1972 honda cb 350 cafe project

1283 Views 4 Replies 4 Participants Last post by miniman, Jul 23, 2020

Mondoh3

Discussion Starter · Jul 18, 2020

Hey guys news here!
I have a couple questions about this build I'm starting.

1: what newish front ends can I put on to get a disk brake or is that even worth it? The guy before me laid it down years ago and never used it again and it is beat to hell. Figured I'd update it.

2: The engine had its exhaust holes open to weather while the last owner had it. What should I do to clean inside and out? Chemicals I should buy. Methods I should use.

3: honestly, how hard is it to rebuild the entire engine. And what paperwork or videos do you guys know of to help guide me.

4: Thanks for helping me out!

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TrialsRider

· #2 · Jul 18, 2020

Rebuild a CB350 if you done one before, no problem.
If you are thinking a really old disc brake replacement, they are not a lot better then a well serviced drum brake. If you are thinking replacement front end then don't go overboard :/ and get the motor running first, or you might be flogging a dead horse.
When you are spending money to get the ignition and all the chains and valves inside the motor working; keep in mind your bike originally only cost about 800 bucks brand new. It was one of the cheapest motorcycles ever built, that was the major selling point.

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TrialsRider

· #3 · Jul 18, 2020

OEM Service Manual, download one for free off the internet, you are going to need it. Memorize the whole book before you take a wrench to the motor.
... and take photos so you remember how **** goes together after.

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Terrell Hunt

· #4 · Jul 23, 2020

Thanks for the tip, TrialsRider! I'll keep that in mind.

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miniman

· #5 · Jul 23, 2020

The bottom ends of these motors are good for pretty high mileages if the oil is changed regularly.
First thing is to check the compression (im betting its low) then
I would go for a full top end rebuild purely on how cheap these little twins are to rebuild.

Pull the top end which means you can check the big ends of the con rods for obvious play.
Get the barrels bored and honed to +.5mm.
Get some +.5mm pistons and rings (i have had pretty good success with cheap ebay pistons and genuine honda rings rebuilding a cb200 like this).
The cylinder head can then be rebuilt and with new valve stem oil seals.
Check the play in the valve guides and the cam journals for wear as these engines suffer from top end oil starvation. Fucked journals mean a second hand good condition head will be needed.
Grind the valves in.
Throw in a new cam chain and call it done.
All this is super cheap and should give you a good starting point.

The first thing before anything is to get the engine running properly So get that compression test done.
If by a miracle its good then you need to get a good spark from the ignition system (new coils, points and plugs will cost no more than £50 its almost rude not to) and a correctly metered fuel supply (clean & rebuild the carbs)

These bikes have such a huge amount of spares available they are a nice little cheap project to tinker with while drinking a couple of beers on a friday night.
Enjoy

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