Gotis, It's not merely a "one size fits all" scenerio on the jetting topic.. Even a small change in air density will cause a re-jet for me, also different mods (My bike vs. yours) will/can cause significant jetting differences.

Please, PLease, PLease get online and search for some jetting info... there's a bunch out there... and educate yourself. Learn how to read piston wash/ plug color, plug chops, etc.
Jetting is no small issue, and can make the difference between a great running machine, and disaster (Total engine failure)

I can't fully explain all the small details here, as I would need several pages and chapters...

 

Its a pretty simple concept guys. If your under 140psi you need a new top end. For other guys out there that dont know a whole lot of the theory behind more or less compression... The more compression you run the more torque you'll have, but the less top end speed. And the less compression is the complete opposite

 

I'm getting my 440 kit and trying to decide what compression ratio to get. Your saying by getting a higher ratio, I'm losing top end?

 

no, i was referring to 2-stokes thor. Your good on your thumper. rule of thumb on a thumper is more compression equals more power

 

Testing to see if this works......

 

Nope. Didn't work. Tried to copy and paste the page from the manual here, but it didn't work.
My motor builder scanned a page from the manual, and it specifically says in there that the compression is to be 170.7-199.1 (I am assuming at sea level).

Looks like it is a pic of the three wheeler, so it may be slightly higher than that for a TRX but still, it is WAY above what was stated earlier for compression.

If anyone wants to see this for themselves, give me your E-mail address, and I will forward it to you.

 

200 is too high for gas, or race gas. stay under 180

 

Thor440 - Do you have easy access to race gas? If not, I would go w/ a 10.3:1 compression and run Premium (93 octane... or 92 if thats all you can get) gas. Also, if/when you go with the 440 kit, what other motor mods do you plan to go with?

Sorry, something came up and I gotta do something. I'll finish this post later.

 

Ok, sorry... I have a race this Sunday and I just had some bolts come in that I really need for the race and they turned out to be the wrong ones and I had to get on some different websites and blah blah blah....

ANYWAYS, I'll just start over.

Thor440 - Do you have easy access to race gas? If not, I would go w/ a 10.3:1 compression and run Premium (93 octane... or 92 if thats all you can get) gas. Also, if/when you go with the 440 kit, what other motor mods do you plan to go with? I ask you because a lot of the stock motor components don't hold up well to the strain of that big HP increase. It would be a good idea to replace the clutch and probably the rod too because they don't last long w/ the 440 kit. Also, a new CDI would be a good idea because the stock RPM limit is to low and you'll probably find it very restrictive. Ummm... I think thats about all I was gonna say. Does that help any?

 

I don't follow you on that one?[img]i/expressions/face-icon-small-confused.gif[/img]

You are saying you can't run 200 PSI with race gas??[img]i/expressions/face-icon-small-confused.gif[/img]