Honda Gx340 hard to pull over after rebuild?

[Lewis]

Hi, i have just rebuilt a Honda gx340 engine i got given by a builder which was used as a pressure washer after its rod snapped and caused carnage in the engine, everything was OK cam shaft wasn't bent or damaged, balance shaft wad fine the crank had aluminum melted to it which came off with a bit of 800 grit all i replaced was the rod and pistons and rings i also honed the bore after cleaning it out thoroughly i assembled it set valve lash as per the Honda manual which i have done hundreds of times and then tried to fire it up it was incredibly hard to pull over i had to put one foot on the engine but when i take the spark plug out it spins freely with no resistance the decompressor isn't stuck either as i took the side case off to see if that was the issue. this is my first gx340 i have only worked on gx160's and gx200's before and i would say it is at least five times as hard to pull over as them is this normal?

 

[bubbatime]

Valve lash needs adjusted, they are too tight.

 

[Clevy]

Compression causing more resistance perhaps? I've got a husquavarna chainsaw with a 36" bar. It's got compression releases because its so hard to pull over without them.
My Harley's got manual compression releases too. Without them pushed in at start up the starter clutch engages and grinds. Starts second turn with them pushed in.

 

[boraticus]

Did you check the crank to ensure it was true? Doesn't take much to throw it off and if it is out of true, things will not move smoothly. You'll find out once you fire it up I suspect. If it does run, it will not be happy.

 

[1 FMF]

on pull start 4-stroke engines there's a compression relief thing that when it's spinning slowly such as less than 100 rpm when starting either the intake or exhaust valve opens slightly before TDC to relieve compression. otherwise you can't pull the recoil rope. once the engine starts and rpm's get over a certain amount then the compression relief thing doesn't do it's thing. it sounds like you didn't put that compression relief thing back in or don't have it in right. i've messed with small engines a while back and even on a little 3.5 hp briggs if you don't have the compression relief thing working for the recoil start, you won't be able to get past the first compression stroke. you're recoil rope thing has a radius of around 3" on the crankshaft so that's all the leverage you get, if you then have 140 psi of cranking compression you'll break the rope or the plastic pulley that the rope is on over the crankshaft.

 

[1 FMF]

just re-read your post and saw you mentioned the decompressor, that's what i was talking about. i would verify it by using a compression gauge and measure cranking compression. if you're getting up around 140 psi then i don't think it's working. i don't remember what cranking compression is supposed to be, i think around 90 psi not much more. it sounds like everything else is ok since you can pull the spark plug and the thing whips over easily.

 

[Lewis]

Finally sorted it I opened it up and pulled the camshaft out and the decompressor was so worn it was hardly opening the valve so I bent it upwards a bit and it seems to work fine now