Who wants to play "NAME THAT CHAINSAW!" .. and put your diagnostics hat on ?

[Lemmy]

Hello all, first time poster. I came across arborsite while researching some issues I have with a chainsaw. I'm hoping someone may be able to tell me what I'm missing, did wrong, or what I can check/try next.I will try to be concise, yet thorough so all the info I have is here. Here's the scoop:


THE PATIENT:
My father-in-law gave me his old chainsaw. It's an older Sears model that is Blue and White, 2-stroke, bar total length is 16" (not sure if this is considered 16" bar or 14" bar) . Can't find the model number on it - the only markings are "Type 647x2" and "Ser No. 006883" I'm not sure what model this is, tried to do some research but came up dry. I pulled a manual for a similar model, but it's not the same as what I have.** [Pic below]


SYMPTOMS:
I couldn't get the saw running. I put gas/oil mix in. pulled and pulled, could get it to turn over and it did finally start but wouldn't stay running and would stop under load of pulling the trigger to run the chain.
First I put some "mechanic in a bottle" in to try to devarnish the carb jets and see if would help. It seemed to help and I could get it running, but then I noticed a fuel leaking problem. I wasn't sure where it was coming from and hadn't ever tore down a chainsaw before - but I did notice someone had shmeared JBWELD all along the bottom of the saw so I deduced there may have been a leak from the gas tank seam, for lack of a better theory....


TREATMENT:
Dismantle and clean. I took everything apart and cleaned down to the motor/carb assembly. I did not take the motor apart because I didn't want to get into gasket replacement just yet, not sure if parts are even available. Removed Flywheel and Clutch (Found this site trying to figure out how to get a flywheel off.. NOW I KNOW, THANK YOU!)

THe tank is molded into the chassis base itself, which a thin plate covering the open end to complete the tank. There is a sealant under this thin plate. [Pic below]
- I remove the plate and applied new JBweld,replaced plate, clamped.
- While I had it apart, i regapped the ignition point to what seemed like the highest point on the cam to the spec stamped on the housing.**
- Pulled the plug and lightly sanded the wire and diode thingy (if that's what it's called).

Reassembled, put new gas/oil/stabilizer mix, Chain/Bar oil.

TEST: Unsuccessful.. wouldn't start, wouldn't turn over at all.

I pulled the plug, held it against the motor housing and pulled the start cord at it appears to be a decent spark**
I sprayed some carb cleaner into the carb intake and a tad in the piston cylinder. No change

I noticed it still had fuel dripping from somewhere. The fuel line seems intact. I don't notice any leaking from the tank seams.
I DO notice that there is a small stainless screen next to the fuel cap that is leaking fuel. [Pic below]
WHen I had the whole assembly apart and was cleaning, I pulled what appeared to be gunk out of a hole behind this screen. At the time I thought "if i pull this gunk out, what is going to keep the fuel from leaking out of the screen??" so I put some of the gunk back in. Apparently something is supposed to be behind the screen that is not anymore so now it's leaking fuel.*


PROGNOSIS/QUESTIONS
After all that the darn saw wont start and the fuel is leaking from at least that metal screen.

To my knowledge, combustion engines need three things FUEL/COMPRESSION/SPARK....From what I can tell, this bugger has all three but still doesn't seem to want to start. I think we can rule out compression as the issue because I was able to get the saw to run before dissassembly. Which leaves FUEL and SPARK


Q1) Who wants to play "NAME THAT CHAINSAW!!!"... What model/year is this little beast?


Q2) FUEL:
- THERE IS NO PRIMING BULB on this model chainsaw, so not sure how to prime it other than PULL PULL PULL.
- Fuel filter may need to be replaced? fuel line is rubbery and appears in OK shape. The saw did run previously so I think these are OK.
- The Fuel filler cap says "Mix 1/2 oz 30 weight oil with 1 gallon Regular gas"
- I mixed .25 oz of 2 stroke oil with 6.4 oz of unleaded gas according to the Oil instructions (2.5oz oil per 1 gal gas)
- I used unleaded fuel because that's what I have... Do I need to be putting a lead additive into the gas for the chainsaw to make it "Regular" ( 70s/80s Regular=Leaded definition ... not the modern Regular=83 to 84 octane definition)

Q3) SPARK:
I've never set the timing on a chainsaw. What I did was rotate the crank/cam shaft until the point had the widest gap, then adjusted the gap with the feeler gauge.
- Is this correct? or should the measured gap be at a different point in the dwell/cam rotation?
- Could it be a Weak spark plug even though it appears to have a bright spark in testing?

Q4) What's up with this stainless screen that lets gas leak out?
- Is this a breather hole for gas vapor?
- Is there supposed to be gunk behind it and if so, what is the gunk? Can I substitute anything else I can get my hand on now?


PICTURES THAT MAY HELP:

Full Pic:
View attachment 300579

3/4 view:
View attachment 300580

Ignition:
View attachment 300581

Bar: "A30 14BR50"
View attachment 300582


Fuel Fill cap and Screen:
View attachment 300583

 

[DSS]

I can help a little. I have no idea what you have for starters, other than a chainsaw.

You gapped the points correctly. I assume there is supposed to be a check valve of some sort behind that screen. Thats what all the gunk used to be.

Mix some 40:1 and it will run fine on it. You don't need leaded gas. I think you need to do some new fuel lines and a carb kit.

I hope somebody can tell you what model this thing is. Cool old saw.

 

[Guido Salvage]

Given the shape of the starter housing on my phone it looks to be a Power Products engine. I would guess it falls between the David Bradley's and the D-44 type saws.

 

[barneyrb]

I think that is a Roper, maybe a C110 or C121 model????????? It would depend on if it was manual or automatic oiling as to which model. Same saw as a Massey Ferguson 190 or 190A

Model Profile: C121


Model Profile: MF190

 

[Lemmy]

I think that is a Roper, maybe a C110 or C121 model????????? It would depend on if it was manual or automatic oiling as to which model. Same saw as a Massey Ferguson 190 or 190A

It's a manual oiling.. the black knob at the top is the oiling control the leads to a small pump at the oil reserve tank.

 

[thesawisthelaw]

major props for excellent write up and posting pics that go along with it !!

hang in there - you will get it running !

 

[Lemmy]

Update - resolved

Hi Folks,

It's been several weeks since I posted. Work, vacation and other projects conspired against my timing to get back to this chainsaw debacle.
I wanted to update the thread with the results in case it helps anyone else with their project.

1) I took the advice to mix a 40:1 gas/oil ratio. I was following the directions on my Oil bottle which was closer to 25:1 ... maybe too much oil in that mix. I could still only get it to sputter but not start and stay running.

2) Even though I had spark at the plug, I decided to try a new spark plug. This seems to have done the trick! It took about 20 or so pulls, but it started to have life. A few more pulls and she started up and stayed running. (this was also with the 40:1 fuel/oil mix).

So, even though i had spark at the plug, the spark maybe wasn't strong enough to get and keep the ignition of the combustibles going.

3) That small mesh screen with the gunk behind it was definitely a breather check valve. Since it was leaking, i put a dab of silicone calk on the outside and let it dry to stop the leaking fuel. When I did get the saw running, i could feel pressure behind the silicone so i broke the seal and the gas fumes "popped" out. Not sure I can find a replacement check valve to replace the gunk I pulled out... and since I JB Welded the fuel tank cover back in place, I'm not going to pull it apart to make the replacement anyway. At least that's my thinking at this point.


Now I have a cool little saw that runs = happy me.

Next is to go try it on some lumber and let it do it's thing.


Thank you all for the replies, suggestions and encouragement. It was the shot in the arm I needed to see this one through!

Best to you and your projects,
Lemmy