650 poor/not running

[Soichiro]

I never could tell if CDI works just by looking at it.

[fossie]

The cdi on the 650 is basically just electric points if you get my drift . It would be my next point of call.

The cdi is under the battery box and earths to the bolt that hold it on usually corroded.

[Soichiro]

I doubt if the CDI is playing up because there's loads of sparks. There's no corroded bolts - all new stainless. I'll make sure it's earthed properly becwuse I painted all those plates under the seat. I may need to put an extra earth to the cdi.

[fossie]

Just a thought does it run ok with a remote tank on? I have come across this before where a new fuel pipe has been fitted but when the tank is on the pipe is either too long or not toughened enough and folds restricting flow.
Also remote tank would prove air breather in fuel cap.

[johnr]

When johnr bought my 250,000 mile 650 it started ,ran smoked a touch......but started fine ...ran better over 3000rpm. When he took the head off , number 3 exhaust valve was so coked up it didn't move , but the thing ran ok..

For my money I would look at coil connections . They earth through the mounting bolts on to clean metal.

i have pictures somewhere, it was a sight to see. almost completely healed up!!!

the bores and pistons were perfect, it was the valve guided that had worn to the extent that the valves were floating about .5mm side to side movement, a vast clearance for guides.

[Soichiro]

I had a quick check of the compression. I didn't check all the cylinders, didn't have to. Pot 1 is hardly any compression so it's a head off jobbie. The compression didn't improve with oil down the bore so it looks like a valve problem. Major pain in the A but at least I know where to look.

[johnr]

check the shims first, if the clearances have closed up, then there is your problem.