BS34 Air Leak Locations ?!?! >(

Got a set of BS34s that have developed an air leak on the 2nd cylinder/carb.
Not the usual location (carb to engine, or airbox boots), somewheres different.
Compression is 147, valves .003 intake, .004 exhaust, rest of engine equally sound.

The leak is very small and only really detectable at, or just off idle (as usual duh!) :silly:
I can get all other carbs perfect at around 1.8 - 2 turns out, but this carb needs to be about 3.5 - 3.75 turns out to achieve best idle mixture (when compared to others) through a colortune plug.

Not detectable with propane or WD40 or the like, and no reeming/destruction of the air bleeds/jets has taken place... no visible loss of parts or damage anywhere. I have swapped mixture needles, pilots, washers, orings, etc - STILL NO DAMNED EFFECT!... ehem sorry

WHA!!??

Anyone with a new thought... more insight would be greatly appreciated.

Thanks!

wg.com

#2 on my J bike is where the vacuum line for the petcock fits.I am running a Pingel so dont use the vac port and have it plugged.Have u checked the vac port? How about an exhaust gasket leak on the opposite side of the mota?bj

That helps. Some website about money lending...

If you mean wiredgeorge, then yeah, I suppose he could respond to an email in august some time... :laugh:

hocbj23 wrote: #2 on my J bike is where the vacuum line for the petcock fits.I am running a Pingel so dont use the vac port and have it plugged.Have u checked the vac port? How about an exhaust gasket leak on the opposite side of the mota?bj

No exhaust leak, and I'm running a non-vac setup petcock as well. All vacuum nips are capped.

Thanks.

TeK9iNe wrote: That helps. Some website about money lending...

If you mean wiredgeorge, then yeah, I suppose he could respond to an email in august some time... :laugh:

ok wgcarbs.com
or magnum fours performance in vendor directory,ask Otto

Maybe the rubber boot for the choke rod? Although I haven't detected any air leaks from that location, it looks like that is a likely area where an air leak could start. My BS34's seriously need these boots replaced.
Best of luck, and let us all know if you find the source of your air leak.
Grant.

Slide set higher? Stronger air flow past slide = more fuel needed. Got a Manometer?
O-ring @ mix screw in good shape?
I spray a bit of carb cleaner around for air leaks.

Grantl wrote: Maybe the rubber boot for the choke rod? Although I haven't detected any air leaks from that location, it looks like that is a likely area where an air leak could start. My BS34's seriously need these boots replaced.
Best of luck, and let us all know if you find the source of your air leak.
Grant.

I've run without them, without any ill effects... I guess the machined plunger and pad works fine - I suspect they are just dust boots.

Thanks.

Motor Head wrote: Slide set higher? Stronger air flow past slide = more fuel needed. Got a Manometer?
O-ring @ mix screw in good shape?
I spray a bit of carb cleaner around for air leaks.

The BS34s are CV carbs with throttle butterflys, but your thought is correct (...butterfly opened to much). I have the carbtune pro 2 manometer I use in conjunction with a colortune plug. With the carbs perfectly synced, (can just barely slide a paper test strip under all four at idle) the result is the same with the colortune plug, or using old method with the ear.

I have found that the sync settings do affect the mixture slightly, but this is a bit more than usual. No results as of yet with spraying stuff around - external leak seems non existant or undetectable.

Thanks.

Oh I Messed that up, I did mean the throttle, but the shaft that the butterfly sits on. It has seals where it goes through the carb body, on the outside. Last time I tried to get those little seals it was a huge PITA.
Just too many brews last night, :blink:

Motor Head wrote: Oh I Messed that up, I did mean the throttle, but the shaft that the butterfly sits on. It has seals where it goes through the carb body, on the outside. Last time I tried to get those little seals it was a huge PITA.
Just too many brews last night, :blink:

Right, i see what you're saying. Well I guess I could try to spray things around again and look more carefully. I havn't had much luck with the spray and pray so far, but soaking those area might prove to be the ticket.