200t 'racing'...

[Bermy]

So my 200t sits for about 8 months...then when I put it back in service this summer, I have noticed lately that after running for a short while (starts and initial run just fine) it seems like the idle kicks up and it races for a while, then settles back down again...

Anybody know what might be causing this? Its not work stopping, just irritating and out of the norm.

I do admit to old gas...but all the saws are running on it...

 

[Tucker943]

Al.......? Al where are you?

 

[woodworkingboy]

Change of atmosphere, low speed screw might be too lean now, give it a slight turn to the left and see if it changes things. You will likely have to readjust idle then, it will probably drop. Possibly a carb rebuild is in order, new diaphragms.

 

[Page]

damn, when I clicked on this thread I half expected to see people racing home made mini bikes powered by 200t's. don't know why yours is "racing" but maybe you should buy a new one and use the old one for "racing"

 

[MasterBlaster]

Man, don't burn old gas!

 

[Pelorus]

Sounds like an air leak, Bermy.
Might want to get checked out before it ends up lean seizing on you.

 

[sawinredneck]

I fought and fought this on the one I sold to Southsoundtree, it's crap in the carb! Took me about eight tries to finally get the little rice looking blockage blown out of it. These new carbs are a pita to work on, and the gas sucks worse than ever!

 

[HolmenTree]

So my 200t sits for about 8 months...then when I put it back in service this summer, I have noticed lately that after running for a short while (starts and initial run just fine) it seems like the idle kicks up and it races for a while, then settles back down again...

Anybody know what might be causing this? Its not work stopping, just irritating and out of the norm.

I do admit to old gas...but all the saws are running on it...

Fiona is this your old 200T or the MS200 I sold you?
Check your throttle linkage for sticking problems, maybe tank vent starting to plug.
Almost sounds like the carb problems my first MS200 I bought about 12 years ago gave me [replaced the carb with a new one on warranty] Fresh gas helps big time.

 

[woodworkingboy]

It was running fine, right, the last time you used it eight months ago? Probably not major, saws don't usually develop problems sitting on the shelf for that period of time, except maybe extra pulls to start..

 

[Al Smith]

Here's what I've found with the few I've worked on .Usually it's not the carb BTW .

The saw is designed using roller bearing mains which only rely on a small fiber thrust washer .A ball bearing will take a lot of side thrust but a roller will not .The crankshaft developes side play which heats up the seals by running the seal up on a carbon ring that forms around the shaft next to the seal .Probabley from bar oil and fine dust .

They run fine for perhaps a few minutes then starts to lean out .The longer it goes the worse the situation becomes .It will get so bad it won't run more than 30-40 seconds before it leans .

The fix is relatively cheap with parts bought OEM state side but I'd imagine a kings ransom in Bermuda .Around 60 bucks bearings and seals .

Northwood saw lists after market seals for a couple bucks a pop but I didn't see the bearing .They may have them for all I know .

Now I can peal a 200T to the bones and reassemble it in a hour or so but I've done many of them .I'd guess it could easily be done it two hours by someone less familiar, three at best with a lot of fumbling .

Now if it doesn't have a lot of side slop you might be able to just change the seals which would be cheap after market and wouldn't be such a big deal to do .If you go that route and need some help I've got plenty of pictures .

 

[Tucker943]

Al, do you think that the issue you proposed would develop while sitting on a shelf? Im leaning towards a carb issue. I know your stance is valid but wouldn't that manifest itself during usage and not during downtime?

 

[Al Smith]

I'm not neccessarily saying it's not fuel delivery related .A 200 or 020 is like an Arabian horse .They can be bull headed as all get out but if everything is right my oh my do they run .

Fact being as I type I'm having problems with the super bee which ran just fine last fall .I'm thinking it's fuel line ,fuel filter or plugged breather .It's not bearings or seals because they are brand new .

So it could really be about anything causing it to either lean out from an air leak or just plain fuel starvation on Fiona's saw .You just have to eliminate it one step at a time .

I think the reported carb problems are more so related to the last of the series which used one variation of the Zama C1Q carb that used a piston type accelerator pump which all did not have .I assume that would be only on the later portion of the production run unless it had been replaced .

 

[Bermy]

This is the saw that lives in Bermuda Willard, not your one!
Its not that old, 2007.

I'll freshen the gas. Then check other things...carb settings etc. When I prepare it to sit over the winter, I empty out the gas, then start it and let it run till it stops...

I always mix my gas in a separate container then fill the jug I take out on the job, so its usually pretty clean unless something gets in the tank during filling.

Hopefully its just the old gas, and I haven't buggered it badly.
Thanks for the things to look for guys!

 

[Tucker943]

Can you get some fuel stabilizer and just add that for the winter? Might keep diaphrams from going dry and becoming hard.

 

[Bermy]

Would diaphragms get dry with a relative humidity of avg 85% and temp of avg 65*? I usually leave the gas cap loose when its stored.

 

[HolmenTree]

When you run your saw dry prior to storage there is no fuel in the carb so stabilizer isn't gonna help. I believe the benzene in gasoline is what drys out diaphrams if left to soak in it.
But I do run Stihl Ultra full synthetic with built in stabilizer which may help reduce diaphragm degradation during operation.
On the topic about the Zama accelerator piston pump carbs on the 200s, My back in the day 1996 020T had this carb I'm quite certain because it was a lot "snappier" then my older 020s. Stihl picked up on these carbs way back in the mid 1980s when they put them on their weed trimmers.

 

[HolmenTree]

I think Fiona started and excellent thread here, that may go for a long long time..."200T Racing".
Here's a little something I'm sure you'll all enjoy, this is a Stihl ad from the summer of 1971 when the 020 was first introduced.

 

[MasterBlaster]

Lightweight, LOL!

 

[Pelorus]

Awesome ad!
Hey Bermy, does Bermuda gas contain ethanol? Is higher octane gas available?

 

[HolmenTree]

Lightweight, LOL!

Still under 10 lbs with bar and chain included

 

[mrdiesel]

Just throwing it out there but do you think its possible that the gaskets dry out or shrink thus creating little air leaks after storing a saw for a long period, perhaps after running a tank or two through it the gaskets swell and seal better

Im just guessing, i haven't seen this happen

 

[woodworkingboy]

No, pretty doubtful is my guess.

It was probably already mentioned, but a tiny hole or crack in the fuel hose from the tank to the carb, can give an uneven and racy idle. A pretty common malady. Also, often a saw will starve for fuel if that is the problem and you rev it up. Sometimes the hole is so small that it can be hard to notice gas leaking, so a bit difficult to spot, but it will major screw things up. The tear can be at a place that isn't exposed to your eye, like when making a bend where it exits the tank or goes through a grommet. If it doesn't adjust to better performance, the hose is a good thing to check. Replacing seals or a hose, possible similar effects from either being bad, but both ends of the spectrum in terms of time to repair.

 

[Tucker943]

When you run your saw dry prior to storage there is no fuel in the carb so stabilizer isn't gonna help. I believe the benzene in gasoline is what drys out diaphrams if left to soak in it.
But I do run Stihl Ultra full synthetic with built in stabilizer which may help reduce diaphragm degradation during operation.
On the topic about the Zama accelerator piston pump carbs on the 200s, My back in the day 1996 020T had this carb I'm quite certain because it was a lot "snappier" then my older 020s. Stihl picked up on these carbs way back in the mid 1980s when they put them on their weed trimmers.

I was wondering if in lieu of running dry, just running stabilized gas through the system and leaving like that.

 

[Tucker943]

Just throwing it out there but do you think its possible that the gaskets dry out or shrink thus creating little air leaks after storing a saw for a long period, perhaps after running a tank or two through it the gaskets swell and seal better

Im just guessing, i haven't seen this happen

This absolutely true on many modern machines. Leave a truck to sit for years then run it around. It will leak every fluid it has in it. Give it time and keep adding fluid and runnin g the truck and its amazing how things swell back into place.

 

[woodworkingboy]

I don't believe there is anything on a chainsaw that can shrink and cause leaks. Possibly the rubber crank seals could dry out and crack or something, but it isn't like they are really much exposed to the atmosphere like drying winds or anything. Most chainsaw gaskets are made from an inert material that doesn't seem to dry out damage. The pump diaphragm in a saw seems to stay pretty wet after gas has been run through, generally wet when you take the cover off, but the metering diaphragm seems to dry out when a saw isn't being run, dry out in that there is no gas on it. Maybe it is different when the metering works is upside down compared to the usual being on top, it stays wet? My 090G might sit for three or four years with the fluids all drained and run dry, and nothing seems to suffer except my arm getting it going the first time again. Eight months isn't long enough to hurt anything, as with Fiona's saw. My guess with diaphragms getting stiff, isn't the drying out that does it, but long exposure to gasoline. They don't just dry out, they get funky.