Bonneville America Forums Forums Technical Forums Performance Mods carb tunin'

Hey all, quick question. I am usung 2 vacuum gages from an auto parts store to synch my carbs. At idle the indication is very eradic and hard to read, however when you advance the throttle the gage stabilizes and gives me a pretty steady needle. Is this a common way of tuning carbs? I.E. make your adjustment and then run the throttle up to see how its balancing out? I just purchased pipes, ai removal, jets, and cold air intake and wanted to check that everything is in good working order before i dig in.

most will tell you to sync at about 1200rpm...also if you meter the hose via a valve (aquarium air valves work well) or a crimp you can steady the needle some more...

the carbtune I use has a reducer in the hose.
prevents a bit of the jumping that way.

Whatever you use to reduce the vacuum, make sure they are the same in both tubes or you will never be balanced.

This includes using alligator clips or whatever to crimp the tubes...

I use little C-clamps on the tubing. Crank down just enough to stop the jumping. Almost completely closed. When done, switch hoses to double-check.

You are supposed to bump your idle up to about 1200 (I think) when balancing anyway. Try that, might smooth it out a little, but do it with the idle adjusment knob.

Bike only runs with the choke on. One cylinder does not want to start. I did have 130's in with 45 pilot and one shim. Removed shim, replace 45 with 40. Still does not want to run. What gives and where should I go from here?

check floats, balance carbs, make sure you have good spark, also make sure jets are clear and not plugged.

Frank

stock pilot is 42 I don't think 40 is a good idea.

When choke is on adds gas so going smaller on jet won't help.

When running on choke if still only on one cyl. I would look at the fireing then if thats OK a blockage like Frank said.

Finally got the thing running. I guess I went to 42 which is the stock pilot I had. There must have been junk in the lines somewhere. Just keep pulling the choke in and out while adding throttle. I guess the engine vacuum did the trick. Now I can't get the needle valves to work, doesn't seem to make much difference if they are one turn out or four. Oh well one thing at a time, it's beer thirty so will attack this new development tomorrow

Have you pulled your bowls to see if there is any crud in them?

Yea, I check bowls, even used some carb cleaner to clean out anything I could not see (which is a lot, seems the older I get the less I see). I will try to pull the needles out tomorrow to see what gives. I did notice a little gas leaking while trying to adjust. I get confused about the "o" rings, washer spring etc. Seems on one carb the sequence was washer, 0-ring spring. Every example I see is o-ring, washer then spring. Maybe I need a new o-ring, where would I get one?

Found the o-ring, off to the honda shop tomorrow, might as well change them when I clean up the needles.

I believe any Yamaha/Honda/Suzuki as well as Triumph shop would have them.

Here's from the manual:

Thanks for the help, will get on the bike tomorrow now have to go work on my website....

Cleaned the bowls again and checked the pilots, it seems that the factory installed 40 pilot. Also, check the arrangement of o-ring washer etc. On one carb the factory had the o-ring and washer reversed. I guess my bike was put together on Mon. after a long weekend.