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Kick starting poor compression

Posted: Sun Sep 11, 2016 10:10 am
by Chip Panfire
Morning all,
Slowly trying to restore a DL125 (with limited knowledge). It's been stored for a good few months now but it was a goer. A couples of days ago I tried to fire it up with no success. On the first kick the compression seems reasonably okay but after that it's fairly weak. Should I be looking at changing the piston rings or are there other things I should be checking beforehand? The spark seems to be okay.
Many thanks for help.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 10:30 am
by Chris in Margate
Can you get hold of a compression tester ?
Different length kickstart, different gearing and possibly a defective clutch can also be red herrings.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 11:16 am
by Chip Panfire
Thanks Chris
I haven't got a compression tester but have seen many advertised for around £15, would that do or do I need something more specific?

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 11:21 am
by Chris in Margate
£10 will get you one on ebay with the threaded adapters.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 11:22 am
by Chip Panfire
Brilliant thanks.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 12:41 pm
by coaster
If it's been stood a while it could just be gummed up rings. Could also be head gasket related, if you are certain that the engine is turning with the kickstart I'd be inclined to whip the barrel off for a looksee. Compression testers can be a bit of a red herring on a 2 stroke in my experience.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 2:19 pm
by Lamaddict
I had a DL125 with a 175 kit on. Sounds simlar to when my kit failed. As said by someone else, a simple problem like the clutch too tight is a possibility. You want about 100 PSI for the compression test. Around 80PSI and there's not enough compression to start it and it could be a bust top end....

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 3:40 pm
by Scooterdude
I'd say you want more than 100, when I first built my 175 conversion I was getting about 125 psi and once it was ran in I was getting around 140 psi.

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 4:03 pm
by a.lo.v2
agree with clutch. sometimes at rest you have the clearence with the shaft and top plate but the act of kicking over brings a new high spot into play and can
compress clutch slightly. i know i had this problem and took a while to diagnose .

Re: Kick starting poor compression

Posted: Sun Sep 11, 2016 6:45 pm
by Chip Panfire
Thanks for the replies, much appreciated help.