Shindaiwa 488 problem finally solved

[auburnblows]

I was given a used Shindaiwa 488 over 2 years ago. I rebuilt the carb, put on new muffler, and filled with fresh gas. The saw fired right up and I was surprised how well it performed. However, at totally random times the 488 would act like it was flooding or muffler was clogged. Even at wide-open throttle there was not enough power to move the chain. Sometimes this "flooding" would last for seconds and at other times it would last until I cursed the saw, threw something, and eventually gave up and grabbed another saw. Over the course of the last 2 years I have changed both the primary and secondary ignitions, replaced the carburetor, put on new fuel lines and tank vent, swapped the kill switch, as well as replaced the flywheel. I was ready to give up and get rid of the saw when I came across this thread:
http://www.arboristsite.com/community/threads/shindaiwa-488-spark-plug-issue.216823/
I replaced the NGK BPMR7A plug with a BPM7A non-resistor plug and the shindaiwa 488 has now ran through 5 tanks of fuel flawlessly. Apparently my older 488 ignition does not like resistor type spark plugs even though the only manual I could find called for an NGK BPMR7A.
This site could have saved me a whole lot of time, money, and aggravation had I found the above thread earlier.

 

[Farmer_Nate]

I have a 488. I had frustration with the same. It appears it may be fixed, or at least the problem masked, by a non-resistor plug. More testing to be done.

Story:
Bought the saw from a seller who said the saw was an easy flooder. I tweaked/stretched the carb metering needle spring and found it improved. It would sometimes still flood. It was hard to start. It would not take choke well. It would turn over after a hard pull on the start cord, then just about the time the engine would coast to a stop, a huge explosion would eminate from the exhaust with a puff of smoke. Sometimes it would jerk the pull cord. Sometimes it ran backward! It was intermittent. Sometimes great, sometimes not.

One day while cutting, it dropped down to idle only and would not rev. I turned it off, back on, and it ran fine.

A second day, after careful warmup, while enjoying the extra power and ear-tickling noises from the latest muffler mod, I smiled as I used the saw's extra power to cut at wide open throttle easily through a couple of small logs. Then, at full throttle, halfway through a cut, a huge puff of smoke blew from the muffler and the saw stopped. It would start easily, but would idle with a laboring chug, chug, chug and would not rev up. I could not get it to stop, so I went home.

I put in a non-resistor plug today and it starts and runs. I'll test more, but I wonder what the deal is.
I conjecture the coil is weak and in need of replacement. It may be somehow degraded just enough it can't overcome the extra resistance of an NGK BPMR7A resistor plug, which the manual calls for. I guess the non-resistor plug allows the coil to keep working, even in a degraded condition? Not sure. I have zero to lose, I figure, if I need a new coil anyway.

Cheers.

 

[SteveSr]

I have a 488. I had frustration with the same. It appears it may be fixed, or at least the problem masked, by a non-resistor plug. More testing to be done.

Story:
Bought the saw from a seller who said the saw was an easy flooder. I tweaked/stretched the carb metering needle spring and found it improved. It would sometimes still flood. It was hard to start. It would not take choke well. It would turn over after a hard pull on the start cord, then just about the time the engine would coast to a stop, a huge explosion would eminate from the exhaust with a puff of smoke. Sometimes it would jerk the pull cord. Sometimes it ran backward! It was intermittent. Sometimes great, sometimes not.

One day while cutting, it dropped down to idle only and would not rev. I turned it off, back on, and it ran fine.

A second day, after careful warmup, while enjoying the extra power and ear-tickling noises from the latest muffler mod, I smiled as I used the saw's extra power to cut at wide open throttle easily through a couple of small logs. Then, at full throttle, halfway through a cut, a huge puff of smoke blew from the muffler and the saw stopped. It would start easily, but would idle with a laboring chug, chug, chug and would not rev up. I could not get it to stop, so I went home.

I put in a non-resistor plug today and it starts and runs. I'll test more, but I wonder what the deal is.
I conjecture the coil is weak and in need of replacement. It may be somehow degraded just enough it can't overcome the extra resistance of an NGK BPMR7A resistor plug, which the manual calls for. I guess the non-resistor plug allows the coil to keep working, even in a degraded condition? Not sure. I have zero to lose, I figure, if I need a new coil anyway.

Cheers.

Hallmark bad coil symptoms... Random timing changes.

 

[Farmer_Nate]

Update, 488 with non-resistor plug now starts cold reliably, with no flooding, using a similar sequence each time:
choke out, then 2-3 pulls to first light or cough
choke in, 2-3 pulls to idle-speed start (I don't like it to fire off with full-throttle locked on)

Idles a long time, and revs.
Yet to cut with it yet. More later.

 

[Bob Hedgecutter]

Update, 488 with non-resistor plug now starts cold reliably, with no flooding, using a similar sequence each time:
choke out, then 2-3 pulls to first light or cough
choke in, 2-3 pulls to idle-speed start (I don't like it to fire off with full-throttle locked on)

Idles a long time, and revs.
Yet to cut with it yet. More later.

Curious- how do you lock on full throttle?

 

[Farmer_Nate]

Curious- how do you lock on full throttle?

The Shindaiwa 488 has a feature which locks throttle trigger to near full throttle. I leave that turned off. I like to warm the saw slowly and not rev it to max while cold.

 

[Farmer_Nate]

Cut update. The saw ran great for 1 hour cutting. Non-resistor plug Autolite 2974 at Advance Auto. I may get the NGK version when I can, may not.

 

[Bob Hedgecutter]

The Shindaiwa 488 has a feature which locks throttle trigger to near full throttle. I leave that turned off. I like to warm the saw slowly and not rev it to max while cold.

You mean like a fast idle setting?
The setting designed for cold start procedures?

 

[Farmer_Nate]

Maybe...but I don't consider roughly 11,000 RPM without chain brake as fast idle.

The manual says to use the throttle lock combined with the choke "when the engine is hard to start" with the chain brake also on, but it is not necessary on this saw because now it is never hard to start.

That throttle latch feature is also not called out for the generic "starting the cold engine".

https://www.shindaiwa.com/en_us/support/manuals