Do you know if your head has been skimmed and/or the mating surface of the cylinder? This would mean the piston would travel higher up into the combustion chamber than it should. I don't think that should happen normally, the piston crown should stop just short of the cylinder head surface. I don't have a fix for you though I'm afraid, what about trying 2 x head gaskets, might work - would give you a mm of extra height. When you buy head gaskets for a car you can get different thicknesses based on whether the head has been skimmed and how many times, so the overal height stays the same and compression ratio isn't altered. Don't think you can get different thickness head gaskets for a DT, but 2 together might work???
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Is that bits of piston ring firing out your tailpipe?
Kalamity Kid is right in a way, it might be that the head has been seriously skimmed but i think you would be suffering from pre detonation if that was the case, it might be that the extra width of the barrel/piston is allowing the piston to kiss the cylinder head, I cant really tell from the picture because of the image quality but does the edge look machined or stamped like its hit the head and are there any marks on the head? 2 head gaskets will not work and the motor will just blow through them, the only place 2 gaskets work is at the bottom end of the barrel, if there is no knocking noises the I wouldnt worry but the piston will travel higher up the barrel at high revs.
If you could can you answer these questions for me 1. Look at the edge of the piston, between the top edge and the first ring, are there any signs of wear or over heat? 2. What does the oil burn spot on the inside of the piston look like, is it about the size of a one pence piece? 3. When the piston was removed from the motor what did the burn pattern look like on the piston crown, was it nearly all the way to the edges, what color was it and was it dry? 4. Was there any sort of powdery aluminium on the edge of the piston or between the rings?
I would try using 2 base gaskets, I used to have an RG 250 Gamma with tuned barrels and a skimmed head, the tuner told me to use 2 base gaskets, I never had a problem with it! It's worth trying imo
hello m8 thanks for the replies guys. i posted in the wrong section to my bad soz
that was my 1st idea m8 that the piston had been machined that way but the groove is off center as was the head bolted on the pizz a bit which made me think it was kissing the head
there wasnt any strange noises or knocks the bike ran fine an the piston is still in a fairly good condition considering the miles iv covered on it
i was just thinkin of getting it replaced an noticed this lip as i was mesuring up leaving me thinkin if i buy a new one itll have no lip an smash the hell outta 20 top end gaskets again
1. the top edge of the piston above the 1st ring is in good nic apart from this top notching an theres a small wiggly line break starting through the next part of the piston beetween rings one and two
2 not to sure about that m8 i did clean internal of it an remember it being dark if that helps
3 the burn pattern on the crown is coal coloured completly covering the crown surface
4, no metal filings the piston was clean little sticky maybe an the plug a nice browned colour,,
i thought 2 top gaskets would blow to be honest if i tried that but stupid me didnt even consider two base gaskets worth a try
yup lift the barrel slightly, by using 2 bases as said,, i wonder if your barrel has ever been skimmed also..only way to tell is to reinstall and see where the crown is relative to the top face of the barrel.
Yeah for future issues like this 2 base gaskets is the fix what a div i feel thinking of putting two top ones an knowing it would blow an not even thinkin of doubling up on base gaskets to increase the height nice one fellaz
