hey there, any body tried any of the big bore kits available for a.c. 500/600 twins? also how do I tell the difference between an "a" case motor, and a "b" case motor?

Alot of guys on here have stated that the D&D 720 mod motor is the kit to get. It's what almost all the top racers run. I believe it cranks out 140 HP.
Caleb

If your a tuner kind of guy buy the big bore kit, it'll be a blast. If your a pull and go type, save your self the head aches and buy a bigger sled. Rick. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/biggrin.gif

i agree with ZR sled head, the more you do to your engine, the more picky it becomes. * after awhile you find yourself tuning your sled more than riding it.
but the D&D 720 kit, once installed and set up should only need changes in jetting.

D&D will give you the jetting and clutching that you need and it will be a pull and go motor. Tried and tested for several years and on the new 02 &03 sno pro's. They know there stuff but best of all they give you good same jetting recomendations if you ask. other companies give out jetting info that keeps you lean for a tad more power then they want a ton of money to rebuild your motor that leaned out when you leaned on it and melted a piston. *D&D all the way for a cat twin.
Caleb

Any aftermarket big bore kit won't be a true pull and go sled. You want more buy a bigger sled.

hey there. thanks for the input ( except for the ski dog guy, just kidding). I'll check out the D&D kit. The new sled idea isn't out of the picture quite yet but I the sled I have now is in great shape and I'm just thinking about making 'sleeper' out of it. What the ####, right? Tuning isn't a problem. I already got another 10mph out of it as well as another 3-4 mpg over stock just with clutching and a little carb work.

I say no to d+d.very slow and not the best tech support not to mention over priced.you'd be better off to go right to hooper, thats where d+d get's their jugs anyway.there are a lot of company's out there selling kits check around.you might want to just get a port job and some pipes.all depends what your looking for and how much $$$$$ you want to spend.

Bore it.I have 1999 711 d.d. power e.f.i. that will run with all takers.Once you get your cluthing where you like it and you can tell the sleds works best it will amaze you.The bottom ends are more than up to task and rings every 2000 miles.I have 144 1" sabre (not enough)wahl light weight disc,hub,all gear,and shafts.This my fouth winter coming up and the best money I spent .I can't wait to hammer on the yammmie boys and there rx-1`s.When in cape breton becareful because down here we call it Cape Breton Stock...

hey there. I've decided. I'm gonna bore my motor. I just picked up a wrecked 98 zl (with only 1500 miles), so if I run into problems I've got a spare motor to get around.