Misfire, three cylinders?

**jumma** · 16th October 2006, 18:46

Hi, hopefully someone out there can provide some insight into my problem.

It started yesterday, and I noticed it soon after a brain-lapse and had accidently taken the bike to it's red line for about 5 seconds (don't ask). Came to a set of lights and taking off from them the engine lost a lot of power and spluttered through the lower rev range (same feeling as if it were out of fuel). I was running on reserve but had only just switched it over. Thought this may be the cause so I filled up, but as I left the gas station the problem was still there and the bike didn't feel right for the 10kms to home.

When I went to restart the bike it wouldn't, so crashed it down the driveway and left it running for a while, although getting it to idle was difficult.

Next thing I noticed was a distinct smell of petrol, so was thinking a cylinder wasn't sparking. Took all the plugs out and checked them, all seemed ok. Once they were cleaned and put back the bike fired up off the starter fine, but had developed a tapping in the top end of the engine while idling.

By this stage I was out of my depth and have spent most of today trying to find a diagnosis on the net. Any ideas? Has my over-revving done something nasty?

Thanks, Jumma.

**Wasp** · 17th October 2006, 07:25

by over-revving what exactly did you take it to?!

6k rpm to take off on a bandit ('90 45hp gj74a), anything less there is no power.

bandits have know problems with the CDIs and the coilpacks, also could be the carbs.

might pay to check out www.banditalley.com (and the 250 forums there)

**jumma** · 17th October 2006, 07:32

Hey Wasp. I was overtaking someone and paying a lot of attention to the road ahead and when I pulled back in was at about 17,000rpm. Would have been there for about 5 or so seconds.
Came to a set of lights further down, and taking off it just coughed and spluttered, rather than just being gutless.
Gonna try some new spark plugs today and if that don't work will investigate further.
The over-revving could be completely unrelated, just the fact the problem came about so soon after it had me worried.

Cheers, have tried Bandit Alley also. Will keep ya posted.

**Wasp** · 17th October 2006, 07:37

hmmm sounds like it just flooded it, sometimes it happens and stutters for awhile till it gets going again.

is the bike stock? custom exhaust? re-jetted?

**jumma** · 17th October 2006, 07:51

Yeah, totally stock.

Stupidly I took it for a run on Sunday after cleaning the plugs, and then put it away in the garage. Returning from work yesterday there was a strong smell of petrol still, some dripping out from under the carbs.

Still sound like it could be flodded, or maybe unburnt? Unfortunately I'm not the most mechanically minded person, but am slowly learning.

**Wasp** · 17th October 2006, 08:52

the best bit is your in welly, slingshot helped me pull my carbs apart a few weekends ago.

**MSTRS:Me** · 17th October 2006, 09:00

Originally Posted by jumma

Returning from work yesterday there was a strong smell of petrol still, some dripping out from under the carbs.

Usually a sign that one or more of the carbs has a floatlevel or needle valve problem

**jumma** · 20th October 2006, 11:15

Cheers for the help guys.

Cylinder three was missing, and after hearing my story a more mechanicly minded friend suggested it could be the cam chain that's slipped and has screwed the timing. Apparently this can happen after revving the tits off some engines. Bikes being checked out at Boyles, hopefully it's not too expensive to repair.

**Wasp** · 20th October 2006, 11:19

oooh crap, let us know - its not like I havnt put mine under stress.

**DingDong** · 20th October 2006, 12:11

Originally Posted by MSTRS

Usually a sign that one or more of the carbs has a floatlevel or needle valve problem

This is where Id start... seem preety unlikely the cam chain would have slipped, (unless it was poked in the first place...) but then again I've seen a tensioner collapse but that was on a race bike being hammered.

**jumma** · 26th October 2006, 15:31

Bikes fixed. Turned out it was just flooded carbs that were causing me grief. So they're nice and clean now, plus the oil was changed as it had a lot of petrol in it. Bikes feeling better than ever.
Now I just need to learn how to fix this sort of shit myself, rather than paying someone else to do it.

**Animal** · 26th October 2006, 15:54

Originally Posted by jumma

Bikes fixed. Turned out it was just flooded carbs that were causing me grief. So they're nice and clean now, plus the oil was changed as it had a lot of petrol in it. Bikes feeling better than ever.
Now I just need to learn how to fix this sort of shit myself, rather than paying someone else to do it.

Don't worry, you'll get the hang of it. Sadly, experience takes time to accumulate. Don't beat yourself up.

**Wasp** · 26th October 2006, 16:03

DOH! i expected you to ask either me or slingshot to help you with the carbs...

how much did it cost?!

**jumma** · 26th October 2006, 16:39

Originally Posted by Wasp

DOH! i expected you to ask either me or slingshot to help you with the carbs...

how much did it cost?!

I was going to, i've been working weekends as well at the moment though so didn't know when I'd have time. Cheers for the offer, it's definitely something I want to sus out myself.

$150 if you must know