Vintage and Classic Hondas

Bang!!! Try to start bike, then bang..

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fighterDaz

Bang!!! Try to start bike, then bang..

Hi, bike ran fine. Got it out for run, its very cold, bike just spining over, sometimes firing, but then bangs, so loud it hurts my ears. Plugs are getting wet with fuel & then just banging. Will not run...?

Youth is wasted on the young.

TOOLS1

Re: Bang!!! Try to start bike, then bang..

Administrator

Have, you checked the coils, or the points, and condenser? It is definitely an ignition problem.
TOOLS

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shinyribs

Re: Bang!!! Try to start bike, then bang..

Administrator

Yeah definitely sounds like the ignition is laying down on you somewhere. The bang,most likely,is raw fuel being ignited while it is in the exhaust system.Basically a backfire.Any chance the timing may have been moved somehow?

fighterDaz

Re: Bang!!! Try to start bike, then bang..

The timing has not been touched, I don't think its on points (82 DOHC). What is strange is it ran ok, then next day it wouldn't? Plugs are wet through, it has a spark? The battery went flat so I am using jump leads from a separate 12v leisure Battery. Would a to high amp battery cause any problems? Bike spins over very very fast when connected to other battery...!

Youth is wasted on the young.

shinyribs

Re: Bang!!! Try to start bike, then bang..

Administrator

No. The high amperage should not hurt anything. As long as it is the right voltage. If the voltage is too high you could wreck a lot of things,but as long as it is a 12 volt battery your fine.

fighterDaz

Re: Bang!!! Try to start bike, then bang..

Thanks ribs, I think its a weak spark prob, everything else is fine...The cold weather here is making it worse... Will have the tank off tomoz and check all connections..fD

Youth is wasted on the young.

LukeM

Re: Bang!!! Try to start bike, then bang..

Administrator

I think the spec for that battery is a minimum of 14 amps. Any more than that is gravy. You can't cram too big a battery in that area. I hear good things about the Gel batteries, if you're thinking of buying a new one.

Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.

fighterDaz

Re: Bang!!! Try to start bike, then bang..

Cheers guys, I will get to the bottom of it this weekend..

Youth is wasted on the young.

fighterDaz

Re: Bang!!! Try to start bike, then bang..

Ok, update. The bike was not firing on 1 and 3, both fed by same coil, removed it and cleaned all conections and mountings, now runs on 1-2 & 4, but number 3 cylinder plug is black (sooty) so seems mega rich on number 3. ? what do you think guys? choke stuck, in number 3 carb?

Youth is wasted on the young.

shinyribs

Re: Bang!!! Try to start bike, then bang..

Administrator

I had a jet fall out into the float bowl on mine.Caused a super rich condition.Could be a number of things to cause that.Once a plug fouls it is hard to recover sometimes.Try a clean plug in that hole and see what happens