Bonneville America Forums Forums Technical Forums Performance Mods What'd I do wrong? Advice, please

Ok, Gurus, I need a bit o' advice:

I'm getting a flat spot in acceleration that needs to go. It's most noticible in 3rd gear, between about 4-6k rmp. The engine just sort've sputters, and then kicks back in above 6k. It's most notable in a roll-on, and it's also there in other gears... I'm also still getting a little poppint on decel, but not very much.

I'm running TOR long pipes, 132/45 jets (I think?), 3 turns out on the air screws, 1 shim under the carb needles, stock airbox with the snorks taken out. (oh, and AI taken out)

Suggestions? Think it needs more air or gas?

--Jaeger

In that speed range, the slides are open a little. You might be able to cure that with a shim or two under the needles. Tbird Sport needles would also probably do wonders.

Well, I have one shim under the needles -- I have another. Maybe I'll see if I can drop that in this weekend. If that doesn't work, I'll see if I can score some upgraded needles.

So you think it's a lack of fuel, not air?

If the extra shim doesn't work for you then you might consider more air or less fuel.
I've got pretty much the same setup. 130/42, TBS needles, snorks out and bottom of airbox/filter drilled out.
I think I'm at peak performance now with long TOR's.
Won't even consider bigger jets unless I were to go with better exhaust and Freak.

Hrm. Ok, I need to check on the jets -- i may well have the 130/42 setup (used the setup recommended by Bella Corse, and it may well be what you're running), but I haven't mucked with the airbox too much; i.e., haven't drilled it. What i may do instead is get the new drop-in K&N and see how that does.

Actually, the smart thing to do would be to dyno the d*mn thing to get some solid numbers to work with.

--Jaeger

i have 130s & 45s w/ 2 shims w/ short tapered tors, ai gone, snork gone, bottom unifilter/airbox drilled and i like my setup...

cat

Jaeger, you are running too rich. try it without the shim and use an exhaust gas analyzer when you adjust yor jets.
Note: The analyzer wont be a hundred percent correct until you find a way to block or remove the crossover pipe.

Ah, hell. Now I hear I'm running too rich and too lean. Uh oh. Well, I tell y'all what: I'll go and

1) remember what precisely I rejetted at; and
2) with a dyno, what the malfunction is.

At this point I sort've suspect I'm running rich, given the popping on decel, but... What I have noticed, actually, is that I'm getting better milage! Hrm.

--Jaeger

I had a similar flat spot when I took the entire snorkel out. Put it back with just the top of it remaining and that flat spot went away.

Try useing Thruxton or TBS needles, these have cured the flat spots on a few bikes on this site.

I run Thruxton needles on mine and they are sweet, but i never had a flat spot to start with.

I had that exact problem and i also think the mids need enrichening via shims and/or needles. At one point i opened the airbox a bit more and thats when it happened. the cure was a shim.

Well, since we're havina wrench day here in NoVA tomorrow (hint hint, if anybody else wants to come play) I think I'll drop in that other shim and see how she does. Currently I only have one in there -- we'll see how two do. If that doesn't work, I'll see about obtaining the needle upgrades.

--Jaeger

Update: put in the second shim, and D*MN, what a DIFFERENCE.

Life is good with an even power band.

Next stop, K&N drop-in filter.

--Jaeger