660 decompressor

[bullet350]

help

i've just put a replacement engine into a friends Skorpion, trouble is it's not de-compressing. using the battery from a diesel escort van it'll only just turn it over compression.

i took the plug out and turned the engine over on the starter but as soon as the plug wen't back in it wouldn't go over compression.

it seems to fire correctly, but the engine can only be turned over so slowly it has no chance of firing.

does the decompressor rely on oil pressure to push the little ball bearing out-wards from the centre of the cam?

the decompressor was working when taken apart and i marked the cam sprocket so it went back on the same way when put back. however i didn't check it before putting the cam assembly back in.


any suggestions?

bullet350

[guest146]

Not sure on the Scorpion but I would expect a good starter and battery to turn an engine over on compression. Try using jump leads direct to the starter and earth to rule out poor cables. Otherwise if the battery is good it sounds like the starter is poor.

Ken

[andy230]

sorry bullet350

No info on the decompressor mechanism on the 660 motor, but I can send you parts diagrams, or a CD manual for the motor if you like?

I dont get long cranking from a standard battery.  But if I try to bump it on flat ground, the hi-comp piston comes up to the top, and if it doesn't lock the back wheel, the clutch slips!

If I get it up to speed down a decent ramp, it will fire no problem. 

Have been doing this for a while as I have a big battery to jump it off in the garage and a big hill outside work!  The scotsman holds on to his pennies for as long as is possible!

But I will replace it one day.  I call it "anti-theft"...

Although I am toying with the idea of putting a kickstart on a 660 motor (or a 660 bottom end).  Not in the immediate future but possibly on the 2008 race motor if it still lives after the season.   Decompressor could be a problem, but this could maybe be overcome using a manual decompressor (a la brit single) using an aircooled top end.

Anyway, we digress!!  Good luck mate, let me know if you need pages from the manual.

a

[guest18]

Can't help with the decompressor sorry, but Andy, if you fancied doing a copy of that cd it would be much appreciated!
Give me a shout on smudgegs "at" yahoo.co.uk if you can.
Cheers mate