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Old 04-06-2020, 08:25 PM
Liberty_Jesus Liberty_Jesus is offline
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Default Super low compression

I put my raptor 3 back together and I can spin it by hand with little to no resistance. It has a new head gasket. Could the cam be in wrong? I lined up the two dots but is there something more? Could I have oriented the rings wrong? It used to have ok compression well at least more compression now there's no resistance when I spin it by hand. What could be the issue? It does "run" just it idles then when I full throttle it it doesn't rev up at all.
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Old 04-06-2020, 08:27 PM
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Stuck valve?
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Old 04-06-2020, 08:36 PM
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Originally Posted by Budget GoKart View Post
Stuck valve?
Nah took the spark plug out and saw em movin. Maybe I messed up the valve seats somehow?
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Old 04-06-2020, 08:47 PM
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Possibly improper timing.

Does it blow excessive pressure out of the valve cover breather?
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Old 04-06-2020, 09:01 PM
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You could've put the compression (top) ring in upside down, or yes if the ring ends gaps are lined up that could also do it. Most (albeit not all) rings have a dot on the edge that faces up, if not you need to try and see the taper on the edge (top of taper goes up). You're sure you put the valves back in their respective spots? Back off your valve lash so much that the valves wont even open, that will tell a story in itself
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Old 04-06-2020, 09:47 PM
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Quote:
Originally Posted by Solomonster212 View Post
Possibly improper timing.

Does it blow excessive pressure out of the valve cover breather?
I'm not at my dad's right now so I don't know but it didn't seem like it was sucking my hand into the carburetor when I hand choked it

---------- Post added at 11:47 PM ---------- Previous post was at 11:45 PM ----------

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Originally Posted by Brianator View Post
You could've put the compression (top) ring in upside down, or yes if the ring ends gaps are lined up that could also do it. Most (albeit not all) rings have a dot on the edge that faces up, if not you need to try and see the taper on the edge (top of taper goes up). You're sure you put the valves back in their respective spots? Back off your valve lash so much that the valves wont even open, that will tell a story in itself
I never took the rings off and made sure none of the gaps were lined up
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Old 04-06-2020, 10:13 PM
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You said you may have messed up the valve seats? Did you do any porting and knick them? Give us a breakdown of everything you've done to the motor please, it will help us help you!
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Old 04-06-2020, 11:17 PM
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Was the piston in the right position when you lined up the dots on the cam?
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Old 04-07-2020, 07:11 AM
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Quote:
Originally Posted by landuse View Post
Was the piston in the right position when you lined up the dots on the cam?
What is the right position?

---------- Post added at 09:11 AM ---------- Previous post was at 09:07 AM ----------

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You said you may have messed up the valve seats? Did you do any porting and knick them? Give us a breakdown of everything you've done to the motor please, it will help us help you!
Uhhhh I replaced the spark plug, drained the oil, cracked open the crankcase cover, removed the head, took out the piston, took out the cam to see because it was aftermarket, I cleaned up some carbon buildup around the valves and on the head with steel wool and wd40 if I remember right (the valves were in and all the way down), I put a new head gasket on and put it back together.
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Old 04-07-2020, 07:46 AM
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maybe you put the head gasket on wrong
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Old 04-07-2020, 08:29 AM
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Quote:
Originally Posted by Karts of Kaos View Post
maybe you put the head gasket on wrong
Is there a right side up?
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Old 04-07-2020, 08:59 AM
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I stand by my statement to back the valve adjuster nuts off until the valves wont move when turning the motor over to see if you're still suffering from a serious lack of compression. It's a quick easy experiment
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Old 04-07-2020, 09:04 AM
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Quote:
Originally Posted by Brianator View Post
I stand by my statement to back the valve adjuster nuts off until the valves wont move when turning the motor over to see if you're still suffering from a serious lack of compression. It's a quick easy experiment
Is this possible ona flathead Briggs? I thought the valve lash was done by grinding the valves?
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Old 04-07-2020, 09:09 AM
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Quote:
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Is there a right side up?
Not if it's symmetrical.
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Old 04-07-2020, 11:01 AM
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Quote:
Originally Posted by Solomonster212 View Post
Not if it's symmetrical.
It seemed the bolt holes only lined up in one direction so that's what I did.
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Old 04-07-2020, 12:08 PM
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that should work.
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Old 04-07-2020, 01:27 PM
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Does your aftermarket cam have a compression release mechanism that might be stuck?
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Old 04-07-2020, 02:05 PM
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Quote:
Originally Posted by anickode View Post
Does your aftermarket cam have a compression release mechanism that might be stuck?
Not that I saw i remember it just being a flat surface on the back of the cam gear no compression release.
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Old 04-07-2020, 06:05 PM
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Quote:
Originally Posted by Liberty_Jesus View Post
Is this possible ona flathead Briggs? I thought the valve lash was done by grinding the valves?

My mistake, I forgot this is a flathead thread! Lol. The point was to make the valves inoperable to isolate where the issue is stemming from, process of elimination is a great diagnostic tool that everyone has in their toolbox. I do have a flathead (1969 B&S 7hp) but have yet to tear into it and learn the mechanics of it.
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Old 04-08-2020, 03:36 PM
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Fixed it the two lifters were swapped I switched the around and compression was back it even started first pull
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