Geez! It's That Poulan Guy Again

[Loggerhead]

I know guys...I'm tired of it too...but I'll ask anyway in hopes that ya'll will feel sorry for me...*L* Question: I mentioned earlier that at WOT, this saw spews a fine mist or fog of fuel out the top of the Carburetor but it doesn't seem to affect the ability of the saw to peak out at top speed. I also mentioned that I attributed the condition to reed valve flutter or bounce and in my shallow thinking, that it may be due to the extremely high RPM's and the reed working so hard and fast that it can't really compensate (open and close) as fast as the RPM's of the engine. Anyway, "Whatsnext" mentioned that if the reed wasn't sealing correctly, it would affect the idle. I removed the carburetor and since the reed valve on this saw sits down below the throat of the intake housing, I shot enough PB Blaster on top of the reed to see if it seeped out and how long it took. It leaked down but not like the reed was hung open and dumping it in a few seconds but more like a slow 20 second drain...should it leak down even that quickly or should the seal hold for a period of a minute, five minutes? Thanks to all for your suggestions and assistance.

 

[Crofter]

The reeds are pressed against the cage when the engine starts to build base pressure. As previous poster said they can even be slightly open (.010) when at rest so they are not needed to be entirely leak proof. If they are not visually bent, broken or curled that is not likely the problem.

 

[Loggerhead]

Thanks again Crofter...I kinda figured that would be the case. You have any opinion on that fuel vapor spewing out the top of the carb?...again, it doesn't seem to affect the running...maybe it doesn't do it as much with the cover installed but I guess I'll find out after I run it awhile (when it will idle) and see if it makes a mess inside the intake housing.

 

[skwerl]

Some backspray seems to be typical in many small 2 stroke carbs. I remember when Stihl introduced the 20T (as opposed to the older 20AV or whatever) that there were some issues with backspray. The $600 saws ran great but the backspray soaked the air filter and the saw would choke down after a while.

I don't know what they did to fix it but the current models have a small piece of foam just in front of/ below the carb intake. This piece of foam stays damp with fuel pretty much all the time. I'm guessing that it helps soak up the spray and allows the drippings to get sucked back into the carb while keeping the liquid fuel from soaking the air filter.

 

[scottr]

Spew

Loggerhead , don't worry about the spew , my 2000 spews and it runs fine . If you're squirting , pull the clutch then squirt some mix oil on the crank seal and see if it smooths out .

 

[whatsnext]

And I didn't tell you that the reed had to be slammed shut when the saw is turned off. What it does when it's running is an entirely different thing. The stiffness of the reed may have relaxed over time, or there could be dirt around the edge somewhere, and it may not be functioning properly at slow speeds. Reeds wear out in dirt bikes all the time that's why I suggested it. Do you have a tach, and if so, what do you think proper idle speed should be?
John...

 

[Loggerhead]

John, absolutely, I understood you didn't mean the reed had to be like entirely leakproof and I assumed that when I shot the PB in the intake that if it didn't disappear as quick as it went in that it was within tolerance at least as far as a non running condition goes...it's a pretty stiff reed in my opinion and I kind of expected it to be a little more flexible...I was thinking it might be causing the spew of fuel more than affecting the idle...I'll pull the clutch this weekend and shoot that mix on the crank seal Scott and unfortunately, I don't have a tach so I can only guage it against my other saw. Thanks again to all of you for your advice and even more, your patience...I never really got involved with 2 cycle engines in the past but now I have so many that I thought I better learn or I'd end up taking them to the doctor more than running them...and probabaly spend as much money as I would at the doctor's if I didn't learn how to work on them...Thanks again all!!!

 

[Crofter]

Loggerhead, there was a thread here not too long ago where guys were talking about methods of makin up a rig for testing the crankcase for leaks. Maybe someone can remember what the thread name was. Lakeside53 was right of course you have to do both positive and negative pressures. A slight leak at the reeds is not the same significance as an external leak at seals etc. Get that crankcase tested for leaks!

 

[Loggerhead]

Frank...you bet I will!...and it will be worth the $30.00+/- greenbacks to keep from wasting more time and beating you guys up for information that I can't apply without the right tools...I think I know just the shop to take it to and will do it ASAP!...thanks again!