Bolens Diablo Rouge and Hus Ski Discussion Forums

Ok i have an overheating ploblem on a 200A that has a bored over .80 252 444 motor in it. Just wanted to see if anyone can pin point the problem for sure with all the modifications on this rat. Couldnt fit a recoil because on the handle bars are in the way so im wondering if the recoil casing helps keep it cooler with the flywheel fins spinning in there? Next there is a 200A muffler on this so im wondering if the motor is getting to restricted because it is small than a 444 muffler? Next it doesnt have the correct carb for the motor, its an HL off a 292 jlo motor? Next is that there is a 200A Primary clutch on this that is on the shaft as far as it can go and then the motor is mounted to line up with the original 200A seconday clutch, so is it rev'in too much? Or is the motor just being bored over that much causeing all of this? There was plenty of piston skirt to go that far with the boring. Sometimes it will run for miles before it shuts down and then sometimes it will go half a mile. Fun Fun!

As per your rewind ,I used a piece of pipe , 1" long as a spacer and longer bolt to move the front of the handle bar out to get the clearence i neededfor my rewind to fit.I also moved the dash 2" back towards the handle bars for spark plug clearence.

Anyone on the overheating problem? Need idea's before changing just changing the motor

Overheating is an interesting problem. There are lots of variables that can cause overheating. Generally it can be caused by
- incorrect amount of oil in your fuel mixture - lack of lubrication
- missing or partially blocked cooling fins on the cylinder head and cylinder
- missing cooling blades on the cooling fan
- dirt and debris build up inside the fan shroud
- high ambiant air temp can cause overheating
- incorrect ignition timing can also cause overheating
- snow conditions
- mechanical defect like a bad bearing or track binding

But two things always come to mind with overheating, one, if it is a problem like plugged or broken cooling fins, it should overheat consistently everytime you use it like a car with a stuck thermostat. When the engine gets to a certain temp, it should overheat consistently if the above problem is the situation.
I would say boring it out to 80 thousand is removing a lot of cylinder wall and making it that much thinner could definitely contribute to it overheating.

The missing starter - this is not an issue as I had a 444 without a starter that I drove for years in all kinds of temps - hot spring time conditions to -40 and never had a problem with it over heating.

As far as the HL carburetor, I had an article about HL carburetors from years ago and my understanding is that HL carburetors all had the same size mounting bolt holes and the same size throat diameter and that the numbers that followed HL stamped in the carburetor meant different options and features of that particular carburetor, just as HR meant a certain bolt size and throat size. Another difference I remember from this article is that HL was compatible with a certain size CC engine and HR was compatible with another size CC engine so I don't think it is your carburetor . The HL carburetor will only allow so much cfm's through the carburetor. I think this will also eliminate your muffler unless it has a bunch of bad baffles in it that is blocking it off. That would not cause an inconsistent heating problem, it would be more consistent. When and if I find this article again, I will post it on this website.

I dont think a 200A clutch would cause the overheating either. So to actually pinpoint the problem could be tricky as there are so many variables. One thing to try other than the boring of the engine which you can't change, is to start unmodifying the engine and see if your problem is eliminated.

I have one question - you stated that it will go for a long time then shut down or go for a short time then shut down - what do you mean by shut down? My final question - if you remove the cylinder head has there been any transfer of metal from piston to cylinder or vice versa or any type of scoring on piston and cylinder wall? This is a sure sign of overheating....

Just some of my thoughts on this topic. I can go on about this. Bear in mind that I am not an expert on this, just some observations to think about from my experience. It would be interesting to hear other people's thoughts on this overheating problem.

Peter, Those are all good thoughts. Thanks for sharing.

Your comments reminded me of one individual who shared a picture of his motor rebuild with me and he had his cylinder head all sandblasted and painted up pretty. I recommended he re-sandblast the cylinder and leave it bare with no paint to promote better cooling. I envision the paint to be like adding a coating of insulation and keeping the heat in. I hope I did not mis-lead him on that comment.

Bruce

Good question - paint or not to paint. I have heard both sides of this. Don't paint because like you said its like adding a layer of insulation holding heat in. The other side is to paint it black to prevent rusting and to create a smooth surface so it will have good air flow over the cooling fins. I have also been told to only use black paint because it will help to dissipate heat better just like most car radiators are painted black unless they are aluminum. Supposedly black is the best colour for dissipating heat.

Overheating is a hot topic

So to paint or not to paint? Maybe some other members on this website could definitively answer this...

Check for the correct spark plug heat range. A plug wich is too hot for the engine can result in overheating. the next thing is the muffler too small and retaining too much build up compression and heat .
op that help.

DAN THE MAN

Hey thanks guys on your input, i havent taken the head off yet pete but maybe i should? As far as it shutting off, it just dies as if i hit the kill switch. then a quik beer later I can get it fired back up by pouring some gas down the carb, (which if you give it a drink right after it shuts down it just boils the gas) and it might go twice as far before it shuts down again.. The first thing im gonna do is get rid of that muffler, those 200a mufflers were alot smaller then the 444's