smp22

Thanks for the fast response. When I put my finger on the cam that opens the throttle plate the surging stops. This is the little cam that the throttle assembly, springs and all, control. When I move it, I can change RPM without surging. The springs are very fine and I believe I stretched one of them out, the return spring I think. I am ordering new springs. However, before I do that I'm going to clean out the pilot jet because I have not done that. I did not know where the pilot jet was when I cleaned the carb the first .. oh, three times! So I guess that could still be it. However, I do suspect the linkage as the cam moves around with the surges and that return spring appears "loose" when the throttle is in the closed position.

Ok, back again to dig up this old thread. I took the carb out AGAIN last night to deal with this "once and for all" and cleaned it all out really well. I think my problem is with the linkage or springs. I've no idea what this is supposed to look like now. One of the springs seems a little loose and I can see the cam that moves the throttle plate move back and forth when the motor surges. Is it possible that there isn't enough spring tension? Thus allowing the throttle plate to "float"? If I hold the cam in place the surging stops. I suppose I should order new springs for the linkage. But before I do that I'm just going to put some wire on the cam to hold it in place at a set throttle position and see if that does anything. The snowblower doesn't have a throttle control anyway so the throttle is fixed from the factory, the only way to change throttle position is by manually moving the throttle lever on the carb. This is under the cover of course so not a user accessible control. Can the spring tension on the linkage cause surging?

Back again.

I have replaced the choke cable and I removed the carb tonight and cleaned it and replaced a couple of the o-rings. Now, I didn't remove any of the jets because I was nervous about breaking them and this is probably where I went wrong. I was nervous because I know one of the jets (is it the pilot jet?) breaks if you take it out and I don't have a replacement. In any case, the thing is running way better now and it starts no problem but it's still surging :/

Here is a video to show you what I mean....

http://www.youtube.com/watch?v=pi5SdAsWZYQ

I'm guessing this is still some sort of carb issue. If I dismantle the carb again, which jet should I really be focusing on and should I be worried about busting any of them?
Thanks!

There is a valve yes, what I used to call a petcock on my old motorcycles anyway. There is a drain on the carb of course and indeed it does appear that the thing was never "summerized" properly. I'll be sure to do so after every winter and probably even drain the carb between uses if it doesn't snow a lot. I'm in Toronto, ON Canada by the way. The carb cleaner I'll be using is some Motomaster stuff that I've used before and seems pretty strong though I have nothing to compare it to. It did a good job on the bowl the other day. Thanks for the continuing advice.

edit: oh, and if anyone can chime on in the need for a air filter of some sort. Again, judging by that parts diagram there seems to be some strainer type thing ahead of the air-cleaner box (what's in that box??? a filter?). One of my buddies told me that "snowblowers don't use air filters there ain't no dust in the winter" but that doesn't sound right to me.

Thanks for the fast response!
There's actually a youtube video of a guy cleaning out a carb from the same motor:

http://www.youtube.com/watch?v=n_eTqL0C3gQ

Being that I'm new to this I thought I would order the gasket set to be sure. It's only $11 or so and I need a new choke cable and some other random bits as well (bolts, clips) to put this thing into top shape. I would rather not take the carb apart only to find that I need the gaskets at that point so better safe than sorry is how I feel about it I guess (especially since I've never done this before).

When installing an in-line fuel filter, do you just splice the existing fuel line and install it there? The replacement fuel line for this thing is like $70 or something ridiculous.

Thanks,
Steve