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  1. #1

    GP 1200 Electrical issue, or Crank bearing????

    I have a 2001 GP1200R that i just did a top end rebuild on. Got it from a friend - no spark and bad #3 cylinder. I re-sleeved the cylinder and replaced the CDI and rectifier. Finished up last week an fired it up. Ran it for 15 minutes in the river at 1/4 to 1/2 throttle to break in (running with extra oil in pre mix during break-in, blocked off the oil injection as part of the rebuild). Everything fine. Ran it one more time for 10 minutes and all was OK. Ran it today at igher throttle positions and had some issues. First, even before getting to high RPM, it seemed to be cutting in and out somewhat. Then after running about 1 mile downriver it bogged and killed. It restarted several times and continued to kill after running for short periods of time. Then it rn for about 1/2 mile, stopped snd would not turn over. after getting it back in the slip it wanted to turn over again, but the battery seemed weak. After 2 hours on the charger I fired it up and rode again. It killed after 10 minutes and would not turn over again. I placed the battery back oin the charger again, but it was indicating 95% charge. Yes - I cleaned and rebuilt the carbs when i did the top end. Any suggestions? Thanks for the help!!

  2. #2
    JKR1300's Avatar
    Join Date
    Jan 2006
    St Louis & 6mm LotO
    Sounds like you seized a cylinder. That's normally the case when it dies on you. Check the plugs, do a compression check

  3. #3
    I thought of that , but with taking it easy on break in and running 20:1 oil. I just did not think that was likely. Someone else mentioned possibly crcnk or rod bearing going out. I did not replace the crank with the rebuild, so (I hope not) could be that?? I guess I'll check compression and go from there. What would the plug look like if a cylinder siezed? Any other thoughts?

  4. #4
    +1 compression check then check charging using volt meter while running on trailer was the top end rebuild by choice or did that motor have a previous failure?

  5. #5
    Engine had a failure of the rear cylinder due to the oil line coming off. I had that cylinder sleeved , the Nikasil was damaged, and put fresh pistons/rings in the others. Also blocked off the oil injection. If it ends up being crank bearing - how difficult is it to replace the crank. I have done plenty of top ends, never a crank. Thanks.

  6. #6
    the replacement is not hard as bearings are allready on the crank.....just pulling it and electrical box pita

  7. #7
    Yamaha artisan Cutlass's Avatar
    Join Date
    Oct 2010
    Madison, WI, USA
    I can't see this being a crank problem. Definitely sounds more like a seized piston. But let us know how that compression test goes.

  8. #8
    Quote Originally Posted by troc View Post
    the replacement is not hard as bearings are allready on the crank.....just pulling it and electrical box pita
    I'm lost about the "Electrical Box" part of that response. Does the whole box need to be pulled to get the engine out?? I was able to do the top end with the engine in the bike, but it looked like the bottom end would have come out with the elec box in place?? Any special tools needed to pull or replace the crank or seals? Thanks for the help.

  9. #9
    Still have not had time for comp check - been repairing a chainsaw instead. Looking at the #3 plug and in the cylinder, appears to have piston damage. Spoke to Mike and he suggested rear crank seal may have gone out - sounds like a good possibility. Any thoughts?? Thanks again fo any help.

  10. #10
    Another question popped into my head while browsing threads just now. When I go in to re do cylinder #3, do I have to match that piston to the ones I just placed in the other two cylinders. Example - I just put Pro-X in all cylinders when I recently rebuilt, could I now go back with an OEM or Wiesco in #3, or do I need to make sure it is another Pro-X? Thanks.

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