zr 800 carb tunning

[mikethomp]

hey guys need some baseline carb setups. Heres what i'm working with Have an 01 zr 800 black magic twin pipes and slp air box conversion no horns in box. the engine is stock no head work no reeds. What i need is help finding a good starting point for the main jet, if i have to jump sizes on the pilot, and if i need to change the needle or just raise it. woundering also if anyone has ran this setup and what did they think.

 

[diggerdown]

Someone would have to know what elevation and temp zone you run in. Twins will be about 4 sizes up from a single.

 

[mikethomp]

0-3000 and 0-20F

 

[diggerdown]

Normaly you would get recomendation from the pipe maker, but BM is no more! I would start with 410's, needle in the middle position and keep reading the plugs. You may need to change your pilot, but I would not mess with it now. If it idles too fast you may need to drop a size. Twins pipes are hard to give recomendations for because they all have such different pressures and are not very forgiving. Twins need to be tuned a lot so you might as well get a good handle on how the carbs work. I have not run your set-up so do not take this as absolute fact, but I do think you will end up around the 400 mark. You may want to put one size larger jet in the mag side. If you have egt's it will help a lot, but plug reading is the most accurate. Good luck with it and maybe someone that has actually ran that set-up will chime in. Black Majic made mostly flatland pipes.

 

[jimmy2424]

I have a similar setup but I have psi twin pipes with v force reeds. 7-14 celsius I run 450 mains 14 - 26 470 mains anything colder 490. Needle jet in richest position. You will also need to reclutch. My sled rips.

 

[diggerdown]

PSI stingers might be a little tighter than the BM but in supprised how big of mains that work good for you. The 900's will run on those! You got a timing key?

 

[jimmy2424]

When I purchased the sled it had a 3 degree timing key. When I rebuilt it i removed the timing key. Did not change the jetting and there was no noticeable loss of power.

 

[jimmy2424]

My jetting is for negative degrees celsius i am canadian eh.