Bonneville America Forums Forums Technical Forums Performance Mods Carb Advice requested

I am having some trouble dialing in my carbs and wanted to see what type of advice the kind folks here could offer.

My TBA:
AI Removed
Freak installed
150 Mains
currently at 3.5 turns
Stock needles - no shims
TOR Shorties with NO baffles-wide open other than some edges inside

Now, the challenge. I have been trying to dial things in with the carb screws and have gotten close, but still can't seem to get to a point where I have little gurgling or popping. I feel that I am in between gurgling and popping, but can't seem to reduce both further....adjusting the screws seems to introduce more gurgling or more popping.

It's not bad by any means, but still trying to get it dialed in. Prior to the Freak install (everything else the same), I had 120 mains, 1 shim per needle, and was at 4.5 turns....no gurgling and no popping/backfire.

Suggestions?

Thanks,
Steven

45 pilots?

yea give 45's a try. best way to dial it in would be a dyno with a sniffer

Frank

I think they are still the stock pilots. My dealer had done some work when I first got the bike and he doesn't think that he changed the pilots. I have not changed them. That would make them 42?

Steven

Yup, the stock pilots are 42.

Sounds like 45 Pilots are the next step to take. Just ordered a pair and will try them as soon as they arrive. Thanks for the quick responses and still interested in any other opinions/suggestions.

Steven

I live at about same elev. as you, I have
Ai. removed
Freak
Bub exaust
Air screws 2.5 turns out
2 shims, stock needles
165 main. 45 pilot jets
In my bike I had poping (dead spot) at mid range shims fixed it

I have the same set up as you except I'm using Bubs and am at 200 ft above sea level. I ran 45's for a while but found the 42's with two shims on the needles worked a little better for me. Try a couple of shims and don't forget to drill out your slide. That gives the bike a little more snap.

"TOR Shorties with NO baffles-wide open other than some edges inside"
If this is true, and you have straight through pipes, you will never get those carbs dialed in without major motor motifications. You need a certain amount of back pressure to get anything to run right.

Try turning the idle screws in to about 2 1/2 turns from full closed. Starting from that point, if you can get the idle speed to peak (probably around 3 - 3 3/4 turns) and then drop off as you keep backing the screw out, your pilots are probably about right. If it peaks at around 1 1/2 - 2 turns, the pilots are probably a bit big. If it doesn't go rich enough to slow the idle significantly by 4 - 4 1/2 turns, the pilots may be too small.
For this test to mean anything, you have to adjust the idle speed down to normal if it speeds up to more than 1100.

Another thing too, if the float level is off, it will make perfect jets look too big or too small, so that would be a good starting point.

Thanks Greybeard. This sounds like an interesting way to get a feel for the pilot jet size. I have new jets on the way, but I'll try this to see if the current 42's pass or fail this test.

Steven

Steven, before going to the effort of replacing your stock pilot jets, try a little test first. Run the bike at about 2000 rpms (thats about 22mph in 1st, 32 in 2nd, or 40 in 3rd gear for a BA with stock 17 tooth sprocket) and see if that gets any surging, hesitation, etc... I believe that was the recommendation of Dinqua, and I tried it, and mine felt fine (I have gutted airbox, 130 mains, 42 pilots, TBS Needles with 1 shim (I think, maybe no shims, have to check), UniFilter, drilled slides, and Bubs at 600 ft elevation, oh and of course no AI) Getting to the Pilot jets is no easy feat so if it isn't necessary, don't do it. I have yet to ever eliminate some popping, tried RTV, reinstalling the Bubs, you name it, and I actually like some popping and gurgling. It also did this stock from the factory though with and without AI, so I think it is the nature of the beast and accept it as such. And to say that drilling the slides gives a little "snap", well, we'll say that is an understatement.

As an update, I have now installed the new 45 pilot jets and also drilled out the sliders while I had the carbs pulled. I still have a small amount of final tweaking to do, but I can say that the new pilots made a noticable difference. I am 3 turns and feel that the popping/gurgling is all but gone.

I going out for another ride today (forecast is in the 90's here in Texas). I'll continue to do a little more tweaking of the carb screws to see if I can get it completely dialed in.

The throttle response did improve with drilling out the sliders...now, I'm trying to find references to the science behind why it provides improvement. Any pointers to other posts or sites that discuss are appreciated.

Another big thanks to all that contribute on this site, my knowledge of my bike has increased dramatically as a direct result of this site....always very helpful.

Steven