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17
Joined
12/6/2016
Location
AU
Hey guys, just building up my 05 rm125
It was oozing oil out the exhaust prior to rebuild so was assuming it was running too rich. Just after a second opinion on spark plug attached and piston
Also the ring around the piston was loose, should it be loose?
Cheers!
It was oozing oil out the exhaust prior to rebuild so was assuming it was running too rich. Just after a second opinion on spark plug attached and piston
Also the ring around the piston was loose, should it be loose?
Cheers!
The piston shows clear signs of blow by. Either worn ring or poor fit to the cylinder.
I would like to see a photo of the underside of the piston as I suspect a leaking crank seal on the clutch side.
Paw Paw
That's what I gathered on my little knowledge on two stroke engines that it was blow by and the jetting was okay. This is my first two stroke and first rebuild. I was assuming worn ring and piston as the previous owner (my brother) doesn't care for things to much just rode and didn't care for any oil changes etc.
Here's a photo of under side of piston, what should I be looking for to know if crank seal is leaking?
Did you clean it? Was there any black residue under the dome?
If no....
With that in mind I would replace the piston and rings, but be sure to measure the piston clearance in the cylinder and the ring end gap prior to the install to be sure all is ok.
I would then suggest doing a compression test and a leak test prior to cranking the engine for the first time.
Remember that single ring piston rings wear out very fast. ( Most cases the life is only about 10 hours or so.)
The plug and piston photos tell the story of being long overdue for a top end job.
You will also need to clean the power valves as they too must have been neglected.
Paw Paw
The Shop
Taking it to the shop today, they've are going to measure the bore and give me the correct piston.
I checked out the power valve, is that the rectangle box on the front of the top end? That seemed clean though it was full of oil, would that just be excess oil blowing past the worn ring?
Is a compression test something doable at home or are specific tools needed?
The compression test can be done at home and most auto supply stores have a "loan a tool" program you can take advantage of at no cost. You may have to put down a deposit for the tool usage, but it will be refunded when you take the tool back. Remember that the compression testing will help you get early signs of the ring wear before you get into trouble. This tool is not expensive to purchase and have on hand.
You would need to make your on fittings to do the leak test.
Pick up a service manual for your ride as well as it will save you money in the long run.
Paw Paw
Looked online they are quite cheap, might invest in one of those to keep track of things.
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