2007 M8 rpm issues

[RMKdude]

I have a 2007 M8 with the following done to it:

y pipe
bmp can
hacked out intake with a K and N air filter on top of the air box
153" attack 20

It had a brand new primary clutch in 2008 and it is all the stock weights (68g ?)and primary spring (it is the yellow and white one for 6-9 thousand feet) The secondary is also stock with the orange spring in it.

The issue is that at elevation say 8-9000 feet i only pull between 7600 and 7700 rpms. down at my house at 5200 feet i pull close to 7900. I am new to the m series and it just seems like with the mods that are done to it it should be able to spin the stock clutching closer to 8000 at elevation And maybe the rpms that i am running are what the m's should be running i am just not sure.

It has a brand new belt on it with about 150 miles on it a freshly cleaned air filter and cleaned clutches.

What are you guys running for clutching on these things and what rpm should i be running at at elevation???? Could cleaning powervalves gain me some rpm on the top end?

thanks in advance guys!

Ken

 

[TheBreeze]

Those mods are likely not making any additional power, and if they are, it is not enough to compensate for the thinner air up high. I would try the proper stock clutching for that altitide (a few grams ligher in the primary) and you should be good to go.

 

[sledheadjake]

X2 That is what I would try first.My sled is a 07 m8 completly stock and I ride around 3-6000 feet my sled turns 7900 .The only thing I cahnged on my sled is I put in a shift assist and i put a arctic cat gold primary spring(to lower my engangement)and a shim kit in the primary.I am running 68 weifgt

 

[CB.8]

The 07 motor is much happier at 7400- 7550 rpms. Pulls much harder.

 

[sledheadjake]

The 07 motor is much happier at 7400- 7550 rpms. Pulls much harder.

I will have to get some new weights and try that out.thank you

 

[CB.8]

I will have to get some new weights and try that out.thank you

I was pulling 75 gram all the way up to 8500 with no problem. My motor seems strong though. I have just a RKT kit and am going to try 77's but I am not sure it is going to be enough.

 

[RMKdude]

The 07 motor is much happier at 7400- 7550 rpms. Pulls much harder.

It does seem like there is not a hole lot of difference from about 7000 on up but i wasn't sure if there was much more power to be had on the top end or not. I know the power curve is pretty flat.

 

[sledheadjake]

Im still learning on clutching so is the only way to bring down your top rpm is by using heavier weights or can you use a combination of a diifrent primary spring and weights or secondary spring?

 

[MAC29]

X2 That is what I would try first.My sled is a 07 m8 completly stock and I ride around 3-6000 feet my sled turns 7900 .The only thing I cahnged on my sled is I put in a shift assist and i put a arctic cat gold primary spring(to lower my engangement)and a shim kit in the primary.I am running 68 weifgt

Should be pulling at least 73s if not 75 gram wts.

 

[White Rad]

Im still learning on clutching so is the only way to bring down your top rpm is by using heavier weights or can you use a combination of a diifrent primary spring and weights or secondary spring?

a lower fininsh rate spring can be used to lower and fine tune peak rpms once you get it close w/ the weights.

 

[White Rad]

Im still learning on clutching so is the only way to bring down your top rpm is by using heavier weights or can you use a combination of a diifrent primary spring and weights or secondary spring?

a lower fininsh rate spring in primary can be used to lower and fine tune peak rpms once you get it close w/ the weights.

 

[RMKdude]

Wondering if maybe a top end would be a good investment before i start clutching. I have almost 2800 miles on it, it feels like it has very good compression but i have not checked it with a gauge.

Any thoughts??

 

[columbus]

check your power valve cables both for proper tension and wear. If one or both cables fray or is loose the valves will not open all the way and will reduce top end power.

 

[RMKdude]

check your power valve cables both for proper tension and wear. If one or both cables fray or is loose the valves will not open all the way and will reduce top end power.

I was wondering if they weren't opening far enough because of grime... I am going to pull them apart this weekend and clean them. I did'nt really think that the cables would be an issue but i will for surely check them.