Bender and Hauck Said not to use 38mm Mach Carbs

MountainMax

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May 19, 2003
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Churchill Falls,NL, Canada
Hey guys, I phoned Hauck and Bender USA and they both recomended against using the 38's on anything except Benders 835 SRX big bore engine, said they are hard to set up and could loose HP, can this be true, I thought with any engine, putting bigger carbs on them and bigger pipes always meant more HP, it will probably lessen the drivibility factory a little if it's too big. But bombardier, Polaris and Arctic cat all use these size carbs on their triples, I know they are a little bigger then 700 but Bender and Hauck said not to use them on 760 and 800 big bore either, how can this be? I though it was a very popular mod for Yamaha Triples in any size/configuration. I know some people here have them done also, so who do you guys find them??? please give me a little help here.......
 

hi MM,

I had oversized carbs on a polaris and coul dnever get it to work properly.
It had the ocasional bog and sputer.
When I had it looked at by a snowmobile racing mechanic he said the carb were oversized for the motor and it would never run right.
I never got an explaination why.
I know this does not really help you but I thought i'd share my experience.

by the way what's the HP of your machine now.
 
Thanks for your input, but I also know the old 1978 yamaha SSR 440 had twin 44's stock, and that ran fast, I asked SLP and they said they may bog a little on take off but would give another 3-4 HP on top end. but in my opinion if bombardier used them on an 800 and it worked great, coulnd't a big bore yamaha 800 be very similar????
 
Kind of the same thing, but....

Back in my younger (read, less educated) days, a friend and I "built" a 305 Chev. Put on Camelback heads from a 327, different cam, new manifold, new "Rock Crusher" 4 speed, etc... Some guys had raved about the 650 Double Pumper Holley. So we put one on.

Damn, the thing would just not pull until 4500RPM, then went off like you lit a roman candle.

Put a 600 vacuum secondary on and it ran way better and was quicker.

Moral of the story.... Bigger is not always better.....
 
Yeah, I understand that, I did the same thing with a 318 dodge when I was 16, lol. but in this case, which i think im right, I may loose a little throttle response off the start but for drag racing, (which i want to use these) they should give me peak HP right? Bender said they will actually make you lose HP, I really can't understand this, as they say they work great on the 835's, can there be that much difference between the 800 big bore and the 835???
Also I figured the 38's would be awesome for the 800's because 600's can use 33's up from 31 stock, 700's can use 36's (bored)from 33 stock, so the 800 should be able to take the 38's right???? maybe?????
 
robertdawe i have the bender 800 bb and i run with 38 tm carbs....i like them alot great carbs for my sled had no problems dialing them in either........course they had projet system so changing jets was little problem just a twist of the dial
 
Bender told us that playing with the 38's wasn't worth the hp gain. They fit kinda tight in that area and are a problem getting big filters to fit right, unless you modify your air box and use that. I believe we gained more than we expected from them. Not much loss on the bottom but more on the other end. We found higher rpm hole shots plays into the equation for the bottom end problem. Well worth the chase to make them work.
 
Thanks Guys, you are making me feel a little better about my purchase, I have installed a couple of spring shims to increase my initial rpm so the bogo should'nt be a problem, I just need some initial settings to get them to work.
 


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