750 with 800 pipes

[rustman]

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

[94max]

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

Mark

[YAMMIEGOD 3:16]

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)

[rustman]

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.

[YAMMIEGOD 3:16]

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)

[rustman]

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

[4ever4]

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.

[YAMMIEGOD 3:16]

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)

[fastmax]

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?

[CaptJager]

Had stock on my 92 and added the 800 twins immediately that is before I went to PSI Quads. Not to hijack but couldn't resist the plug 800 twins for sale (http://www.vmax4.com/vbulletin/showthread.php?t=6522)

[YAMMIEGOD 3:16]

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)

[rustman]

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

[gitterdun1985]

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

[YAMMIEGOD 3:16]

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)

[rustman]

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.

[gitterdun1985]

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>>>>>>>...

[YAMMIEGOD 3:16]

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.
WHATEVER. !!! GLAD YOU DIDN,T GET A ANSWER. lol. 3:16 (yammie tony)

[4ever4]

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.

[gitterdun1985]

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.

[4ever4]

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.

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

[gitterdun1985]

i get what your saying, but why will it still beat an 800 and is 10 hp less....

[4ever4]

No one said a 750 would beat an 800. I have 2-750s and 2-800s. I did say neck and neck. The reason I feel this way is because of rotating mass in the driveline. Remember, every pound of rotating mass is the equivalent 7 pounds of stationary mass when it comes to racing. In other words, if we had identicle sleds and you stripped 7 pounds of weight off yours and I shaved 1 pound of rotating mass from my driveline, we should still have about the same performance.

[gitterdun1985]

a 750 will beat a 800 neck and neck with added 800 exhaust

[4ever4]

Ahhh! I see what your getting at. You know what, I'll place my money on the 750!

[YAMMIEGOD 3:16]

I NEVER SAID THAT. FASTMAX DID. AND IF HE MADE THAT MUCH OF A PERFORMANCE GAIN ON HIS 750, THAT MAKES MY POINT EVEN MORE. REALLY DON,T KNOW WHAT YOU GUYS DON,T UNDERSTAND. WE ADDED A 800 EXHAUST TO A 94 750 AND WE HAD TO REJET AND RECLUTCH. THATS ALL I NEED TO SEE. THAN WHEN WE FIELD TESTED THEM MY 800 WAS 1/2 SLED AHEAD. LOOK, LET ME UNDERSTAND THIS. YOU CAN BOLT ON QUADS ON A 750 AND ADD 18 EIGHTEEN HORSE, BUT YOU WON,T GAIN 9 BY ADDING 800 TWINS ? OK, !! LIKE I SAID LEARN SOMETHING NEW EVERYDAY AT vmax4.com. lol. 3:16 (yammie tony)

[4ever4]

Tony, good to hear of a real world field test! I would have lost money on that one!lol.

[750max]

anyone have jetting/ clutching specs after doing this mod? debating doing this, thanks

[fastmax]

Use stock 800 jetting(mains and needles) if you put 800 pipes on a 750. I use a comet primary and a cat secondary on my 750. It is way different clutching than a yamaha setup.
We will see which one is faster when I get my 800 dialed in. Right now my 750 is faster than my 800. (my gut tells me the 800 is gonna win)

[Ken]

Just for the sake of conversation.

92/750 - 130hp - .1733 hp/cc

93/750 - 140hp - .1866 hp/cc

95/800 - 150hp - .1875 hp/cc

In the 800, 50cc's equates to about 9.375 hp.

I realize that there are a lot of other factors involved but it does give some idea of hp vs. cc's.

[VMAX535]

Had stock on my 92 and added the 800 twins immediately that is before I went to PSI Quads. Not to hijack but couldn't resist the plug 800 twins for sale (http://www.vmax4.com/vbulletin/showthread.php?t=6522)


$$$$$$$$$$$$$

[INLINE4]

What about a 1992 880BB....Ah......Yea......:frech11:

[rustman]

Just for the sake of conversation.

92/750 - 130hp - .1733 hp/cc

93/750 - 140hp - .1866 hp/cc

95/800 - 150hp - .1875 hp/cc

In the 800, 50cc's equates to about 9.375 hp.

I realize that there are a lot of other factors involved but it does give some idea of hp vs. cc's.

This actually proves my point. You have it right here. The difference in hp is 9.3hp. Now if the pumped up pipes on the 800 make 9 extra hp then the extra 50cc's are only responsible for about .375hp. If this holds true then if you were to put pipes from a 750 on an 800 they should have 140.375 hp. Does anyone hear what I'm trying to say? The only other thing I can figure is that the 800 pipes are so perfectly designed for a 750 that they coax out 9 more hp while making no difference to an 800 letting the extra 50cc's make the hp instead. Maybe.

-Kenneth

[dermestid]

I know the 750s have problems with the crank going out of phase but would adding 800 pipes increase the risk?

[speedmax4]

[quote=dermestid;47348]I know the 750s have problems with the crank going out of phase but would adding 800 pipes increase the risk?[/quote

I would say there would be little to no increase in risk because your peak RPM should be the same with either pipe. Tom