050 051 075 076 Info Thread

[president]

Your right about the gaskets, in those locations.#5 allen screw is difficult to get at unless
you access it by removing the top air filter base and remove the heat shield underneath it that
deflects the exhaust heat away ,oops forgot about that impulse hose on this refferance ,my 075 doesnt
configure like that,but I will check again tommorow.I have 2 075s abd an 051Im in peachland 4 hrs away
....Keith

 

[sefh3]

Make sure your impulse line is flexible. I had the same issue with mine and replaced the impulse line and it solved the problem.

 

[cwmntgm]

Thanks for the suggestion!

Impulse line (from the case to the carb) is brand new, along with the fuel lines. Unless the little nipple from the case itself is gummed up. Maybe I'll give it a little suck/blow to see if it has airflow.

I do believe that its an air leak somewhere, just a matter of finding it now.

 

[cwmntgm]

Just tore the thing down again, tightened every relevant bolt, and still not pulling fuel from the tank to the carb. Gave a little suck on the impulse line and the gas line, and no blockages at all. Both lines are slightly longer than needed (but flexible enough not to kink). Would that be a reason for not sucking up fuel? Just grasping at straws here.

Also, the aftermarket cylinder I bought didn't come with a decompression valve, rather just a flathead screw screwed in its place. I tightened that up real nice, so it should be air tight. Another possible issue?

Continues to fire up when mix is poured directly into the carb, so spark isn't an issue either. Any more input would be greatly appreciated!

Thanks guys (and gals? not so sure...)!

 

[PogoInTheWoods]

If there's sufficient impulse activity but you're still not drawing fuel into the carb, revisit the carb, Double check gasket to diaphragm orientation and also double check to be sure you're using the correct carb kit from a reputable source. An incorrect diaphragm won't correctly react with the pulses to suck enough fuel.

 

[cwmntgm]

Carb is brand new, so I don't have any worries there. Had the whole thing apart for the second time today, so unless the gaskets are SUPER finnicky in their placement, I don't think it would be that either.

Running out of possibilities here. Any thoughts on the decompression valve, Pogo?

 

[backhoelover]

i have a o51 on bench as we speak was doing the same thing. cranks seals and the oil control lever orings were leaking oring was so bad i assuming they came apart when puller lever to check both orings where not there

 

[cwmntgm]

Wondering I have the new carb tuned right. The side of the saw says 1 1/8 turn for the H and 1 turn for the L. No mention of the idle. 1 1/4 turn out?

 

[cwmntgm]

Getting pretty frustrated with the saw. I assume that if I cave in and take it into my local shop, they will be able to hook it up to a vacuum and find out once and for all where the air leak is?

Getting to the point where I might just give up altogether and buy a functioning one on CL for $CAD350. That's about $USD18.85 with the exchange right now, for all you Americans in the house. Stupid oil prices...

 

[sefh3]

The idle screw would not make a difference unless it's screwed all the way in. I'm working on one right now. Runs on prime but won't pull the fuel. I have a kit coming for it and new carb gaskets. I haven't ran a leak test but I put in new seals 2 years ago and boxed it up when I moved. Just getting to it now.

 

[sefh3]

Another issue with these saws is the case gasket gets weak and it pours bar oil into crankcase. This would cause it not to pull fuel. Can you put a vacuum gauge on the impulse line to see if it's sucking.

 

[cwmntgm]

I'll have to take it into someone in order to do the vac test, but I will make sure they test the impulse line. I sincerely hope that its not the case gasket, as it will be permanently placed on the backburner, if so.

When you say you put new seals on it, are you referring to the crankshaft seals? Replaced those on my 200t last summer. Much of a pain to change them on these saws?

 

[sefh3]

They are not as hard on these older saws. Seal replacement is pretty easy. Has your saw ran at all?

 

[cwmntgm]

Yep. Ran the day I bought it. Brought it home, fired it up, piston pretty much exploded in the cylinder. Pretty brutal.

The air leak could be at the seals then, huh? That would allow it to fire with the gas in the carb, but that could be where the vacuum fails?I've pretty much ruled out everything from the cylinder to the carb. Cranked everything tight, can't imagine there are any leaks there.

 

[cwmntgm]

When the piston exploded in the cylinder, could that have caused the crank seals to blow as well?

 

[PogoInTheWoods]

Thanks for the suggestion!

Impulse line (from the case to the carb) is brand new, along with the fuel lines. Unless the little nipple from the case itself is gummed up. Maybe I'll give it a little suck/blow to see if it has airflow.

I do believe that its an air leak somewhere, just a matter of finding it now.

You can put a small dab of grease or thick oil on the impulse hose or barb/nipple opening to see if it gets drawn in as you pull it over. It should. As for the decomp assembly or other leak source, pull the carb off the intake assembly and use a piece o' Gorilla tape as a seal. Same with the exhaust port (poor man's way of doin' it quick and dirty) and pump sone very low pressure air (10psi or less) into the impulse hose and start sprayin' soapy water on the suspected areas and look for bubbles. You may even be able to just hear a leak if you use a compressor with the regulator dialed way down. If the tape doean't hold, it's pretty easy to fashion a couple of block off plates to use with pieces if inner tube to seal off the ports.

If there's a leak large enough to inhibit the crank case pulses to the extent that the carb won't draw any fuel, it should be easy to find. Otherwise, you're back to the carb....even if it's a brand new one. The saw should run (or try to) even with a significant air leak unless it's directly associated with the intake assembly. Something you can try as a test there is to prime the carb as you've described as being successful to get the saw running temporarily and spray WD40 around the intake assembly to see if the saw immediately dies. If it does, there's a leak there somewhere.

May also want to double check the base gasket for correct position and that it isn't somehow blocking the impulse passage.

Just thinkin' out loud now....

Good luck with it and keep us posted!

 

[sefh3]

They make expensive tools to find leaks but as Pogo said duct tape or gorilla tape and a piece of inner tube work great. If you don't have a means of using air you can use a vacuum gauge also. Once you apply air or vacuum make sure you rotate the crank. It might not be leaking until the crank spins. How are the bearings on the crank? If the are bad it will allow the crank to push against the seal and cause a leak.
Try the wd40 trick. It will tell you if you have a bad gasket around the carb.

 

[president]

Try 2 turns out on the (L) screw

 

[cwmntgm]

UPDATE

So, I'm beating myself over the head here. I took my saw into a local mechanic (not MY local mechanic anymore!) after I put the P+C on, to get the pressure checked and to make sure everything checked out. Turns out, he got excited, and decided to change the impulse/fuel lines, and put the impulse line on the intake nipple, and the fuel intake line on the impulse nipple. Of course, my untrained eye didn't catch it, and just assumed it was put together correctly. To be fair, how the nipples are oriented on the carb, its pretty easy to think that how he had them hooked up could be correct.

Needless to say, that's where my problems started. Bought a new carb, which I didn't need. Saw was 'out of commission' for a month, when it was actually fine. Sigh. Saw has be milling some beautiful west coast wood for the past few weeks now.

Thank you to everybody who scoured the inner reaches of their minds for possible solutions. Too bad the problem was literally staring me in the face the whole time.

We had an old Mr. Fix-it type TV show up here in Canada called The Red Green Show. One of his mottos certainly rings true to me now

"I'm a man... and I can change... if I have to... I guess"

 

[arrow13]

UPDATE

So, I'm beating myself over the head here. I took my saw into a local mechanic (not MY local mechanic anymore!) after I put the P+C on, to get the pressure checked and to make sure everything checked out. Turns out, he got excited, and decided to change the impulse/fuel lines, and put the impulse line on the intake nipple, and the fuel intake line on the impulse nipple. Of course, my untrained eye didn't catch it, and just assumed it was put together correctly. To be fair, how the nipples are oriented on the carb, its pretty easy to think that how he had them hooked up could be correct.

Needless to say, that's where my problems started. Bought a new carb, which I didn't need. Saw was 'out of commission' for a month, when it was actually fine. Sigh. Saw has be milling some beautiful west coast wood for the past few weeks now.

Thank you to everybody who scoured the inner reaches of their minds for possible solutions. Too bad the problem was literally staring me in the face the whole time.

We had an old Mr. Fix-it type TV show up here in Canada called The Red Green Show. One of his mottos certainly rings true to me now

"I'm a man... and I can change... if I have to... I guess"

I've been following this for a while and scratching my head trying to figure out what the solution was. I also learned and relearned more about my big stihl saws. Thanks for the follow-up and sharing your humble findings. Hope you find a new and talented/experienced mechanic. Happy milling.
Arrow13