XP Jetting

[live2beel]

Wondering what everyone is running for jetting (800R) with HPS can? I here some are putting a shim under the needle. I did notice the HPS is close to 3mm tighter. Thanks

 

[JLeosnow]

live2beel,
I was told no jetting/carb changes needed for running a HPS on the 800R Summit XP. We'll see what others have to say....

Thanks,
-John

 

[madmax]

There is already a shim under the stock needle, are they adding another one? Anyway I have the HPS can, but also a RKT head. I took the stock shim out from under the needle, 450 mains. Runs very, very well.

 

[ReTodd]

There is already a shim under the stock needle, are they adding another one? Anyway I have the HPS can, but also a RKT head. I took the stock shim out from under the needle, 450 mains. Runs very, very well.

What elevation? We had two of our 800R's bog down and die when we got up to about 8000ft because they were so rich. Had to hold her WOT to start again and she didn't clean up until I crept about 500 feet down the hill. I think 1 of them was running 490's so dropped to stock 470's but after seeing my pistons (completely black) I decided I must be running pretty darn rich. Runs hard, but would be nice to be jetted correctly.


Rt

 

[winter brew]

We have HPS 's on 3 different '07's and 1 '08 and all run stock jetting/needles at 3-7000ft with no problems, run strong.

 

[HOOTS]

What elevation? We had two of our 800R's bog down and die when we got up to about 8000ft because they were so rich. Had to hold her WOT to start again and she didn't clean up until I crept about 500 feet down the hill. I think 1 of them was running 490's so dropped to stock 470's but after seeing my pistons (completely black) I decided I must be running pretty darn rich. Runs hard, but would be nice to be jetted correctly.


Rt

Completely black is lean. Rich = washed clean. Should be black w/some wash (clean spots) by intakes.

 

[HPJUNKIE]

Completely black is lean. Rich = washed clean. Should be black w/some wash (clean spots) by intakes.

Ditto.... 1/2" wash is considered good... black = bad = $$$

 

[ReTodd]

Ditto.... 1/2" wash is considered good... black = bad = $$$

I guess I misunderstood piston wash. It sounds opposite from plug readings then??? When plugs are black it is rich, grey is good, white is lean? Why are pistons different?

Rt

 

[tinman800]

Thats why is called "piston wash" the raw fuel washes the carbon deposits off the piston, the larger the washed spots the richer the mixture, the smaller the wash the leaner

 

[ReTodd]

Thats why is called "piston wash" the raw fuel washes the carbon deposits off the piston, the larger the washed spots the richer the mixture, the smaller the wash the leaner

Copy that. So do you need to read piston wash when you are up riding like you do your plugs? Will it show different wash for different jetting circuits (light throttle, mid range, WOT)?

Rt

 

[canucklehead]

yes and yes

It's just like reading a plug. Make a pull at a specific throttle position and kill it. At the same time you are checking your plugs you can also check the pistons with a small bore light. I'm sure if you did a search on the old 4m or the internet in general you would find some good info and pics of piston wash. Compare the plugs to the wash, it's another way of seeing how it is running.