Stihl BT45 4 stroking

[openspaceman]

I have had one of these drills returned as it was rough running. Had a quick peek in the exhaust and bore and rings OK but it is running very rich even with filter off and HI and LO screws on minimum. I have had something similar before on a Husky when a welch plug leaked but before I take the carb apart any suggestions?

[spudulike]

I have had one of these drills returned as it was rough running. Had a quick peek in the exhaust and bore and rings OK but it is running very rich even with filter off and HI and LO screws on minimum. I have had something similar before on a Husky when a welch plug leaked but before I take the carb apart any suggestions?

 

Holed pump diaphragm, leaking needle valve, incorrectly adjusted metering arm, incorrect diaphragm fitted, leaking/ missing welch plug, choke stuck on:confused1:

[openspaceman]

Holed pump diaphragm, leaking needle valve, incorrectly adjusted metering arm, incorrect diaphragm fitted, leaking/ missing welch plug, choke stuck on:confused1:

 

Thanks spud, diaphragm looked good, filter from pump section to metering valve clear, I bought this from new 2 years ago and whilst I hadn't seen it for two years I am certain it has not been opened up, our guys just return faulty gear to base.

 

The welch plugs looked good and seemed to a have a fillet of red sealant around them. Choke is external on these and was off.

 

having convinced myself it was an over fuelling issue I'm now not sure that the 4 stroking was over fuelling, it ticks over fine but doesn't make the transition to HI idle. It will not rev high enough to engage the clutch.

 

I'm going to change the plug and see if I can drip a little fuel in at full throttle to see if it will pick upon Tuesday.

[spudulike]

I did one of these once and there was a spark arrestor in the muffler - if you clean this it may well sort your issues!

[Tilio-acerion]

I did one of these once and there was a spark arrestor in the muffler - if you clean this it may well sort your issues!

 

I run two of these and they both did the same, you can actually remove the spark arrestor and it'll run fine then.

[spudulike]

I run two of these and they both did the same, you can actually remove the spark arrestor and it'll run fine then.

 

From memory, think I got the blow lamp on it and knocked the carbon out when damn hot but agree, leave it out if you are not working in dry arrid conditions with bracken or dry grass around!

[openspaceman]

I did one of these once and there was a spark arrestor in the muffler - if you clean this it may well sort your issues!

 

I run two of these and they both did the same, you can actually remove the spark arrestor and it'll run fine then.

 

I finally got around to looking at it again and indeed it was the spark arrester blocked as predicted by you two. Much too noisy for our work left out so I burned and blew it clean.

 

Never having come across them before I'll keep my eye out for this problem. A darn sight easier to fix than taking the frame apart to look at the carb which turns out was a waste of time.

[spudulike]

I finally got around to looking at it again and indeed it was the spark arrester blocked as predicted by you two. Much too noisy for our work left out so I burned and blew it clean.

 

Never having come across them before I'll keep my eye out for this problem. A darn sight easier to fix than taking the frame apart to look at the carb which turns out was a waste of time.

 

Thanks for the update, glad we were able to help, interesting tool, not seen another since fixing the one I had in!

 

All good:thumbup:

[Tilio-acerion]

I finally got around to looking at it again and indeed it was the spark arrester blocked as predicted by you two. Much too noisy for our work left out so I burned and blew it clean.

 

Never having come across them before I'll keep my eye out for this problem. A darn sight easier to fix than taking the frame apart to look at the carb which turns out was a waste of time.

 

Glad to be of use. From memory with ours I unscrewed the spark arrestor from the exhaust and then cut of the mesh element with a hack saw and then re-fitted. Exactly the same size exhaust opening so should be the same db, just with no screen to get blocked up.