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Discussion Starter #1
the bike i bought two weeks ago wasn't idling well so i pulled off the carbs planning on cleaning them, maybe putting in new gaskets or whatever. i didn't expect this:

so now i need new carbs i guess.

unless someone has that flap/panel thingy chilling on the shelf on some busted up carburetor that they'd want to sell me?

assuming not... are cb350 carbs interchangeable with the 360s?

also what do you guys think about this:

http://cgi.ebay.com/ebaymotors/Mikuni-vm-32mm-carb-carburetor-Honda-CB350-CB360-CL350_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem587f149083QQitemZ380089176195QQptZMotorcyclesQ5fPartsQ5fAccessories

not that i'd be really excited about putting in carbs that cost almost as much as the bike itself but if it was gonna improve performance and make things less of a hassle you could probably talk me into it.
 

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You should have already heard about SFL and their 'correct' jetting. (190~200 main jet :()
Pay a little extra and get carbs that will work from a CB350 specialist, the difference in engine capacity (326cc vs 356cc)wont make enough difference to notice.
Decent ones rarely come up on eBay but a cheap set to rob parts out of should be pretty easy to find (or use and keep the ones you have for parts)
you may have to 'bite the bullet' if you want them 'quick'
350 carbs don't interchange with 360.

PJ
 

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You should have already heard about SFL and their 'correct' jetting. (190~200 main jet :()
Pay a little extra and get carbs that will work from a CB350 specialist, the difference in engine capacity (326cc vs 356cc)wont make enough difference to notice.
Decent ones rarely come up on eBay but a cheap set to rob parts out of should be pretty easy to find (or use and keep the ones you have for parts)
you may have to 'bite the bullet' if you want them 'quick'
350 carbs don't interchange with 360.

PJ
 

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A better question is where the missing parts are. Did the engine swallow one or both of the missing screws? I have seen them embedded in the piston crown or the head. That could be the cause of your poor running engine, too.

Ken
 

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Discussion Starter #5
the bike does fine once you're going ten miles an hour, it's just below that that there's a problem, so i'm hoping the engine is ok. <profuse knocking on wood>
different question:
the big gasket you get in a carb rebuild kit:


are you supposed to jam that into the float chamber? it looks too big...
 

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i really dont know if i believe you when you say it runs fine past 10mph... thats a pretty gnarly carb prpblem. really strange too for both screws to be gone. i'd get some
mikunis if you got some change to spend.
 

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Yep, the big 'O' ring is float bowl gasket.
Get some Permatex Indian Head gasket shellac compound, its how Honda originally 'glued' them in (kinda sucks you have to buy 4oz for 5 spots per carb)
Pilot jets/passages are probably still blocked
It's too unusual for both screws to fall out, someone probably removed them to clean carbs (or thought it was a 'performance' mod?)

PJ
 

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I feel like an idiot for selling my stock carbs. For 35 years old, they were MINT. The guy that bought them slapped em on his bike and said it has never ran better. Now im stuck kicking myself in the ass trying to figure out those retarded mikuni carbs from the so called properly jetted kit SFL sells.
 

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Discussion Starter #9
so correct me if i'm wrong because i really don't know much but...

the flap that's missing is what flips when you use the choke, in the normal position it's wide open so the the flap is extraneous. if i'm not using the choke then it shouldn't be a problem... right? or do i have it backwards?
 

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Don't use the choke. You'll be fine.

Just move somewhere warm.
 

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Discussion Starter #11
so people say trouble idling could be caused by a clogged jet. if that was the case would the jet be visibly clogged or are we talking some microscopic stuff here? cause mine looked fine... some of the gaskets definitely looked worn, i'm waiting on the rebuild kit to show up before i put the carbs back in.
 

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missing that butterfly is a problem. if you cant buy a replacement, make one. shouldnt be too hard.

to check your jets youd need to pull them out of the carburetors, which im not convinced youve done.

what ken says about the screws being embedded in your pistons is possible, but its more likely that they made it out of the chamber (if they ever made it in) and arent doing any damage, unless you hear some funky rattling noises, that is. you can pull the plugs and look around with a flashlight with the piston in question at TDC.

i dont know enough about these specific carburetors to say more.
 

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They are the butterflies for the choke (enrichment) circuit. As long as the butterflies on the other side of the carbs are there, the bike will run OK (it's not ideal, but it will run).
 

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All the jets?

There are more than 1 per carb

Anyway - just pull carbs into atoms- (everything that comes off should come off) and clean them well. Simple green is good but will take a while to dissolve the harder gunk. Carb cleaner spray is very toxic and nasty stuff.

Just seeing through a jet is not necessarily enough - you can find really thin copper wire its ok for scrubbing. Don't use anything too hard.

do you have stock air filter and snorkels on when trying to ruin the bike?
 

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Discussion Starter #16
yeah i know there's more than one jet. i got the rebuild kits so i'm not gonna bother cleaning the old ones. yes to the stock filters.
 

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If it were me (and it isn't), I would be concerned about the missing parts.
Here are some possible scenarios:

The butterfly broke at the little spring loaded flap and a piece got sucked into the engine doing some damage before it got spit out the exhaust bending both the intake and exhaust valves on its way in and out.

The screws backed out allowing the choke plate to hang up and the PO just pulled out the pieces and either found all the parts or they gut sucked through the engine.

The PO just pulled the missing choke plate for fun and threw the parts away just to mess with you.

the fact is that you have a running issue and you haven't done anything to try and diagnose the problem. Why are you throwing rebuild kits at your carbs?

My questions are these?
What is the compression and/or leakdown?
How are the idle passages in the carbs?
How are the points and timing?
How is the valve adjustment?

Any of these issues can lead to idle/low speed running issues.

Ken
 

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Discussion Starter #18
i'm putting in rebuild kits because some of the gaskets are brittle and i figured since i've already taken the carbs off and rebuild kits aren't too expensive i might as well.
i've got a friend of a friend who does motorcycle repair that i can probably hit up for help but removing and cleaning carbs is one of the few things i know how to do so i figured i'd try and do what i can before i bug him.
i'm not sure what the idle passages are... nothing looked clogged in the carbs but i cleaned them anyway.
compression... does putting your thumb over the sparkplug holes count as checking? i haven't even done this but i don't have any equipment for measuring compression.
points/timing/valve adjustment i do not know how to do.
i think maybe i didn't mention it but it's idling poorly because it's only idling on the left cylinder. i switched the spark plugs and it still idled only on the left cylinder. not sure if this rules out or points to any of the causes you listed.

i am concerned about the missing parts i'm just not sure what to do about it other than looking in the spark plug hole like spif300 mentioned.

anyway thanks everybody for the help.
 

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I don't want to be mean, but if you don't know what and where the idle passages are, then you don;t know ho to clean carbs either. The idle passages are in the carb bodies under the idle jets. They are very small and easily clogged, They are probably the cause of most idling problems, if the carbs have been sitting with old fuel in them.
Figuring out how to check and adjust your valves and timing isn't hard and needs to be done. Then get a compression guage and check the compression.

Ken
 

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It's gonna be hard to keep an old motorcycle running if you don't know how to gap points/set timing, adjust valves. Both are easy to do.

I'm not so sure the missing choke parts went thru the motor. I think it's just as likely an idiotic PO fucked around with the carbs & just neglected to replace the stuff. Those screws are kinda mushroomed on the backside after they're installed as a means to keep them from backing out and doing just what's been described, and it can be hard to thread them back in once you've removed them. But how would one know for sure?

I'd set the timing, valves, and do a thorough carb rebuild (since they're already off the bike anyway) and see if you can get the thing running properly. And make sure you have a good battery holding a charge. CB360 will drop a cylinder if the battery doesn't have a good charge.

Step 1: Buy a manual for your specific bike. All these processes (including carburetor rebuild) are explained in the manual.
 
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