Thread: noisey gpr
10-26-2009, 07:51 PM #1
Alright I have 2 gprs I picked up late this year. an 04 and an 05. 04 has around 83 hrs and the 05 has about 50hrs. At idle the 05 has a tick but only at idle. If you rev it up at all the noise goes away. Is piston slap common of these or is something bigger going on. I was planning to send the head out to jim to get milled and thought it would be good to check things out. I pulled the head and noticed light scoring by the ports. I cant catch them with my finger nail but I was still suprised to see them there. The pistons seem loose in the bore as well but I am used to building turboed engines and not a pro on 2 strokes by any means so this could be normal. I attached a few pics of the cylinders. let me know if this is normal or not. Hopefully its not a problem but the 04 doesn't have any noise and it just sounds abnormal to me. It seems to soon to have to rebuild but I don't know the past life of the ski. Its runs great and has plenty of power but that damn tick at an idle. I want to catch any problem now before it turns into a big and expensive one.
10-26-2009, 07:55 PM #2
It is normal for the pistons to rock in the bore at TDC. Light scratches are normal too, as long as they are as you described.
The tick worries me, though. It could be 100 things, from loose exhaust bolts to whatever else. Or, it could be a piston rattling itself to death. I had this happen earlier this year and am just now getting the engine together. A compression check will not always show the damage, either. If the noise is truly unusual, I would pull the cylinders and do a good inspection.
10-26-2009, 08:14 PM #3
Do I replace rings if i pull the cyclinders? Its not a loose exhaust bolt or blown gasket. It's not that kind of sound. It sounds like bad piston slap or even a slight rod tick/nock. Deffently a metalic tick noise. but it goes away if I bump the throttle so it leads me away from a rod problem. It has me worried tho
10-26-2009, 08:39 PM #4
Might check the piston skirts. Looks like new rings and light hone may cure it. Very light home though (clean up). Compression test like Fullboogie said. If the rings are wore, the piston will start to mark. Look and see if the pistons are scoring were the cylinder marks are. I would turn the motor by hand if you pull the cylinders and listen for crank noise also and eccessive play in the rod shims.
10-26-2009, 08:39 PM #5
Well, new rings aren't going to fix the problem. Tear it down and get it fixed. Send it to Lowell or Woody.
10-26-2009, 08:49 PM #6
what kind of hone do you guys use? I didnt think you were suppose to hone nikasil cylinders.
10-26-2009, 08:51 PM #7
You can hone plated cylinders, were talking a "light" hone nothing more.
10-26-2009, 08:54 PM #8
do you use a 3 stone hone or one of the ball ones? Also should you replace rings if you remove the cylinders?
10-26-2009, 09:04 PM #9
Definatly get new rings!
10-26-2009, 09:13 PM #10
Alright I will pull the cylinders and see what the pistons look like. When you guys go big bore do you get the cylinders plated again?
Woody what does an average port job run?
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