NO COMPRESSION

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NO COMPRESSION

Postby phil23 » Mon Jun 26, 2017 9:46 am

Morning All
Rebuilt the carb this weekend, tuned it and took it for about a 16 mile spin, and all was well. This morning, kickstarted first time got a 100 yards down the road, realised I'd forgot something, pull up outside the house and leave it idling, after 30 seconds it stalled. I didn't think much of it, went to kick start it and there is no compression!!.

Anyone got any ideas??. I just put it in the garage and came to work in my car, so haven't looked yet.

Cheers
2014 LML 125 Manual 166 kit
phil23
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Re: NO COMPRESSION

Postby Leigh » Mon Jun 26, 2017 11:31 am

Hi Phil,

This will be a top end problem. It could be a few things, I'll list them in order of ease of checking:
- Spark plug coming loose (unlikely if you haven't touched it).
- Cylinder head loose (unlikely, as before) but you can check by removing the cylinder head cowl and shining a torch around the join to the cylinder to check for leaking fluids.
- A holed piston which can be caused by overheating and the top of the piston literally gets a hole blown in it. You can try to check this by removing the spark plug and shining a torch down the hole. If you can't see anything the next step is to remove the cylinder head to check properly, otherwise,
- Stuck, or broken piston ring/rings, normally caused by heat seizing, or a lot of miles. You need to remove the cylinder to check that the rings are free in the slots.

If the compression was good before, and you've only touched the carb, then it is probably options 3 or 4 unfortunately. I'd guess something you did with the carb has caused it to overheat. Are you using autolube still? if so a common mistakes are that you get air in the autolube tube, meaning that it can't be pumped into the fuel mixture, the gasket has blocked the autolube channel under the carb, or the carb hasn't sealed on the gasket and is leaking the autolube as opposed to pumping into the mixture. All of these will need looking at if you have heat seized.

Best of luck buddy,

Leigh.
Another fine tip stole from Mick Maidment!!!!
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Re: NO COMPRESSION

Postby phil23 » Mon Jun 26, 2017 7:05 pm

Cheers Leigh. Just got in from work. Don't have the energy to look just now. I fear you are right....most likely 3 or 4 :roll:
2014 LML 125 Manual 166 kit
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Re: NO COMPRESSION

Postby NICK » Fri Jun 30, 2017 7:21 pm

At least it was only idling so once the possible carb culprit is sorted, it should only be a new piston and oil change. Good luck.
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