Engine INTAKE AIR LEAK ?

My two year old Troy Bilt four stroke string trimmer was hard to start and then wouldn't run any faster than idle. Thinking I had a cure, I installed a new Troy Bilt OEM carburetor fuel filter, and gas lines. Now it's still a little hard to start and will run full speed only with the choke half closed. Reading other forums this seems to be a common problem.

My Troy Bilt, eight hp "HORSE" tiller is more than thirty years old and running it's second motor so I thought I was doing right to get a Troy Bilt string trimmer. Maybe not.

Any suggestion will be appreciated. thanks.............Raptor

Don't know your product and only have 2 stroker trimmers...If you suspect lean starve condition it should be reflected by light coloration on plug. My 2 strokers have a low and hi speed jet adjustment tamper proofed by EPA regs, but which can be adjusted by a dealer or tinkerer at home. My two stroker would not take throttle from new and needed to have the hi speed jet opened slightly. Also I believe 4 strokers are purposely selected by states with higher restriction on emissions because they are easier to control as lean machines.

motoman said:

Don't know your product and only have 2 stroker trimmers...If you suspect lean starve condition it should be reflected by light coloration on plug. My 2 strokers have a low and hi speed jet adjustment tamper proofed by EPA regs, but which can be adjusted by a dealer or tinkerer at home. My two stroker would not take throttle from new and needed to have the hi speed jet opened slightly. Also I believe 4 strokers are purposely selected by states with higher restriction on emissions because they are easier to control as lean machines.

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thanks for the reply.............I suppose I could take the trimmer to a shop and give $100.00 for someone give his opinion. There are no visible adjustments. My problem is going cheap with a Troy Bilt. I guess I'll just live with it for it's short life expectancy.

RAPTOR said:

My two year old Troy Bilt four stroke string trimmer was hard to start and then wouldn't run any faster than idle. Thinking I had a cure, I installed a new Troy Bilt OEM carburetor fuel filter, and gas lines. Now it's still a little hard to start and will run full speed only with the choke half closed. Reading other forums this seems to be a common problem.

My Troy Bilt, eight hp "HORSE" tiller is more than thirty years old and running it's second motor so I thought I was doing right to get a Troy Bilt string trimmer. Maybe not.

Any suggestion will be appreciated. thanks.............Raptor

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Your Troy built horse was built by Troy built and was a top quality product which is why they went broke

Your new trimmer is made by whoever B & S got to make it ( most likely China , Brazil or Mexico )

bertsmobile1 said:

Your Troy built horse was built by Troy built and was a top quality product which is why they went broke

Your new trimmer is made by whoever B & S got to make it ( most likely China , Brazil or Mexico )

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I didn't know Briggs and Stratton was the maker of all these knock offs..............thanks

Check the valve lash.
Not easy as you will need to cut down a few leaves to around 1/16" wide to get into the gap.
Sthil BR 600's seem to go out of adjustment very quickly.
When yours is running put some WD 40 or similar in a TRIGGER pack & spray all around the carb.
You are only interested in the area between the carb & the engine.
Blows smoke, goes faster goes slower indicates an air leak.
Then you go from spray to jet and try to narrow down where the hole is .

Check your head bolts. Mine could be turned by hand. I tightened them and all was good.

RAPTOR said:

I didn't know Briggs and Stratton was the maker of all these knock offs..............thanks

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Actually I was wrong, MTD bought Troy built not Briggs ( the glass of wine was obviously a little too low when I responded ) .

bertsmobile1 said:

Actually I was wrong, MTD bought Troy built not Briggs ( the glass of wine was obviously a little too low when I responded ) .

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And MTD supplies Craftsman and a couple of others with a motor they engineered and designed but manufactured in China. I don't have a problem with the Chinese motors I run a modified Harbor Freight 212 Predator hemi head in a racing kart been going strong for 3 years now but I keep it highly maintained. My other kart has a briggs LO 206 for stock class racing wished I could mod it but it's factory sealed and hurt my wallet to have to buy one for the class. When I got my new mower last month I asked the guy who made the motor and he laughed and said Craftsman. As we loaded it in my truck he and the guy in back that does the mechanical part of the warehousing chores told me it was MTD. I can't find much info on them. Apparently MTD engineers worked with Chinese manufacturing to come up with a dependable motor that would run on todays crappy ethanol laced gas and be real easy on fuel. I can't find any mention of horsepower either I know the 30" has a 420 cc and my 42 has a 547cc and so on. What I do know is that the motor is good on fuel and getting better with break in time. Last cut I burned a little over a half gallon cutting a touch over a half acre with a 12 degree slope in the back. Friday it will get a test cutting a heavy growth of weed/field grass and St. Augustine. Had 3 days of soaking rain followed by 3 days of sun so now I have a thick 8 inch base and counting that will need to be beat back down to it's normal 4 inches.