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Redmax GZ500 (husqvarna 450)

Mkinslow

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Needs some help here guys. Gotta redmax GZ500 on my bench. Came in half running. would run ok but as soon as I let off throttle it would instantly die,messed with carb adjustments and really didn't change anything. So I rebuilt the carb,still the same thing, changed plug ,fuel filter and lines, same reaction. Noticed it was wanting to flood,went back in and made sure metering lever was at right height, it was fine. tried starting again,wants to pop but nothing else, still flooding. So I ordered a brand new never used carb from Ebay put it on tonight and it's still doing the exact same things I've also changed the primer bulb. I'm starting to think the primer bulb is the problem, I read a post somewhere about one being a problem and the person ran lines away from it to eliminate it and the problem was solved, by the way compression is at 145psi and piston and cylinder looks great I'm at a loss for what to do next
 

Stevetheboatguy

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Needs some help here guys. Gotta redmax GZ500 on my bench. Came in half running. would run ok but as soon as I let off throttle it would instantly die,messed with carb adjustments and really didn't change anything. So I rebuilt the carb,still the same thing, changed plug ,fuel filter and lines, same reaction. Noticed it was wanting to flood,went back in and made sure metering lever was at right height, it was fine. tried starting again,wants to pop but nothing else, still flooding. So I ordered a brand new never used carb from Ebay put it on tonight and it's still doing the exact same things I've also changed the primer bulb. I'm starting to think the primer bulb is the problem, I read a post somewhere about one being a problem and the person ran lines away from it to eliminate it and the problem was solved, by the way compression is at 145psi and piston and cylinder looks great I'm at a loss for what to do next

I had a 450 husky not long ago that was doing almost the same thing.

I didn't find the problem until I tried running it late one night. Noticed a flash when I let off the trigger and it would die. Turned out that two of the case bolts had fallen out the bottom.

Something simple to check anyway.


Steven
 

Terry Syd

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I doubt that the primer bulb is the problem, but if you want to take it out of the equation, just disconnect the line from the bulb to the carb and stick a nail in it to block it off.

I noticed when I was setting my coil gap on the 450 that the factory specs didn't work. The specs say .2mm to .4mm. I set the gap at .3 and I couldn't start it. Went smaller, same thing, opened it up to .35mm and I could at least get it started. I checked to see where the best range was on the coil gap in a darkened shed while watching the color of the spark on the plug. The best range for a hot spark was .43 to .48 - I set the coil gap at .45 which should have been out of the range. You might check you ignition also, perhaps the spark is weaker when the revs drop.
 

Mkinslow

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I got three 450s from a dealer a couple summers ago. One had an out of time FW.
Man I have checked everything and changed some some things. I'm actually starting to lean towards a bad coil. Some of the reading I've done points towards that too. So I guess I'll be looking to get a coil.

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cuinrearview

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Man I have checked everything and changed some some things. I'm actually starting to lean towards a bad coil. Some of the reading I've done points towards that too. So I guess I'll be looking to get a coil.

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Come to think of it one did have a bad coil too Marshall. Luckily I had three so I could swap stuff around to diagnose.
 

Mkinslow

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Come to think of it one did have a bad coil too Marshall. Luckily I had three so I could swap stuff around to diagnose.
I thought I had one but can't seem to find it, so I'll have to order one.

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Terry Syd

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Try checking it in a dark environment. You might open up the plug gap a bit to create a little more resistance and also make it easier to see. If the spark is weak, try changing the coil gap, it made a BIG difference with mine.
 

Mkinslow

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Try checking it in a dark environment. You might open up the plug gap a bit to create a little more resistance and also make it easier to see. If the spark is weak, try changing the coil gap, it made a BIG difference with mine.
I've checked the spark also, I can see it pretty good, even under the super bright led lights in my shop,but I'm starting to wonder if it's not strong enough under compression?

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Terry Syd

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When it is not strong enough under compression, then it usually shows up when you give it the throttle or put a load on it. Your problem arises when it drops back to idle and the load is reduced. You might try reducing the gap on the plug a bit and see if that reduces the resistance across the plug and allows the saw to run. If that has a positive effect, then the problem is more likely the coil.

However, it sounds more like an air leak problem, but you don't mention the saw leaning out.
 

Mkinslow

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When it is not strong enough under compression, then it usually shows up when you give it the throttle or put a load on it. Your problem arises when it drops back to idle and the load is reduced. You might try reducing the gap on the plug a bit and see if that reduces the resistance across the plug and allows the saw to run. If that has a positive effect, then the problem is more likely the coil.

However, it sounds more like an air leak problem, but you don't mention the saw leaning out.
I gotcha, no airleak. Passed pressure and vacuum tests.

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Mkinslow

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Out of curiosity, is the GZ500 made in Sweden like the 450?
I'm pretty sure bud.
061e1e9bfb272080c09adcd25ffc60fd.jpg


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FergusonTO35

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Thanks. Redmax made in Sweden, that's funny. Yeah, that saw is a Redmax like a Saab 900 is a Toyota Camry.
 
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