Hi, I have a lawnboy proline lawnmower 6.5hp and a few seconds after starting the mower, the engine goes up and down and I am doing nothing to it. My friend just gave it to me for free as he was moving and he said it did this but still works. Is this a serious problem? Will it get worse? What to do? THanks in advance.
Regards,
Stevan

Brand engine?

The Lawnboy model is 10323 and the engine says Duraforce. SilverPro series. 6.5Hp. 2cycle engine. I found some links around the web saying things like the gas may be stale, the gas vent cap is not venting, spark plugs may need replacing, etc as all possible problems for the engine surging. I haven't tried any of these yet, just wondering if this is a one of those "of course" problems with a simple fix so I don't try everything and still have the problem. I just tried to cut the grass today in my backyard and the engine surging was frickin annoying, but it worked. Only when the mower was cutting some thick patches of tall grass did it stabilize to a humming sound. Thanks again if anyone has any ideas.
Steve

Did it always happen with the other guy? I've heard about these duraforces being set too lean, and reworking the main jet fixes the surging... Gas cap not venting would eventually cut it out, spark plugs are a no, stale gas a maybe.

He said not when it was new. It is around 8 years old and he can't remember when it started cause he's gotten used to it. The other thing I noticed is that it cuts off if I put it on slow. I have to keep the choke lever on fast only. Could those two things be interconnected? Thanks again.
Regards,
Steve

Hi, ddscull here .I have the same problem that stevanrk does only with a 10 Hp techumseh engine and was looking for any results to his post , if he got the question answered
Thanks
ddscull

Try to clean the carb (take it off and apart and blow it out with carb cleaner through any and all holes a few times) and see if that helps...

Now I am not an exoert, but when it is idling and surging it is just chomping at the bit.. it wants to get to work... you said when you put it in long grass it levels out.. hmm
\i had the same problem with an older lawn boy and that is what I came up with.. I did move the governor linkage after a while and the thing smoothed right out, whether it was idling or cutting grass... cheers