High Altitude 5000' running 800 SXR ?'s

[goinxtreme119]

I just brought 04 800 SXR up from tampa, fl to Bozeman, Mt which is 5000'. Has Factory B wetpipe, carbon tech reeds, aftermarket - flame arrestors, airfilters, waterbox, intake and ride plate. Ran it first time yesterday. Actually very impressed ran great except for a low end bog. When sitting and go to take off ski just bogs down and have to feather the throttle to get it up and going then is fine till stop again. I think this is a rich problem. Trying to figure out where best to start carb adjustment...if adjust popoff pressure or start with a smaller low speed jet. Any advice?

 

[RMBC Freeride]

Two things you need to do... get the compression up w/ an aftermarket head & get a lower pitched impeller.

Do that and you really wont need to worry about carb tuning. These carbs are somewhat self-compensating for altitude due to their diapragm fuel pump and diaphragm operated needle valve.

In the mean time, turn up your idle slightly, it might help a little

my .02.... from 4700 ft elevation...

 

[goinxtreme119]

So you don't think I need to adjust the carbs at all, just change the other items. If change head would getting one that still allows pump gas 91 octane work?

Any suggestions on impeller pitch? And brand of head?

 

[RMBC Freeride]

ADA head, look at their compression chart (for sea-level) and find the domes for 91 octane, but dont buy those (unless you can use them in Florida).. buy domes with 4cc less than the sea-level 91 octane domes.

EDIT: I just looked it up, you should order their 28cc domes for your elevation. (32cc for sea-level)

Impeller, call Impros and get Dave to set you up. tell him your elevation and he will help you out. Generally you go 1 degree less pitch for your elevation compared to sea-level.

 

[63chevyll]

He knows his sheeeet. (dave and RMBC)
i dont think hes saying NOT to adjust your carb.
just that carb adjustments are very small