4 replies to this topic

[poornebbing]

i have a 240 fantic that has a scary top end knock like a detonation type noise can anyone help?

[midlife]

Try higher grade fuel. Dont forget these bike were built to run on leaded fuel.(try octain boost for mx engines 10cc pre ltr)

[Grib]

I run my 240 on unleaded (50:1 Castrol TTS) and only get a knock very occasionally. It could be a build up of carbon in the cylinder head if it has been run with too much oil in the past, or if the head has ben skimmed there could be too much compression which could be cured with a thicker/extra head gasket.

[poornebbing]

thanks for the help am already using an additive but would anyone know what figures i should be looking for on a compression test?

[rontheyank]

poornebbing, on 16 January 2011 - 09:04 PM, said:

thanks for the help am already using an additive but would anyone know what figures i should be looking for on a compression test?

A compression test is a bit pointless, if you suspect low compression put in a new ring, if you put in a new ring replace the small end bearing at the same time and when you have the barrel off you can check the big end at the same time.