Originally Posted by
onewalker
Hey All,
Recently lost cylinder 2 and decided to have both 1 and 2 rebuilt. The tech different pistons that I guess do better under heat. He also had all fuel injectors rebuilt. He has done this same job on several Yamaha's with good success including for my buddy 2 years ago.
I had several issues during and after the break in hours. REALLY rough idle and running overall, burned thru a ton of gas and oil in 2 hours of part of the break-in time, HORRIBLE hole shot (seemed like it took a minute to get on pad) and lost top end speed.
* so, I adjusted the idle and I'm good there now
* replaced plugs since all were fouled which I figured was the cause of all the other problems. (fouled from the heavy lube used for rebuild I guess)
* felt like a shimmy, prop slip or plug missing while running - even after replacing all plugs (kind of felt like running thru current eddy - was on CA Delta with strong current but never felt that before the job was done?)
* Top end speed loss - still not corrected.
* compression matched in both new cylinders at 110 and all other cylinders were at 116-117
Took it back to the tech and he hooked it up to the computer. He said it sounded like a possible coil problem... but, he tested all the coils, injectors and basically checked all motor stats and said EVERYTHING looked good. He suggested to change props (mine had some damaged blades - but was that way prior to losing cylinder), he also adjusted my hot foot (maybe the cable had been stretched) and he said that he noticed my motor bushings were worn and he thinks I may have lost some trim range.
So, here's where I'm at as of running it yesterday on Folsom Lake (CA):
* idles good in neutral and in gear (after adjustment)
* swapped props to non damaged (same prop - Yamaha Ti 25)
* very good hole shot
* very good mid range power
* NO top end - can't get over 60 MPH (5400 RPM max)
* back to normal fuel and oil consumption (been using Lucas oil products)
Anybody ever had the same problem or any Yamaha mechanics out there have any idea's of what's going on?
Also, if I have lost say 1/4 inch of trim range, would this be enough to lose that much top in speed?
Thanks much for any thoughts
Randy