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06 suzuki rm 250

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Hi im new to the foru, so go easy.

Well to start i have a 2006 suzuki rm 250 that i have just had a top end rebuild , barrel replated and new wisseco piston , now my problem is that after 20 minutes of test riding i took the expansion pipe off to take a look at the barrel to see if every thing is ok and what i found is that it has dark lines running up the cylinder now im not sure if this is the normale running in wear marks or do i have serios problem , I made sure every thing was clean even the crank chamber sorry dont know the corect name . Any help is welkom thanks Ian. :bonk:

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Is it on the cylinder or piston? Either way, it may just be carbon/oil that is harmless. Can you reach the lines to wipe them? Try to see if they wipe off. If they are deeper gouges then something is wrong and should be taken apart to find out what.

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Did you thouroughly clean the bore with soapy water then premix on a paper towel wiping till no more residue on the towel? If not, You might have carbon material left in the crosshatch in the bore from the honing process. This step is skipped by most. It eventually creates premature wear on the rings and piston, and can cause discoloration. I have no idea why replaters never recomend for people to do this. Sooner replates I guess.

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Hi well i took it apart again yesterday to find it is not a score line its more of a smooth dark marking probabaly 1-3 in width and it is all over the barrel not just at the back more so on the exhaust side of things. the lines are not in one place but all over as in on the right side , left side , exhaust side , and intake side of the barrel.

No i didnt wash it with soapy water i was never told but i had to rins it off due to fillings found and a putty type stuff was left in the ports so i thought id best rinse it off.Im guesing it was a rushed job as my power valve was getting jamed up from a small bur left , but i used a dimond file and took care of that problem and cleaned it staight away.

I took it to a loacle mx shop and the technision said i must take it back to where i had it replated and they must have it replated again so it was nothing i did wrong , but the wiseco piston they suplied has i larger clearance to the bore than the stock as i have the manual showing what the clearnce should be, stock clearance is 0.045-0.055 mm , and the wiseco piston clearance is 0.064mm so im guesing this is the probable cause to the damaged bore posibly.

Thanks for the replies :bonk:

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Is it damage or just black markings? Will it clean off? Try cleaning it with carb cleaner and wiping with a rag. If it cleans off, you will be ok. If not, then I would talk to the person who replated it. They may be able to clean it by re honing it if you can't get it clean. Clean off the piston and the cylinder good then wipe down with two stroke oil like bambam said. I believe Wiseco pistons have a little more clearance than stock because they expand a tiny bit more. That's what I was told by my machinist. When I redid my DRZ the piston was loose and I thought it was the wrong size, but he said that it was in spec for a forged piston.

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this happens more than people like to admit... You have to check that ring end gap every time along with the piston clearence

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I'm guessing you don't want to go out of your country to have it replated, but Powerseal here in the U.S. does excellent work. I friend of mine who has tons of old Hodakas and rebuilds motors for many ARHMA and ISDT vintage racers uses them and highly recommends. He says reboring is trickier than most think, if done too fast the tool heats up and makes the cylinder the correct size on one end but too big on the other, creating an inconsistent bore diameter.

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Hi thanks for the replys , well its dark markings and it wont clean off so im going to take it back next week friday as the company has been closed over christmas and new year. It sounds as if it could be what bambambennett said they never cleaned out the bore and didnt tel me to clean it out. But ill poast back to let you know what it was. thanks Ian

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Ok just been to get my barrel checked by the company who did the replate , and it turns out that the ring gap was too small so they rehoned and washed the barrel for me and gave me a new set of rings free of charge.

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