ms200t on idle

[billpierce]

hi, noticed my 200 idling up and down a wee bit when dangling on a strop and occaisonally would cut out. it used to idle all day no bother.

 

is the first thing to check the carb boot and fuel lines (for splits) or is there any other likely candidates.

 

thanks

[Stubby]

Yep check those first but could be crank seals . If it does in one attitude but not another sometimes its the crank seals .

[spudulike]

Could be a slight air leak, the carb may need a tweak, the carb acclerator pump may be showing early signs of failing, it may just need a slight increase in idle speed.

[billpierce]

whats the best way to check crank seals? will a visual inspection of carb boot achieve anything?

[spudulike]

whats the best way to check crank seals? will a visual inspection of carb boot achieve anything?

 

A visual on the carb boot will tell you the thing isn't badly split. Another check is getting the saw idling and on the deck and, holding the engine down, move the top handle around with force and see if the idle changes at all. If it does, the thing is possibly leaking.

 

The only way to check crank seals is to pressure & vac test with the correct equipment. You can just replace them if you are OK doing that. You could take the clutch and oil pinion off and then start the saw, put it on its side and pour thick oil around the oil pump and see if the speed drops but this is hypothetical, will only check one seal and isn't something I have tried!

 

An air leak will tend to make the saw hang on to revs when the throttle is snapped shut after reving the saw - the revs should drop immediately on a well set saw. You will also note the top end revs being too high and the L screw needing to be more than one turn out to get a satisfactory idle.

 

You will also chase the idle setting to get it correct rather than it being easy to set, working on one turn out as it should!

[billpierce]

just had a quick look, revving up to 13200-13400 - so reckon thats fine, could get the rev's to change by wrenching the handle about, but when the saw is hanging or tipped so the flywheel side is facing down the idle speed goes up to 3500 (from sitting at 2800).

 

sounds to me like crank seal is on its way out?

[spudulike]

just had a quick look, revving up to 13200-13400 - so reckon thats fine, could get the rev's to change by wrenching the handle about, but when the saw is hanging or tipped so the flywheel side is facing down the idle speed goes up to 3500 (from sitting at 2800).

 

sounds to me like crank seal is on its way out?

 

Try changing the one under the oil pump - it is usually this one that goes!