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Yamaha Rhino Engine Swap Discussions Yamaha Rhino engine swap discussions.
Rotax swap, R1 swap, etc.

Thread: Rotax 1004cc VS 840cc vs 800cc Video Reply to Thread
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  Topic Review (Newest First)
08-04-2009 01:20 AM
warlock Well I have driven some of the best just to let you know. This aint my first rodeo. Ive been around fast shit my whole life and weve always worked at makin it faster. Ive seen plenty of whats out there on the Kawierider forums and Ive seen some fast kawies but there maxxed way out and blowing shit up no reliability. Dan Kelleys Tyrex made some impressive #s and high speed runs around 99mph and then the rod let loose. Done fuckered it up good. The only way there really getting the #s is mega RPMs like 13k this shit cant take those kind of RPMs. I hear of some guys going through belts every 22hrs or so. There is always room for improvement and more HP so as long as your willing to be the Guinea pig and dont mind working on broken shit and your buddies dont mind towing you in out of the dunes all the time go big then.
08-03-2009 08:44 PM
Brian B Well, I'm sold!

I'll be doing a liter kit next summer along with a ground up resto!
08-03-2009 08:29 PM
V2PRODUCTS
Quote:
Originally Posted by warlock View Post
My brothers Tyrex has the custom intake
If it has the plenum on it ...... it is not working as good as it could. An AFE intake is not adding much over stock and is far from custom. The AFE is barney bolt on.

Quote:
Originally Posted by warlock View Post
I really dont see it gaining much more in the 39 carbs maybe a little bit
If it is ported and had a open intake it would gain more then you think i bet ..... just go to the brute force forums. They have been building these engines for years and are getting great HP numbers.

Quote:
Originally Posted by warlock View Post
but it runs great the way it is.
Best you know is the best you have driven.

Quote:
Originally Posted by warlock View Post
But I dont think there is anywhere close to 7 to 10 hp to be found. Maybe 4hp to 5hp. Maybe ?????
I guess we wont know till someone does it. I dont care and am not arguing .... just saying these engines have alot more potential then what is out there now.
08-03-2009 07:22 PM
warlock
Quote:
Originally Posted by V2PRODUCTS View Post
Is it running stock carbs and a stock plenum? If so there is some serious HP to be had by getting rid of the stock carbs and going with some 39's ... then ditch the plenum and run an open intake ontop of the carbs. Soem guys on the teryx forums have done this.

Also no porting right? ..... stock ports on the Teryx are not so hot. There is some more hp to be gained with a mild port job on the teryx.

I would bet with 39's, open intake and mild porting that car would gain 7 - 10 HP on that same dyno .... EASY.
My brothers Tyrex has the port work done too. and has the custom intake, I really dont see it gaining much more in the 39 carbs maybe a little bit but it runs great the way it is. The next thing he could do would be to cut the intakes off weld the big intakes on and do all of the big valves and thats about a Grand. Then the big carbs might come into play. But I dont think there is anywhere close to 7 to 10 hp to be found. Maybe 4hp to 5hp. Maybe ?????
08-03-2009 05:21 PM
michaeltom401
info

Quote:
Originally Posted by V2PRODUCTS View Post
I would bet you can get a pump gas 840 teryx into the mid 80's low 90's on that same dyno with the right combo of parts. Its just finding that RIGHT COMBO. I would also bet the rotax will lay down the same kinda numbers WITH THE RIGHT COMBO.
Maybe at 80 but not much over that! I know that weller race 800 that have everything put out 70+ hp but that is with everything. Custom fuel injection, valves, port, etc...40 more cc are not going generate more than 80, beside even in the 70+ range cases are cracking, diffs are blowing out etc... That is still lots of power that gets you well into the 80+ mph range.
08-03-2009 05:11 PM
V2PRODUCTS I would bet you can get a pump gas 840 teryx into the mid 80's low 90's on that same dyno with the right combo of parts. Its just finding that RIGHT COMBO. I would also bet the rotax will lay down the same kinda numbers WITH THE RIGHT COMBO.
08-03-2009 05:06 PM
michaeltom401
Quote:
Originally Posted by V2PRODUCTS View Post
Is it running stock carbs and a stock plenum? If so there is some serious HP to be had by getting rid of the stock carbs and going with some 39's ... then ditch the plenum and run an open intake ontop of the carbs. Soem guys on the teryx forums have done this.

Also no porting right? ..... stock ports on the Teryx are not so hot. There is some more hp to be gained with a mild port job on the teryx.

I would bet with 39's, open intake and mild porting that car would gain 7 - 10 HP on that same dyno .... EASY.
Jason is right that the 840 Teryx are putting out approx 63 to 65 with their kit. That is with stock carbs, no porting, no big valves, no clutch work. I think the rex I've seen are in the 70+ hp with 840 because they have Everything. I think the 840 kits on the rotax can put out just as much and with the lighter Rhino frame will be much quicker!!!!
08-03-2009 04:24 PM
V2PRODUCTS
Quote:
Originally Posted by warlock View Post
My brothers Tyrex 820cc motor built by himself and Dave Maxwell at 2x motorsports, Muzzy exhaust , AFE intake, Dasa intake mod, programable cdi by Dynatek and coils, Vforcejohn clutching, All perfectly tuned and runs on pump gas. It made 59hp on the Wellers dyno. and Jason Weller said his 840 was making 64hp.
Is it running stock carbs and a stock plenum? If so there is some serious HP to be had by getting rid of the stock carbs and going with some 39's ... then ditch the plenum and run an open intake ontop of the carbs. Soem guys on the teryx forums have done this.

Also no porting right? ..... stock ports on the Teryx are not so hot. There is some more hp to be gained with a mild port job on the teryx.

I would bet with 39's, open intake and mild porting that car would gain 7 - 10 HP on that same dyno .... EASY.
08-03-2009 03:46 PM
max powers here is a little help, I think. On a car dyno, not sure the maker, my stock 800 dynoed at 52.9 which is what the specs say it should do and 39 on the dyno jet.
my 840 put down 54 on the dyno jet, that's a increaese of 15 rwhp
rick's cat laid down the same # on the dyno jet, so I am assuming I am in the close to 70 rwhp now.
08-03-2009 03:38 PM
poflo
Quote:
Originally Posted by warlock View Post
Im assuming that most of the 840cc rotax motors that are not pushing fully modded heads are in the mid 60s hp.

My brothers Tyrex 820cc motor built by himself and Dave Maxwell at 2x motorsports, Muzzy exhaust , AFE intake, Dasa intake mod, programable cdi by Dynatek and coils, Vforcejohn clutching, All perfectly tuned and runs on pump gas. It made 59hp on the Wellers dyno. and Jason Weller said his 840 was making 64hp. So maybe a full tilt high compression radical port job big valved, race gas only spining some higher rpms will see 70hp but I dont think there every day 840 will do 70hp. atleast thats what Jason told me.
I believe Jason is right on
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