I took my bike out for the first time today (illinois) and over the winter I did a motor swap... I have a 1996 YZF600 and lost 2nd gear due to clutchless shifts I was told... (shifter fork bent or broke.. dunno). So my friend layed down his 99 YZF600R with 4,000 miles on it and gave me the whole bike.. I swaped out the wire harness, motor, and guage cluster. Winter went by and now I took it out, first gear sounds like it will wind all the way out 2nd.. maybe, but in 3rd and up... you can wrap the throttle, it will get to a certain speed/rpm and just stop... sounds like rev limiter is at 8,000 or something... just won't go! any ideas?

 

update: in 2nd on up... it will never hit rev limiter it stops around 11,000 and just kinda boggs, top speed is like 75mph on the bike.... I went to the dealership and they said the carbs need cleaning, thats it... and it would be $400.... I've taken the carbs out myself before.. should I atempt cleaning them myself???????? Do you really think its the carbs?

 

is the air cleaner and exhaust the same as it was on the 99? it sounds like it's running rich you might have to re-jet

 

I'm havin about the same problem with my F4. I was told it may be a couple of things....the one technician, who is nationally ranked (whatever that means) said the cams need adjusted...while i was also told it could need rejetted

 

I had kinda the same problem. Whenever I hit like 85 it was like I hit a wall and the bike just wouldn't go. Then I would grab some more throttle and it would take off again. TUrns out one of my carbs was running too lean while another one was running too rich, so I just had to get them synchronized. But if this is the case you can hear it at idle like its missing. But it sounds like your just isn't getting enough fuel. I would check the pump to make sure its still working good. I would also check the plugs and the usual stuff. Mine is a 97 with about 11k on it now, and it had been sitting up for 6 months(previous owner) and I pulled the carbs and they were still clean. It might also be the cam timing I guess. Sorry, I'm still not too familiar with working on bikes, only cars. You just gotta go sown the list and check/test everything.

P.S. The Honda dealership around here told me the same thing, the carbs are dirty and needed to be cleaned. Told me $315. Took me 2 hours and $5 worth of carb cleaner and they didn't even really need to be cleaned. Also, when you swapped motors did you swap out the ecu?

 

Is the throttle cables the same length?

 

i was having the same problem and just got my bike back from getting it fixed....for me the problem was with the cams....the compression wasn't right...so they adjusted it and it runs great now...i hope that helps

 

Hey I'm with Joneser!!
Just came from the bike shop today, a friend had a bike that he had taken apart for a few months for cosmetic work. Guess what happened, the dummy criss/crossed two electrical connectors that looked identical while reassembling the bike. No need to run the whole story by ya but the bike never started and there was all sorts of elecrical malfunctions.
Just thought this might be some good food for thought as it is always easy to overlook simple things!!!!
In my experience, there's always less headaches when you start with the simple things. Start with the Airbox, cables,ect..

 

yea i was going to say that i fixed a 98 gs the other day and they had the 2 plugins the same and they were backwards it happens all the time and somtimesit can be the ecu start it up and tap test it