FarmerTec MS250 shortblock upgrade to MS210

[Fruecrue]

@Fruecrue i looked awhile today on ebay trying to find a link to post for the exciting racing motors. I couldnt find um for the life of me. Do they still make them?

I don’t know, haven’t seen them in a while.

 

[PogoInTheWoods]

The crank on ez start saws and regular start saws is the same.

That's already been established..., except for the 210 which has a different crank and stroke and the 'special' 250 crank specifically for Brazil -- presumably with an even less advanced keyway than the normal crank to help minimize pre-detonation of the lousy fuel typical of third world areas of S. America. The picture I posted clearly shows a difference in keyway location between a 210EZ crank and a FarmerTec 250 standard crank. What I lack is an OEM 250 crank to compare with the FarmerTec crank, but the plan now is to remove the cast in key from the 210 flywheel and advance the timing to hopefully get this damned thing running -- unless the coil is the problem. Then it's 'officially' junk.

Still looking for tips to get rid of the cast key without screwing up the flywheel and/or mating surface.

 

[Fruecrue]

That's already been established..., except for the 210 which has a different crank and stroke and the 'special' 250 crank specifically for Brazil -- presumably with an even less advanced keyway than the normal crank to help minimize pre-detonation of the lousy fuel typical of third world areas of S. America. The picture I posted clearly shows a difference in keyway location between a 210EZ crank and a FarmerTec 250 standard crank. What I lack is an OEM 250 crank to compare with the FarmerTec crank, but the plan now is to remove the cast in key from the 210 flywheel and advance the timing to hopefully get this damned thing running -- unless the coil is the problem. Then it's 'officially' junk.

Still looking for tips to get rid of the cast key without screwing up the flywheel and/or mating surface.

I have used various needle files and a dremel in the past to remove cast in keys, not a big deal.

 

[PogoInTheWoods]

@Fruecrue i looked awhile today on ebay trying to find a link to post for the exciting racing motors. I couldnt find um for the life of me. Do they still make them?

The FarmerTec kit is actually a fairly decent kit for the money but I have read somewhere that the timing needs advanced to get the most out of it. Hmmmm.

 

[PogoInTheWoods]

Thinking about notching the middle of the key with a small grinding piece and using a chain file. Guess I can't screw it up any worse than it already is.

 

[JohnnyBlade]

Thinking about notching the middle of the key with a small grinding piece and using a chain file. Guess I can't screw it up any worse than it already is.

Its soft. U can use a burr bit or needle file or 80 grit. If ur looking at the back of the flywheel, with the key at the bottom u would file the
Left hand side of the key. It doesnt take alot of swipes with file to get some movement/advance in timing. I Woud just leave part of the right side of key present just incase its another issue and u need to return to stock.

 

[PogoInTheWoods]

Fixed..., in ten freekin' minutes after pissin' up a rope all this time. Sheesh. Got rid of the whole key, advanced 1/2 the width for starters and it fired right up and at least runs, revs, and idles now -- which obviously eliminates the coil as the problem and puts it square on the crankshaft keyway. Still needs dialed in a bit but I need to clean and polish the crank and flywheel surfaces before committing to a final position, then crossing my fingers, and gettin' this thing the hell outta here and back to the owner. Geezus.

'Preciate the input on this, fellas. And let it be a warning to anyone using a FarmerTec MS250 shortblock kit for an EasyStart saw. They simply won't work with the EasyStart coils unless the timing is advanced. Period.

The end.

(Hopefully)

 

[JohnnyBlade]

Glad u got it! Get back when u find a deffinate positon of the flywheel. As in how far u had to advance it to be perfect. Thanks

 

[PogoInTheWoods]

Not sure 'perfect' will apply here. More like 'close enough for horseshoes and hand grenades'. That said, it's my understanding that the Stihl timing curves are fairly forgiving within a few degrees or so in the cheaper and mid-range saws. I advanced it a little more than half a key after cleaning the shaft and f/w and it's a little too much now. Just hafta dick with it a little more I guess.

 

[PogoInTheWoods]

I don’t see why timing would change due to stroke. Degrees before TDC is degrees before TDC.

This got me thinking so I did some searching and came up with an old AS thread that explains various aspects of ignition timing advance and pretty much covers my thinking on the stroke aspect.

A shorter stroke achieves greater piston movement (in degrees) for the same diameter crankshaft (and flywheel) rotation, so the timing actually is affected by the stroke relative to the f/w and coil poles. Compensation is achieved by changing the position of the flywheel on the crank when the same flywheel and coil are used for different stroke lengths, hence the different keyway locations in the example pic I posted -- though I still believe the FT 250 crank has more timing delay than we'd find in an OEM 250 crank. The difference in keyway positions is the difference in the stroke (in degrees over the length of the stroke) relative to the same coil and flywheel.

Here's the thread: https://www.arboristsite.com/community/threads/timing-advance.249182/#post-4617787

one.man.band gets into it with all the math on the second page if you're interested in the details.

And fwiw, I ended up having to advance the flywheel the entire key width to achieve a relatively normal running condition...which is about what the difference looks like it should be by the pic of the two cranks. So we were both right. LOL

OK. I'll go now. Thanks again for the input. Let's never come here again!

 

[Fruecrue]

Glad it worked out.
Now my brain hurts.

 

[cobey]

If you can find my 250/025 build thread
There is things about the little standoffs not match the bottom of the block,
Pictures of the repair i did

 

[cobey]

@cobey was the guy.

I forgot to use the quote... sorry

 

[PogoInTheWoods]

If you can find my 250/025 build thread
There is things about the little standoffs not match the bottom of the block,
Pictures of the repair i did

Yep. I read it somewhere along the line. Good catch. There is definitely an offset from the housing mount points with the aftermarket pan that raises the entire engine to the extent that the oiler rod could hit the tabs on the case and could even be enough to change the timing from the flywheel also being raised relative to the position of the coil.

If the indentations for the mounting locations don't match, (or are non-existent) on an aftermarket bottom pan, the OEM pan must be used or the AM pan modified to fit correctly.

 

[Fishnuts2]

I tried a 025 kit in a 021 last Fall and it just wasn’t doin the job. Slow to rev, hard to tune, you know the rest of it. Anyway, after reading this thread I found one of my parts 025’s and used it’s flywheel. I advanced the timing a few degrees too. Comparing the two flywheels shows the magnets are about a keyway’s width apart from each other.

So, if you use a 025 kit in a 021, saw make sure you get a 025 flywheel to go with it.

Well, now it runs great and I thank you guys for this thread!


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