# Exhaust Valve Issue???



## dtakushi (May 8, 2019)

I bought a used Predator 3500 generator recently and it was running rough. After cleaning and checking the carburetor I moved onto the valves to make sure they were adjusted properly. The exhaust valve had no gap and I had to adjust it quite a bit to get to the recommendation of .007", the intake valve was fine. After adjusting, if you tried to started it was tough to pull after the first couple pulls. I'm guessing there was too much compression or something. If I remove the spark plug and then try again the same thing happens. After trying to learn how the engine works (haven't done too much with small engines other than carburetor work), my guess is that when I adjusted the rocker to the correct setting the exhaust valve isn't opening anymore and that's why it's having an issue turning over.

Does that sound correct or is there something I'm missing? 

If that is the issue, any ideas what would cause this? It's a fairly new generator, I haven't disassembled any further to look and see what else might be wrong.

Thanks in advance for any help or ideas!


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## Coco (Dec 21, 2018)

dtakushi said:


> I bought a used Predator 3500 generator recently and it was running rough. After cleaning and checking the carburetor I moved onto the valves to make sure they were adjusted properly. The exhaust valve had no gap and I had to adjust it quite a bit to get to the recommendation of .007", the intake valve was fine. After adjusting, if you tried to started it was tough to pull after the first couple pulls. I'm guessing there was too much compression or something. If I remove the spark plug and then try again the same thing happens. After trying to learn how the engine works (haven't done too much with small engines other than carburetor work), my guess is that when I adjusted the rocker to the correct setting the exhaust valve isn't opening anymore and that's why it's having an issue turning over.
> 
> Does that sound correct or is there something I'm missing?
> 
> ...


When you were adjusting the valves did you have it on the compression stroke at top dead center?


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## dtakushi (May 8, 2019)

Coco said:


> When you were adjusting the valves did you have it on the compression stroke at top dead center?


I didn't measure compression, but it seemed normal.


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## iowagold (Jan 22, 2020)

dtakushi said:


> I bought a used Predator 3500 generator recently and it was running rough. After cleaning and checking the carburetor I moved onto the valves to make sure they were adjusted properly. The exhaust valve had no gap and I had to adjust it quite a bit to get to the recommendation of .007", the intake valve was fine. After adjusting, if you tried to started it was tough to pull after the first couple pulls. I'm guessing there was too much compression or something. If I remove the spark plug and then try again the same thing happens. After trying to learn how the engine works (haven't done too much with small engines other than carburetor work), my guess is that when I adjusted the rocker to the correct setting the exhaust valve isn't opening anymore and that's why it's having an issue turning over.
> 
> Does that sound correct or is there something I'm missing?
> 
> ...


when setting the valves, the piston needs to be at top dead center of the compression stroke.
you can see this on the valve action.
both valves need to be shut and the cam at the bottom of the lift.
then set to the spec

if it is not set proper..... the compression relief will not work right!


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## dtakushi (May 8, 2019)

iowagold said:


> when setting the valves, the piston needs to be at top dead center of the compression stroke.
> you can see this on the valve action.
> both valves need to be shut and the cam at the bottom of the lift.
> then set to the spec
> ...


I was fairly sure I had it correct, but grabbed another predator 3500 I had to confirm. Made sure both were at TDC and the one that runs fine had the correct gap so I'm confident that was done correctly. I pulled the spark plugs to confirm and watched the rockers/valves.


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## iowagold (Jan 22, 2020)

something is going on inside the gen set...
you could have a stator coil shorted or flashed over.
that will make the pull rope feel like it is locked up at the crank shaft.

pull the flywheel assy and inspect the stator coils visual and with an ohm meter.


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## dtakushi (May 8, 2019)

I appreciate everyone's feedback, I think I figured out the issue after looking at it further and comparing it to another Predator 3500 generator I have. The valve spring retainer on the exhaust side is defective. I'm not sure if it got damaged or was defective from the factory since the generator has such low hours. The spring retainer is causing the gap to not be accurate as it sits further out/closer to the rocker than it should. As a result if you adjust to the correct gap, then it's really too loose and the valve doesn't open as much as it should. Once I replace the valve spring retainer I should be able to set the correct valve gap and get it running better and determine if there are any other issues.


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## iowagold (Jan 22, 2020)

there ya go! atta boy!
defective part!
yea also check the valve as well...
you might have to replace the valve if the groove is not right...
i have seen that on the other brands like this.


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## dtakushi (May 8, 2019)

iowagold said:


> there ya go! atta boy!
> defective part!
> yea also check the valve as well...
> you might have to replace the valve if the groove is not right...
> i have seen that on the other brands like this.


Thanks!


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## jveccs (11 mo ago)

dtakushi said:


> I appreciate everyone's feedback, I think I figured out the issue after looking at it further and comparing it to another Predator 3500 generator I have. The valve spring retainer on the exhaust side is defective. I'm not sure if it got damaged or was defective from the factory since the generator has such low hours. The spring retainer is causing the gap to not be accurate as it sits further out/closer to the rocker than it should. As a result if you adjust to the correct gap, then it's really too loose and the valve doesn't open as much as it should. Once I replace the valve spring retainer I should be able to set the correct valve gap and get it running better and determine if there are any other issues.


what was the out come and was the valve also replaced?


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