Another jet-question...

[Carbguy]

Hi CRM'ers!
I recently rebuild an AR with a new TRX piston bored to 66.50
When i took it for a testdrive, i turn over the gas and i died at
Midrange. So i went for a bigger main jet and then it going better.
But i felt a lack of power on high end. So... I have an 150 jet in it
And it has an 99' CR expansion pipe. Should i go for 165 jet?
It was runing an 132 main jet before the rebuild was made.
This is my first rebuild with a TRX piston so i have no idea if
It makes such a huge diference...

[Active Rascal]

I'd probably suggest a plug chop.

[fishtail]

thats a pretty big difference.. I put a TRX piston into a mk 3 - the difference was no where near so big.... ( actually I forgot what jets in there now .. wished I'd kept a log!! )

got a feelin it aint far from standard....

[Carbguy]

Thanks mate!
I guess the jetting was never right. The owner installed the CR exp. Pipe
And did'nt know that i has to be rejettet then. so it seized all the time.
Poor guy...
Well with parrots on every tree and boars running after a fox in
The backyard... Who would expect that somebody would know something
About jets? "keep it stock an reliable" thats the word around here in the bushes.

[knackeredMk1]

Dennis - Have you seen the downloadable AR manuals in the FAQs and previously mentioned by Fishtail. I'm not sure what jetting the AR runs but I doubt it is a 132 main which happens to be the Mk1 setup.

[fishtail]

and the AR jet size is up in the specs section.....

http://www.crm250.com/specs.asp

and I put all the manuals wiring diagrams I could find ever mentioned on the site here

https://www.dropbox.com/sh/on0rn3im7qiorb2/dJA3lj_A8T


( I use that for my biz - so think that link will be around for a while..... and I think since its small and a few gig is free it will be permanent,,

altho if steve signs CRM.com up for a free dropbox account - you get a certain amount for free indefinitely....

( nothing to do with carbs )

[knackeredMk1]

Matt - The AR jets sizes are not on the specs chart .

I don't run this site. Admin (Paul) does. I sort of fell into the forum moderator function..................

[fishtail]

sorry steve!

coulda sworn they were in there...?

are they in the manual?

[knackeredMk1]

I assume they are in the manual that is why I pointed Dennis in that direction.

[Active Rascal]

Pretty sure stock AR is 48 pilot, air screw 1 3/4 turns out and 148 main jet.

[Carbguy]

Ladys and gentleman...
Succesfull rebuild! Thanks to my heroes here i realised
That the entire vacum lines where all in the wrong place.
Having the service manual makes things realy easy!
Im runing the 165 main jet and she pulls straigt now. Got
To find a 50 pilot jet somewhere. Shes way to rich on low end.
The point about that 132 jet was probaly the owner wanting
To save some pennys on petrol. Wasting them later on
New pistons.

[Carbguy]

Changed pilot jet for a leaner one. Still the same issue. No low end power.
Feels like its running rich and when it pasts the midline, it goes of like a rocket.
Could someone tell me if that would be a reed or a powervalve related issue?
Would apreciate any info...

[knackeredMk1]

The symptoms are like the power valve being stuck open. Have you watched it working .

[Carbguy]

Its works. But sometimes is gets jerky. Like faulty reg/rec or CDI.
I checked the servo and potentiometer. They are ok. Maybe the
Valve is out of line?

[Active Rascal]

Is the valve free by hand, and are the cables in good condition? At certain RPM and on over-run the action can appear jerky.