VMAX 540 big bore

tyler440

tyler440

Member
Joined
Jan 20, 2006
Messages
363
Age
41
Location
Clarion, PA
Website
www.vintagevmax.com
there a while back i posted about how i won some big bore jugs and a head from ebay... along with a junk piston.. well here is an update... the piston had "venoila" on it so i got ahold of them and they said they didnt have the specs on it anymore but they could certainly make me one for $100-$150...(x2) he actually said 150 would be "the extreme high end" so thats good(could be worse at least).. i didnt ask if that included the ring or not but ill worry about that when the time comes... instead i told him that i have to get some more of my ducks lined up before i decide what im going to do... which leads me to my next question.... back when i originally posted someone told me that i would need to run 44mm carbs with the big stuff... my question is... what should i be looking for?... there are a few different models of mikuni 44mm and i would have to think one is better than the other but i dont have a clue which one... also to the guy that said the pipes need cut... did you ever manage to find any pics of those? thanks again
 

I used to know someone with the formula 3 porting specs for the 540 and he told me about the pipe mod which I have confirmed since as well. He told me to cut the flange off at the engine and remove just 10 mil, then weld them back on. But that's for stock displacement, don't know what you should do for the big bore. Good luck. G.
 
I have a set of Bender racing modified stinger race pipes on Ebay right now for the f3 V max 540. Jeff Wurl
 
yeah ive been seeing those on ebay.... im not really sure they are what i need for this motor tho... it has been proven that the aftermarket pipes only lost power on a STOCK vmax motor... however this motor would be far from stock but that doesnt mean the bender pipes would be a good match for it either... i dunno im just looking for some insight... as i am not sureonly anything when it comes to anything thats not stock on a vmax
 
hmmm ill look into that company... that would be awesome if they still had some parts laying around that they wanted rid of.... they might not fit this motor tho since the stampings on it lead me to believe it came from Spencer Sports Racing or dave delaughter.... either way thanks

EDIT: got an email back from SLP and they said they only did that for a short time about 20 years ago, there wasnt much interest and nothing is left on the shelves
 
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I have a 81 SRX with an FIII ported 540 Vmax engine in it with 44s ect. The only reason you would need the pipes cut on the "Big Bore" is if you want to run a higher RPM. I would suggest that the Big Bore would probably work better at the stock RPMs that the stock pipes are designed for. Back in the day, Dyno Tech tested the cut down pipes against stock + Aaen pipes on an FIII engine. The shortened pipes made slightly more HP then stock but I would suggest that most of the gain would be lost in the clutching/belt efficency loss of raising the RPMs.
I didn't know Bender made pipes for these 540s[they may be modified stock pipes]...if Tim was running them in his FIII I would say they must be good! Bender raced the VMAX 540s successfully before he moved to the Exciters and then his absolutely dominant VMAX4!!!
JM.02c
 
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NOT TO HIJACK HERE, BUT I TOOK MY 1983 VMAX OUT FOR A SPIN TODAY. SLED IS ALL STOCK EXCEPT SOME CLOWN NAMED '' YAMMIE GOD '' BUILT A CLUTCH KIT FOR IT. 21 DEGREE,S TODAY AND MAKING JUST PURE HP!!!!!! THIS SLED FLYS. 3:16 (yammie tony)
 
@sideshowbob.... hmmm you may have a point there about losing all the gained power in the driveline.... also i am curious exactly what 44's you are running... im slowly trying to gather parts to put everythign together and i want to know what i should be looking for.... i see all kinds of 44mm carbs on ebay but im sure their has to be a preferred one.... have you ever been to vintagevmax.com? i dont recognize your name but maybe you have a different one over there... either way you should check it out, we would sure appriecate your knowledge over there... thanks
 
Just saw this after looking at old posts if you still have that could you send it to fournier2870@yahoo.com the 44 mm carbs had power jets in them if I remember right but can't remember the jetting. any how if you can send thanks in advance
 
I realize this post is from many years ago, but wondering what the Big Bore kit talked about here came out to for size. Mine is 617 using 670 Skidoo pistons I'd have to look but i think its 73mm. Also have a SRV Fan engine of the same size.
 
Thanks Jeff, I haven't thought about doing any other big bore engines for a while .Might look into something alittle stronger for my wifes 81 Eltigre 6000, right now shes the slowest of the 3 and Wendy ain't liking that.
 
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