Running lean??

[Jazzscot]

Found this on another forum and wondered how useful it would be???




Ok guys I hear a lot of this on this forum how do I tell if I'm running rich or lean, so I will let you in on a "Bike Technicians" old secret for tuning by ear.
I've been a bike tech now for 4 years and this was a technique I had to drag out of my favorite instructor at MMI.

Blip test:
1. Start by warming the bike up to normal operating temperature.
2. Blip the throttle up several thousand RPM's or up to redline if you so desire.

As it comes back down to idle one of three things will happen and these are the three results:

1. Upon return to idle it hangs. Where ever it hangs in the RPM's it is running lean. Even a slight hang just before returning to idle means it is running lean at idle.(Must return directly to idle without popping,lag, or hanging).
2. Upon return to idle it goes slightly past and below idle then returns back up to idle speed momentarily. This is a rich run condition.
3. It returns directly to idle w/o any lag, hesitation, or going below idle you have a perfect a/f mixture and run condition.


This system has been around for years and it is proven. It will work for carbed bikes or fuel injected bikes. Once you have your result make your adjustments and repeat process until you get result #3. Happy tuning.

[agentpineapple]

very interesting jazza..........

[Burner]

thanks for sharing - will try

[VTRDark]

I've read that somewhere before, useful info, but not quite as straight forward as it sounds. I believe that helps immensely with getting a the right mixture setting on the a/f screw alongside with your ear and hearing the revs drop or rise. But carbs are tricky things, your adjusting the mixture mainly according to the pilot jet size. This in turn affects the needle height setting as it overlaps into the pilot jet and the mains at the other end. You change one thing and it affects another. It's all about getting an even balance throughout.

(:-})

Something else I should add to this!

My bike used to fluctuate at idle and I used to have the idle speed set at 1400 so when it dropped it didn't cut out. Without changing any jet sizes, needle height etc. I left at original factory settings. I just stripped the carbs gave them a clean through with carb cleaner and put it all back together. Reset the the TPS to 500 and synced carbs. I noticed the drop in idle went and the bike ticked over at whatever I set it at. So It's always a good idea to check this as well as to not confuse a badly set TPS with mixture/fuel settings.