help me diagnose my engine

[pblr89]

so i got a gokart finnaly and it worked fine the first day besides the carburetor leaks. well when using the pullstart on the engine it started stopping suddenly and jerked the pullcord right out of my hands. so i took off the pull string, made sure it wasn't twisted and such but it all looked okay. i turned it by hand and it will turn easily for about 2 rotations then it gets caught like air buildup inside. if i take the spark plug out it doesn't get caught up at all. someone help i cant find anything on this. i can turn it by hand through the air buildup so someone told me its not seized because it does move.

thanks in advance

 

[Jake.B]

Try it again with your pull rope, the air buildup it fine its called compression. It is hard to turn by hand. take your Pull cord shroud or fly wheel cover off and there will be a square shaft. Turn it left and right. One way should spin super easy and the other should turn the engine over if they are both hard to turn i can tell you what to do from their when you reply.

 

[DustinWolfe]

is this ohv or flathead?

 

[pblr89]

says OHV on the back metal plate..... and jake the pullcord still jerks out of my hands when i pull it sometimes, so i took off the flywheel to where i see the turbine looking area(sorry im not great with engines) i rotate it with my hand easily still for about to revolutions and then it sticks with airpressure build-up. i rotate it the other direction and it does the exact same thing. it feels like the same spot.

 

[Doc Sprocket]

You're feeling the compression stroke. Normal. As far as the cord ripping out of your hand, that's very often indicative of a sheared flywheel key. The "turbine" thing is your flywheel. You're going to have to remove that to inspect the key.

 

[pblr89]

i cant find the brand of my engine anywhere. how do i tell if its sheared and do all keys look the same/universal?

 

[landuse]

i cant find the brand of my engine anywhere. how do i tell if its sheared and do all keys look the same/universal?

Flywheel keys are not all the same. You are unfortunately going to have to get the flywheel off to see what you have. Post some pics of your engine. Someone here might be able to identify it for you and save you some trouble

 

[DustinWolfe]

i dont think this is normal. i feel you have either sheared your flywheel key(most likely and also already mentioned) or your exhaust rocker is no longer being affected by the pushrod. flywheel (woodruff) key is easy(search the forum bountiful info is available) its likely aluminum and is there in case of ubrupt stop it will shear and let the momentum of the flywheel dissipate a little bit slower(emphasis on little bit) which helps avoid serious engine damage

 

[ghostdog]

Good read here.
http://outdoorpowerinfo.com/repairs/flywheel_key.asp

 

[r_chez_08]

I had a similar issue with my clone. It was a b!tch to start, but I just lived with it. TBH I couldnt be arsed to find out the problem. Turns out my valve lash was way to high, causing the compression release on the valve to be almost useless. Maybe inspect the lash first (rockers are located under the "OHV" cover, use a feeler gauge, it should be .002 or .003, around that. Check service manual)

It may be the key, but it takes under 5 minutes to check lash with correct tools. Flywheel 'requires' torque wrench etc.

 

[pblr89]

heres the problem im having i posted a video. the first engine is my other gokart engine withought a carburetor and the 2nd one is the one im having trouble with. as you can see from the video the 2nd one gets caught up at points, and was wondering if this is normal?

http://www.youtube.com/watch?v=4uUmV9g-_TQ&feature=g-upl&context=G2dced21AUAAAAAAAAAA

 

[anderkart]

I had a similar issue with my clone. It was a b!tch to start, but I just lived with it. TBH I couldnt be arsed to find out the problem. Turns out my valve lash was way to high, causing the compression release on the valve to be almost useless. Maybe inspect the lash first (rockers are located under the "OHV" cover, use a feeler gauge, it should be .002 or .003, around that. Check service manual)

It may be the key, but it takes under 5 minutes to check lash with correct tools. Flywheel 'requires' torque wrench etc.

Chez gave you really good advice there ^^^

Here's a video showing you how to set your valve lash:
(just disregard the parts about replacing the valve sprigs)


http://www.youtube.com/watch?v=4QZWV6S-5aA&feature=player_embedded

 

[slideways]

My money is on valve lash too.

 

[pblr89]

i did the valve lash the best i could it didnt seem to fix anything . i reasembled and its still as if the compression stroke is to hard to pull past. its at the point where if i dont pull hard enough if stops it about halfpull and if i pull harder i actually lift the backend of the gokart off of the ground.

 

[fowler]

what do u mean as best u could?

while the valve cover is off turn the engine by hand and see if the valves are moving
u may have broken or stripped somthing further down
dout it but its a simple check to reveile any problems

how old is the engine
new engine will be tight for a while till they wear in, same applys for rebuilt ones

also its a dumb question but is the oil full and fairly clean
it sure will be hard to turn if the oil is watered down with petrol and dirt

 

[r_chez_08]

If taking the spark plug out makes it easy to turn, then you probably have a problem with valves.

Try taking the plug cap off, does it make any difference? (it wont start, but it will tell you if you have a key problem)

It is possible that the compression release on your camshaft is stuck.

 

[91blaze]

Definitely a valve problem like they said. The same thing was wrong with my engine and I adjusted the valve lash, and it started right up. I would also take the valve cover off and turn the engine to make sure nothing is stuck. Check the last page of this thread for a video on adjusting the valves:
http://www.diygokarts.com/vb/showthread.php?t=15222&page=2

On my engine, the tightening nut was in a different place, but still adjusted the same way.