I have a meerkat 50 with ~200hrs that just stopped running while idling
It only runs for a couple of seconds
changed with new: carb,spark plug,gas,cdi,voltage regulator,coil,magneto/pickup assm.,new cylinder, piston,rings,head assm,head gasket
wiring checks out ok
was 35 psi compression
now 50lbs without carb
still only runs a couple of seconds,choke doesn't help,push throttle and kills it immediately
ring gap old and new top and bottom around .012"-.016"
I think ring gap should be .004"x1.53"=.006"
just doesn't seem like it has enough compression but everything is new
timing looks ok, mark on cam aligns when flywheel at mark for TDC
flywheel key ok
any ideas would be appreciated!
Thanks!

 

Well, all that new stuff was a complete waste of money if you only had 50psi compression. Ring gaps are correct, so it is either leaking compression through a scored bore, faulty valves or seats, or a blown head gasket. Did you set the valve clearances when you did the engine? Did you grind the valves in? Your new head, barrel, or piston could be faulty.

 

Hey Merryman,
Thanks for info.!
Bore is new and looks good(I did not hone new cylinder), piston new looks good, rings new look good, new head gasket-have had it apart a few times now
When I got the head in, the packaging was tore up and the gaskets were damaged-they sent me a new gasket set quickly(Fancy scooters)
But you may be correct the head might be damaged but I did not see anything.
I did not lap the valves because head assm. was new from Fancy Scooters.
Valves I have set the valves .002" over/under nominal setting of:
Intake .004"
Exhaust .006"
No difference!
I am going to call Fancy scooters today and see if they can send new head
I also ordered new rings, all of the water cooled engines I have done I always use a general rule of .004" * dia. of piston" = ring gap (~.006"), but it does not seem like you can find over sized rings to grind but that's the only place I can think of loosing compression
.015" seems like a lot but I have to say I have never measured any of the air cooled engines I have done before.
Tried setting timing chain 1 tooth both ways-would not run at all
Set timing back still only runs a few seconds then dies, if you push throttle it dies immediately
Never have seen this before usually I just change bad part and its fixed!-got me baffled!
Thanks again!

 

You could be right about ring gaps, I'm used to Honda 250s and upwards, which all seem to have circa 0.020" max gap. Checked a Honda 90 manual and it is 0.012". I would be checking the parts you took off, if they are OK, put them back on, may just be the machining on the new parts has left the combustion chamber too big. I fitted a Chinese cylinder kit to a Honda 70 a while back with no problems, original bore and rings were so worn the rings fell through when I tried to check end gap, but the bike was still running, though bad to start and gutless.