OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Buying a Scott bonnar

I'm after a Scott bonnar and looked at one not running its a 2.5 b&s are there any common faults? It didn't feel hard to pull start so maybe no compression?

Depending on the model of scott bonnar there are a variety of common faults on a non maintained machine. As for the enigne being hard to pull over, they never did have much compression, sometimes valves get stuck open, etc.

Hi Michael_xr8, what is the model of Scotty that you're looking at? If it is a Model 45, all parts are still available; for other models, parts are pretty thin on the ground. This is something to consider if you are going to use it regularly and need to keep it well maintained.

Like all the side valve lawnmower engines I can think of, the Briggs has a rather low compression ratio (6:1) and it also has a feature called EzySpin, which holds one of the valves slightly open during the first half of the compression stroke, to act as a decompressor and make it easy to pull over. If you want to check the compression, Briggs recommends that you disconnect the spark plug lead then turn the engine backwards (by the output shaft clutch housing in this case) until you find compression. Then flip the clutch to make the engine turn backwards until it hits compression. If it bounces back, compression is OK. If it soggily keeps turning through the compression stroke, it's not OK.

If you conclude that compression is bad, tell us about it and we can talk about how to diagnose the problem.

Well with your knowledge would you buy a 17" Scott bonnar not running for $175? The thing that turns me off it is that I saw it at his work and he works at cash for scrap! He claims "it's not been started for 2 years and was serviced 3 years ago"

I highly doubt it, a non running machine would want to have a really good catcher, not bad paint and good decals for me to think about paying that much. He probably got it out of the steel bin, offer double the going rate for steel

Hi Michael, I agree with Joe completely there mate, it would have to be in good condition for those dollars.
The thing here is you don't know its history (and by the sound of it....neither does the guy selling it!!)
Best to wait for one that is running; the come up often.

I'd expect for $175 that it would be a good machine. That means plenty of meat on the reel for multiple future resharpenings, good chains and sprockets, a good catcher, a Briggs engine, and essentially, nothing much to spend to get it into prime mowing condition. In other words, that sounds like the price for a good one. I'd expect a non-running one of uncertain provenance, with no catcher, but with a good reel (i.e. lots of resharpening potential) to be in the $50-70 range. I suppose I'm a relatively keen shopper, but with what it will cost to replace all the chains and sprockets (which are usually shot on randomly selected old Scott Bonnars), sort out the clutch, buy a catcher, and do something about the paint and decals, it would easily owe you $200 by the time it was ready to use. You should be able to buy one for that price that is already good and needs no more than sharpening, adjustment and a tuneup. Why do all the work for nothing, and risk getting nasty surprises along the way?

I seem to have seen reports from Outdoorking members of buying very nice SBs that haven't been used much, for around $170. These are machines that may have ratty paint and need a sharpen, but are otherwise good to go for a decade or two. Just be sure and check the condition of the chains and sprockets, that it has a good catcher included, and that it hasn't been used to mow water pipes or old bolts, so the reel is undamaged.