Author Topic: Replaced piston/cylinder now won't fire  (Read 1080 times)

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Offline jmester

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Re: Replaced piston/cylinder now won't fire
« Reply #30 on: October 26, 2013, 02:56:10 pm »
First I would check all your wiring to make sure there are no bare spots that would cause a ground. Or a broken wire. Then I would check to make sure the spring that attaches to the spark plug is ok. Then I would check my coil to flywheel gap. Before all that I would try another plug and see if it is just the plug,just because it is new does not mean that it is good. Look for any blue color on the flywheel and the coil as these usually mean one or both could be bad. Hope this helps a little.
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Offline jmester

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Re: Replaced piston/cylinder now won't fire
« Reply #31 on: October 26, 2013, 03:00:35 pm »
Also if you had spark before you should not lose it. By replacing the cylinder unless you pinched or cut the wire. I still think if your plug is not wet with fuel you have a fuel related problem. Have you done anything to the carb, is the impulse hose connected?
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Offline wbhburn

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Re: Replaced piston/cylinder now won't fire
« Reply #32 on: October 26, 2013, 08:47:11 pm »
Done nothing intentional to the carb. However, after having disassembled the thing three times who knows about unintentional?

When it locked up initially, it was literally "Smoke'n hot". Could something have overheated like the coil? What kind of ohms should the coil read - with leads from where to where? sp 

Offline wbhburn

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Re: Replaced piston/cylinder now won't fire
« Reply #33 on: October 26, 2013, 11:30:36 pm »
The more I think about it the more I realize that as hot as it got, anything plastic or rubber close to the head could be messed up (like the manifold), though the impulse line was not impeded.

Offline mountainlake

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Re: Replaced piston/cylinder now won't fire
« Reply #34 on: October 27, 2013, 06:21:54 am »
The small line should be the impulse line and it should run from the crankcase to the carb flange or the pump side of the carb. Try to remove the spark plug and put some fuel in and try it out. With the spark plug not moist sounds like a fuel problem to me. Do you pressure/vacuum check the crankcase. Is your spark threw a tester or the plug grounded on the cylinder. My be a bad plug.

 Yes,  If you haven't tried a new plug and dumped some mix down the plug hole do that first.  Keep in mind when you dump fuel down the cylinder it will take quite a few pulls on fast idle (put the choke on then back off should get it on fast idle) or with the throttle held open to get it to fire.  If it fires and then stops go over the carb again or get a new one making sure you don't have the impulse line blocked off with the carb gasket.  One other thing is your piston the right one for the cylinder, don't think a open port piston will run with a closed port cylinder  Steve

Offline wbhburn

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Re: Replaced piston/cylinder now won't fire
« Reply #35 on: October 27, 2013, 12:33:11 pm »
Just tried the starting suggestion from Mountainlake including a new plug. No go. However the pressure release did kick out a couple of times during the process. I'm thinking a new manifold may be the nest thing.

Offline mountainlake

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Re: Replaced piston/cylinder now won't fire
« Reply #36 on: October 27, 2013, 01:38:53 pm »

 Did you check your compression after the rebuild, if too low it won't start.  Steve

Offline wbhburn

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Re: Replaced piston/cylinder now won't fire
« Reply #37 on: October 27, 2013, 03:56:04 pm »
No, will do!

Offline wbhburn

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Re: Replaced piston/cylinder now won't fire
« Reply #38 on: December 01, 2013, 10:47:33 pm »
Checked compression with a automotive tester. Could only get it to 95 lbs after lots of pulls. What does that mean? Sounds low to me. Why would that be with a new piston/head. I scored it slightly installing initially but would that do it? Can hardly see it.

Offline Cut4fun .

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Re: Replaced piston/cylinder now won't fire
« Reply #39 on: December 01, 2013, 10:53:54 pm »
No adapters needed that are shown. Valve in end. Just screw in tght with o-ring seal. Pull till psi quits climbing.  http://www.walmart.com/ip/Equus-3612-Innova-Compression-Tester/14644667
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