99 vmax sx 7000 rpm at 75 mph!?

[swooper311]

Ok need some help. I have a 99 sx 700 red head. Runs very strong from launch to 70 mph around 8100. After 70 the RPM drops and holds at 7100rpm and top speed is 75mph. I have been reading and found this machine has a fuel filter in tank that might be plugged. I have also noticed that the primary and secondary clutches have after market springs.my question is will a clutching problem cause the engine to drop 1000rpm after hitting 75 and wipe open throttle? Carbs are clean and jetting is stock. Stock pipes and engine 100% stock......

 

[00sxrjoe]

Sacked pri spring over shifting pulling down rpm?

 

[drew24]

I had the same thing happen with my viper. Put new springs in clutches and problem is gone. It was inconsistent which is what led me to the clutches. Sometimes the rpms would jump up for a second and then bog and sometimes it would stay up for a few seconds and then bog.

 

[swooper311]

So your thinking clutch is closing to early causing the engine to load at higher mph? That's what I'm thinking too. The secondary has a hauck helix and the spring is silver. Do u recommend going back to the green factory spring?

 

[swooper311]

Also the secondary spring is maxed out on the 0 setting 3 on the inside setting.....

 

[drew24]

Is this a new setup or did it work fine before. I am not familiar with the hauck stuff but seems like 30 on the secondary is light. I think my problem was my secondary spring was weak and letting the belt get sucked down too early.

 

[A couple of bucks]

Replace w/ fresh primary & secondary springs(especially secondary) and reset preload to 60(3 & 3).

 

[swooper311]

Always had issue since we bought it. And should I go back to the stock helix?

 

[drew24]

Do you know what weights are in the primary? If the weights are stock you could put new stock springs in and the stock helix and it would be right. Try wrapping the secondary at 60 or 70 and see what difference there is. I would say someone was trying to clutch it and never got it right.

 

[swooper311]

No I don't. My plan is pull the clutches and really go through it and put back to stock. Than do the upgrades

 

[A couple of bucks]

Two NEW springs and a NEW belt is a perfect place to start. That alone solves many issues. The springs are tired and the belt is not the same width as new.

 

[Weatherbyman]

Try setting the secondary preload at 3/3 as was mentioned or even 1/6. (60 degree preload or 70 degree) That will make a huge difference.

 

[00sxrjoe]

Could be worn pri clutch slides making clutch bind or even worn rollers. Someone put a clutch off a twin on it. I find the twin clutches ware alot compared to triples

 

[yammy]

check the rollers in the primary ..sounds like the bushings are shot

 

[swooper311]

Thanks everybody. I really think you guys are right. The belt only has a few rides on it. Going to do both springs. And for the hell of it we removed the oversized studs and that alone gave us 10 mph!? So I am guessing the springs will get the rest. Gonna do that fuel filter to be safe too......

 

[Whammy]

Pull and clean both clutches,,,,,,,, make sure it all looks good to go,,,,,,,,,,cleane em good...........