Sled engines+silly people+warm weather=bad advice

[squat251]

this is a bit of a rant, so I'm just going to warn you all. input is welcome however.


Okay, everyone who tells someone that a snowmobile engine will not work/ run properly in warm weather needs to get their facts straight. I just want to point out a few common errors in thought, and correct them.

Stupid comment #1 "You could use a sled engine, but its going to over heat." FALSE! ever heard of turf drags? I've even attended sled drags on pavement in the heat of summer, no problems.

#2 "Those engines are tuned for cold weather, so they wont run worth a **** in the summer." FALSE worst thing that's going to happen, is its going to need the mix screw adjusted to run a little richer/leaner, after that it will perform just as good as a Motorcycle engine.

#3 "Your only going to be able to use a liquid cooled motor, cause everything else will run way to hot." FALSE a liquid cooled may run a "bit" cooler, but will run just as good as a fan, or even air cooled engine. Hogs run just great don't they? the answer is yes, yes they do.

#4 (and final) "Don't use anything bigger than a 340cc or it'll burn up." WTF ARE YOU ON? if i need to explain this, after all that, you need your head examined.

final thoughts: what have we hopefully learned here? I hope that you wont hesitate to use a sled motor now, as long as you can fit it, and it wont be too much for you or the frame to handle, do it, you wont regret it. By the way, this isn't written out of ignorance, here, in Michigan I have either built, or helped to build at least 20 sled engine powered carts. all of them run great, and will continue to run great with proper maintenance.

If you need more proof, I might be tempted to track some of these carts down, and tape them. Or you can just look up summer sled drag racing its pretty common.

If I've missed something, please feel free to post it.

 

[Affair_driven]

No argument from me.
I don't disagree with anything you speak of.
Many posts on this site are just plain false/wrong/incorrect.
Too many to list here.
Maybe a "de-bunking" thread could be started.
I can think of one thing that would top the list. Saw a post on it today.

 

[EagleTalons]

I don't think you covered Airplane engines in that post very well...

On a more serious note, why doesn't someone do a thread like Oscaryu1's lil 5 hp guide?

 

[squat251]

I don't think you covered Airplane engines in that post very well...

On a more serious note, why doesn't someone do a thread like Oscaryu1's lil 5 hp guide?

well, if airplane engines would fit on a cart, I'd try it lol
on a side note, a guide on sled engines? I'd be willing to give it a go, provided i knew what people expected out of it.

 

[Kaptain Krunch]

I don't think you covered Airplane engines in that post very well...

On a more serious note, why doesn't someone do a thread like Oscaryu1's lil 5 hp guide?

I'd be willing to give it a go also, but it seems pretty straight forward to me?

The only argument i have, is about the free air sled engines, although they may be fine, i still would jet them a bit rich, and make sure they get lots of air flow. A lot of karts have engines behind the seat, where airflow is VERY low. If i were to use a free air engine, i would most likely make some ducts or something to get airflow over the cooling fins.

Otherwise good job.

 

[squat251]

i don't think that ducting would be entirely necessary, the seat makes a natural vacuum behind it when it moves, so air flows faster there to fill the gap. as for jetting, you would just need to see how the motor runs first, most issues can be solved via adjusting the mix screw on the carb.

 

[EagleTalons]

I mean what needs to be done to them to make them fit on a kart, step by step and lots of pretty pictures.

 

[squat251]

well, besides a jackshaft and making the mounting plate, i don't see what else you need special

 

[Kaptain Krunch]

i don't think that ducting would be entirely necessary, the seat makes a natural vacuum behind it when it moves, so air flows faster there to fill the gap. as for jetting, you would just need to see how the motor runs first, most issues can be solved via adjusting the mix screw on the carb.

I would rather be safe than sorry, but i think most would agree, fan is probably the easiest route.

I'm not sure which sleds you've been working on, but most i've had/seen have had round slide Mikuni carbs, and only have idle adjustments, to adjust mixture you would have to change out the main jet. But carbs around my thing, so correct me if im wrong.

 

[squat251]

I would rather be safe than sorry, but i think most would agree, fan is probably the easiest route.

I'm not sure which sleds you've been working on, but most i've had/seen have had round slide Mikuni carbs, and only have idle adjustments, to adjust mixture you would have to change out the main jet. But carbs around my thing, so correct me if im wrong.

fan are pretty common (provided sleds are common XD)
the only engines i would use or reccomend using are old ones, and all the old one that I have used/worked on are butterfly carbs, which have a mix screw, as for the newer slide's yeah, you have to re-jet them, or you wont be running them very hard.

 

[Kaptain Krunch]

Is there a reason you only recommend the old ones? cheaper? Less Power?

I can think of one thing that would top the list. Saw a post on it today.

Alright, now you got me wondering, could you post a link to the thread maybe?

 

[squat251]

well, in many cases, they run better, plus they are normally bug free designs. also much more readily available, and plus if the sled is in bad shape (messed up hood, the track is bad, the suspension isnt working right ect ect...) most people don't mind taking the engine and drive components off for other projects, me included.

 

[Affair_driven]

Alright, now you got me wondering, could you post a link to the thread maybe?

Could, but...don't want to piss anyone off.

 

[squat251]

heh, might as well post it, this is for pointing out errors, and if that person made one, it should be recognized, after all, that's how we learn.

 

[Kaptain Krunch]

Could, but...don't want to piss anyone off.

Oh well.
You should just post it, then delete it once i click on it

Squat, i see where your coming from. Simpler is better more often than not. However i wouldn't think twice about ripping apart a decent newer 440 or 340 sled for a kart motor. However i wouldn't rip apart a decent 800, or anything big, it would just be overkill for the kart and would most likely be much more fun in sled form.

 

[squat251]

your looking at a 500-1000 dollar sled for a newer 440, little cheaper for a 340 but still, i would just ride it if its in good shape, but its all preference, and if you have a really nice 500 or higher, and you don't need the smaller sleds, then yeah, go-kart works.

 

[mike75925]

ive read that if you change altitude more than two thousand feet, you have to rejet. being in texas, i would have to use larger jets all the way through because of thicker air. never having been around them i would say that their castings are thicker to maintain heat. our avg temps here are 100 or better with the heat index, it seems possible that it would run hotter. fan or radiator. i think i heard there are no thermostats in sleds, that will be a problem if riding for very long.

 

[squat251]

if its liquid cooled it has a thermostat. as far as needing to re-jet it, you might not need to depending on teh age of the engine, and or type of carb. as far as thinker castings, that wouldn't make sense as the engine wants to be cool, cooler engine runs better. 100 degree weather doesn't seem to bother a lawn mower, why would it bother a sled?

 

[Kaptain Krunch]

if its liquid cooled it has a thermostat, to an extent. as far as needing to re-jet it, you might not need to depending on teh age of the engine, and or type of carb. as far as thinker castings, that wouldn't make sense as the engine wants to be cool, cooler engine runs better. 100 degree weather doesn't seem to bother a lawn mower, why would it bother a sled?

Well, a free air sled engine, or any sled engine for that matter is VERY different from a lawn mower engine. For one, most lawn mower engines are four stroke, and use the flywheel fins to cool. They are governed at 3,600 rpms vs the sled which can be anywhere from 6k-10k, and they are meant to be run without air going over them. Now im not saying a sled engine wont work, i know they will, just pointing out the differences.

As far as the 100* weather, if its jetted properly, and has airflow over it, i cant see that as a problem. Jetting shouldnt be an issue either, when you run a sled in the summer, you should know that it needs to be re-jetted, and although im sure the summer jetting for texas would be different for me in VT, it can still be easily figured out by a few plug checks and some common sense.

Also, like squat said, liquid cooled sleds do have thermostats. for cooling, you also have to think of how they were cooled in sleds. First off sled radiators look like heat sinks, and are placed under the running boards, and rely on snow kicking up and cooling them, so having a small car radiator is a huge improvement. As for fan cooled sleds, there stuck under a small hood, which does get fresh air in, but it also reuses a decent amount of air, so if your running the engine without a hood around it, it will get much more fresh cool air.

 

[Affair_driven]

100 degree weather doesn't seem to bother a lawn mower, why would it bother a sled?

Excellent.
...and vice versa. I've run lawnmowers at 15° F.