Slightly off-topic - 2-cycle blower performance

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atpchas

atpchas

AtA
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I'm working on an Echo PB-251 blower. I can't get it to run at the maximum RPMs it should (6700-7200 per Echo). It maxes out at less than 5500 RPM unless I put my hand over air output to increase load on engine - then revs increase to more than 7000 RPM. Of course, that defeats the purpose of the blower...
Things I've checked/done:
changed spark plug
checked muff for carbon buildup
pulled little black plug on carb (Zama RB-K90) and adjusted mix
tried a new carb and tried same adjusting
compression is 135psi, no scoring visible through exhaust port
checked fuel lines and replaced fuel filter
run with and without air filter - no change

Anything else I should check?
 
My Stihl SH-86 C-E was bought new from a dedicated Stihl dealer. IMO, it hasn't been running like it should since I bought it. I used it for a few months and got several tanks of fuel thru it.

When running, it would seem to bog down when you throttled it up. Once past that issue, it didn't seem to want to rev up as far as it should. I called the dealer and was told to give it a bit more time. I gave it 8 months of more time. Nothing changed.

I finally decided to take it in to the shop and have them take a look at it. The tech said it was a bit rich and retuned it. From that point on, it was a bit better, but it still acts as if it could rev higher.

With the blower tube on and running, if I place my hand over the end of it to block the air, it immediately revs higher. Pull my hand away, and it falls back to where it usually runs. I don't have a tach to check the rpm's.

My brother has the same exact brand / model of blower, only his is a year or two older. He's used mine and says it's off. He says his runs so much better.

Mine is still under warranty, so I'll be going back to the dealer again. My blower gets canned fuel, and all the loving care it can stand. No blower on this planet leads a better life than it does. Always cleaned top to bottom after each use, and it rests securely inside a climate-controlled garage / shop.

It's always been a bear to start. I think I finally got the procedure / routine down somewhat now. That was the biggest issue itself. Hard starting.
 
Free Will said:
My Stihl SH-86 C-E was bought new from a dedicated Stihl dealer. IMO, it hasn't been running like it should since I bought it. I used it for a few months and got several tanks of fuel thru it.

When running, it would seem to bog down when you throttled it up. Once past that issue, it didn't seem to want to rev up as far as it should. I called the dealer and was told to give it a bit more time. I gave it 8 months of more time. Nothing changed.

I finally decided to take it in to the shop and have them take a look at it. The tech said it was a bit rich and retuned it. From that point on, it was a bit better, but it still acts as if it could rev higher.

With the blower tube on and running, if I place my hand over the end of it to block the air, it immediately revs higher. Pull my hand away, and it falls back to where it usually runs. I don't have a tach to check the rpm's.

My brother has the same exact brand / model of blower, only his is a year or two older. He's used mine and says it's off. He says his runs so much better.

Mine is still under warranty, so I'll be going back to the dealer again. My blower gets canned fuel, and all the loving care it can stand. No blower on this planet leads a better life than it does. Always cleaned top to bottom after each use, and it rests securely inside a climate-controlled garage / shop.

It's always been a bear to start. I think I finally got the procedure / routine down somewhat now. That was the biggest issue itself. Hard starting.
Click to expand...
Sounds like you should borrow your brother's blower and do some educational parts swapping, for the sake of knowledge, at least... And see if you can isolate the problem area.
 
atpchas said:
Harley, the blower is running with the tube attached. The RPMs increase if I put my hand over the end of the tube. Not sure what your observation suggests as to my next step.
Click to expand...
My asking a lot of questions lets us know what you have and can lead to more meaningful suggestions.
It saves a whole lot of wild goose chasing, if the reason is something we could visably see. Which is why I always ask for pics, etc..
 
atpchas said:
I'm working on an Echo PB-251 blower. I can't get it to run at the maximum RPMs it should (6700-7200 per Echo). It maxes out at less than 5500 RPM unless I put my hand over air output to increase load on engine - then revs increase to more than 7000 RPM. Of course, that defeats the purpose of the blower...
Things I've checked/done:
changed spark plug
checked muff for carbon buildup
pulled little black plug on carb (Zama RB-K90) and adjusted mix
tried a new carb and tried same adjusting
compression is 135psi, no scoring visible through exhaust port
checked fuel lines and replaced fuel filter
run with and without air filter - no change

Anything else I should check?
Click to expand...
I had the exact same issue with a PB 250 and chased everything on it. fuel lines good, got another good carb and it still did the same thing. I had to wait until another one came in so I could swap out the muffler as that was the last thing I could think of. Sadly that did not work so the unit was binned. Echo was useless in all this with no help at all. I believe the rumors are true that they are going to pack it in judging by how little they support the product.
 
So, what happen when you lean out the high speed? Does the engine speed increase? Or does it stay the same?
 

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