 3 holes around the whole hub?
 
Thanks for that info, very helpful. Is there a source of data to compare the offset numbers for different models? I know that the 750F triples have slightly less offset which will increase trail slightly. Wondering what would be the difference with 450, etc. More homework to do.
Man, I wish - I spent hours of summer downtime scouring and couldn't find a resource with all of them in one place. You can kind of get to a directional number doing a bunch of math with rake angle, wheelbase and trail to find your triangle and backing into an offset from there, but I found that going model by model was about the only way.
 
Only next to the stiffening webs, four places.
I do try to keep things symmetrical. and balanced.
The 350 folder only had pictures of seam welded frame, normal modification to prevent some of the flex.
To be clear, alternating 2 and 3 holes around the whole hub?
Oh, use a pipe or something that slides down inside of stem from top and give a few good whacks. Be careful not to use too small a diameter as you need the 8mm thread to help pull things back into place.
The stem isn't actually very tight in bottom yoke, I think I knocked it out with an alloy plug and 4 lbs 'lump hammer' (I think they may be called drilling hammers in U.S?)
Wood wasn't quite hard enough, have to be a little careful not to damage threads on stem.
I found Honda stem was a 'direct replacement' in Suzuki Katana lower yoke.
The weld in ones need the welding ground off, I use angle grinder.
This was stock Suzuki, bearings completely wrong for Honda frame.
GKatanaYokeHondaStem.jpgKatanaYokeHondaStemtop.jpground welds from Honda and Suzuki, knocked out stem and switched with Honda. Cleaned up the bare casting (forging?)
KatanaStockYoke.jpg
 
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Thanks for the info, it’s going to be very useful in the days ahead. Lots to think about and consider.
 
Only next to the stiffening webs, four places.
I do try to keep things symmetrical. and balanced.
The 350 folder only had pictures of seam welded frame, normal modification to prevent some of the flex.

Oh, use a pipe or something that slides down inside of stem from top and give a few good whacks. Be careful not to use too small a diameter as you need the 8mm thread to help pull things back into place.
The stem isn't actually very tight in bottom yoke, I think I knocked it out with an alloy plug and 4 lbs 'lump hammer' (I think they may be called drilling hammers in U.S?)
Wood wasn't quite hard enough, have to be a little careful not to damage threads on stem.
I found Honda stem was a 'direct replacement' in Suzuki Katana lower yoke.
The weld in ones need the welding ground off, I use angle grinder.
This was stock Suzuki, bearings completely wrong for Honda frame.
GView attachment 36921View attachment 36922round welds from Honda and Suzuki, knocked out stem and switched with Honda. Cleaned up the bare casting (forging?)
View attachment 36920
You mentioned welding the frame seams, another topic that I have questions about. It is allowed under the class rules so I am planning to do it.
It is my understanding that the welds should go along the backbone seam of the frame from steering head down to the swingarm pivot. I have read that the prescribed method is to grind down the raised flanges and spot welds and butt weld the two frame halves. Does this sound right? I would be interested in seeing your photos of how this is done.
 
As for the clutch basket, the edges have a little bit of a bevel to them. The serrated indentations are right along the leading edge of the bevel, the rest of the face of the fingers look pretty clean. Very curious. I will probably clean these edges up.IMG_6096.jpegIMG_6099.jpeg
 
For the steering stem, looks like I will be grinding this one out. Lucky me.IMG_6094.jpeg
How about this gusset across the spine right behind the steering head. Should this be ground off to weld the seam or left intact and welded from this gusset back?IMG_6095.jpeg
 
If you're going to be removing the pedal mounting bar you want to brace that section of frame, the red area. If you weld the brace in place be sure that the engine case is installed and bolted securely to keep the frame straight. Welding the seam of the backbone is also done for frame stiffness. Need to read the rules and verify if this is allowed.
7047870347_a8a16fb618_b.jpg
 
Welding seams is legal, adding any bracing is not. I was planning on ditching that stuff to save weight. I could probably cut the footpegs and side stand off and just leave the crossbar in place. It would serve the same purpose.
 
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IMG_6094.jpeg

If I’m seeing this correctly, the steering stem tube is protruding below the bottom yoke and is fillet welded around the protrusion.
I will need to grind this weld out and then drive the stem tube out of the bottom yoke. Then, transplant the 350 stem into the other yoke and weld it back in leaving the same length of stem tube above the top. In this way the new yokes should fit back up to the 350 steering head, no? Will I have to make adjustments for the possible difference in thickness between the two top yokes?
Msny things to consider.
 
You right about correct way to weld frame although you cut out a section and weld not remove entire seam before welding..
Boxing in rear section where shocks mount is usually done as well.
Leave seam on front of steering head but put a tube inside so seams don't flex.
The gusset at back of steering head is already welded correct position to prevent frame cracking, (it doesn't get welded all the way around) underneath steering head can be pretty rusty so a plate there is normal frame repair connecting to front down-tube.
This frame was pretty rotted in a few places, steering stop was missing, bits got boxed in.
The frame brace I think rules are talking about is the tube from center box section to the outer frame tubes above swing arm, very similar to Yamaha XS 650 frame brace.
I don't have a good picture of XS frame though, only one I modified to mono-shock although the swing arm pivot factory bracing can be seen plus the diagonal tubes just above it
It got a lot more gussets and braces around top shock mount and rear frame got welded back on but I won't bore you with those..
Stretchedandlowered5.jpgCB350framemods4.jpg

CB350framemods3.jpg
 
Thanks crazypj,
Yes, I absolutely would only grind out sections at a time and weld the seams. Good tip. The rules prohibit adding any bracing, only seam welds.

IMG_6094.jpeg

Going back to the steering stem, that fillet weld looks like it would be tricky to grind out and still try to save the bottom of the stem tube to drive it out. Might be better to just cut the yoke off from around it and grind it down to the tube? What is your approach here? That’s a big fillet weld.
 
Your clutch basket looks fine to me, I have seen a few high mileage/abused units that I would hesitate to reuse but overall they hold up very well. It is also a worn fit so even if you smooth them out they will just reappear.

The fillet weld doesn't penetrate very deeply on the ones I have ground down so I would try that first.
 
If you just use an angle grinder to make it flat there 'should' be around a millimeter of weld left.
In fact, in your picture, it looks like original tube flat end is showing a little?
I would just use angle grinder on edge with a slightly worn grinding disc instead of cutting the yoke up. (in fact, that's what I do when I can't remember where I put burrs for die grinder)
Your not going to be 'leaning' on it so the $10.99 at Harbor Freight angle grinder works as well as anything else
In 30+ years using angle grinders I've only ever had one disc break on me, and that was my fault cutting through a very badly twisted U' section'(I knew it wouldn't work before I started but wanted to see what happened, the twist closed up halfway through and grabbed disc, had to break it to get out of cut then come back from other side.
Usually I break discs knocking grinder off bench but only happened two or three times.
I guess I'm just lucky, guy about 2 miles from where I lived in Britain had a disc shatter, broken piece caught him in the throat and he 'bled out' before ambulance could get to him (may also have made me more cautious?)
I have seen yokes cut in half to make clip - on bars but it isn't something I do (7/8" tube fits into the recess reasonably well and you can always carve on stuff to get bars angled to your liking before welding up)
Even if you get into the tube a little it doesn't matter, just weld a little deeper, (although you will probably assemble new parts onto stem first to check lengths and positions are OK)
I used to have some old fork tubes that I assembled top and bottom onto to make sure things lined up but didn't bother after the first few as tube was tight enough in hole and supported over enough length it stayed in line in all directions
Pretty sure some I did were better than factory alignment? (or maybe bikes had been 'dropped' before I got them?)
 
Engine tear down is complete. I split the cases and removed all the subassemblies. Parts are grouped together in separate bags and tagged for each.IMG_6106.jpegIMG_6108.jpegIMG_6109.jpeg
I didn’t find any nasty surprises in there, so that’s a relief. The surfaces all look good with no signs of galling or overheating. I’m going to finish dismantling the frame and then I will begin to clean up and make a closer inspection of the engine parts.
A question for the veterans, the oil baffle under the crank has two screws in it. I removed the screws but the baffle plate doesn’t seem to want to come out. Is this fixed in place or is there a way to remove it? I’m not going to force it and bugger things up.IMG_6107.jpeg
I thought the little buttons were just locating pins but they seem to be some kind of rivet or fastener. Thanks for any help you can provide.
 
The windage tray(baffle) is held by the 2 screws and 3 aluminum squashed rivets that are part of the case. Many people don't remove it because of those 3 rivet heads. I cut the heads off with a Dremel, remove the plate and clean the sump out completely.
Re-installation is grind the rivet stands so the top is flat removing all traces of the rivet. Center punch the stand, drill & tap for a 6mm bolt, reinstall the tray.
Be sure to look closely at the tray around the screw/rivet holes, they are prone to developing cracks which have to be fixed when/if they happen.
 
And in counter point to LDR I say never remove the tray unless it is cracked and needs to be replaced and a replacement bottom case is not available.

I have never had any issues cleaning up under the tray and check it with my inspection camera. Worst spots are on either side and if there isn't enough gap to slide a brake cleaner spray nozzle hose then using a dremel tool with a round diamond cutter on it will make quick work to make a gap.

Taking it out is a makes work project and it will never be as secure as original.
 
IMG_6112.jpegIMG_6113.jpeg
Steering head bearing races are out and the bike is down to the bare bones.
IMG_6111.jpeg
A box full of dismembered body parts.
 
Appreciate the points of view.
I also do not remove the windage tray, much like cylinder studs that haven't been disturbed in 50 years I like to leave them alone if at all possible (though the comparison isn't quite the same, of course). I took my 450 crankcases to a local speed shop and had them hot tanked, and that cleaned them up nicely and removed all the sludge from under the windage tray.
 
A box full of dismembered body parts.
Looks like you got lucky and your top bridge is not cracked/broken as so many are by this time. Look to be sure the D-shaped washers are there so when you reinstall it, it will be safe to tighten to proper torque without cracking.
 
Looks like you got lucky and your top bridge is not cracked/broken as so many are by this time. Look to be sure the D-shaped washers are there so when you reinstall it, it will be safe to tighten to proper torque without cracking.
Yeah, I am aware of the D-shaped washers in the top clamp pinch bolts, I have them in my CB 750.
I am planning on swapping for a 35mm front fork, probably from a ‘78 CB750K.
 
The tiny drive rivets, or brads, for the vin plate can easily be pressed or knocked out from the inside. WD40 and a thin feeler gauge blade can loosen the glue under it.
 
I've knocked out the chassis plate rivets a few times, bit fiddly but not too bad.
First time it was use a 1" bar and tap it sideways, externally with dead-blow hammer bit awkward to hold on top of pin.
Used smaller diameter bar after that with a slight flat.
Plate is held down with what looks and acts like rubber cement, be careful not to use solvents , they shouldn't attack anodized plate but I have seen them get wiped away (not as bad as Yamaha printed stickers though, you have to replace them except they were discontinued decades ago)

As for windage tray, I've always removed them to de-burr underneath and check for any hidden bits (I think I radiused or polished a few places to aid oil drain and pick-up? (last time, was close to 20 years ago, I've built other stuff since that tends to blur memories)
Drill through the peined over 'rivets', thread 5mm or 6mm and use countersunk flat head screws.
Plate needs minimal opening up or dishing to self center and is usually 'tighter' than original and 'dimples' around holes make it less likely to crack
I know if I had a 350 motor here to look at I would remember 'instantly' what needs doing but I only have some scrap parts from when Marc was looking to build a 'massive' oversize motor ( (I think around around 430cc)
I was boring case and block to see how much off-set we could get on bore position.
I think Kawasaki Z1000 forged 1200 'race' conversion oversize piston had right pin size and crown height (I remember pin is too big on GS1000 kits to fit 350 rods and needed a pair of 1983 (?) GS/GSX1100 rods, (pre-SACS motors before they went to high pressure plain bearing with split rod )
 
I have another question regarding a fork swap, this having to do with the front axle. The front axle on the 350 has a threaded sleeve that makes up on the end of the axle and holds the brake and hub together.IMG_6115.jpeg
This assembly is made up as a unit and then installed on the forks.
IMG_6116.jpeg

My question is this, what is the process if the axle doesn’t fit correctly into the forks that you swap into the bike? This wouldn’t be a matter of using the donor axle, especially if the forks are from a disc brake model as you would probably not have the same sleeve arrangement to hold the brake drum, etc together. It would be beneficial if the 350 axle fits right in but what are the odds?
Inquiring minds want to know.
 
Thanks LDR, I’m going to be using the 350 hub and wheel with a donor 35mm fork. After doing some more research the 500T triples are a pretty close match to the 350 and have 35mm tubes.
My question is what is the fix if the 350 axle doesn’t fit up to the 500T fork lowers? I assume that with 35mm triples I could use forks from other models with same size tubes? Many questions.
 
Thanks LDR, I’m going to be using the 350 hub and wheel with a donor 35mm fork. After doing some more research the 500T triples are a pretty close match to the 350 and have 35mm tubes.
My question is what is the fix if the 350 axle doesn’t fit up to the 500T fork lowers? I assume that with 35mm triples I could use forks from other models with same size tubes? Many questions.
Good question with no answers other than SWAG, scientific wild ass guess. It'll be a case of waiting to see what does/doesn't fit and align.
 
In these moments it helps to know a good machinist.


I realize the adapters would show, but if you're allowed to use another period-correct front end it would seem they'd allow you to adapt it somehow if needed.
 
Yeah, I suppose those details will have to be sorted out as I go along. If I don’t know a machinist now I’m sure I will before this is all over.
 
Just use 500T axle, you will need different spacers for the wider forks but making them from 6061 means they are a lot lighter than the steel ones.
You can also treat 6061 to make it tougher or use 7075 which is quite a lot harder than 6061. Hard anodizing will give a surface harder than the original steel (aluminum oxide is what ordinary grinding wheels are made of)
If you look through my posts on various sites from 2008 you'll see I've already done similar multiple times, speedo drive removal spacers, etc.
On a race bike it doesn't have to look so pretty so some parts could be made even lighter
A few years ago, it was my only form of income allowing me to buy materials to make more 'stuff'
I'm actually doing better since retirement as I now have a small pension coming in.
I forgot Photobucket deleted all the pictures and I haven't gone through the download to sort them out to re-upload in threads (I don't even know where all the threads are)
I have found picture of the rear wheel spacer set I made though, have the weight of steel vs alloy somewhere, you can pretty much swap ounces for grams

CB360rearaxlespacers.jpg
 
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I started building CB350 and other vintage race bikes in the 80's as a mechanic, then started racing myself in 1992. There were no "Supersport" type rules until USCRA introduced them mid-90's with the stock CB350 down graded from Lightweight Supervintage (Sportsman in WERA and AHRMA) to 350 GP class.

Your engine has very low wear and was not abused. My personal and customer Stocker CB350 builds are as follows:
-Clean and degrease all engine parts, especially cleaning the crank oil-slinger "sludge trap" groove with a pick and spraying a can or two of contact cleaner through the big end pins to clean. You can rotate the con rod and feel the debris getting loose and washing out. Inspect all parts for replacing. Stock intake and exhaust valves will need to be replaced in most cases.
-Bead blast all cases, clean again to remove all blast media, then wash the cases with S-100 or Bike Brite to remove more media dirt stains if needed. Cut/dress the valve faces and check the seal as per my video. It is critical to thread a sacrificial bolt into every threaded hole to keep the media out during blasting. If beads are blasted into a blind threaded case hole, throw out the part and start over.
-Assemble with all new gaskets, o rings and oil seals. All oil seals need grease in the ''groove". Include an upgraded camchain tensioner, Ken Miller KA slipper type is my preference, I have not tested or used the newer roller types on the market. It is not necessary to use a flat sided chain with the KA tensioner, the stock chain is good. Beef up the shift drum detent with my mod as per my video.
-You need a good electronic ignition, crank mounted PVL type is my preference. Stock CV carbs are fantastic, run without filters like a real vintage race bike. You may change the Primary and Main jets for tuning. Be advised that all of these carbs now have eroded needle jets and good O-rings need to be sourced. You will want long tapered megaphones on each headpipe. 2 into 1 exhausts will loose power.

The engine output will measure 27 rear wheel HP on a Dynojet 250i.

What I don't do:
Do not slot the cam sprocket, stock timing is optimal.
The stock oil circulation is excellent, no need to modify in any way, even up to a 11,000 RPM 48HP engine.
Completely stock clutch is good.

The stock drum brake is garbage. The GT500 Titan drum brake will crack and try to kill you when the wheel collapses. The CB450/CB77 drum sucks. The only affordable brake that I have not destroyed or make fade into oblivion is the 4LS GT750 drum. It is NOT too heavy, and I promise to wave to you when I pass you on the brakes if we ever meet on the track.

Read what I wrote about chassis mods:

I do no extra welding or boxing or bracing to the stock CB350 frame. I still hold the lap record of 1:48:9 at Mid-Ohio 2011 for this class of bike, plus the next class up. I'm not the fastest rider, do I have the best handling bike?

I like 35mm CB500T forks simply because the have chrome all the way up. Straight weight springs, Gold Valve emulators.
Stock fork clamp offset will allow the bike to fall into the corners, trail needs to be increased.
Here are the numbers:
Steering head angle 27°, front tire radius 310mm.
Stock offset 58mm/ ground trail 92.86mm
48mm offset/ 104.08mm ground trail.
There is a CB750 clamp that has this offset.

100_5106.JPG

100_5107.JPG

100_9859.JPG


Curiously enough this particular bike was built for Larry Macoskie in 2008, it was then raced by another racer, and is currently raced by Andrea Blake. The engine has never been apart.


Cheers, Stan
 
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Hi Stan, interesting reading.
Pretty much completely stock CB350 makes 26~27 bhp, literally just remove all the road parts and put different pipes on it (or remove silencers )
I was teaching at MMI Orlando back then so had access to dyno 'after hours' and between classes.
I remember Marc being very upset about it as it was supposed to be 36bhp (even though he was an instructor, he never really knew how the catalog HP was measured and refused to accept my explanation about no generator or 'ancillaries, direct from crank reading (YOU CAN'T LOOSE THAT MUCH IN TRANSMISSION!)
It was kinda funny to see him 'performing', made him a lot madder
:rolleyes::LOL::LOL:
Doing various modifications just makes things somewhat more reliable, if area's can be improved for more reliability or better drive-ability, why wouldn't you do it?
Carb mods with 3 jet Kei-Hin really are needed, it will run rich with stock jetting somewhere between 4,000 rpm and 6,000rpm, it can't do otherwise when air-box is removed, the tuned intake length gets completely messed up (I think original set up equated to an intake around 22" long, although it's been a long long time since I did the math)
Fuel is showing exactly the same as I've seen, transition around 3.9~4K , slightly rich then good for 500rpm at 6K.
I'm guessing the 2600rpm plot is starting jetting?
From print out, it's easy to see it's 'all over the place' even though acceptable limits for street use (bit lean in most places)
I have yet to see a Honda from 1970's that didn't exhibit clutch 'creep' at high rpm under load, plus, I've seen too many seized cam bearings not to do the oil flow mods.
The fact the CB 360 with a much better trochoidal pump suffered far more than 350 should tell you oil flow is the problem (I had CD 175 seize cam bearing twice, first time, about after about 12 miles 'flat out, second time, the left big end also failed, but, as I had been 'chasing' a Suzuki GT500 across Salisbury Plain at 80+mph it wasn't too surprising. (in 1976, on way to Stonehenge)
Homestead, where 350's can be held flat out for longer on the banked track, several had top end issues back in 2002 (or maybe 2003, I forget, they put a chicane in coming onto the start finish the next year) Friend was doing CCS Series in Florida/Georgia (Jennings GP)
It isn't an 'instant disaster' and 11,500 rpm is OK, as long as it isn't held there for more than about minute or two, it was actually more common on the street than racing as a 350 could be run flat out for hour at a time (or until you had to stop for gas / it just stopped)
Maybe I just knew people who rode harder? (In Britain you were usually limited by what you could afford to insure, it meant people usually had smaller bikes than they wanted, riding without licence or insurance would get you in real big trouble first offense.)
 
I started building CB350 and other vintage race bikes in the 80's as a mechanic, then started racing myself in 1992. There were no "Supersport" type rules until USCRA introduced them mid-90's with the stock CB350 down graded from Lightweight Supervintage (Sportsman in WERA and AHRMA) to 350 GP class.

Your engine has very low wear and was not abused. My personal and customer Stocker CB350 builds are as follows:
-Clean and degrease all engine parts, especially cleaning the crank oil-slinger "sludge trap" groove with a pick and spraying a can or two of contact cleaner through the big end pins to clean. You can rotate the con rod and feel the debris getting loose and washing out. Inspect all parts for replacing. Stock intake and exhaust valves will need to be replaced in most cases.
-Bead blast all cases, clean again to remove all blast media, then wash the cases with S-100 or Bike Brite to remove more media dirt stains if needed. Cut/dress the valve faces and check the seal as per my video. It is critical to thread a sacrificial bolt into every threaded hole to keep the media out during blasting. If beads are blasted into a blind threaded case hole, throw out the part and start over.
-Assemble with all new gaskets, o rings and oil seals. All oil seals need grease in the ''groove". Include an upgraded camchain tensioner, Ken Miller KA slipper type is my preference, I have not tested or used the newer roller types on the market. It is not necessary to use a flat sided chain with the KA tensioner, the stock chain is good. Beef up the shift drum detent with my mod as per my video.
-You need a good electronic ignition, crank mounted PVL type is my preference. Stock CV carbs are fantastic, run without filters like a real vintage race bike. You may change the Primary and Main jets for tuning. Be advised that all of these carbs now have eroded needle jets and good O-rings need to be sourced. You will want long tapered megaphones on each headpipe. 2 into 1 exhausts will loose power.

The engine output will measure 27 rear wheel HP on a Dynojet 250i.

What I don't do:
Do not slot the cam sprocket, stock timing is optimal.
The stock oil circulation is excellent, no need to modify in any way, even up to a 11,000 RPM 48HP engine.
Completely stock clutch is good.

The stock drum brake is garbage. The GT500 Titan drum brake will crack and try to kill you when the wheel collapses. The CB450/CB77 drum sucks. The only affordable brake that I have not destroyed or make fade into oblivion is the 4LS GT750 drum. It is NOT too heavy, and I promise to wave to you when I pass you on the brakes if we ever meet on the track.

Read what I wrote about chassis mods:

I do no extra welding or boxing or bracing to the stock CB350 frame. I still hold the lap record of 1:48:9 at Mid-Ohio 2011 for this class of bike, plus the next class up. I'm not the fastest rider, do I have the best handling bike?

I like 35mm CB500T forks simply because the have chrome all the way up. Straight weight springs, Gold Valve emulators.
Stock fork clamp offset will allow the bike to fall into the corners, trail needs to be increased.
Here are the numbers:
Steering head angle 27°, front tire radius 310mm.
Stock offset 58mm/ ground trail 92.86mm
48mm offset/ 104.08mm ground trail.
There is a CB750 clamp that has this offset.

View attachment 37259

View attachment 37260

View attachment 37261


Curiously enough this particular bike was built for Larry Macoskie in 2008, it was then raced by another racer, and is currently raced by Andrea Blake. The engine has never been apart.


Cheers, Stan
Stan, thanks very much for that write up. A lot of excellent and useful information to digest.
There are many differing opinions depending upon who you ask about all the various race mods. Some will say, “can’t do without this” while others will say, “that makes no difference”.
Personally, I’m of the opinion that in this race class with these old bikes engine reliability, rideability, and good handling characteristics are going to be more useful than hot engine mods.
If you don’t mind, I may PM you from time to time for some advice and guidance as I move along. This is my first attempt at putting together a project like this so I will have plenty of questions. Thanks again.
 
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