Instant backfire ?

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

lwhaples

ArboristSite Operative
Joined
Sep 6, 2010
Messages
383
Reaction score
123
Location
Vermont
My project saw came Saturday,Yep sure was happy to see the mail lady. Bought it off Ebay knowing it had spark,compression,and didn't run off prime.
It's a 2065 Jonsered needing a few parts,but was hoping to hear it run first. Cleaned all the crud off and fixed the kill switch. Didn't have the right Zama carb kit so I only took the top off. Found some sawdust inside and cleaned thinking it may run enough to at least know it's a keeper.
Put fresh gas in and after a few pulls on choke,it fired. Will run for a few seconds and pop,then die. Refire,same thing. Won't take much throttle which I'm sure is the carb,but the pop is more prominent and still dies .
Compression 145
muffler clean inside
flywheel looks fine
new spark plug
Hard to think it's the coil,won't run long enough to get warm.The pop sure acts like it's backfiring. Any idea's Thanks, Larry
 
i would take the flywheel off and very carefully inspect the key, even if it is slightly sheered it will throw it off time slightly causing it to backfire, i have had this happen to me before
 
Yea,that was my first thought.Sure acts like timing. The flywheel has a built in key that sure looks good to me. Larry
 
Yea,that was my first thought.Sure acts like timing. The flywheel has a built in key that sure looks good to me. Larry

By looking good....do you mean that you pulled the flywheel and checked it?

When you put the flywheel back on, make sure you degrease the tapers on the crank and the flywheel. I hear that starting fluid is a good degreaser. The key is to align the two parts, the taper does the holding with the proper torque on the nut.
 
By looking good....do you mean that you pulled the flywheel and checked it?

When you put the flywheel back on, make sure you degrease the tapers on the crank and the flywheel. I hear that starting fluid is a good degreaser. The key is to align the two parts, the taper does the holding with the proper torque on the nut.

Yes, pulled the flywheel. Sure was hoping to see a bad key. But the key. flywheel as one was a surprise. Sounds like I should pull again, to double look it over.
 
Update, Cleaned the Zama carb and was able to get it to idle. Touch the throttle and it would quit or sound like it was struggling. Went to the dealer to get a kit,he said he thought it was the fuel line. So, I bought a line and filter. Then found he had a 2165 in a box. So picked up some parts and the Walbro carb.
Replaced the fuel line and filter while still having the Zama carb on. Same deal no matter how I tried to adjust. Put the Walbro on with high hopes,but still the same. Will not take any throttle. ? Thanks, Larry
 
needs three things to run Compression Ignition and Carburetor
start with compression check which i see was already done checks out ok next go to the ignition system check everything wires connectors etc. then go to carb checking fuel line etc.
 
Last edited:
Maybe you meant "compression, ignition and FUEL"

It may not run well, but it will run if you have those three.
 
is this ignition adjustable ... meaning can timing can be advanced. try repositioniung the coil to facotry specs. it sounds alot like ignition . check muffler screen , could be holding excess gas in muffler then igniting.
 
I pulled out one of my 070 i bought recently and did some cutting with it yesterday. Was hard to start (these saws are usually easy starters) but ran ok after i adjusted the carb. Tried starting it today and it wouldnt go. I noticed the spark plug was loose, so i tightened it down and it fired up without choke and locked throttle. Turned it off and now the fun starts.

Pulled on it and it almost tore my arm off. Tried again, and it backfires every single time, even if i pulled gently. Its no fun getting backfire from the 107ccs either.. :dizzy:

I might have heard a strange sound when i turned it off, or i could be just imagining it. Any idea what went wrong? Time to take off the flywheel?
 
Tried it again after it cooled down a bit, started right away. Turned it off, and here we are breaking fingers :eek:

Im thinking i mussed have messed up the carb settings.
 
Back
Top