Ms200t refurb

[KyleOZ]

Hi all

Newbie to fourm here
I've manged to get my self a job lot of 10 ms200t with the intention of carrying out repairs to sell on. 6-7 feel to have good compression so I'm starting with those. (topped out at about 160 psi on my gauge?) 
Im not too faimialr with 2 strokes/chainsaws so I'm hoping you guys may be able to point me straight.

Parts, I'm after bars, chains and various ms200t specific parts such as chain sprocket covers, fuel lines, av mounts maybe even crank seals etc.
Best place I've found so is L&s engineers? Any others I should try?

Crank play, I've found end play in the cranks on all the saws, is there a maximum measurement?

I've also found slight up and down play in the cranks (only checked on clutch side), how much is allowed?

Vac and pressure testing, I've got myself a cheap vac bleeding kit and the stihl adapter that fits in place of the carb, I've never done this before so any advice appreciated.

Value, whata the value of a vac tested, good compression saw these days?

And finally, carbs. I've jumped the gun a bit here and got two Chinese carbs, any one have experience here?

Sorry for the wall of text, I've got a lot of questions haha

Kyle

[adw]

Not really a lover of Stihl, however L& S have always been a good source of parts when I have touched the, my experience with those Chinese carbs has been bloody terrible, a good friend on here gave me good advice, and it was always far better to rebuild the original carb, accelerator pump is the first port of call on the carb, sling the Chinese carbs as they will send you round the bend trying to tune them, the roller bearings used on these machines will always give you end float, so quite normal.

Over to Spud now.

[spudulike]

Yup, L&S are a very decent supplier for Stihl, holding a good stock level of most parts.

The Chinese aftermarket carbs are like water torture, you think they are tuned and 5 mins later, they are not...some machines are OK with aftermarket carbs, these are generally not Ok...unless you get really lucky.

I always replaced the accelerator pump on the later carbs. It is a tricky job but gives a decent result. The older, non accelerator pump, carbs can get to a point when they become impossible to tune and have never found a repair for this.

End float on the cranks is fine, the "up and down" is really a feeling thing and the type of bearings used, allows for a bit of play. If you are stripping the saw down, check for wear and pitting on the crank. If the saw is running, you can hear a bad bearing tapping on idle. If you are pressure testing, a leak may sometimes accompany a worn bearing.

Generally, the worst play will be in the clutch side caused by overtightening the chain.

Vac and pressure testing....piece of rubber between the muffler and port, fit the inlet manifold and clamp...stick a large felt tip pen or similar down the manifold. Check the flange on it as they can split. 

Put pressure and vac on the cases, turn the crank through 360 degrees wobbling the crank up and down on the clutch side as you go. It should lose nothing.

MS200s are great machines when you get used to their little ways!

 

 

[KyleOZ]

Cheers for the replys

 

I've ordered the adapter flange for the Inlet for the vac/pressure test, just need to sort out fittings to allow use of the vac bleeder. I'll need a pump also but I imagine a basic hand pump could be made to work here. I'll blank the exhuats as you describe

 

All the saws are showing slight up and down play in the crank, 2 slightly more than the rest. 

I've picked 2 at random, I'll vac/pressure test and go from there I guess. 

 

Regarding carbs, these two are both fitted with the s126a, looks to have the accelerator pump. 

Would you advise the blanking/glue method over replacing the piston?

 

If I end up splitting cases etc is it worth fitting new rings or leave whats not broke alone? 

 

Cheers

 

[Muddy42]

Sorry what do you mean by a pump?  Something like a mityvac that tests vac and pressure with the same setup is ideal.  I agree about avoiding chinese carbs.

 

Also have you considered using the worst saws as donors? It depends what price you got them for and how far you want to go, but ordering new parts can soon get expensive.  Maybe once you have pressure tested the crankcases, you could salvage parts from the ones that fail or have issues with the cranks.  Rebuilding crankcases requires special tools and a fair degree of skill to do right. 

[tenner]

Is that diagram right? Apparently axial play along a MS200 crank is perfectly normal because it uses roller bearings instead of ball bearings?

I'm eagerly watching this thread because I noticed radial play in my 200T's crank the other day. "They" say it's quite an easy saw to rebuild but I'd still rather not have to.

 

Blocking the carb's accelerator pump: this does work but not for long in my case and you can't un-epoxy it to rebuild the pump afterwards, no? I got another 10 tanks or so out of my old carb, but performance was noticeably reduced and eventually the un-tuneable and airleaky symptoms returned so I had to spend more time/money working on it anyway. Got a brand new OEM carb, night and day difference.
 

[spudulike]

I used to block the accelerator pump but it is possible to get your sealer pushed in to the check valve and sometimes, you can get strange running. 

I then worked out how to change the accelerator pump and then did this with a lot of success as many of my customers will vouch for getting a few years service out of the rebuilt carb. £10 repair against £130 for a new carb - whats not to like. Your choice on the sealing method.

On the radial play on the bearings. If the bearing is a bit sloppy, the saw will run and probably not sound too bad - it may tap a bit on idle. The thing to check is that there is no pitting on the crank as the bearings run directly on it and any pitting will get worse very quickly.

The leakage on a vac/pressure test when the bearing is worn, I mentioned earlier, is caused by the seal getting wear on it due to the sloppy crank. It is an indicator rather than 100% accurate.

If you have rebuilt a few of these machines, you get to know the feeling of a worn bearing on the crankshaft.

Fitting new bearings is relatively easy BUT - THE BEARINGS GO IN ONE WAY ONLY - PLASTIC RETAINER TO THE OUTSIDE. Is that clear

[bmp01]

4 hours ago, tenner said:

Blocking the carb's accelerator pump: this does work but not for long in my case and you can't un-epoxy it to rebuild the pump afterwards, no? I got another 10 tanks or so out of my old carb, but performance was noticeably reduced and eventually the un-tuneable and airleaky symptoms returned so I had to spend more time/money working on it anyway. Got a brand new OEM carb, night and day difference.
 

 

Yeah, I'm in the 'blank the accelerator circuit' camp but using epoxy never filled me with confidence, excuse the pun. Making an interference bung and stuffing it down the drilled hole vacated by the accelerator piston does it for me.

 

Edited July 24, 2023 by bmp01

[KyleOZ]

Hi all, 

 

Regarding the pump,  I haven't got a proper pressure/vac tester so I have rigged up a old vaccum bleeder to test vac bit would need a pump for the pressure test, I should really invest in the proper kit. 

 

There is 7 good compression saws and 3 bad so I plan to steal parts of the bad 3 if required. 

 

The interference bung is a nice idea although I don't have access to a lathe, presume that would be required. Any one ever tryed threading the hole and fitted a grub screw? 

 

Should get the first two vac tested tonight, hopefully also pressure tested.  Should know more about how these will go then. 

 

Cheers

 

[tenner]

I'm no expert but the first thing I'd do is stick my £6 USB borescope down the plug holes and pick donor saws based on visible top end damage and the wobbliest cranks.

 

Good compression could just be a shitload of carbon buildup. Low compression could be an otherwise perfect saw which just needs new rings. Or differences in gaskets?

 

On 23/07/2023 at 20:48, KyleOZ said:

If I end up splitting cases etc is it worth fitting new rings or leave whats not broke alone? 

 

 

No need to split cases to replace rings. Personally I think if you're aiming to sell the saws for good money then it'd be expected that they've been thoroughly serviced to a high standard. Not necessarily a full rebuild in every case but definitely new seals, full carb rebuild, good top end, absolutely no leaking caps or fuel lines, etc. 

 

200T is a front line saw, your target customer probably isn't a millionaire but someone who will be sending it up a tree 5 days a week on a money making mission. People pay for good tools!