Surge or something else?

[jeremybhm]

I did the barbarian mod +7, g2 throttle tube, idled up to 1200, and took all but the tiniest amount of slack out of the throttle cable. The throttle control is about 100 times better, and I'm having to learn how to ride the bike all over again. It's amazing how fast I became scared to twist the throttle transitioning off of the brake in a turn. Now it's smooth as silk, and I can take my delayed apex line with weight distributed properly. :yahoo: :yahoo: :yahoo:

The only wierd thing is that right after it's cranked, sometimes when you blip the throttle in neutral or with the clutch pulled in, the RPM's race up to almost 3K, then slowly come back down. I haven't noticed it after it's warmed up.

Not that it really matters, I'm just wondering what it might be. I think that I need to do another TBS since I changed the idle speed... Any other ideas?

 

[Fred H.]

When the RPM hangs after blipping the throttle, this is usually an indication of a lean condition. Since it sounds like it is happening when the engine is cold, it probably clears itself once it warms up a bit.

The general rule of thumb is that lean conditions will get better as the engine warms up, and rich conditions will get worse as it heats up. If the bike has many miles on it, you might want to go get a bottle of Chevron Techron fuel cleaner and run it through to make sure all the injectors are clean and unclogged.

You might also try dropping your idle back down to 1,100, as the high idle may also be playing into it. Since it only happens when cold, I wouldn't worry a whole lot about it tho, as long as it is starting fine.

 

[John_Dumke]

I think Fred hit the nail on the head.

I assume the bike is already warmed up enough to be past the high idle choke circuit. Is it more of a problem when it is cold out rather than hot? I also assume that you don't have a PCIII installed.

If all of the above is true, and Fred is correct, then it is just a lean condition. It shows how absolutely MARGINAL the stock jetting is on this bike. Without a PCIII, the bike simply doesn't run correctly. Specifically in two areas. On/off throttle control and lean surging at cruising speed.

It is night and day with a PCIII. With the PCIII you get a bike that was what the engineers envisioned. Without it the throttle is like an on/off switch between partial and no throttle.