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CL350 Vintage racer project

For those more curious about the product, it's here:

www.electrexworld.co.uk

Honda CB350K4 CDI Ignition Stator Kit - STK-350D

Product Information Fitting Instructions Component List Warranty & Returns Race Ignition Kit Fits: Honda: CB350K4 High performance cdi ignition system for twin cylinder 4 stroke with a 180° crank. Self generating (no battery required) race ignition system, digital pre-programmed CDI producing...
www.electrexworld.co.uk www.electrexworld.co.uk

I really like the left crankcase cover with crankshaft oil seal in place, I'm thinking of buying one for my 450 drag bike engine.
 
IMG_7350.jpeg

A company called Vintage Performance makes this custom cover to work with the race ignitions. It has cover screws located at 6 and 12 o’clock to fit the modified factory cover. Also has a slider plate to aid with crash protection.
 
ancientdad said:
I haven't looked in the 350 FSM, but 45° does seem like more than stock.
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The way I interpret it is that the unit has a static timing of 10’ at idle and an additional 35’ at full advance for a total advance of 45’. This is all controlled electronically, along with rev limiter, by the CDI units.
If you follow the graph, the unit will give 35’ advance at 4K rpm and continue to max 45’ at 13K.
Someone way smarter than me worked all that stuff out.
 
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Emlupi said:
A company called Vintage Performance makes this custom cover to work with the race ignitions. It has cover screws located at 6 and 12 o’clock to fit the modified factory cover. Also has a slider plate to aid with crash protection.
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It takes a LOT of internet leg-work to find all the bits that are out there for a specialty project like yours. I just benefited from some of your efforts.
Emlupi said:
The way I interpret it is that the unit has a static timing of 10’ at idle and an additional 35’ at full advance for a total advance of 45’. This is all controlled electronically, along with rev limiter, by the CDI units.
Click to expand...
I understand the premise, I just wondered if 45° total is greater than the stock figure. With only mild mods to the engine, I wonder if that long a lead is going to be helpful. Just found the spec in the FSM, it's apparently 5° at idle, 32° to 38° max.

1738940643154.png
 
ancientdad said:
I understand the premise, I just wondered if 45° total is greater than the stock figure. With only mild mods to the engine, I wonder if that long a lead is going to be helpful. Just found the spec in the FSM, it's apparently 5° at idle, 32° to 38° max.

View attachment 42383
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I believe that by rotating the stator in it’s slots you can retard and advance the timing by a few degrees if necessary.
 
ancientdad said:
I understand the premise, I just wondered if 45° total is greater than the stock figure. With only mild mods to the engine, I wonder if that long a lead is going to be helpful. Just found the spec in the FSM, it's apparently 5° at idle, 32° to 38° max.
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With it being computer controlled, I wonder what the advance curve looks like
 
EzPete said:
With it being computer controlled, I wonder what the advance curve looks like
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I'd be curious too, though I wouldn't be using one on any of my bikes because it precludes the use of the stock alternator (if I'm understanding it correctly). And my drag bike engine will run total loss. I just want that crankcase cover with seal built in, and it's probably lighter than the 3/16" flat plate my machinist made for me.
 
ancientdad said:
I'd be curious too, though I wouldn't be using one on any of my bikes because it precludes the use of the stock alternator (if I'm understanding it correctly). And my drag bike engine will run total loss. I just want that crankcase cover with seal built in, and it's probably lighter than the 3/16" flat plate my machinist made for me.
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Check with ElectrexWorld, maybe they will sell you the plate separately?
 
Emlupi said:
Check with ElectrexWorld, maybe they will sell you the plate separately?
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Looks like they will, it's listed separately.

www.electrexworld.co.uk

Baseplate - BP450

Product Information Warranty & Returns Baseplate Fits: Stator Kits: STK-450D NOTE: This part is usually supplied as a spare for our stator kits and is not suitable for other applications. Manufactured by ourselves here in the UK. # Warranty Road bike components - one year from the date of...
www.electrexworld.co.uk www.electrexworld.co.uk
 
Emlupi said:
Looks like you have a winter project now, too.😃
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I was hoping to get to it this winter but it doesn't look that way now, plenty of other distractions lately (household and vehicle-related). And now I'm in prep mode for a week in the mountains in a couple months.

I am going to be curious about the weight of that plate from your kit.
 
Pretty cool. Minimal rotor drag = minimal power loss.
42-45 advance, depending on rev limiter setting.
I read in Bill Silver's guide about Pops Yoshimura in the 60's, welding advancers at 45 in CB72 to race. Wonder if it was hard to start?
 
ancientdad said:
I am going to be curious about the weight of that plate from your kit.
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It’s an aluminum plate so it’s pretty light weight. Sorry, it’s already installed so I can’t weigh it now.
 
IMG_7364.jpeg
Installed clutch, oil pump, and filter. New clutch friction plates , o-rings, seals, etc.
IMG_7365.jpeg

Right side all buttoned up.

IMG_7368.jpeg

Installed pistons and slipper cam chain tensioner. I used copper spray on the base gasket. Could provide some benefits and certainly can’t hurt.
Installing rubber bumpers for tensioner pin is certainly a heart in the mouth moment 😃. Having to slide them in underneath the gasket is not exactly the ideal situation. Anyway, that’s done.
 
IMG_7369.jpeg
Cylinder barrels installed.

IMG_7370.jpeg
I used this piston ring compressor and it made the job go smoothly. I know that some people don’t like doing it that way but it worked well for me.

IMG_7371.jpeg
I modified the left rear cover to save a little weight. I would remove it altogether but, of course, the clutch actuator is part of it.
 
Emlupi said:
I modified the left rear cover to save a little weight. I would remove it altogether but, of course, the clutch actuator is part of it.
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Everything is looking good, but it seems to me you could go this far with the cover. I believe the 2 JIS screws (okay, allens) would be enough to support the clutch lifter mechanism.

1739144062494.png
 
Yeah, you’re probably right. I can still change it. I’m thinking about following the radius of the curve and preserving the shift shaft hub like so.IMG_7371.jpeg
 
I'm chicken and would leave the upper rear bolt too. A 3 point triangle is much stiffer and there is opposing force from the cable stop as well as the lifter axis.
 
There’s so little material removed the only gain would be a speedier sprocket/gearing change, literally only grams for weight.
 
Yes, gearing changes are also a consideration.

IMG_5902.jpeg

Some riders have completely removed the cover and fabricated a clutch actuator for this purpose.
As far as only grams of weight is concerned, a few grams everywhere adds up. I have also gotten rid of mounting tabs, etc, from the frame for the same reason.
I have all the stuff that I took off the bike in a box. The weight of it all in total is pretty significant. There are race teams that drill out the centers of the bolt heads to save weight.
 
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Granted that these bikes have no power, but giving the chain an even more direct path to messing up your foot/boot in the name of style is a little silly.
 
oldjeep said:
Granted that these bikes have no power, but giving the chain an even more direct path to messing up your foot/boot in the name of style is a little silly.
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If you build a decent road race bike with solid new parts from the beginning, that's not likely to happen.
 
ballbearian said:
I'm surprised that the starter drive housing isn't amputated somehow.
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Not sure if that level of crankcase mods are legal for his class, but it would also be a project for a good aluminum welder. Believe me, I considered it for my drag bike engine but machinist Russ convinced me it wasn't worth the effort for the weight savings.
 
Emlupi said:
Some riders have completely removed the cover and fabricated a clutch actuator for this purpose.
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I've seen that done and was going to suggest it, but wondered if your class rules would allow it. Seems they do, so it could be a consideration. Doesn't look all that complex to fab up.
 
ancientdad said:
I've seen that done and was going to suggest it, but wondered if your class rules would allow it. Seems they do, so it could be a consideration. Doesn't look all that complex to fab up.
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Shifter shaft support is still there too.

A different mod topic is the outer swing arm pivot to frame cradle brackets. I'll wait for it.
 
ancientdad said:
If you build a decent road race bike with solid new parts from the beginning, that's not likely to happen.
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Yeah, I've broken an almost brand new 530 DID x ring chain - stuff happens with good parts. (Granted, this was on a 140hp bike)
 
oldjeep said:
Yeah, I've broken an almost brand new 530 DID x ring chain - stuff happens with good parts. (Granted, this was on a 140hp bike)
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Yep, his mostly stock 350 engine would be lucky to break a 420 chain when simply being ridden around a track, I'm sure he won't be powershifting either. Now at the drag strip doing holeshots, different story.
 
ballbearian said:
Shifter shaft support is still there too.

A different mod topic is the outer swing arm pivot to frame cradle brackets. I'll wait for it.
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I’m not sure what mods you’re referring to.
 
Emlupi said:
I’m not sure what mods you’re referring to.
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I was just looking at your reference pic in post #377 and noticing another approach there where the original outer bolt on plates were removed, but other mods were done. I just went back and quick reviewed this thread, including Stan Lippert's comments on frame mods. I don't think you've covered any swing arm, or pivot mods yet, so I'll wait. Seems like a great deal of variety in approaches there.
So much cool stuff in this thread. Thanks for sharing.
 
By the rules of the class, frame mods are not allowed. The only thing that can be added to the stock frame is non structural tabs and brackets used for mounting footpegs, steering dampers, etc. Same goes for the swingarm, stock only, no added bracing.
 
I'm a new, old guy here and have little interest racing bikes. But I find this build thread very interesting and full of great information. I really appreciate all the effort that has gone into photographing and documenting the process, and sharing it so others can learn. Its also great to see so many helpful people chiming in with suggestions and tips.

I'm interested in learning more about the 350 inner workings and this and other discussions have been very helpful. I'm very glad to have found this forum :)
Thanks
Steve
 
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ndnchf said:
I'm a new, old guy here and have little interest racing bikes. But I find this build thread very interesting and full of great information. I really appreciate all the effort that has gone into photographing and documenting the process, and sharing it so others can learn. Its also great to see so many helping people chiming in with suggestions and tips.
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It's what makes VHT different than most other forums. We all enjoy these bikes, and enjoy being supportive of others' projects as well. It helps make it more fun for everyone, with a little discovery and learning added to the mix.
ndnchf said:
I'm very glad to have found this forum :)
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Thanks, we're glad you're here and appreciate the same things we do.
 
Hey Emlupi

Great looking racer so far!

So, I see your socket heads on the stator cover have washers underneath and the socket heads on the clutch hsg cover do not. Any particular reason for the lack of washers on that cover? Just wondering. On my Scrambler I used washers under all socket heads because of smaller head diameter of the socket vs. OE screw. Weight reduction??

Also, with the use of ss fasteners...What is the general consensus of reduced torque values in conjunction with anti seize compound? When i did my scrambler back in 2012, I reduced the torques by 10% on those fasteners but in some threads here i've seen up 25% reduction. I'm in the process of a '71 cb350 going back together and defer to your vastly more experienced opinion.

Thanks,
Art
 
guzziart said:
Hey Emlupi

Great looking racer so far!

So, I see your socket heads on the stator cover have washers underneath and the socket heads on the clutch hsg cover do not. Any particular reason for the lack of washers on that cover? Just wondering. On my Scrambler I used washers under all socket heads because of smaller head diameter of the socket vs. OE screw. Weight reduction??

Also, with the use of ss fasteners...What is the general consensus of reduced torque values in conjunction with anti seize compound? When i did my scrambler back in 2012, I reduced the torques by 10% on those fasteners but in some threads here i've seen up 25% reduction. I'm in the process of a '71 cb350 going back together and defer to your vastly more experienced opinion.

Thanks,
Art
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Hi Art,
I didn’t use washers under any of the engine cover screws. If it looks that way it is only a trick of the light.
As for reduced torque on the stainless hardware I also used 10% reduction. These were values I took from a data table concerning stainless hardware in aluminum.
I appreciate your feedback but I wouldn’t consider my opinion to be vastly more experienced. There are many others here with much greater knowledge and experience on these bikes than me. I try to use sound mechanical techniques which I have learned over the years but there are plenty of details to which I will defer to the gurus here. Good luck with your project.
 
I’m waiting on a degree wheel and a few bits before I continue with the engine so I turned my attention to some chassis work. I painted the CB750 triple clamps and fitted the washer, seal, and bottom bearing.IMG_7390.jpeg

Here’s the 750 stem with the 350.IMG_7391.jpeg

I did some preliminary fitting on the frame and everything is looking good. You can see the amount of space that needed to be made up to make the 750 stem fit the 350.IMG_7392.jpegIMG_7393.jpeg
 
I also mocked up the front end with some old fork tubes, the clip-ons, and the fuel tank. Checking to make sure everything fits together without the bars hitting the tank at the stops. Plenty of room.IMG_7394.jpegIMG_7395.jpegIMG_7396.jpeg
 
I wire brushed and degreased the underside of the fuel tank. I had some POR-15 silver caliper paint on the shelf so I used it to undercoat the tank. This stuff works well and dries with a hard cerakote like finish. IMG_7397.jpeg
IMG_7398.jpeg
 
Nice call on the Por 15. I hadn’t thought about using that stuff for those areas that always seem to get chipped up. I usually just end up clearcoating the primer on the underside.
 
Thanks, I’m trying to use the stuff I have on hand to do some of the work. That’s why I painted the triple clamps with flat black paint. I had a couple of mostly used cans on the shelf so I put it to good use. I’ve used that POR-15 for a couple of other things and found that it does a good job.
I don’t intend to do a repaint on the fuel tank. I’m going to clean up the original paint and run it as is. It maintains the original vintage look and, if I happen to crash out on track, I won’t wipe out a fancy new paint job.
 
Nice. I did the same as there wasn't much left or the sketchy underside paint left on mine after cleaning either.
qyfW27Wt.jpg


I use an extra long fuel line on the cross over that stays above the frame for easy on/off of tank. If I need more reserve, I'll just lean the bike over far on the right.
 
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