I was wondering if anybody with the 686 or other big mods has had the tranny let go? I am getting a 686 kit in feb. and was concerned about the tranny. Do i need to budget in the fourtin gears?

 

so far no problems but just to make sure I ordered the sparks clutch and should be replacing that this weekend

 

I believe that the trans can and will fail on many Raptors. You can either replace the gears, OR drive like a grandma OR, if you build the engine to a 686, use a final gear combo that allows you to move through 2nd gear fast and use 3rd as your base line gear. With a 727 or 760cc Raptor, using new gears is the only way to go since you will be pulling stock gearing easily and therefore using 2nd gear more often.

By the way, the clutch has nothing to do with the gear failures so, don't believe that a Sparks or any other clutch assy will save the day. Once you experience some missed shifts to 2nd or experience it popping out of 2nd, failure is just around the corner.

 

my clutch was just starting to slip and due for replacement anyway, it may not have anything to do with the tranny failures but no need to stress the weak parts (tranny) any more than necessary.

 

King,

Good luck at the Wars!!! If you experience the trans failure, pray that it happens at low speeds. I have been on a Raptor when the trans failed at speed. The broken trans parts locked the trans up so hard that the teeth on the counter sprocked sheered off. At the same time, I was thrown over the bars as my wheelie came to a sudden halt.

 

Raptor 720
I got mine back about a month ago
for the tranny failure you ain't
kidding about the lock up the only
thing that stop me from going over
the bars was yamaha's safety switch
(the chain snapped)but I was wondering
did you fix yours with aftermarket gears
or the ones yamaha replaces them with!!!
Thank you

 

Ah, perhaps that is my problem. I always replace my chain with a better quality x ring chain. I can say that the chain (adjusted just 30 minutes before the event) is now about 1/2 inch longer! I also believe that all engine parts should be aircraft certified after a trans failure. There is no way you can trust parts that have been placed under that kind of shock.

Yamaha has provided all new parts BUT I elected not to use the gear set. The Fortin gear set is the way to go for safety. Problem is that they are a pain in the ars to get.