Starting Point for Jets

[timhoward7]

Need help with this new engine....

800 sxr cylinder on 750 sxi pro case. Recreational freestyle porting by blowsion. Running a JSU girdled head with 28cc domes and a factory dry pipe for the sxi pro.

Stock mikuni dual 44s. Factory pipe recomends 170 front and 172.5 main jets and recommend stock pilot jets. I am running at 3250 feet however and with these mods dont really know a good starting point. Factory pipe said they would not make any recomendations.... Please help!!

 

[tom21]

yeah they are very helpful- I love that tech lady. I am in the same boat cept the head. the stock jetting hits about as hard as stock. If I ever get a second to get to watetest again, I will let you know what I come up with.

 

[timhoward7]

also forgot I am running 5 degrees timing advance. any ideas how to adjust jets for altitude though. is there some formula like go down so many jet sizes per every 1000 feet of elevation?

 

[tom21]

your altitude would make the ski fat compared to me at sea level right? that would at least be a safe place to start.

 

[timhoward7]

yes you have to lean it out for the altitude because there is less air. Im going to try 142s this weekend and see what happens...

 

[Big Kahuna]

Pick up the phone, call blowsion............ Then call whoever they had port the cylinders.

 

[timhoward7]

ran today with 142 main jets, ran too hot, going to try 160s next weekend