Suffolk engine

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Series3boy
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Last seen: 9 months 1 week ago
Joined: 12/02/2019 - 20:03
Suffolk engine

Hello 

I wanted to pick people's brains before I attempt to fix. I have a qualcast commodore with a suffolk engine. Which did run really well one of the best I have come across.

The last summer I noticed it struggling / sputtering under load when the mower is climbing the incline of the lawn. I noticed the spark plug cap was in poor shape so thought I had found my problem. Soldered on a brass spade connector which has made some improvement. But still is hesitant under load. I have also tried adjusting the carb which has made no difference.

Has anyone else experience similar? It idles really well. I can rev the engine no problem. 

Do people think it is fuel or ignition related?

I wondered if it needs a carbon decoat?

Just wonder ed if anyone has any suggestions before I tackle it.

I was going to try cleaning the points first. And then the carb.

If that does not work will decoat and lap valves.

It has the usual problem of throwing oil out of the engine breather so will tackle this too. Does anyone think this could be the issue. It makes a certain note out of the exhaust when it struggles.

Thank you for your help.

Rob

 

 

 

 

DJD
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Last seen: 2 days 59 min ago
Joined: 06/09/2013 - 14:19
Oil forced out of a breather

Oil forced out of a breather or filler hole usually means too much pressure in the crankcase, a worn bore/rings will allow compesson pressure to leak past causing this.

Series3boy
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Last seen: 9 months 1 week ago
Joined: 12/02/2019 - 20:03
Thank you, the engine has

Thank you, the engine has good compression and does not burn oil. I have a suffolk colt with worn rings on my list of jobs to do. It burns oil and you really can feel the low compression. It runs ok surprisingly. 

Is the a better method to check the rings are ok.

Suffolk a seem to develop an issue with their breather. I have turned the plaxline disc around on a then and cleaned the breather which seems to fix this issue.

Series3boy
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Last seen: 9 months 1 week ago
Joined: 12/02/2019 - 20:03
Thank you, the engine has

Thank you, the engine has good compression and does not burn oil. I have a suffolk colt with worn rings on my list of jobs to do. It burns oil and you really can feel the low compression. It runs ok surprisingly. 

Is the a better method to check the rings are ok.

Suffolk a seem to develop an issue with their breather. I have turned the plaxline disc around on a then and cleaned the breather which seems to fix this issue.

Series3boy
Offline
Last seen: 9 months 1 week ago
Joined: 12/02/2019 - 20:03
Thank you, the engine has

Thank you, the engine has good compression and does not burn oil. I have a suffolk colt with worn rings on my list of jobs to do. It burns oil and you really can feel the low compression. It runs ok surprisingly. 

Is the a better method to check the rings are ok.

Suffolk a seem to develop an issue with their breather. I have turned the plaxline disc around on a then and cleaned the breather which seems to fix this issue.

DJD
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Last seen: 2 days 59 min ago
Joined: 06/09/2013 - 14:19
A well known method of

A well known method of checking bore wear on a car or bike engine is to obtain a compesson tester, give engine full throttle and screw in tester and check the cold reading, then do another test with about half a thimble full of oil added, then lastly do a test with a warmed up engine, a decent engine won't show a great difference.

With a small single mower engine it's not that easy, especially without a self starter etc.

Have you got the oil level correct? The looped dipstick end should just touch the floor of the crankcase.

Is the correct head gasket in place? I've heard of folk stoning heads and barrels and just using gasket cement, which increases the compression.

You may have a jammed in ring or two in the piston also, allowing bypass of gases, taking off the head alone won't tell you much, but you can try wiggling the piston, it should hardly move at all, if you can get a 15 thou feeler gauge between piston and bore engine is worn.

villiers98
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Last seen: 2 months 4 weeks ago
Joined: 30/09/2017 - 14:59
1 Try brand new plug

1 Try brand new plug

2 Carefully clean and gap points . If burnt looking it may need a new condensor . Put a spot of oil on felt that lubricates the points cam .  While the flywheel is off just check the rivets that hold the  ht coil laminated pole piece to the backplate are not loose. This lets the rub on the magnets giving the engine a tight feel and probably not doing it any good. Take off backplate and stake them with a punch holding the pole piece towards the centre of the back plate .

3 Try again - if still not good try with choke half on. If this is better then look at carb

I have the same mowers- usually run fine - even  the one with very worn engine