Bonneville America Forums Forums Technical Forums Performance Mods Jetting ( my turn )

So my current setup is as follows : 865 Carb, Specialty Spares short slash cut, Uni filter. Otherwise stock. I went with 130/42 and the bike starts great ( way better then with 40 pilots ) idle is good, but the pull and engine noise is really terrible at about 1/4 throttle. It seems to pick up good again past 1/2-3/4 ( haven't over done it either to cause possible damage ). Decel seems ok. Calculator says 128/42. I removed the top snorkel to give it a chance. It didin't do much difference ( or very very little ) wich should have, since the calculator goes with 129.5/42 with no top snorkel.

As an external factor, bike haven't ran in the last 5-6 month other then idle. Can old gas and a freshly re-oiled filter cause that kind of problem? I doubt it.

Otherwise, should I play with the Air/Fuel Screw. I didin't touch it yet, so I think the stock adjustment is 2.5 out?

Thanks

What do you mean by engine noise? skipping, spuddering, backfire? Old gas can screw things up(plug passages up and lose its octane)change out the gas and put some fresh stuff in with some carb cleaner in it.

I guess I could call that skipping. The engine revs up as the throttle is turned, but at some point( bout 1/4 ) the bike stops accellerating in it's regular way. It gives little hits here and there and manages to get at gear changing speed.

With those exhaust and intake mods, you will have to adjust the idle screws. This is a touchy feely affair. You need the bike at operating temperature. The screws should be adjusted individually. Some fellows short out a cylinder and adjust one running cylinder at a time. If you do it this way, make sure you ground the high tension lead securely to the block. I keep both cylinders running.

Adjustment - Simply turn one screw in until the engine begins to slow down then turn the screw out slowly noting an improvement in engine rpm, then continue to turn out until the engine slows down again. I then find the halfway point. Adjust the other side the same way. You might have to do this several times. You should then note the position of each screw by turning them in until they lightly seat counting the turns. The number of turns out each screw has doesn't necessarily have to be the same. Make sure you don't have any vacuum leaks in the intake system (check the squirrel condoms and intake manifold rubber boots). You should balance the carbs also after this is done.

Another item to address is the needle height. With stock needles you will probably need to shim each with 1 or 2 shims. This is a relatively quick process that is outlined in the tech vault or on Dinqua's website.