June 1, 200620 yr Hi all I've got a 02 280 pro that I purchased used a year ago. Since I've had it, it seems to have a fair amount of top end noise at idle (Piston slap) The bike runs great and has good compression. I'm not sure if its something I should worry about....I don't have another to compare it too but my sons Scorpa doesn't have the rattle at idle. There isn't a dealer in my area that could listen to it. I did talk to a dealer in another state and he stated he hasn't had to replace a piston or cyclinder on any of his pro 280's. Just rings. On motorcross bikes I've owned in the past, the solution has most often been piston replacement or rebore and piston replacement. I know the GG's have matched piston and cylinders in a-d flavors. A very expensive affair (Almost $500.00 to replace the matched set with old cyclinder trade in. Has anyone had to do this to their bikes? Appreciate any info you all could give me.
June 1, 200620 yr Does the noise get noticabley less when the clutch is pulled in? As these bikes normally have rattley clutch fingers
June 1, 200620 yr Author It's not the clutch.......I'm quite familiar with piston slap noise........also, moto cross bikes with power valves make a similar rattle at idle and goes away with throttle..........returns as engine rev's back down toward idle.
June 2, 200620 yr Author I'll give it a try and see if it indeed is the clutch. It doesn't sound like it is coming from there though.........thanks for the input!
June 19, 200620 yr Author Well guys Took it apart and the barrel and piston where *****. It looked like it had siezed at one point (I'm the second owner) the piston was severly scored, blow by everywhere below the piston rings. The bore coating burned through and piston cylinder wall clearance way to much......Sent the barrel off for trade on recoated one with fitted piston. Hope to have it back together within a week or so. Does anyone know how much anti-freeze it takes when refilling radiator? Thanks again for all you input.
June 19, 200620 yr when i got my gasser 125 about six months ago no one had done a thing to itso i thought i better change the coolant to make sure it didnt freeze in the winter! i bought rock oil kool it is premixed with anti freeze in it! If i remember correctly when you take the cap off there is a minimum and maximum line or i just filled it up to where it was before i drained it! Hope this helps you out and you get motoring again soon! super smashing great Cheers sean
June 30, 200620 yr Author Hi guys The top end is done and it runs and sounds like new again! Thanks for all your input....and the grease on the o-rings was invaluable advice. One thing I did run into, I had to run a tap in the head bolt holes. There was so much plating build-up in the threads that I couldn't get the bolts in. So for anyone else using a replated barrel, get yourself a 6mmx1 tap and chase the threads. Cheers Cris
July 21, 200620 yr Author I'm in the US so I just swapped out my cylinder with a replated one. GG USA has them in stock fitted with the proper size piston. Seemed like the easiest route and it worked out well.
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