I recently rebuilt my 86 trx350. The orginal compression was 8.5:1, and I used a Wiseco piston giving it a 10.5:1 ratio. I have a slight valve rattle(pinging sound) while running under a heavy load in 3rd gear going uphill. If I am going uphill in third gear and it loses speed and I get on the throttle it will rattle until it gets up higher into the power band. Would running 89 or 93 octane be that much better than running 87? What kind of hp would you guess I have now as compared to the 25hp in had orginally? Thanks

 

hate to bust your bubble but there isnt a 350 out there with 25 horse power, you may have around 14, or 15 hp at most!

 

I can't recall at what points when you bump up the compression, where you need to up the octane....but I say give it a tank of 93 and see how it likes it!

 

10.5:1 92 or 93 what ever the pump gives. On air cooled 11:1 you usualy want race gas but some times dont need it.

On water cooled 13:1 needs race gas but some times 12:1 needs race gas depending on the cam. Im 12:5.1 on mine and its just fine other than running hot.

Higher oct gas makes you run cooler.

 

12:1 and higher!

 

I am sorry. According to the factory service manual, the 86 trx350 creates 24.5hp @ 5000rpm and 21ft/lbs of torque @ 5500 rpm, not the previously posted 25hp. I stand corrected! [img]i/expressions/face-icon-small-wink.gif[/img]