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Discussion Starter #1
Well Im so happy I decided to share my joy!

Finally after an entire year of fiddling I've finally gotten the sled running right! Ok, well I didn't get it running right, but it's running and I'm joyous!

Ok some background:
I bought the sled at the start of last season. After I had looked at the sled and took it for a test ride I decided to buy the sled. The guy told me he'd take it to a dealer and get the carbs redone and give it a full tune-up. He took it to a local Polaris/Suzuki dealer.

This dealer jetted the sled to 330/320 and put the carbs on the wrong side. (put PTO carb on Mag side and vice versa). Not a big deal since the jetting is pretty close anyways, but it really set the standard for what was to come.

They had tuned the sled to have the plugs gapped at .030, quite a bit larger than Ski-doo's .018. It would not run with the plugs gapped any lower, I had to replace the coil half-way through last season. Whether this was due to the gapping or not is up for debate. On top of this, it had a very serious flooding problem, so I finally broke down and took apart the carbs myself. Boy was I surprised when i found the main jet sitting at the bottom of the float bowl. I was ecstatic, problem solved! Or so I thought.
Put the jet back in, and now it ran a bit better and didn't leave me stranded, but it had severe starting problems and was a MOFO to pull over. It also would run at full performance (or close to) for about 20 minutes, and then it would start flooding and wouldn't have enough power to climb the ramps to get on the trailer. I was stumped, my father and father in-law were stumped, both are mechanics.
Now I know these things are tough to pull over, but this thing would kick and try and rip your arm off. After I replaced some track/suspension parts and went for a rip it suddenly became easier to pull over, I assumed a clutch was sticking... but that wasn't the case either. At this point i had less than half a tank of gas.
So I finally decided to take it to a guy who knew Ski-Doos. We fired it up and he IMMEDIATELY knew what was wrong (God I wish I would have taken this route before). Apparently the needle isn't sealing and the crankcase is filling with fuel, way more than it needs. The reason why it is kicking so hard when you pull it over, is because the engine is hydrolocking! When the gas tank is above half full the needle is low enough that the fuel will be constantly gravity fed into the crankcase, so it's always got too much fuel. This is why it was such a ####### to start and why the damn thing wanted to dislocate your shoulder when you pulled it over!

Neither me, my father or my father in-law had every worked on a rotary intake engine so all this was news to us. We all knew HOW a rotary engine worked but never put it all together to figure this out.
After only 20 minutes of working on it, it was already pulling over ALOT easier, starting better and running ALOT better.
Anyways, I've decided to let this guy go over the entire thing and completely re tune it. I get it back in a week and we have tonnes of fresh snow here! WOOO!

-Thanks for reading, just had to share my joy. If anyone else is having similar problems they can now find this thread! I didn't want to give in and take it to someone else, but I'm glad I did now.
 

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erm hmm well .. Its not a rotary engine.. Its just a 2 stroke.

I had that problem once, took a bit of time to figure out why one side wouldn't fire till it warmed up a bit or ran for a minute, took the drain plug outta the bottom and fuel seemed to come out forever!

Good to hear you got it going, sometimes the machines just like to be f'ing stubborn!

:thumbsup:
 

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Discussion Starter #3
erm hmm well .. Its not a rotary engine.. Its just a 2 stroke.

I had that problem once, took a bit of time to figure out why one side wouldn't fire till it warmed up a bit or ran for a minute, took the drain plug outta the bottom and fuel seemed to come out forever!

Good to hear you got it going, sometimes the machines just like to be f'ing stubborn!

:thumbsup:[/b]

It's a rotary intake valve 2 stroke ;).
http://ezinearticles.com/?Rotary-Valve-Engine&id=205241
I got lazy and skipped the 'intake' part a couple of times in my initial post I believe... I had never heard of the rotary valve until I bought the Ski-Doo. My dad had, but like I said, he only had a vague idea of how it worked.

From what I've read only Bombardier/Rotax have ever used the rotary intake design. Since we've never worked on a 1980's Can-Am dirtbike or any other bombardier product before, we had NO idea the inner workings of the rotary intake valve, only a very vague idea of how it worked.

The new sled's use a Reed valve set-up.


PS: Thank God its not a Wankel Rotary Engine... lol... I remember my friend had a Mazda RX7 and he tried finding someone to rebuild his engine, he was told there were only 3 mechanics in all of Canada who were certified to take on the task!

EDIT: Apparently Kawasaki and Suzuki have also made rotary intake engines, according to the link I used.
 
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