Shindaiwa 488 wont start

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joe.snow

joe.snow

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I'm trying to fix this old saw. Last week it was idling great but died as soon as i touched the throttle. I then cleaned out the carb and put it back together, would not fire at all, backfired and smoked once. There is blue spark and it is wet after several pulls. Removed the spark plug and pulled it with open throttle several times in case it was flooded. No start. Spark plug is a BPMR7A. I even tried starting fluid and still no start. Ignition coil is new so i don't think its that. I don't have a compression tester but it is more difficult to pull than my Husqvarna 435 and pulls easily without the spark plug in. Spark arrestor is clean.
saw1.jpg
 
tomalophicon
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Those saws need a non R plug.
Try with a BPM7A.
I tried absolutely everything on my Shindaiwa 577P that had the same problem. Nice bright spark with a BPMR7A but it would often not start and shoot blue flame out the muffler. Sometimes would start but absolutely could not be relied upon.
Hopefully changing the plug helps you.
Tom.
 
joe.snow

joe.snow

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Those saws need a non R plug.
Try with a BPM7A.
I tried absolutely everything on my Shindaiwa 577P that had the same problem. Nice bright spark with a BPMR7A but it would often not start and shoot blue flame out the muffler. Sometimes would start but absolutely could not be relied upon.
Hopefully changing the plug helps you.
Tom.
Thanks for your reply. I'll try that and get back to you. I thought the 'R' was for radio interference or something though, so i don't know how that helps, but i'll give it a shot.
 
Chevboy0167

Chevboy0167

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Yes, R means resistor.

The “R” indicates a resistor type spark plug. Resistor type spark plugs reduce the amount of radio frequency interference (rfi) that can cause ignition misfires and static on the radio, if so equipped. The number at the end indicates the recommended spark plug gap in tenths of a millimeter.

 

J D

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The “R” indicates a resistor type spark plug. Resistor type spark plugs reduce the amount of radio frequency interference (rfi)
Correct.
Ignition systems are specifically designed to work with either a resistive or a non resistive plug, using the wrong type will cause either excessive Voltage or excessive current... Neither of which your coil will appreciate long term.

The number at the end indicates the recommended spark plug gap in tenths of a millimeter.
The number generally relates to the heat range of the spark plug (unless it's a specialty gap)
NGK_Plug_Chart_1.jpg
 
tomalophicon
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tomalophicon
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Motherboard

Motherboard

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Did you put a new diaphragm in the carb and adjust the metering valve, did you replace the metering needle, some have been replaced with the wrong needle
and the fuel eats the rubber tip, the all steel one was better.
The 488 was known as the 490 over here, Great saws, the new 490 is not the same saw at all, you have to go to the 501P over here to get similar saw as the
old 488 / 490. I think the older saw was better, I had three of the new 501P models and only one of the 488 / 490 models.
 

J D

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Too much scoring is enough to drop compression, anything much under 120psi & it won't run well, get down to around 90psi & they don't run at all.
That looks like enough to do it.
You may get away with cleaning it up & putting new rings in it if you don't want to spend anything much on it
 
joe.snow

joe.snow

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I'm a pretty strong guy and the starter rope is difficult to pull like it has good compression, maybe it isn't quiet enough.
 
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