Rotax 537?

[Sentrek]

I got a guy possibly wanting to trade me this motor for my GSXR 750 motor (mine not running, this one runs). I havent had a chance to research it much yet. Just thought I would get your opinions on it. I am wanting to build a 2 seater shifter Kart, I want something I can dump the clutch on or downshift and increase the rpms / power on demand. This is a belt drive setup correct? HIt the gas and go, no gears or anything right?
I am afraid I will not be satisified with this setup.

Shot at 2011-08-17

Shot at 2011-08-17

 

[karl]

Its a free air so it will overheat quickly.

 

[jrmints1415]

VERY quickly

 

[karl]

VERY quickly

Yes my 77 arctic cat jag free air would overheat in weather alitte bit above freezing point.

 

[Sentrek]

Thanks guys, Just one more good reason to pass.

 

[redsox985]

If you provide it proper ventilation, it will not overheat. BigHead has used many snowmobile motors will no issues. And you're correct, it does not have gears. It uses a torque converter-esque CVT. Just a lot bigger for more power and RPM.

 

[fowler]

why doesnt your 750 run

it will probs be the better opion

 

[Sentrek]

I don't know, I think it may be the stator cuz the spark is kind of weak. it will try to fire from starting fluid but won't catch and run.
I got another guy wanting to trade me a 07 gsxr 750 (motor only) for my entire (incomplete 92). I think I am going to go ahead and trade him, even If I can't use it, it is much more desirable than my 92. Not to mention I only paid 600 for my bike and I already sold some parts off of it for $200

 

[karl]

If you provide it proper ventilation, it will not overheat. BigHead has used many snowmobile motors will no issues. And you're correct, it does not have gears. It uses a torque converter-esque CVT. Just a lot bigger for more power and RPM.

He uses fan cooled motors not free air. Also the clutches he uses are on the snowmobiles on the first place.

 

[KILLDOZER]

I've got a kart with a 340 free air engine, behind a seat; never once overheated. I run a little rich, and a little extra oil, and as much timing advance as the stator plate allows. No problem ever.

Keep in mind that 2 strokes are pulling ambient temperature air in through the crankcase at all times - and this provides a much cooler environment for the piston than in a closed crankcase 4 stroke. A little extra gas and oil help cool things down even more. The porting on my engine brings this cool air up the cylinder on both sides, which would cool the cyliner walls in transit. The free air motors have large and thick cooling fins, and the entire engine is aluminum - all of these elements provide for quick heat transfer and rejection. If it was originally a free air motor (ie not a FC motor with the fan and tins removed), it will be fine.

It has been a trend on this board to flatly state that free air 2 strokes overheat on a go kart. I actually built one, I actually drive one around (and I'm quite mean to it) and the fact is - they just don't over heat like everyone is so fond of saying here at DIY GoKart.

 

[the-cyborg]

I've got a kart with a 340 free air engine, behind a seat; never once overheated. I run a little rich, and a little extra oil, and as much timing advance as the stator plate allows. No problem ever.

Keep in mind that 2 strokes are pulling ambient temperature air in through the crankcase at all times - and this provides a much cooler environment for the piston than in a closed crankcase 4 stroke. A little extra gas and oil help cool things down even more. The porting on my engine brings this cool air up the cylinder on both sides, which would cool the cyliner walls in transit. The free air motors have large and thick cooling fins, and the entire engine is aluminum - all of these elements provide for quick heat transfer and rejection. If it was originally a free air motor (ie not a FC motor with the fan and tins removed), it will be fine.

It has been a trend on this board to flatly state that free air 2 strokes overheat on a go kart. I actually built one, I actually drive one around (and I'm quite mean to it) and the fact is - they just don't over heat like everyone is so fond of saying here at DIY GoKart.

I agree 100% I've heard people say that several times, and have never understood what their logic was, now if it were a forced air engine bastardized I'd agree, but a an engine that is built for free air is built for just that.

 

[KILLDOZER]

I agree 100% I've heard people say that several times, and have never understood what their logic was, now if it were a forced air engine bastardized I'd agree, but a an engine that is built for free air is built for just that.

And they do work! A month or so ago, I bought some rims and tires from a guy selling some of his spares to use on a new kart I am building. These were off of his midget outlaw sprint race cars. What do these cars run for an engine? Old free air sled motors with a centrifugal clutch put on where the CVT driver originally was... These things race sliding around on oval tracks where they're probably running between 6-8000 RPM the whole race. Obviously, DNF's due to overheated engines would have these cars running L/C motors, but they're not. The guy actually commented on how reliable they are.

And they're laying around for next to nothing. I've been eyeing a complete Kawisaki 440 sled in one of the local bone yards, guy wants 15.00 for the engine... just to keep in stock... I'm thinking of trying the centrifugal clutch thing on a sled engined kart. My 340 kart has the whole CVT from the sled, and it takes up a lot of room, and adds weight. These F/A sled motors are compact, light, and look great. I think a cent clutch/F/A sled motor kart could be built very small, and extremely light... I'm thinking something like Russ's twin lawnboy kart, same size chassis, with a an old 440. It would all be ultra cheap except for the clutch that needs to handle 40+ HP...

 

[Sentrek]

I figured it would be fine, just didnt want to get in a debate about it. The real reason for not wanting to get the motor is because I am looking for something with a gearbox, something I can dump the clutch and do smoky burnouts or downshift to get the rpms up high in a hurry.
I got this instead. Its got so few miles on the exhaust ports are still clean.

Shot at 2011-08-28

Shot at 2011-08-28

 

[karl]

Really? Mine must be running alittle lean. I might haft to put my 340 jag free air a cart. Killdozer, if you find a clutch for it can you post the link?