mbk nitro/ yamaha aerox 50cc not starting after rebuild....

davethenorman · Derestricted Danger Joined: 05 Aug 2005 Karma :

fitted new crank piston and barrell but now will not start.
I have a spark, lots of fuel in the carb, but the plug seems dry, and no sign of life.
Does any one know if the crank has to be alined with the maneto/ ignition in any way, as I think that the spark is at the wrong place in the stroke.
Any ideas?
Thanks
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Dave The Norman

edd · Nearly there... Joined: 06 Jul 2005 Karma :

do you have compression?
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davethenorman · Derestricted Danger Joined: 05 Aug 2005 Karma :

I have done a compression test, and only get about 45 pounds of compression.
Is this right for a small 2 stroke engine, as I have only worked on cars before which needed 120lbs plus.
We still have a spark, but not sure if petrol is getting to the plug, as it seems to come out dry.
Any ideas as to why it will not start?
Thanks for your help.
Dave
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Dave The Norman

J.K.R · World Chat Champion Joined: 06 Feb 2005 Karma :

Could it be that you have a different crank (eg the woodruff hole at a different point?)

Id check the carb > cylinder/case rubber as it may be perished, and is the reed valves and cage good?
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Kye · Scooby Slapper Joined: 13 Sep 2004 Karma :

Replaced the crank seals properly?
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