Anybody had symptoms of a loud crack...as if something is colliding inside and instantaneously cutting out At the same time?. Happened twice in start up the morning. Won’t be starting up again until problem has been identified. Maybe a trip to Carl Harrison for the sps
Not had this problem before. Starts fine, idles, but idle will suddenly drop at tickover, that’s when the loud crack and cut out occurs. Dare not start it again as being unsure, I’m not happy to start it up again. Will have to look for a reliable bike courier to get it to Carl Harrison.
Thanks for the replies, always appreciated. I’m pretty sure it’s mechanical as it’s a crack and kind of grinding noise, happens in a nano second and cuts out.
Sprag clutch without a doubt, left hand engine case easy enough to do, usual symptoms slow to turn over which is the main reason the sprag wears, slow cranking over and a couple of very loud scary cracks when starter button pushed
Indeed! - I could quote a few tuned (arguably overtuned) Italian cars that could decide to run backwards during starting resulting in many bent valves.
What a nightmare! If I ever won the lottery and could afford one of those V12's, I'd be beside myself if it somehow ran backwards & effed its engine up. I'm not going to buy a ticket now...
Bike starts fine, spins up instantly and no crack noises when pushing the starter button. It’s after that...It just idles crap from cold and occasionally you get such a big drop in rev, it forces it to cut out. That’s when you hear the crack noise. When Upto to temperature you can stop and start it as many times as you like and it’s perfectly fine.
Having read your latest and previous symptoms, I don’t think it’s the sprag after all. You say it starts fine but then cuts out after a while all of a sudden with a crack noise... My 749R used to do this often when starting for the first time...spit back into the air box and cut out. A remap at CJS sorted it. Nothing to worry about basically.
That’s my thought on it too. Really does start well but crap idle. Remap, fuelling, tb balance as @final_edition says too could sort it.
I can deal with the initial rough idle. My old 749R and 916 was always the same, esp when not started for a while. Only takes a few mins and idles pretty much stable. It’s as if there is a big misfire which drops the rpm way too low causing it to cut out and the noise I think is because it’s cut out whilst ingnition/electrics still on, very different to switching off at ignition that cuts everything.
