Help needed with a Stihl ms200t

[GLynch]

I have a 2004 ms200t that was bought as a non runner, it fires on choke then can usually get it running as long as I keep the throttle going, as soon as the revs drop it dies 

So far I've cleaned the carb and tried a working carb off another running 200t, also changed the plug and have good spark, changed fuel line, fitted new tank breather, new crank seals and still won't run, seems to have good compression 

I'm at a loss what to do next

 

 

[spudulike]

Remove the muffler and check the piston - look for scores. I have seen many feel like that they have good compression but have been seized. If you can't do this, check the compression when the engine is warm - expect at least 150psi+

The working carb rules out the carb and generally that means it is probably the engine rather than the HT system.

[GLynch]

I've looked at piston but looks pretty clean to me, I'll try and take another look at some point, my struggle to check the compression as I don't have a tester

Can't think of anything else it can be

 

[Stubby]

20 hours ago, GLynch said:

I've looked at piston but looks pretty clean to me, I'll try and take another look at some point, my struggle to check the compression as I don't have a tester

Can't think of anything else it can be

 

Have you checked the impulse line . You need to stretch it to check for a split .

[spudulike]

As above but usually a pressure and vac check is the best way of checking for leaks. You may find it not connected to the union on the underside of the handle and this is much more common.

A split inlet manifold boot will give the issues that you have so worth checking.

In my world, most of these saws have had 10-15 years hard life and most are due a full strip, inspection and new parts as most owners just abuse them until they die!!!

2004........18 years of abuse!!

[GLynch]

I've checked the impulse line for splits and all looks good, I've stripped the tank off and checked everything I can think of even went round it checking that all screws were done up tightly, I haven't fully checked over the boot though so that may be worth another check over, I've ordered a compression tester so I'll give that a go aswell

[spudulike]

Most issues are carb related on these saws but am assuming the working carb from another saw rules this out!!

Have you increased the idle speed a bit on the working carb? 

The impulse line rarely splits on this saw - coming off is more common. Split manifolds are a lot more common. You can often get the saw working and it will die if you hold the engine down and pull the top handle upwards.

Compression should be 150 -170psi - higher the better. Worn piston/rings or a scored piston can cause the saw not to run well. 

Without seeing the saw, it is difficult to tell what is wrong but a 2004 saw with probably a lot of abuse will have its issues.

Worth cleaning around the flywheel, the 200 isn't bad but the 150 and 201 are prone to a build up of shyte behind the flywheel causing the saw to stop at low revs because of the friction slowing the engine....the 150 particularly.

[GLynch]

I have changed the seals on both sides and it felt very tight with the new ones fitted I couldn't turn the crank by hand

[spudulike]

Relatively normal for them to be tight - is that turning by the crank shaft stub or the flywheel or clutch? Did you put them in the correct way round?

[GLynch]

Turning by the stub of the crank, I think they are in correct the smoother flatter side in first