Bench Sync CV 32's

Did a search for this and as with all other searches i have done found sweet FA,
Have a spare set of Keihin CVK32's ready to put on as my others are being a pain the ass again,
Been dealing with this shit for a couple of years now and just about to throw a match in the tank,
Carbies are only problem - (bike runs perfectly) - all is new in problem ones - float needles, gaskets, needles,
They are great for months and then start to weep - No2 carb is the culprit,
Fuel tap passes all tests - pulled it apart and fine and no fuel weep or leak when tank is removed , Changed bowl and gasket on 2 several times - same. Float level spot on in all carbs,a little under spec mm or so,I did put in some fuel from another petrol brand (Caltex) last week - i always go to the same service station at home (Shell) anyone had a similar problem ?
Tried other carbs and dont appear to be any problems - yet ! but the sync is way out - always used manometers for this so can anyone advise as to the correct procedure to bench sync Keihin CVK32
I gave it a shot but dont seem to be able to get them close as they should be, I know some tricks but i never learnt this one - have spent farking days not hours on this one and it is getting a bit old and farking depressing,
Any help much appreciated !! Mick.

MORE INFO - i know my way around the Keihins - do i set the butteflies so they are all even and near closed just about covering the pilot hole . I can get 1 , 3 and 4 the same with hole almost out of sight but cant get 3 near them - no adjustment left - tried several times to back it off and start again but same every time.

Start over. Lower the idle set screw to the bottom. Set #3 at spec. then adjust the others to match. #3 is the lead carb on my Miks. I set them the same as #3 and vacuum sync from there. CV carbs are a pain in the ass. Good on gas, altitude changes and emissions but I like VM's better.
Steve

The carb pilot circuit should be as-new clean and clear.

No gasoline should be allowed into the freshly cleaned carbs without first passing through a good aftermarket in-line fuel filter.

Here's an illustration that might be helpful toward assuring that the orifices are clear where the pilot circuit exits into the carb bore.








Good Fortune!

Thanks Fellas
Steve - Do you mean loosen them off almost completely ?
Checked out some you tube stuff - Keihins - same as my old Honda had they used #2 as a base and some other method which looked crap using 2 drill bits the same size.- WSM is useless
So i am not sure which is base carb on mine . i will give it a shot with #3 - was trying it with #1 yesterday.Fuk knows - i dont.Net search gave nothing.Been using CV carbs for 32 years - never had a problem till now.
Patton - carbs could not be any cleaner - carb cleaner , compressor etc.Spent time doing them thoroughly.
Only thing i havnt checked on weepy carbs - (it is not dripping - just forms a thin coating on bottom of #2 bowl after a few hundred km and getting worse) is main fuel line orings between #2 and #3 but it is great for a while then does this - especially in hot weather- always use a good inline filter.
Heres to another day of swearing like a farking trooper - i have great patience for some things but not when there is no logical explanation for the problem and i have spent many hours with no progress.Thankyou, Mick.

One other thing - i am suspect about what is in the fuel at some stations - every time it does this i pull the bowl from the weeper and the gasket just about falls out - new oem rubber gaskets - just doesnt stay where it is supposed to- someone suggested super glue but i wanna be able to get it out if i need to- is there anything i could use just to spot each corner of gasket so the bastard stays there, Mick.
I always reinstall gaskets in bowl from underneath so it cant go anywhere.

Mick, I was suggesting #3 because it wouldn't adjust like the other ones. Make them all the same. The drill bit is to have them open the same tolerance amount. If you can get them even, then sync them with your gauges. The float levels should be just below the mark you are useing. In hot weather gas will expand as well as the gaskets. Check the vents, tank and carbs. Try some grease as a sealent. Done it for years. Hang in there.
Steve

Zephyrrider wrote: ...Carbies are only problem - (bike runs perfectly)...They are great for months and then start to weep - No2 carb is the culprit...Float level spot on in all carbs,a little under spec mm or so....

Hoping that Float level means fuel level as per the clear-tube test.

Other than sync difficulty, is the only unresolved issue being that carb #2 starts to weep after a few months?

Is it possible that the bowl ears may be slightly tweaked due to over-tightening, whereby the bowl is not fully seating against the carb body?

Good Fortune!

Could be the gas is attacking the rubber gaskets. Don't know where to go there.
Steve

swest wrote: Could be the gas is attacking the rubber gaskets.
Steve

It can be a real PITA trying to find the source of weeping gas.
The bowl gaskets in my Keihin CV34s are really big rubber O rings and are shaped like the outline of the gable end of a house. They fit in a groove in the float bowl but alcohol in the gas - usually about 10% here - makes them swell. If I want to reuse them I have to throw them in the freezer for half an hour and then fit them perfectly and quickly otherwise they swell right up again not fit properly and the bowl will weep.
The last time I had weeping gas in the carb area it was from one side of the fuel T and I'm sure the alcohol has f****d that O ring. Rather than tear apart the carbs to replace the O ring I drained the carbs and put a bead of JB Weld around the T fitting where it enters carbs 2 and 3. My T fitting is no longer movable but I dont really mind as long as fuel gets there without leaking or weeping

Seems to me that rubber eating gasoline would munch on all the float bowl gaskets and not just the carb #2 float bowl gasket.

If the weeping is from a deteriorated o'ring on the fuel pipe (tee fitting) or other hose connecting float bowls, it might be tightened by wrapping with teflon tape, or perhaps replaced with a more fuel resistant o'ring such as viton.

Where teflon tape is used on a fuel line fitting, the yellow color tape is reportedly more gasoline resistant than the white color tape.

Mentioning the tape option because some stock carbs have fuel pipes designed with a permanent raised area instead of an o'ring where pressed into the carb.

Good Fortune!

Steve - #3 is the trick - all very close now - was never gonna get anywhere using 1 as a base.
My carbs that run spot on but leak have been synced many times over years with Morgan Carbtune .
Pic is crap but you get the idea .

Dont seem to be able to get spare set bench sync the same but as long as they are even i can go from there ?
Patton - Yep float level = fuel level.Tried several different bowl/gasket combinations with same result every time on weeping carb.I always tighten just firmly and never overtighten.Brain is a bit fried from last day or so and of course if the suspect crap fuel was swelling gaskets they should all be weeping but 1, 3 and 4 are dry outside.
JR - they sound a similar shape gasket - fits in the groove.I just let them sit and air dry for an hour or so and they usually go back in no worries.I will pull that main fuel line between #2 and #3 and check out orings - easy job.
Can a bad petcock diaphragm do this sort of stuff - good for a while then bad - i wouldnt have thought so and guts of petcock is all good. I have a shitload of spare plastic fuel lines and orings so here i go again
Thanks everyone

So you have them even? Dial them in. I use grease on all O rings and used gaskets. Water proof grease it good to have on hand too. It will help seal if just a light coat is used and the excess will desolve in gas.
Steve