I'm looking for my horsepower and rpms that used to reside above 5400 rpm. They are both missing after a 50 mile ride through hurricane Ernesto.... It was a gradual decline but never the less prior to this ride I had no problem bumbing up against the rev limiter. The weekend started with a freshly cleaned K&N. It wasn't caked but I am wondering if it should have had more oil on it the last time. This time I was generous with the oil. The temperature was 50's and 60's and well "hurricaning". No visible signs that I injested H2O.

When I let off the gas from a full throttle run the motor sounds like it goes out for a moment and I mentioned that it breaks up about 5400 rpm. It has always back fired a little when letting off or EBS. I can't say it got worse.

I rarley get to ride 50 miles at a shot and the bike seemed to be enjoying the stretch (Lots of WOT) until the last 10 miles... runs fine at idle and in the 4K range.

Based on the carbon or lack there of at the end of the pipe I believe is has been running leaner since I got it but I hoped it was do to some careful snorkel modifications. Since from the factory they were all shipped real rich.

Any ideas?

 

Adjust your valves lately?

 

if its back firing letting off, chances are you running rich from to much oil in the air filter. i know my buds bf 750 will do the same thing. your on the throttle and let off and the build up of extra gas is ignited causing the back fire.

 

popping when letting off the throttle is usually indicative of a lean condition.

 

well most of the time i would agree w/ on that one. but thru some factory reserch the front carb is running w/ a rich condtion in this case. the plug in my opinion is still the best indercator of the lean condtion. just pull the plug and take a peak.

 

One thing you may want to do is take the carb apart and clean it. In both my brother's and my buddies 04 YFZ's, the carbs got gunked up from running the newer gas with the extra ethanol.










I was just saying usually that's the case. With your buddies over oiled air filter, I can see how that would choke the motor out and create a mixture too rich to burn and sending un-burnt fuel into the hot exhaust.

 

Thanks everyone.... I'm going with to much oil on the filter judging by the fouled plugs. Haven't got a chance to do the WOT test, but I think the new plugs will do it.

Thanks again.