Exhaust Question?

[prettynifty4u]

Is it better to have the exhaust outside the machine or does it hurt to have it directly on the motor and then pipe it out (I know this will cause more internal heat under the body) but wondering if anyone had any experience with this?? The motor already has a factory exhaust on it or I can cut it off and pipe it out to the old 2 stroke muffler that is mounted outside the unit? The motor is a 22hp kokler v-twin and this is on the sears sportster that I am restoring. Let me know!!!

[jerrynuss]

How much ventilation to the motor will you have? All the new Maxs have the internal muffler and the Kohler command machines have had internal mufflers from the beginning.

[prettynifty4u]

Vetilation

This unit has 2 side vents tht are about 6" X 6" and the whole part of the top shell at the back has multiple oval vents that are open. It seems it would vent well, I was also thinking about installing a small cooling fan in the inside that pushes air out of one of the side vents.

[jpswift1]

I had the same thoughts about my Attex green machine 4 stroke conversion. I decided that I will mount the muffler outside the body in the stock location where the 2 stroke muffler originally was. I want the engine compartment to be as cool as possible. That is probably what I would do with your Sportster if it is possible (if you have the clearance available). Just my two cents.

[prettynifty4u]

Which Muffler

Jeff do you think that it would be better to retro fit the stock muffler from the kohler to fit outside since it is tuned with that motor or use the old 2 stroke muffler that is already fitted to the machine. The only concern I would have witht the 2 stroke muffler is a possible restriction.

[jpswift1]

I would certainly retrofit the Kohler muffler to fit the vehicle rather than use the old 2 stoke muffler. How is the Sportster coming along by the way?

[prettynifty4u]

SEARS

Right now all of the axles and shafts are at the machine shop, I should get them back by next weekend and I am going to paint the frame this weekend and the bottom tub next weekend. I bench ran the motor the other day and it purrs like a kitten. Everything is coming together, Im trying to find a good clutch, I would like to go with the 1190 (Quality Drive, Roy is the guys name) and then I will be able to start working on the motor mount.

Im ready to get it going!!!

[gunny]

I am not sure but it seems as though the 4 strokers are more heat tolerante than the 2 strokes are. There are kits for the 4 strokers that move the muffler into the engine compartment (Richards Relics), but if you had the 2 stroke variety I would think the more heat you could keep away from it the better.

[Robio_8x8]

I would think 2 strokes can handle more heat

I am not sure but it seems as though the 4 strokers are more heat tolerante than the 2 strokes are. There are kits for the 4 strokers that move the muffler into the engine compartment (Richards Relics), but if you had the 2 stroke variety I would think the more heat you could keep away from it the better.

All materials being equal the two stroke has less moving parts,handles a higher red line RPM. In snowmobiles the only reason I can see some are 4 stroke are for environmental reasons. The only way I can see a 4 stroke can handle more heat is because it has to operate at a lower RPM, gives you less power to weight ratio so you need a bigger block for the same power .
Even when you increase the displacement of a 4 cycle it doesn't give you the same response a 2 cycle. Other then environmental and fuel oil cost 2 cycle is superior in power and performance.

[Jeff t-boss]

It's a combustion thing guys. We all know a 2 stroke fires every time the piston hits TDC and a 4 stroke every other time. However, a 4 stroke only has to burn a gas/air mixture, which requires less heat than a 2 stroke. Reason being; the oil that is added to the gas/air mixture in a 2 stroke. This all relates to what you guys are discussing. You've all heard of 2 strokes "LOADING UP" and fouling the spark plug from idling. That's cause the rpms are not running high/fast enough at a consistant rate to maintain the needed heat/compression to efficiently burn the oil that is mixed with the fuel. I don't want to come across as scientific, but just want to help understand the relation between the two. 4 strokes don't require those extra RPM's. 4 stroke advantage as you stated is better temp management. Disadvantage is weight/throttle response. 2 stroke advantage quicker throttle response and lighter weight. Disadvantage oil/fuel mix, requiring higher temps/rps to cleanly burn off the oil, noise. (However, the exhaust systems have qiueted down quite a bit over the years.) Hope this helps......Jeff

[gunny]

I want to party with this guy !!!