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Advice please, wont reach max rpm...

8839 Views 11 Replies 5 Participants Last post by  slarson
Hello Guys,

Please help me if you can, I have a 98 FIII 600 with 4000 miles on it.I did my first 100 miles today, fairly hardpacked condition, about 18 degrees Farenheit, about 300-500 feet above sea level. I have 280 Main Jets in all 3 cylinders (290 is stock) and The TRA clickers are now on position 5 (4 is stock). Plugs look good in color (still slightly rich, dark brown color after 1/4 mile run a w.o.t.). The problem I have is when I hammer the throttle to wide open, it only goes up to about 7500 rpm, and the slowly reaches 8000 and goes no more. The max rpm setting according to my Doo factory manual says it should rev to 8500rpm. I was under the impression, when I hammer the throttle it should shoot up to 8500 rpm, and pretty much stay there. My raves are clean, carbs are clean, new OEM belt, all new bearings in sled pretty much including the one behind the secondary, clutches are aligned, clutches are clean and all stock (done this fall),  new plugs....etc.... I suspect that my primary spring is weak, does this sound logical, or is it in the secondary?.....when I first got the sled, it would go over 8000rpm and go approximately 105 mph in good conditions (speedo) and now it only goes about 90 mph at 78-7900 rpm......any other suggestions, as this is my first clutching diagnosis and repair job. I do have the proper tools to do it if it is the spring, just want to make sure my theory is sound.......any other suggestions???

Thanks in advance folks......Ride on!!
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change your primary & secondary spring they sound like they
are week
 A freind of my just went through similar problems with his
 96 f-111,turned out to be a weak stator.He has about same
  mileage as you,check your drive spring first if its good i'd bet
  stator is on the way out.Another buddy had 98 mach z do same thing,it just kept on getting slower until one morning it
wouldn't start.The f-3 never did quit completely.
Need to know more about the rpm's, are they hitting 7500 rpm's then creeping to 8000?  If so check your belt deflection, and tighten up your secondary.  You maybe shifting out too fast.  Yes, the 98's did have a lot of stator problems also.  I think your TRA should be on clicker #3 from the factory.  clicker #5 is too steep in my opinion.  Always start on #3 and work from there.  Your primary spring should be replaced if you haven't done that since new.  I would try the secondary first, then replace the primary spring.  It wouldn't hurt to replace the secondary spring also.   I replace both the secondary and primary every year.  Cheap insurance.
Yes KR,

It is going up to about 75-7600 and then slowly reaching only about 8000 max, deflection is good as per factory manual, according to my manual clicker 4 is factory, I plan on trying the Primary Spring first, and then the Secondary, it has not been done in the 3000 miles I have owned the sled. I do not suspect the stator, there is no misfire at all, and all of my accesories work good, my lights are even bright at 2000 rpm, and I checked the voltage and it is in spec by the manual. I suspect that the Primary spring is the most likely suspect, allowing the weights to overcome the tension of the spring too easily. Just wanted to make sure what I was thinking was sound!
slarson,  I would put money on the primary spring.  For about $20.00 it should fix the problem.
I would put the clicker on 3 and try it, it doesn't cost any thing, also check the secondary spring tension with a scale and see if it is within spec.
Slarson let us know what you find out,by the way even if your
stators going it will not misfire.The two i changed for freinds
never missed a beat, they just kept getting lower&lower in rpm. Ihope it is your spring,but we tried changing clutching to
and end up changing stators as the triples seem to eat them up.
                    Goodluck GREYGOAT
looks like I will try the spring first, it is only about 18 bucks, and I will also check the secondary spring too......I will keep ya posted, doing it this weekend.

I changed the primary spring, come to find out it has a blue/red spring in the primary and should have had the green violet spring, so needless to say it is now about spot on, so thanks for the replys!! I am checking out the secondary this week to make sure all is alright there too!
slarson, glad to hear it was minor.  How did that darn spring get in there?  LOL..
Thats what happens when you buy a used sled! I bought it with 900 miles on it and ASSUMED it was all stock like I was told. I am thinking someone may have attempted to clutch it? Just glad it is better, and that it was an easy fix.
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