Slight miss just off idle (2000 R)

[Benzmac]

I have a 2000.5 mille R. I have read over and over about problems. Well, I have had NONE.....until now. The bike runs perfectly from start up to full operational temp. It will idle at 1200 rpm all day and run perfectly.

I have noticed a SLIGHT glitch in drivability though. When at very low RPM, if I get on the gas a little, I will have a slight miss and a 'lean pop' from time to time.

Have you guys heard of this before? Is there an easy cure?

BTW. I have a Leo carbon high mout and 3 different chips.

[Bill in OKC]

I'll go out on a limb (a short one) and suggest a bit of techron or some type of fuel injector cleaner.

[King Atlas]

I know absolutely nothing about your problem or what might fix it. I'll just say that the guys at the dealership I bought from said 1400 was the ideal idle speed for my '03 Tuono. Could be completely unrelated or completely different than your bike.

[milleX2]

very recently there was a post with close symptoms and it was throttle sync. problem that stemmed from a vacuum leak. generally a lean missfire in his case due to a nipple plug missing. if nothing has recently been adjusted or changed look closely at all vacuum hoses or fitting, also look back for this previous post it may be helpful

[apriliarsvr]

Most off Idle problems can be fixed with TB balance. I would just do a complete "tune-up" beginning with valve check/adjust, plugs, CO check and finish it with TB sync. I've found that a balance more towards front cylinder worked better...ymmv

Chuck B
Arizona
00 Aprilia Mille "R" - Stage 1
99 K1200LTC

[Benzmac]

So I figured that after 10+ years of EFI tuning on turbo and supercharged motors, I could easily tune this one.

Here is what I have found so far.

The rear throttle body has a vacuum port that goes to the clutch AND the crank case vent system. This makes me wonder.??

Why would they port the clutch and the crank vent to the same rear cylinder and not seperate them??

When we tune enignes, we always start by getting rid of all of the vacuum leaks. You can't do this to the Mille R because the vent system will always make a little pressure thus creating a vacuum leak in the rear cylinder.

I now understand why people adjust the front a little stronger (or actually leaner) with the idle bleed screws. You won't need nearly as much bleed in the rear because of the vent line.

Any body?????