Clutching question

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gabbett1

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Feb 25, 2015
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Location
Valparaiso, IN
So I have a 700 SX with triple pipes and some really different clutching. Used to be a fully built 800 by RPI Racing. They put on it and it still has a Comet 108 (if I remember correctly) primary and a Bearcat Arctic Cat secondary. The engine is back to stock other than the pipes. Took me a lot of playing around but I finally have the clutching right in the sense that I pull RPM and hold. Now I'm just not seeing speed. I'm getting maybe 90mph out of it. I marked my clutches and I have about 1/2" to 3/4" on the primary that isn't being worn. Is that normal? I am also running a gear that is one tooth down from stock. Did I go the wrong way? Perhaps I should go up a tooth from stock?

Any advice would be helpful.

Also, a side note, I have noticed my speedo is off by about 10 mph (90mph reads 80 on speedo). Any thoughts on how to fix that?
 
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if your running pipes you need to rejet! also ,are you geared to stock? if your running pipes you need to regear to get the most out of her ! need to know what kind of pipes so you can tuner up! the way it should be according to the pipes and how they make power! also clutching is going to be an issue.
 
yammy said:
if your running pipes you need to rejet! also ,are you geared to stock? if your running pipes you need to regear to get the most out of her ! need to know what kind of pipes so you can tuner up! the way it should be according to the pipes and how they make power! also clutching is going to be an issue.
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Yes I've already rejet the sled. I guess I should have specified that since I wrote it's stock but pipes. I also have the thin cylinder head gasket mod. I have EGT's on it to monitor it. I'm running AAEN pipes. It runs well. Just not going fast. Stock is 23/40. I'm running 22/40 right now.

I thought about going to 23/38 like the SRX. Would I need to re-clutch again if I changed my gearing that much?
 
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I believe the Aaen pipes need to run around 9000 RPM...22/40 is a good ratio and should give you over 100mph on a sx700 with pipes on the hard pack.
 
If your speedo is out by that much there is something a miss...usually the speedos over indicate not under indicate.
How many teeth on on your track drivers?
What track are you running?
What is the track pitch? 2.52? 1.86? 3.0?
Lots involved when setting these sleds up
 
sideshowBob said:
I believe the Aaen pipes need to run around 9000 RPM...22/40 is a good ratio and should give you over 100mph on a sx700 with pipes on the hard pack.
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I've been told by a buddy of mine that races sleds that 22/40 is going to slow me down. I want good accel for sure, but I want top speed too. I ran the sled about half a mile and only got to ~90.
 
sideshowBob said:
If your speedo is out by that much there is something a miss...usually the speedos over indicate not under indicate.
How many teeth on on your track drivers?
What track are you running?
What is the track pitch? 2.52? 1.86? 3.0?
Lots involved when setting these sleds up
Click to expand...
Track driver is stock (9 teeth I think). Pretty sure the track pitch is 2.52 but unfortunately I don't remember the exact track I'm running. Ripsaw 2 I believe.
 
Was just out doing some tests. I got a GPS to test my MPH and it's actually dead on accurate... That means instead of doing 90 I'm only doing 80! Noticed something though. My tach on my sled looked to be right around 9000 but my EGT tach said 9350 one run and then 8700 on another. Not sure which would be more accurate and or if some variation like that is normal.
 
sideshowBob said:
If your speedo is out by that much there is something a miss...usually the speedos over indicate not under indicate.
How many teeth on on your track drivers?
What track are you running?
What is the track pitch? 2.52? 1.86? 3.0?
Lots involved when setting these sleds up
Click to expand...
Was out looking at the track. I think it might be a Camso Hacksaw.
 
what about your air intake box ? has it been modified? 700 sx's are very finicky with a modified air box!
 
yammy said:
what about your air intake box ? has it been modified? 700 sx's are very finicky with a modified air box!
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The air box is basically stock. I did remove the inner divider but that seemed to make little to no difference. A buddy of mine had a stock SRX he did that to and said it helped him so I tried it.
 
Tell us what weights, rivets and springs you are using.
I assume you are now using factory clutches?
 
What brand are your pipes?
Stock clutching wont cut it with triple pipes, but if you know the brand, I can help you get to the correct RPM for that set of pipes.
 
MURDER YAMAHA said:
Tell us what weights, rivets and springs you are using.
I assume you are now using factory clutches?
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No, I'm not using factory clutches. Like I said in the OP, I have a comet primary and an Arctic Cat Bearcat secondary. The primary has a light blue spring and 10MB weights (might need to go up just a tad in weight) and the secondary has a yellow spring. I have no idea what the spring rates are on either. I had help picking those out.
 
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Oh, ok, you said it “had” a comet clutch, figured that meant past tense.
I’m out as far as help with that goes, know nothing about those.
Would be very easy to clutch with stock clutches too.
Maybe someone else can chime in,
 
MURDER YAMAHA said:
Oh, ok, you said it “had” a comet clutch, figured that meant past tense.
I’m out as far as help with that goes, know nothing about those.
Would be very easy to clutch with stock clutches too.
Maybe someone else can chime in,
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Ah, didn't mean to imply that it no longer had them. Fixed the OP to remove that confusion. I figured people would be able to answer general questions about how much of the clutches should be used by the belt to get full use. I received advice from one of the guys that used to be at RPI as far as springs go. Weights I figured out by trial and error. Just curious if for some reason I'm not getting full range of use.
 
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