Author Topic: mis-fire (Read 3537 times)

alhuggy · « **on:** October 27, 2005, 01:23:54 PM »

hi I hope someone can help.
I have just bought a b12 which had a intermittant misfire between tickover ans 3 half thousand rpm. the bike has only done 1000 kiles in the last 4 years and still only covered 13800 miles. I decided to have the carbs cleaned and a dyno jet kit fitted. This is where my real problems started, now it will not run at all unless the fuel flow is reduced leaning it out until it runs or it just floods and the plugs just go black. I have been told it is either carbs are knackered as when he went to fit the kit he said there was the remains of a kit in there, or its the pick-up coils or ECU. He has checked the carbs three times and can`t find anything wrong.
Before the work was done the bike was running fine apart from the mis-fire, and when you cleared it`s throat (so to speak) it seemed to run fine apart from when you made small throttle changes would cause it to mis-fire again and it you open the throttles futher it would be fine and pull as it should.
I would be gratefull for any idea`s

tacoman · « **Reply #1 on:** October 27, 2005, 02:48:37 PM »

I would probably rule out the wires or ignition being bad as it ran fine when its "throat cleared out". What I don't like and I'm sure others will agree, is that a dyno jet kit (these have a bad rep here) was put in and there were remains of an old kit in there. Bad news, you've got what a tuner friend of mine calls a "witch's brew" of carb mods. Your floats, needles, everything is messed up and confused. You will not get this bike to run right. My advice; buy a Holeshot or Ivans kit, pull the carbs, take out all the crap and reassemble with the kit so you know exactly what you have. You and your bike will be much happier together

alhuggy · « **Reply #2 on:** October 27, 2005, 03:22:15 PM »

many thanks I have now brought another set of carbs to try and will go from there. I`m convinced it`s carbs not electrical

ChuckD · « **Reply #3 on:** October 27, 2005, 10:01:57 PM »

What you need is a base line. I'm an F-15 Avioncs Technician in the US Air Force and when we get in to a situation like this (known as a goat rope or BF) We go back to bone stock. I just went thru installing a jet kit and having my bike run fine then not start. My problem was a combo of fouled plugs and bad gas, but I did wallow in the mire of carb adjusting for a time. My advice would be new gas, new plugs, shims at the third notch and the mixture screws between 2 and 3 turns out 2.5 in fairly standard. Oh and a freshly charged battery. That should give you an excellent starting point. Also the carb system on these bikes can be touchy but are extremely simple, I would say give it a rip yourself especially if you have any doubt about your homeboy's ability. (or sobriety) I am no expert but if you want PM or email me I'd love to help.
Cheers,
Chuck

Red01 · « **Reply #4 on:** October 27, 2005, 10:50:14 PM »

Quote from: "tacoman"

What I don't like and I'm sure others will agree, is that a dyno jet kit (these have a bad rep here) was put in

+1

Dynojet + Bandit =

FactoryPro + Bandit =

Holeshot + Bandit =

Ivan's + Bandit =

Dynojet makes some great kits, just their Bandit kits aren't one of them.

Wish you would have found us before you bought the jet kit.

alhuggy · « **Reply #5 on:** October 28, 2005, 01:52:54 AM »

what I have just found out it that the neddles were from a dyno jet kit but the jets were smaller than standard when he took them apart. He also said the emulsion tubes are all scratched were someone has had them apart, so what other damage have they done?

he has tried new plugs and the mixture screws are set to standard but all it does is foul up the plugs again.

see what happens with another set of carbs!

tacoman · « **Reply #6 on:** October 28, 2005, 02:07:29 PM »

That may be the best thing. It sounds like you had a "hacker" working on your bike. Did they do any other mods? On the bright side, the motors in these things are stout and normally not be damaged by bad carbs unless it was run real lean which doesn't sound like your problem.

alhuggy · « **Reply #7 on:** October 29, 2005, 09:06:03 AM »

the bike had a dyno kit and micron exhaust fitted when nearly new and I have the print outs fron where it was set up on a dyno, but since then I think it has been played with as I only get 86 miles to a tank riding moderatly. before I decided to cure!!! the mis fire at low revs

alhuggy · « **Reply #8 on:** November 05, 2005, 12:48:20 PM »

thanks for all your help

carbs had been drilled not sure wear abouts so fitted new set and now running as good as gold

many thanks