Overbore Clearance

I seized my polini kit so now I'm overboring it with the 46.4mm replacement piston, but no where on the site can I find what the clearance is suppose to be. Does anyone have an idea on what the clearance should be between the piston and cylinder?

This is the carnage from the soft seize. I'm running a VM18 (connected via rad hosing), 80 main jet idle and pilot are whatever came with the carb, stuffed crank, stock head (untoched), 1.5k springs, and some other bullshit. I found a head gasket leak and a leak at where the intake and meets the rad hosing.

Not sure what all the scaring and burning indicates other than shit was real hot. SO some input would be nice. Gracias

What the hell caused the wrist pin to get so damn hot?!

Re: Overbore Clearance

Are you running any/enough oil? Also don't use rtv anywhere on your moped. You don't want any sealant like that on your base gasket especially, it gets squeezed out into the port.

Re: Overbore Clearance

Thanks for the RTV heads up. I've only ran it on top end once. I usually use it for transmissions.

I was running 25:1 cheap Marathon oil. I always run Ams Dominator oil but I was out. So I grabbed what was laying around.

Re: Overbore Clearance

matt boda1nz /

hows your plug look?

Re: Overbore Clearance

black black black with an 80 jet. jetting should be higher though around 95

Re: Overbore Clearance

Overpriced Parts /

Kits require synthetic oil

Re: Overbore Clearance

Just clean up the cylinder and get some new rings. Hobbit polini kits can take a beating. Like, unless you have big gouges out of the wall or chunks missing from the ports it should be fine. Jet it properly and adjust your point gap if you haven't already.

Re: Overbore Clearance

My point gap is beyond the factory clearance. i think its .524mm. someone suggest I set it to factory (.3-.4mm) and pull the came off and retard the timing thatta way.

I was just going to put on some new rings but there are some deep scrapes on the cylinder wall.

Re: Overbore Clearance

To much oil..40:1 is sufficient.

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