Running Issues

[Lamaddict]

Looked at other threads but can't see my problem (

Rebuilt engine, kicked off 2nd kick and always did. Smooth tick over. Runs for about 2 miles then the tone of the engine changes to a rattle, then the revs change and it dies. The inlet manifold was leaking a bit so I fixed that but no change to the iratic running issues. Changed the whole top end with another carb and exhaust, kicked off second kick, same problem persists so it's down to the stator, CDI or the crank seal(s). It's made me feel very depressed. I know we've all be there with Lambretta's. Can't face the strip down right now. Anyone got any ideas on what it could be?

[Lamaddict]

Update.

Dragged myself into the garage and took off the mag housing. Spotted some grease had squeezed through into the Stator area but that's insulated from the crank area by the other seal I recon?
The Stator testing between the white and red wires was 92.7 Ohms but Stickys book says that should be between 95 -120 Ohms, any idea on this?

[hendy]

Try a leak check. Dead easy.

[Lamaddict]

Thanks, I did try and build an leak tester but couldn't get it working properly.

Seems like the Stator reading is within the limit according to other sources. Seems like another full strip down as it has to a leak either side of the crank. I thought a leak on the pressure plate side would blow the white smoke out of the exhaust? I'm still also wondering if the smaller leaking seal on the mag housing could cause an air leak. Of courses there's also the mag gasket but that looked okay.

[hendy]

Inner race loose on mag side bearing and running up against seal?

[HxPaul]

What makes you think that it could be a seal ?

[bristolmod]

the fact that it "rattles" after 2 miles or so is worrying. Metallic rattling?

[ForemanBob]

Pinking "as a result of a lean mixture" can sound like metallic rattling... complete your leak test before you hole a piston... Whats your plug look like?

[Lamaddict]

I checked tightened everything and the spark plug was a bit loose. Took it out this morning, opened it up after a few miles and it played up with erratic reving and died (it kicks off immediately with a steady tick-over). It was just so hard to work out whether it's fuel, ignition or an air leak. I decided to changed the CDI, HT lead and surpressor cap. I also put a new bit of fuel pipe in and took off the small fuel filter. Took it out again and it ran better!! BUT after holding it open for a mile or so, throttling off it dies but kicks off easily and the tick-over is again fine. Any more ideas?

[Timbo]

I had a similar problem (not the rattling) and it was the stator breaking down...