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Blow back through the carb on 314


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#16 shantzonpoint OFFLINE  

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Posted May 22, 2016 - 09:53 PM

Which carb is it?  Carter/Kohler or Walbro?  

It's a Carter/Kohler. 



#17 shantzonpoint OFFLINE  

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Posted May 24, 2016 - 11:04 AM

eeeeek sounds like a valve to me to....I would do as stiemmy suggested and do a compression test. That will tell you if its a valve or not and also give you info on the condition of the engine. From there I would look into the flywheel if all checks out. As far as running it ...yes you can damage the carburator gaskets and I have even seen a blown float bowl do to back firing though the carb worse case it can even catch on fire so if you run it just be aware and be ready to save your ride.

Compression seems fine. Could it be a timing issue? Like I mentioned before it only spits near or at full throttle

bea2ce10e8ba37143fb95a30a4ae204f.jpg

Edited by shantzonpoint, May 24, 2016 - 11:04 AM.


#18 John Arsenault OFFLINE  

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Posted May 24, 2016 - 04:00 PM

while you have the carb off I would check the valve gaps

set valve gap when cold

 

 

 

This would be my next step 



#19 John Arsenault OFFLINE  

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Posted May 24, 2016 - 04:03 PM

Compression seems fine. Could it be a timing issue? Like I mentioned before it only spits near or at full throttle

bea2ce10e8ba37143fb95a30a4ae204f.jpg

 

 

I believe you have a koler K series if so you can adjust the valves, I am betting with good compression thats all it is. Keep me updated I have a koler K on my wh and want to know the fix for this. 



#20 Sawdust OFFLINE  

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Posted May 24, 2016 - 04:27 PM

Check the valves as mentioned. My briggs 16 hp did the same thing. Blew gas out the carb to the point it would flood itself, back fire & hard to start. Checked the valves exhaust right on but the intake was way off. After adjusting COLD it ran well.
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#21 Auburn David OFFLINE  

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Posted May 24, 2016 - 07:07 PM

I still say its a worn Loose shear pin in the flywheel..



#22 John Arsenault OFFLINE  

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Posted May 24, 2016 - 07:57 PM

I still say its a worn Loose shear pin in the flywheel..

 

 

That it still may be but at least he will know he has good compression and his valves are adjusted. 


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#23 lyall OFFLINE  

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Posted May 24, 2016 - 08:42 PM

I think you need to set the valve gap per the manual.  If you do not have a Kohler manual you can download it from the manual section of this site.

When you do a compression test the motor is normally cold, so you get a good compression reading.

If the valves are not set when cold and you motor warms up the valve stem expand and the gap for the valves get smaller, causing the valves not to close properly.  If the intake valve is not closing it causes blow back out the carb.

If the exhaust is not closing, you can burn the exhaust valve, hotter exhaust, popping noise, and the lost of power.


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#24 JBRamsey OFFLINE  

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Posted May 24, 2016 - 11:21 PM

It's not a carb problem. Rebuilding the carburetor won't solve the issue. An engine is just an air pump. In its simplest form, it sucks air in, compresses it, sets it on fire and pushes it out. You're getting blow by either because during the compression stroke the intake valve is not sealing fully and letting compressed air push up through the intake or during the exhaust stroke the intake valve is not sealing properly, again allowing gases to push up the intake.

Why is it not sealing correctly is the solution to your problem. Do the easy, simple stuff first. Adjust the valves properly and see what happens. If that doesn't take care of it, you either have a seat/valve issue, a sticking valve or the timing is off.

It's not difficult. Slow down and take your time. Don't immediately start taking things apart, that usually just costs you money. You can always take them apart later after troubleshooting first.

It's not likely that anything is horribly wrong because the engine runs pretty well.

Good luck.
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#25 shantzonpoint OFFLINE  

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Posted May 30, 2016 - 06:54 PM

I took the head off of the engine this afternoon. Here are a few pics. I think I mentioned before I'm very noobish when it comes to engines. This obviously doesn't look right so if you guys could take a look and see where I should go from here or point me in the right direction it would be certainly appreciated.

I haven't checked the valve gaps yet
69dedfa38536cff13580565bf88d401b.jpg

Crud caked under this valve.
a145d34f0acdb6846aa54128393bfe6f.jpg

Neither valve looks properly seated to me.
2964b21abcd1f40989bb5ae33add15f3.jpg
be8f615ad3b6037a50c080b42616b3ab.jpg

And a short video for reference.
https://vimeo.com/168703064

Edited by shantzonpoint, May 30, 2016 - 06:55 PM.


#26 JBRamsey OFFLINE  

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Posted May 30, 2016 - 07:25 PM

The crud under the valve is keeping it from properly seating.

#27 JBRamsey OFFLINE  

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Posted May 30, 2016 - 07:29 PM

There's no need to check valve gaps at this point. If it were mine, I would pull the valves, clean them up, remove all of the carbon and hen lap the valves. After that clean it all again, put it back together, set the valves and see what you have.

It looks like you have something going on in the cylinder. It's hard to tell from the picture. It may just be reflection from the piston top in the cylnder wall.

#28 shantzonpoint OFFLINE  

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Posted May 30, 2016 - 07:44 PM

The crud under the valve is keeping it from properly seating.

That's what I was thinking it could be. I'm wondering if the valves not being centered on the seat is part of the issue as well?

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#29 JBRamsey OFFLINE  

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Posted May 30, 2016 - 07:48 PM

Pull the valves out. That will tell you a lot. It could be bent.

#30 shantzonpoint OFFLINE  

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Posted May 30, 2016 - 07:52 PM



It looks like you have something going on in the cylinder. It's hard to tell from the picture. It may just be reflection from the piston top in the cylnder wall.


You're seeing a reflection. The cylinder wall is very smooth and clean (how round it is up for debate)

I'm thinking you're thoughts on the valves is the best course of action. After reading everybody's thoughts from the start, I'm pretty confident my issues are in the valves.


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