engine hick up

[bobtrx]

I went on a ride with a big group ,started out ok speeds of about 80 - 100kph for 3/4 hour . As we pulled in for a stop the bike started to run on one cylinder . When we restarted after 1/2 hour I checked the down pipes and both started to get hot so it was firing on both cylinders but running rough . On a constant throttle it back fired thru the pipe and occasionally spat back thru the carbs. It could still accelerate ok . As the ride progressed the back firing thru the pipe got worse and running on 1 cylinder .but would still accelerate ok so I parked it and trailered it home.
I was thinking valves but they don't happen that quick unless one has let go . I put it up on the work station , tipped the tank up onto it's rear bolt to have a look see at the fuel lines / vacuum lines for kinks etc all looked ok. Started the bike ,it ran sweet as a nut so now I have to take it for another ride and see what happens . The more I think about it the more I think it may be fuel related but I can't get past why it was back firing so much . I will also get hold of a compression gauge for a test .How can I test a coil under load Any thoughts from the brains trust ?

[bobtrx]

I went and seen my car mechanic mate who is ok with bike stuff and he thinks it sounds like electrical so I sprayed the coils / spark leads with a water spray while it was idling and that made no difference . It is running great today. I will throw in a new set of plugs this week . Maybe the bike has cracked the shits cause I don't ride it enough , bit like the opposite with the missus

[cobbadiggabuddyblooo]

Yer my old bonneville did something similar a few times and I found that the coils under the seat would get a pile of crud built up on the terminals and I'd just give em a clean and ZOOM prob solved... so I'm betting its electrical..

[phuk72]

My money would be on a coil braking down

[CH_R1]

Try swapping the coils over and if the misfire shifts to the other cylinder it's the coil or HT lead.

[rick54]

Mine did something very similar...running on one cylinder and backfiring, then running on two, but roughly...thought it was a coil but after fitting another one still had same problem. Then checked plugs ( should have done this fisrt ) and right plug was wet with fuel...turned out to be very worn needle jet(s) letting way too much fuel through...new jets installed...instant road rocket! Anyway, hope you get yours sorted...Rick54

[bobtrx]

Went for a ride this morning and it started to play up again . I was happy to ride home with it spitting and farting knowing now I will find the problem . Right cylinder was not firing so I pulled out the plug and tried it against the frame. Nice blue spark . I put in a spare plug and it still wouldn't fire so I changed the coil wiring and still the right cylinder would't fire . Then I noticed fuel dripping onto the work station. It was coming from the carb vent pipe .I start to think , a blocked jet While googleing for fcr41 diagrams I see a message from Rick54 with a similar problem . Thanks Rick I couldn't get out to the bike quick enough to operate on the carbs







The culprit a blocked main jet




I put it back together and went for a run , alls good so thank you to all that offered help , now its time for our Australia day BBQ with me mates if I can find any

[Killerwhale]

The culprit a blocked main jet



[/quote]

That´s the slow jet huh? Would be consistent with the popping and farting as it goes lean as ´ell....

[bobtrx]

I stand corrected thank you , killer

[dandywarhol]

I'd have thought Mick would've jumped off the bench and given you a pointer towards solving it..........................

[Stankflapper]

I put it back together and went for a run , alls good so thank you to all that offered help , now its time for our Australia day BBQ with me mates if I can find any

Hey BOB, Tell me you only keep that bottle of VB to put fires out with... God only knows how anyone can drink that stuff!!

[bobtrx]

Stankflapper don't be such a peasant the mighty VB has magical powers
one -- three relaxing after a days work and stare at the bikes in the shed , admiring my choice in bikes
three--five the missus's voice drifts off into the distance to become a low mumble in the back ground
and plans formulate for the next bike modification
five--ten all the worlds problems are solved and maybe I can ride as quick as Sir Casey
ten --to what ever , next day it was a good idea at the time but now I don't feel too great , no riding today

[Mincehead]

I quite liked it when I was in Aus, can`t abide `normal` lagers.

[Stankflapper]

I Still reckon the stuff is incorrectly labeled weed killer. However,, if it is functioning as a Wife muffler at 3 to 5 it has at least one good point.