Importance of lawnmower governor?

[A.Lee]

My spare lawnmower, a Mountfield, B+S engined SP470 is playing up. It is revving and slowing, revving then slowing etc.

It is all related to the governor springs/fan, which slow it down when it is revving too much. Now this wouldnt be a problem if they work, and are easy to adjust, but they rarely work properly, and are a pain to adjust - approx 10 mins for each adjustment. So I had an idea of doing away with the governor altogether and attching a throttle cable to the linkage, to adjust engine speed that way. This engine has no throttle adjustment, when under load, the governor is meant to adjust it to give a constant RPM.

So , the query is - is it viable to do away with the governor and control the engine speed manually? Thanks Alan.

[The Natural Philosopher]

Yes, but he main problem is that you will be constantly fiddling was it runs into different loads.

It sounds like you have some friction in the governor..not just maladjustmemnt.

[Mark]

Or it is running very weak (fuel mixture)

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[meow2222]

messagenews: [e-mail]...

yes, much more likely.

NT

[mike]

I had exactly the same problem on mine so I removed the governor and attached the throttle direct.

It does work... BUT.

It's very easy to really rev the nuts off it if you're not careful

It does tend to slow when you cut long grass and speed up for shorter grass.

All things considered I prefer it without the governor and manage fine with it.

Good luck Mike

[PJ]

I had a similar symptoms with a Mountfield which was due to a partially blocked fuel intake filter.

[A.Lee]

No, it is the spring adjustment on the governor. There are 2 springs, both of which slacken with age, or when messed around with.When viewed from the side,with the engine running, it is clear that they are too slack, so I've tightened them slightly, which leads to over revving, so readjust, and it is too slow etc. It is a pain to adjust them, as you need to remove the top cover and starter puller plate to get at them. If they were open, then adjustment would be a lot easier. Thanks Alan.

[The Natural Philosopher]

New springs maybe?

[Autolycus]

Adjustment of governor springs is non-obvious. Download a copy of the engine manual, if you can, and you may well find that the springs are designed not to be in tension all the time.