am6 crank seals

[nigel smith]

hi all i hope everyone is well.

Im doing a little project with with an Aprilia RX50 moped 1998, AM6 engine 70cc metrakit cylinder 21mm quality carb. 

The bike runs perfectly when warm but when starting and after taking choke off it runs fast about 3000rpm until it has a little heat in it. probably two minutes.

The engine was rebuilt 5 years ago did a thousand miles and then stood for a number of years.

is it possible the crank seals have hardened and letting in a little air when cold?

anyone have any other ideas?

or is this completely normal?

also does anyone know if the crank seals can be replaced on the AM6 without splitting the cases?

will also mention again once warm it runs in rides well pulls hard (for a moped) and the plug is a good colour

thanks in advance for any advice

nige

[drewpy]

crank seals will have hardened a bit, but as its fine when warm, I would think that's fine.

Could be a bit of crap in the carb pilot system for low running.
was the bike stored with the carb and tank dry? was there a fuel filter fitted?

[nigel smith]

Hi drewpy 

it’s all been cleaned out and yes I have fitted an inline filter. I might go up a size on the pilot jet and see if it has any effect. But the pick up is excellent 

I have found out you can change the crank seals with the engine in the bike so may do as a precaution.

thanks for the reply 

[drewpy]

10 hours ago, nigel smith said:

Hi drewpy 

it’s all been cleaned out and yes I have fitted an inline filter. I might go up a size on the pilot jet and see if it has any effect. But the pick up is excellent 

I have found out you can change the crank seals with the engine in the bike so may do as a precaution.

thanks for the reply 

I remember when I did the Gilera , i had plethora of pilot and mains jets. and just kept swapping till I hit the right combo
Also the height of the mains needle makes a difference