XR600R XR 600 bigbore 102mm best dual carb setup

[drestar]

Hello i have a xr 600 1987 with dual carburetors, bigbore 102mm. with JE piston. RVS exhaust and akrapovic 

slowjet is 45,

i'm looking for the best main jet setup for bigbore

132/132

132/135

132/138

135/135

138/138

please say the combination for the best power.

 

 

[baldy110]

Stock jetting

[drestar]

Stock setting is 2x 122 and to poor. spark plug is now grey-white with 2x 132

[drestar]

 

with 135/138

[Fingers]

What’s the advertised compression of that piston? Are you sure it was made (pin height) for an XR-600 (and not an XL or XR-650L). That will affect the compression greatly. I ask because if your compression is same as stock, or lower, then jetting will not be affected as much by the extra displacement.

[drestar]

Ik have a picture from the piston box. 

 

and yes it is for XR 600,

[Fingers]

That’s a JE piston 10.8 compression. How did it run with 135/138? Usually on Euro XL 600 (PD-04) stock was 115/115 on LM and 118/118 on RM. It would seem to me 130 size and over would be very rich but both your plug photos seem lean.

[drestar]

Yeah i have JE piston 102mm bigbore. and the tuner did flow the cilinder head intake,

stock main jets of XR 600 are 2x 122 .

 

i have testing now 2x 125 . and i runs very wel,

than testing 2x 132 .runs very wel with a little popping if i turn the gas off . than 135/138 it popping a little more with turn the gas off and ride very wel

feel no different between these combinations .only popping more on the ride with turn the gas off with bigger main jets

 

but why the spark plug looks so lean?

[drestar]

I have now 2x 150 main jets and the spark plug has a little more color. the bike runs normal and can take more

maybe i must go up to 2x 160 jets,