MM 700 runs awesome at 2000 ft and terrible at 10,000 help please

[live2rideyamaha]

Hey guys my buddy has an 03 Mountain Max 700. he bouught it from a guy out in colorado so i figured that it would run good out west. He got it back and had a local mechanic jet it back for around here and install an attack system to compensate for alltitude. it is pretty much stock but it has a peak performance head, and SLP tripple pipes. we have it jetted for 2,000 ft according to what SLP recomends and around home it just rips, runs completly awesome with no problems. but we took it out west and it has absolutly no power on the low end, it will eventually rev up and runs pretty good at high Rs but nothing on the low end, the last time we were out there we even took a variflow and switched to that cause we thougth that maybe the attack was bad. still nothing and we are giong out there again this week Can anyone help me out with this would really like to get it running good, could it possibly be something with the pipes or even the head
let me know what you are thinking
thanks guys

 

[mysledblows]

bypass the compensator and jet the motor the old fashioned way.

 

[Turk]

Yepper...been der dun dat. Could not get any tempaflow device to make a modded sled run welll at altitude. The old fashioned jetting change is the only thing that would work for me.

 

[Ricardo]

I had almost the exact same sled. 02 MM with an ATACC and SLP triples. Would rip at 2,000 ft but at 6,000 + it had poor bottom end and would occasionaly foul plugs. With the stock pipe the ATACC worked great but with the trips it just never worked quite right at elevation. I'm afraid I have to agree with these guys that to get it to run right your going to have to re-jet it.

 

[live2rideyamaha]

another mountain max

Hey guys thanks for the info, do you think that its the slp pipes or the head, i have another friend that has an 02 MM 700 it has the stock head and Power inc pipes and he runs a variflow and that thing absolutly rips at high elevation, is there something with that head or are the slps different than the power incs that much
anyway thanks for all the help

 

[Ricardo]

I had the stock head on mine and had the same problem so I doubt its the head. Some guys say the SLP's do not get quite enough back pressure at low rpm and that causes some of the problems. The common denominator still seems to be the ATACC not compensating enough. ALthough it's a PIA to manually re-jet, I would try that once using SLP's recommnedations before I would change anything else. Good luck.

 

[live2rideyamaha]

mm

ok thanks for all the help guys hopefully it works

 

[shortman]

mm

Have you checked to see if the reeds are OKAY? Fought the same problem last year and first ride this year till I pulled the reeds as a last resort and found that they were not closing tight against the cages . Have the same parts--slp pipes, attac,stock head with 1 shim removed, boysen reeds & spacers. jetting 143.8 mains 62.5 pilots ( need to put 65 pilots in ) 3rd position (middle) on the needle ,1.0 air jet

 

[kingofthemountain]

make sure the domes on your peak head are the right size. for 10000+ feet they should be 20cc

 

[RXMax]

Ran exact same setup. slp pipes, peak head with 19cc domes, carbon tech reeds reed spacers and an ATACC.... Ripped at 10,000 feet in Cooke all the way through.. Are you jetting to -20 below or the coldest temp on the chart for 2000 ft by SLP specs? That is where I was... How about clutching? Set up exactly to SLP specs for 10k ft .... belt slipping?

 

[live2rideyamaha]

mountain max

well it does not matter now, his brother took it out and brought it back blown up. we tore it out tonight and found one of the plugs that are pressed into the bottom of the case for oil had fallen out, i guess i didnt think that was possible. the case now has a hole in it and the crank is shot and the cluthch side cylinder is gone. would any of you old mountain max guys have parts to get this thing back together
let me know hope to get it back together befor the last week in april. also the peak head does have 19 domes in it where could i get just one dome
thanks for the help in advance

 

[kingofthemountain]

wow that sucks im sorry. replacement domes are $50 from mountain performance if you cant find a cheaper set on ebay or something.