750 with 800 pipes

rustman

rustman

Active member
I have a quick question. If 800 stock pipes add 9hp to a stock 750 and there is roughly 10hp difference between the 750 and the 800 stock, what did the extra 50cc's add?.....1hp?

-Kenneth
 

A better Crank and a ton of improved Stock potential. and Don't forget the better secondary clutch on the 800.

Mark
 
REALIZE THE DEFFERENCE BETWEEN THE 750 ENGINE AND THE 800. YOU REALIZE HOW HARD IT IS TO ADD 10 hp TO A MOTOR. PIPES NOT INCLUDED. 3:16 (yammie tony)
 
It still doesn't make sense to me. Call me what you will but it really makes no sense. The 50cc's alone should be enough to make up the 10hp difference between a 750 and 800. If the pipes add 9 hp then a stock 800 should have 160 hp or so. I'm not a mathematician but I ran a few numbers and it seems to me that a stock 750, '92's not included, makes about .186hp per cc, based on 140hp, while a stock 800 makes .187 per cc based on 150hp. If 800 stock pipes alone added 9hp then the 50cc's did nothing. I think that the 9hp claim is a little on the high side, has it ever been dyno'ed and proven? Has anyone ever dyno'ed an 800 with 750 pipes on it? If logic holds true then an 800 with 750 pipes should run 140 and a couple horse.
 
I THINK I PROVED IT. TWO THINGS I SAW WHEN ADDING 800 PIPES ON THE 750. FIRST 750 WAS SO LEAN IT POPED WHEN YA HIT THE GAS. WE REMOVED PLUGS AND THEY WERE SNOW WHITE. WE THAN INSTALLED 800 STOCK JETTING AND PLUG COLOR WAS SPOT ON. NEXT WE FIELD TESTED THESE AT THE DRAG STRIP. MY 95 800 WAS DYNOED AT 151. MY 95 AND MARKS 94 WERE WITH,IN 1/2 SLED OF EACH OTHER. AND YOUR CORRECT, DYNO WOULD TELL FOR SHURE, I CAN TELL YA 750 QUADS ON THE 800 ENGINE ADDED NO HP. SO NO DOUBT 750 TWINS ON THE 800 WOULD LOSE HP. IF THATS YOUR 94 IN THE PICTURE INSTALL 800 PIPES ON IT AND GO FIELD TEST IT. YOU WILL NO RIGHT AWAY IF YOUR MAKING MORE POWER IF YA HAVE TO REJET AND RECLUTCH. 3:16 (yammie tony)
 
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It's funny because someone else I was talking too actually said they put 800 pipes on their 750 and it ran too rich. And if the pipes do add the power claimed then it almost illustrates my point even further. If a stock 800 and an "800 piped 750" run within 1/2 a sled then doesn't that mean that engine size is irrevelant when running a vmax-4 assuming you can get the pipes from an 800. Was the '94 750 running stock driveline, not the setup but the components? Now this may seem a little naive but I have never seen an 800 before, I own 2 750's but have to yet to look at an 800 up close and personal. So what I was wondering is if they run the same pipe setup? ie two manifolds feeding twin pipes into the silencer. I have aaen quads on mine right now, yes that is mine on my avatar, so my jetting isn't stock but it wouldn't take much to change that back so that I could try a set of 800 pipes out. Just trying to understand why a set of 800 pipes makes such a difference, 9hp is quite a bit to gain for the price of used "very stock looking pipes".

I actually had to go outside and check my manufacture date after seeing it called a '94 because I was under the impression that it was a '93. The date said 09/92 making it a '93, funny because my registration says '94 too.

-Kenneth
 
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750 vrs 800? could get to be a touchy subject here.
The pipes- 800 pipes have a little larger Y's and inlet to the expansion chamber, therefore would have better breathing capacity and apparently in this case improve performance.
The engines- I'm assuming that Yamaha made the port timing a little more conservative on the 800 along with other changes, such as eliminating the bridges in the intake ports and using better coupling in the crankshaft, to make a more durable engine.
The 800 also had a beefed up driveline making it a much more durable trail sled. There is no doubt in my mind that across a lake the 750 could stay neck and neck with the 800(again, just my opinion). This come down to rotating mass in the drive train vrs Hp. That being said, unless you are trying to eliminate rotating mass for racing purposes, the 800 is a much more solid platform especially when doing mods. Example: no crank welding needed to increase RPMs with pipes. Remember, not all 750s are equal. Before Yamaha raised the port timing in 93, these only put out a little over 130 hp. Raise the port timing in the 800 and I'm sure the numbers will change.
 
KENNETH, HOW MUCH HP YOU GAIN ADDING AAEN QUADS TO YOUR 750 ? FOURTEEN, EIGHTEEN ? LOOK AGAIN ALL I CAN SUGGEST TO YOU IS TRY A 800 EXHAUST ON YOUR 93. IF YOU NEED TO RE-JET AND RE-CLUTCH. YOU ADDED POWER. ITS THAT SIMPLE. YOU CAN DO ALL THE MATH FIGURES YOU WANT. TWO WAYS TO TEST THE BOLT ON PERFORMANCE GAINS OF A SNOWMOBILE. ONE IS DYNO TESTING, THE OTHER IS IN THE FIELD. 3:16 (yammie tony)
 
I put 800 pipes on my 93 750,jetted it to 800 specs,got the clutching dialed in, and it just eats my 800 now.(I mean it just blows the doors off it!!) Cheapest upgrade I have ever done to a sled.
Now I have to re-clutch my 800 so it will keep up with the old 750.
Tony I am going to try a 52-42 helix,with a Dalton red secondary spring and a Dalton Black/red primary spring in the 800.Think it will work?
 
DO YOU THINK YOUR 93 750 WOULD EAT YOUR 800 BEFORE YOU INSTALLED THE 800 EXHAUST ? I DON,T KNOW WITHOUT LOOKING THE SPEC ON THESE SPRINGS FROM DALTON YOUR USEING, I DO KNOW THAT HELIX SHOULD WORK NICE FOR YA. 3:16 (yammie tony)
 
It seems to me my question is just about answered. The 800 engine just seems to not have to work as hard to make hp, making it more reliable. I'm sorry if I sounded a little bull headed but well I am sometimes. Instead of making a 750 that is "stretched to the limits" maybe an exaggeration, they opted to increase cc size and add better pipes to make more hp. 750cc's always seemed like an odd size to me, it's too big to race in the 700 class but seemingly undersized to race against 800's. At least that's what they told me around here, I have never raced before so I have no idea about classes and what not.

I'm not sure how much my aaen's added for horse, those pipes sure improved the sound and has added some top end. They claim 18 but I'm not sure, no dyno or radar or anyone around that I can really compare to. I changed my mains to 140's, not sure if I should put bigger or not. The plugs are just about perfect color, a nice cardboard brown. I drink black coffee so it's hard for me to compare plugs to that. I also am sure I need to change helixes. It seems to me that at low speeds under hard acceleration I'm revving higher than what I'm pulling away but after 80 or 90 mph all seems fine. Also seem to be revving quite high, I was on the river about a month ago looked down and saw the needle at 9300. I backed out quite quickly. The speedo was at the slash in km/hr though, that was nice. I found out too late in the season that a guy just down the road has a radar gun, too bad the snow is gone now. Next year I guess.

Kenneth
 
When we were always on the river tryin them out their was never no cats around haha or neone must have heard the mean ROAR of the V4 engine and went in hiding HAHAHAHA!!! Theirs always next year BRRRAACCCKKKKKK OBAMA
 
ONE OF THESE DAYS, I WILL POST TO YOU THE DEFFERENCE BETWEEN THE 750 AND THE 800 VMAX 4. IT WAS NOT JUST INCRESE cc. 3:16 (yammie tony)
 
I really wasn't interested in all the differences. I was just interested in what the extra 50cc's added in terms of power. And from what I've been able to discern, nothing is the answer. Well 1hp.
 
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Its still not clear why a 750 with 800 pipes will pass a 800 with the same pipes in my opinion its not logical ........ so if you raise the timing ports and all that other bullshit done to the 800 the 750 would be the machine to beat.. AM I CORRECT>>>>>>>...
 
rustman said:
I really wasn't interested in all the differences. I was just interested in what the extra 50cc's added in terms of power. And from what I've been able to discern, nothing is the answer. Well 1hp.
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WHATEVER. !!! GLAD YOU DIDN,T GET A ANSWER. lol. 3:16 (yammie tony)
 
Kevin, you have it backwards. The 800 has more conservative port timing than the 750. Like Tony is pointing out, 750 is a great engine, 800 is better. A lot of variable come into play when comparing apples and oranges.
 
What i'am saying is if your can get the port timing the same with the 2 engines the 750 would destroy the 800.... right.
 
gitterdun1985 said:
What i'am saying is if your can get the port timing the same with the 2 engines the 750 would destroy the 800.... right.
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No, just the opposite! Remember, when the port timing was more conservative on the 750 in 92 they only produced a little over 130hp. So the most fair comparison, which you guys seem to be trying to do, would be the 92 750 to the 800. That's 20hp difference, and even if you use 800 pipes there's 10hp difference. As Tony said that's huge for 50cc!
Hope this makes sense.
Peter
 
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