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  1. #1

    GP1200R banging noise after rebuild? Yay!!

    So....I just rebuilt the motor in an 02 GP1200R after seizing #1. Took everything apart down to the crank, blew out all the bearings, etc. I didn't find any metal in the bottom end. The crank bearings appeared tight for the most part. I also pressure tested it to make sure that was good after reassembly. I fired it for the first time last night. It started right up no problem, but has an intermittent banging noise at idle. It doesn't make the noise when under a steady rpm above idle, just occasionally at idle. It is a loud metal to metal banging noise. This is also while on the trailer. I haven't water tested it yet.

    I thought it may have been piston slap due to excessive clearance. I pulled the head off tonight and everything looks fine. No scoring, pistons are tight in the bore, everything rotates smoothly by hand. Has anyone else ever experienced something similar to this? Thanks to anyone who can help.


  2. #2

  3. #3
    no one has experienced this?

  4. #4
    banshee350racer's Avatar
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    ya its nature of the beast, what's your compression?

  5. #5
    TX21's Avatar
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    My ski did that last year. I had an air leak but not sure if it was related. Kinda think it was, mabey a lean backfire? Does your ski hang up a bit at high rpm on the trailer? Like if you blip the throttle does it come right back down?

  6. #6
    I have a cheap Harbor Freight gauge, but they were at 105 across the board. Keep in mind also that the rings haven't set yet with only 5 mins run time on the trailer. Otherwise the ski seems to be running great. Very responsive with the trottle. And yes, it comes right down when let off the throttle. It doesn't make the noise until it settles back down to idle. I would think if it was a lean backfire, it would pop after being goosed? I'm leaning toward possibly a wrist pin/rod bearing issue as these are all used parts.

  7. #7
    Do you guys think a lack of thrust washers on the wrist pin could cause this? When I took the engine apart, I know at least one piston didn't have thrust washers on it. The replacement parts that I put in there did, but I know I have at least one without thrust washers still. I just figured maybe it was a different design? I looked at the microfiche a second time and see it's supposed to have the thrust washers.

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  9. #9
    TX21's Avatar
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    Quote Originally Posted by mi11ertyme26 View Post
    Do you guys think a lack of thrust washers on the wrist pin could cause this? When I took the engine apart, I know at least one piston didn't have thrust washers on it. The replacement parts that I put in there did, but I know I have at least one without thrust washers still. I just figured maybe it was a different design? I looked at the microfiche a second time and see it's supposed to have the thrust washers.
    I can't remeber if I have washers on my wrist pins or not. Do you have the full cage wrist pin bearings? Or the loose needle bearings? If you have the full cage ones I think you don't use the washers, but the loose needle bearings you need the washers.

  10. #10
    I believe they are all factory yamaha bearings

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