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A few guys have told me that the 81 440 SRX is faster then the 540, I was lookin at the blown up 81 440 on my bench and want to put together the 440 motor again but reluctant because you cant get pistons and they blow up. I also heard of guys using the 81 440 pipes on the 540 motor because it can rev higher.
Which is faster??

The 81 was set up more for top end and I think it is a little faster,but the Vmax has a lot more bottom end and mid range so it is a little quicker then the 81 .If you set them side by side and run them off the Vmax will get a good lead and it will take a while for the SRX to run it down. BUT it is like anything else ,different sleds different results. The last I knew Lemans still makes pistons for these sleds.
Do the SRX up and enjoy it ,yes they are finiky but if you jet them for temp and altitude and use GOOD GAS they aren't as bad as people make them out to be.

also one of the major issues with the srx was that the clutch mounted further away from the bearings than the vmax... you may want to consider using a vmax crank when you build your motor.... i guess the mikuni 38's will work pretty good on the srx also.... vmax-540 is right about what he said.... the 81 has actually a couple more ponys on top end... because it has some huge ports and wild port timing... all depends on how many lakes you plan on tearing butt across.... if you do go with the srx motor i suggest you also go with the srx chaincase and drive spockets if you can.... yamaha had this stuff pretty well engineered to begin with... after all they were the top of the line racers for all of the 80's.... case and point, no one could make pipes that worked better on a stock 540 than yamaha shipped... stock

Hey guys would I be ok putting the 540 engine in the 81 srx with its gearing and afew guys told me that putting the 81 srx pipes makes it run like a big version of the srx and I could just set the clutch up like a 81 srx. It would be like a srx on steriods lol.

eh ive heard that too but im not so sure if i believe it.... it might rev higher but that doesnt mean its going to make more ponies... if you look in our article index you will find the 540 pipe tests... there is says how the stock pipes were better on a stock motor than any other pipes made... now granted they did not test the 440 pipes on the 540 motor but, i would just find it suprising if they 440 pipes were actually better...


as far as the chain case goes... everything will work alright, i know the gears arent the same tho.... im not positive but im thinking the SRX probably has a lower gear since the motor turns a higher rpm... also the shafts that the gears go on is different from the srx to the vmax, therefore you cant just take the vmax gears outta of one sled and put them in the srx.... in order to do then you have to swap the jackshaft, chaincase, gears, chain, and "drive shaft"


the sled will go and it wil be fun with either setup and either motor but to get the full potential will take a bit of thinking/ tinkering

Only have a min before its off to the track for the week end but hope this will help understanding. Clutching and gearing are related, but not the same thing. The clutches will be set up to give you the rpm you want the engine to run at as it goes from its shift out point on up. That rpm range you ( or the factory) picks is based on the power curve of that particular engine.
Gearing like the rear end gears in a car, will give you the option of balancing two different things. A lower gear ratio ( higher numerically) will give you faster acceleration. A higher rater ( lower numerically.) will allow a higher top speed until the clutches go into over rev, or you just flat run out of power.
Whenever you change gearing, the shiftout point of your clutch will change some, if your looking for max power from your engine, clutch weights and possibly spring should be changed to again put the shift point where you wanted it to be.

pipes are designed to work with the design of a given engine. V Max pipes are very good is my understanding. Many things determine where an engine makes power, port layout, the bore/stroke ratio along with the rod length will determine where that engine makes the most power, and how broad that power band is. Swapping pipes may or may not find you some power depending of course on the design of both pipes your trying and how good each pipe was made for its engine. Then of course you have to go back to clutching to make sure your engine NOW runs at the rpm the new pipes want.

Engine builders use dynos to precisely pin point all these little details, randomly throwing parts at something seldom gives the desired results

wow thats spot on bob... you get bonus points

No contest the VMAX will out run the 81 srx 440!!

Undertaker#13 wrote:No contest the VMAX will out run the 81 srx 440!!

I'd be curious to hear your reasoning on this? if you have any

Where do I find some piston kits and cylinders for the 440?? Ive tried to get ahold of chuck because he has that parts list but I cant get ahold of him.

Posted: Sun Aug 16, 2009 4:53 pm Post subject:

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Undertaker#13 wrote:
No contest the VMAX will out run the 81 srx 440!!


I'd be curious to hear your reasoning on this? if you have any ?? I've raced agains't some of the best iron for 19 years! I've battled 1977 z cat sno pro's, Indy 650, other VMAX 540, 78 srx 440, ski-doo and so on! !Like I stated 'no stock 81 srx 440 will out run my VMAX!! tyler,I know a 81 440 srx will not run mid 90's in 1000ft on radar!

Ive never rode a 440 but I can see a 540 beating it in a dragrace, my vmax has a lot of power and I cant even get it to hook up out of a hole shot with a track that has a few studs in it. But ive heard the 440 has crazy mid-top end horse power its looking like i will soon find out.

HI chrisrider63 what are you running for studs? This is the issue you can't trail ride & race you have to do one or the other.I have mine set up for racing 1000ft. My VMAX pulls out of the hole great. Have you ever checked the ice to see what your scratch marks look like? I do my own stud patten. Also don't run just a few studs you will damage the track, by bending the studs or ripping the studs out! I still say the VMAX was built way ahead of it's time! These sleds still run and beat the new iron! I've added a picture of my 78 srx 440 top speed mid 80's in 1000ft

chrisrider63 what year VMAX do you have? Mine is a 1984 with just over 3000 miles

sure no stock srx will beat your precisly tuned racer.... no stock(street) impala can beat a nascar toyota camry either i dodnt know which will beat which because ive never seen them lined up side by side... and even if they were you cant guarantee that which one will win evertime, everyday... beside not all of us go straight on ice... you cant just think that the 540 has 100 more cc's than a 440 so it has to be faster... you do realize that stock the 440 actually has more HP, cause thats a fact....

my personal opinion is that the 540 is faster, because it has more torque to get out of the hole but i wouldnt not be a damn bit suprised to get my ass handed to me by a 81... they really wind and actually make more power.... i think there are too many factors to say for sure