Peak Head Re-Jetting?

M

maxco

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Sep 30, 2009
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348
Age
57
Location
coloraDO
So I have been wanting to get a peak performance head. I finaly got one. Yay. I was wondering if enyone knew if and how much you have to re-jet. I know I will do plug checks after this, but wanted to know what I might be looking at. I have a stock head, on a ported motor. I am going to a peak head with 20cc inserts. I always run high octane fuel. I am just wondering if higher compression cancels out needing more gas. I was looking for a range of magnitude. mains,pilots and needles? or more just a little needle tweaking. If it's alot I might wait until later in the spring when it's easier and warmer to do this in the field. Thanks. :2strokes:
 
When I did my sled I bumed the main for safety. You may want to try and move(add) a shim in the mid to see how it responds. I am running 20cc domes at under 1k ft. Really noticable response just above low speeds, also noticable crackle sound out the exhaust copared to stock at idle, meaning my piped sled sounds tough now.
 
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This is for a 2000 Mountain max. It has and is running SLP tripple pipes. it has been ported. It seems to be jetted correcly for this configuration and my altitiude 10,000 ft plus. I am running 137.5 , 62.5 and third e clip up spacer up and down. I am wanting to add a peak performance head to the mix. Thanks :2strokes:
 
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My MM has SLP's and porting. I don't have a peak head, but I'm running a single layer head gasket. I run leaner jets than you with plenty of wash at 6-10000 ft. My guess is you won't need to re-jet, but maybe go up a size and check wash to be safe. I'm thinking you'll have too much wash and will be able to back it off. How much wash do you have now? Also, how far down the strap on the plug is the heat?
 
I have not checked wash. I guess I need to. I check plugs. Nice cardboard colored to the bend, slightly darker there, oil three threads deep. very slightly whitish haze at the very very tip of the electrode. From what I have read this sounds right on. :2strokes:
 
Heat range on the plugs does sound good. I would check wash at WOT after a good powder climb. I'm guessing you'll have a good 1/4", which is very safe. Do you know how to check it?
 
I guess I need help

The only wash I know is piston wash. This would involve removing the head. this is difficult to see how this is possible in the field. Am I missing something? Thanks
 
you can get a real good visual by rotating the piston to bdc and supplying yourself with a wash light. mine came from snobunji at around $12. most auto parts stores will have them. basically a 2 AA maglight with a flexable monofilament attached. you would be surprised at what you can see in there.
 
You have to field test it to do it right. Make a WOT run and hit the kill switch while the throttle is still pinned. Once it stops, pull the plugs and use a cylinder light/flexible light to look down into the hole. You will have to turn the primary clutch to drop the piston to bottom. Be careful not to break the bulb when you're moving the piston. Be sure to look around the entire surface of the piston at all transfer ports to see how all the wash. Keep in mind what elevation and temp you are checking it at to use for reference (i.e. if it's 38 degrees at 10,000 ft and you have minimal wash, then you're in trouble at 20 and 7000). Whole process takes 5 minutes and you don't have to pull the head.

I bought my lights years ago from Bender. Not sure what retailers sell them now, but should be easy to find. I'm sure other members on here could tell you where to pick one up. Good luck.
 
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