Wont Run

[mikelhuff]

Hi all,
I am a good mechanic and have had skis for a very long time, but this is my first Rotax.
I have rebuilt the carb, yes replaced all of the gaskets etc. that comes in the kit, all nice and clean.
The Ski tries to start with a shoot of quick start, but its just a half second start and not like my other non-Rotax do when you shoot it with quick start. What I did notice is that the carb (yes, this is a singel carb version) seems to have air coming out of it which is strange.
As I've never worked on this type of engine before, what would cause that?
I bought this not running so I have no history on it at all.
Any help would be great! Thanks

 

[97gts717]

Did you rebuild with OEM mikuni carb parts ?

 

[etemplet]

Sounds like the timing is off.

 

[etemplet]

Pull the rotary valve cover and have a look. You're right there.

 

[mikelhuff]

Yes, I used the OEM rebuilt kit from Mikuni.

Regarding the timing, do you have a link to show me how to enure the timing is set correctly? I've downloaded a service manual but it doesn't seem to cover the Rotax version, only the 2 carb type.

So what would I be looking for in the rotary valve cover?

 

[etemplet]

It's the same timing method. I"m assuming your engine is a 717. The oil pump is gonna be in the way. You'll need to print out a degree wheel wheel if you don't have one. The numbers to set the timing are in the book. Gonna look like this I suspect.

 

[etemplet]

This is pretty funny but you'll get the idea. Do a search on Bombardier Rotary Valve Timing and such as that.

bombardier rotary valve timing - Yahoo Video Search Results

 

[jts32]

They are all Rotax motors. Did you replace needle and seat? Did you test pop-off pressure. Can't stress enough that it needs to be GENUINE Mikuni parts. Lots of aftermarket kits claim OEM, but they are crap. A genuine kit should run around $50-60 per carb

 

[benjilafouine]

On these engine and rotary valve, if timing is off by a bit the ski will be very hard to start. Also, you will not be able to accelerate easily as it could take a long time to reach maximum speed (if ever capable).

 

[mikelhuff]

Hi all, I did do the search and found a good video and that's what I was after, a good video..
The carb kit was from the Sea Doo shop and from the manufacturer..
I got it apart and found the issue, the rotary valve has a chunk missing on one side but from the video and where the the value was, it looked rather close to being correct..
So I would assume just by the common logic of how this works that this 1/4w by 1/2 inch long missing chunk that this would cause the air feedback through the carb.
So now the part hunt.. Think the Sea Doo shop will be to expensive vs cheapcycleparts.com
Do you recommend any other online parts house for these?? Do they make performance valves?

 

[97gts717]

Hi all, I did do the search and found a good video and that's what I was after, a good video..
The carb kit was from the Sea Doo shop and from the manufacturer..
I got it apart and found the issue, the rotary valve has a chunk missing on one side but from the video and where the the value was, it looked rather close to being correct..
So I would assume just by the common logic of how this works that this 1/4w by 1/2 inch long missing chunk that this would cause the air feedback through the carb.
So now the part hunt.. Think the Sea Doo shop will be to expensive vs cheapcycleparts.com
Do you recommend any other online parts house for these?? Do they make performance valves?

Have heard good things about OSDparts dot com

 

[jts32]

You need to find the missing chunk and whatever caused it, most likely a bolt off the flame arrestor base that went down through the carb. Unfortunately it's fairly common and strips the brass rotary gear. Also need to check the condition of the RV cover and cases. If there are deep gouges that go all the way from hole to hole, those parts need replaced

 

[mikelhuff]

Thanks for the help everyone.. Got all the parts on order and hoping to have it running for next weekend..
The RV cover and case had some very minor scratches and I smoothed those out with a fine file and are nice and level/smooth now..
Again, thanks for the help.!

 

[etemplet]

No pictures ?? We like to see the carnage. And follow up is always a necessary item. Good Luck !!