Yamaha TRX850 Enthusiasts Forum

Does anyone actually know the true compression ratio of the JE 878 pistons??
Kedo have them listed as an 11.5 : 1 compression ratio but I recall something about them being a 10.5 : 1 due to the deeper valve cut outs in the piston crown.
I sent Paul in at TTS an email For verification about 4 weeks ago but still no answer. Maybe they are flooded out????

cobbadiggabuddyblooo wrote:Does anyone actually know the true compression ratio of the JE 878 pistons??
Kedo have them listed as an 11.5 : 1 compression ratio but I recall something about them being a 10.5 : 1 due to the deeper valve cut outs in the piston crown.
I sent Paul in at TTS an email For verification about 4 weeks ago but still no answer. Maybe they are flooded out????

11.5:1 yes, due to the "dome". My 900 wiseco´s are 11.2:1
As is TRX 10.5:1 & TDM 10.2:1