Forum

[Leon Novello]

A Bullet suddenly loses compression and stops a few yards from home, a new spark plug is fitted and the bike returns home, albeit, running erratically, and no compression again. My thoughts are sticking rings, as my Bullet would have no compression sometimes when trying to start from cold, but would regain compression once it started. Any thoughts? between eating Easter eggs.

[Bullet Whisperer]

Hi Leon, the fact it was running and suddenly lost compression rules out piston rings - which, incidentally have to be left idle for many years to be the culprits of lost compression in a formerly good compression engine. My money would be on a loose valve seat, sticking / dirty / burnt valve, seized rocker, loose pushrod adjuster, or blown head gasket - plenty to choose from in that lot! Regards, Paul.

[Leon Novello]

Thanks, Paul, I`ll pass it on.

[Pwayman]

Although it's a few years since I sold my Bullet ( and not posted in here since ) I do have an occasional read of the message board.

Leon, the symptoms you've described could have been written by me as I had exactly the same problem. After removing the cylinder head it was immediately obvious that the exhaust valve had overheated and burnt. Valve seat was OK and only required the new valve to be lightly ground in.

The bullet's gone but I still have the burnt valve

[Adrian]

Kept the good bit, then? A.

[Pwayman]

Adrian - I kept the bit I couldn't sell.

Rather than being burnt as in eroded it looks as though one small part of the valve head had been almost molten and had cooled leaving a deformed seat face. Never seen a valve do that before.

[Leon Novello]

News from the front. The head was removed and nothing untoward was found. The head was serviced by an engineering workshop, refitted, and has been running well ever since. I blame climate change.

[Scalyback]

I go for sticking valve. Tornado has done this 5 times in 2-3 years. It's the inlet valve, so the ignition blows the carb off. Had a new head and has only happened once since then.

[Chris [Stockport]]

Does Tornado have some sort of connection that makes red traffic lights flicker in time with his engine? Black magic?

[Leon Novello]

Chris:
Green lights suck the electricity out of them, you stopped too close to the lights.