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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: ENGINEERLARS on August 18, 2019, 01:03:17 PM

Title: Bike running lean on low revs & load
Post by: ENGINEERLARS on August 18, 2019, 01:03:17 PM
Hi
Got a problem, bike (FJ110) is running lean whatever I do. What can be the problem?
I have:
- right jets (pilot 40, main jet 115) FJ110 E47
- cleaned the carbs thoroughly (including small channels) with special attention on pilot jets
- new inlet rubber = no air leak
- running with original filter box and new air filter
- trying to adjust pilot screw with help of Carbotune and can't get flame to turn yellow
- tried to run with pilot screw open 3.0, 3.5, 4.0, 4.5 and some setting in between
- synchronized carbs thoroughly
- plugs really white

Bike is running good on throttle more than 25% but shitty on low revs and loads (sitting still and only revving motor sound good).     

Is there any good ideas what might be my problems?

Grateful for any suggestions
Title: Re: Bike running lean on low revs & load
Post by: racerrad8 on August 18, 2019, 06:07:52 PM
air bleed size?
flat or curved slides?
main jet needle?
Slides drilled?
Stock Slide Springs?

Since the mixture is not changing that indicates the idle circuit is plugged/restricted.

But, the above questions also play into the equation.

Randy - RPM
Title: Re: Bike running lean on low revs & load
Post by: ENGINEERLARS on August 21, 2019, 01:10:17 AM
Hi Randy
Thanks for the advice, I will go over the pilot circuit once more to see if i can mitigate the problem.
BR
Title: Re: Bike running lean on low revs & load
Post by: roverfj1200 on August 21, 2019, 03:22:29 AM
Sounds like a weak fuel pump..