01 rm125 compression

Does anyone happen to know what the factory specs on a 2001 rm125 cylinder head is.


i recently re-built my sons bike (cylinder plated w/ std bore, new piston, rings, gaskets) everything except the lower end due to some seriouse detination damage.


I checked  the compression before i started it up for the first time and im getting 210 psi. to me this seems a little on the high side. so im not sure if this motor had some work done to it by the PO or not (maybe milled the head) to boost compression.


i measured the head volume and its 9cc. not sure if this is what it should be or not.  I called suzuki directly and they couldnt even tell me. any help would be huge. thanks

210 psi is too high. Should be about 150-165 psi on a 125. My 250 has about 200psi.

150-180 imo. just rebuilt mine and got 173 on a fresh rebuild, but i didn't replate.

This is the highest comp reading i have seen on any of the 3 2t's i have owned. this is the first with an exhaust valve. it was 185psi when i baught it 10 months ago. then the ignition went. replaced it with oem. then the plating on the cylinder came apart (detonating), replated the cylinder and put a new top end in and its now 210.


i have been doing some research and i if all the numbers i have (54.00mm bore, 54.5mm stroke, 9cc head volume, displacement, etc) are correct using one of the many CR calculators out there. my CR is way up at 12.7:1. thats 20% over the stock advertised CR of 10.7:1. this is with the exhaust valve closed. this would explain the 210psi comp. reading.


i just need to make sure i am taking the right steps to prevent problems if i am in fact running a higher than stock comp ratio. like higher octane fuel or retarding the timing to compensate.


if the head was milled. then i may try and get a stock head and bring the CR back down to normal so i dont have any issues like this again.

So has anyone out there ever dealt with a high compression ratio like this in a 2 stroke?

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