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Who still makes big bore kits

Well I grew up around yami 2 strokes and had a 97 MM 700 that I modded out a little bit(pipes 151 track and bar risers) I loved that sled but I sold it for a Polaris gen II mod with an 800 xcr triple in it. Sled ripped but blew up. I'm wanting to get back into a yamaha MM or viper but I want it to eat up all the new stock 800s

I know the union bay 944 is great but no longer available.
I've also heard good things about price big bores but can't find a website or anything for them.
I know there were some 800 big bores for both the MM and the viper but can't find that either.
All I can find is a hauck 760 for the MM and a hauck 900 for the viper.
Are there any companies left that make big bores for these amazing engines?
Or am I going to have to go to an A-arm sled if I want to hang with the new sleds?
If rather spend lots of money to make a MM or viper beat a new pro or m8 than get an A-arm sled.
I'm I stuck in the past or is it doable?
Any input would be great!
Thanks
Spencer
 
M
Nov 26, 2007
127
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Red head is the Mountain Max. Blue is the SRX. Black is the Viper. I had a 770 BB kit for the Mountain Max. Made 153 hp if I remember correctly. THey were super reliable, and pulled a bit stronger than a well build 700 MM. Keep in mind though, that porting on a MM, there are huge differences in what is done out there, and what makes POWER, and does so reliably.

The CNC was used to bore the cylinders, then I ported them, and then sent them off to be renicasiled. And, then the heads were cut in the CNC to proper squish and compression ratio.

It is VERY hard to beat the 700 though, with good porting, and good setup. They just plain work. Buck for bang, thats a good little weapon. the 770 kit made about 4 to 5 hp over the 700. ( 148hp or so, to 153hp) Some of the 800 kits for the MM out there, that utilized a cylinder base spacer, didnt make very good power.. due to a multitude of reasons. One being crank case volume on a short stroke engine.
 
The 700 is a great motor I just need more power than it makes. I don't know if my dream of making an old mm beat a new 800 is realistic. There has to be some reason why people are selling there full mod 1000 mountain maxs for less than 4000.

So say I can find a union bay 944 or any other big 700 based engine that isn't made anymore, will I be out of luck as far as parts go? Like rebuilds?
 

TRIPLESWILLNEVERDIE!

Well-known member
Lifetime Membership
Feb 19, 2008
526
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Northwest, MT
Stay away from the Price 950 kits. They dont like base gaskets. LOL!
The Union Bay/Fastrax 944 is basically the same thing only monoblock cylinder design that helps eliminate the base gasket issues I had experienced with the Price kit. You might give Curt a call. He might know of a customer or two that have 944's up for grabs. Never hurts to ask around.
Also, you cant go wrong with MadMaxPerformance port job! Never seen his 770 kit on anything in my neck of the woods but I wouldn't hesitate to try one. The guy knows what he is doing.:thumb:
 

madzx2

New member
Premium Member
Aug 1, 2008
38
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X2 on Mrviper700 on TY, had him set me up a 780 for my srx. The thing flat out hauls the mail.

Sent from my DROID BIONIC using Tapatalk 2
 

Wrenchmaster

Member
Lifetime Membership
Jan 24, 2011
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B.C. Canada
I Know this is an old thread, just thought I'd see if you got a modded MM700 or found a BB for one?
Considering the cost of a custom engine, why not build a turbo setup? I know it's been done and Gus says 200hp, don't know how reliable lol but it'd make that at 6500 feet elevation too and that would waste a stock 800 on top of a mountain, I see the turbo 4 strokes do it all the time.
 

Ford428CJ

Well-known member
Lifetime Membership
Jan 16, 2009
380
52
28
Klamath Falls, Oregon
Red head is the Mountain Max. Blue is the SRX. Black is the Viper. I had a 770 BB kit for the Mountain Max. Made 153 hp if I remember correctly. THey were super reliable, and pulled a bit stronger than a well build 700 MM. Keep in mind though, that porting on a MM, there are huge differences in what is done out there, and what makes POWER, and does so reliably.

The CNC was used to bore the cylinders, then I ported them, and then sent them off to be renicasiled. And, then the heads were cut in the CNC to proper squish and compression ratio.

It is VERY hard to beat the 700 though, with good porting, and good setup. They just plain work. Buck for bang, thats a good little weapon. the 770 kit made about 4 to 5 hp over the 700. ( 148hp or so, to 153hp) Some of the 800 kits for the MM out there, that utilized a cylinder base spacer, didnt make very good power.. due to a multitude of reasons. One being crank case volume on a short stroke engine.

Still building a 770 Red Head kit?
 
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