Stuttering/Misfire... UPDATED

[Gosling1]

Thanks guys, I'll try a new battery and see how it goes. I will try and get most of the other work done anyway.

I also have a wet airbox on the carby side, it's not evaporarting off - any ideas?

hmm....that seems odd - is it wet inside the box, like pooling up ? This sounds like either a leaking fuel tap ( is it a vacumn tap ? might have a dud diapghram with a hole or split in it)....

at least with a new battery, you will (or should) be able to remove that as a source of any problems.......

[photomike666]

Dry cell batt ordered.

The wetness in the airbox is a wet film on the inside of the lid right above the induction ports. I will try and post a pic tonight.

I ran the bike connected to a car battery with no tank and airbox to run the fuel out of the carbs on Sunday and it sounded like it was 'spitting' back through the carbs.

[oldman]

A liquid?? Is it gas, water, Jim Beam? Try and find out what it is. Wipe your finger across the wet and smell it. If it's Jim Beam don't change a thing and figure out a way to collect it, but it's probably gas and you may have a needle and seat that is not shutting off fuel flow. I would do this logically, however, (like i've ever done anything logically) start by having a couple of shots then take a compression check. When you pull the plugs note the insulator colour. It should be from almost white to a nice tan. Keep track of which plug came out of which cylinder as one may be fucked and the rest ok, (an indication of which carbie or cylinder is fucked). Then check your compression noting each cylinders pressure. If you have one plug that is wet or black that means it's rich so the compression of that cylinder will read low as the excessive fuel will wash the oil off the rings and cause blow by. Squirt some oil in that cylinder through the spark plug hole and re check the pressure. If its ok then your valves are good. The rest is fairly obvious if all cylinders are low even with the oil your valves are farked. If they are all ok but one plug is fouled or wet it's the carb for that cylinder etc. etc. etc. It could also be a lean condition but I doubt it with the moisture inside the air box. If that moisture is water or anti freeze then we have a totaly different problem. If it's anti freeze, (coolant) it will taste sweet, don't swallow it though as it's poison, Keep us posted please.

[Gosling1]

.......Dry cell batt ordered.

The wetness in the airbox is a wet film on the inside of the lid right above the induction ports.....

Dry cell ?? Like a big pack of D-cell batteries ??

do you mean Gel-cell ? (maintenance free )

That wetness - almost looks just like a bit of blow-back through the carbies to me. It looks to be on a vertical surface ?

[oldman]

By the way if you are blowing back through your carbies, your intake valves might be farked. It could also be a timing chain issue. The Jim Beam and the compression test will address some of that.

[Smitty]

.......Dry cell batt ordered.

The wetness in the airbox is a wet film on the inside of the lid right above the induction ports.....

Dry cell ?? Like a big pack of D-cell batteries ??

do you mean Gel-cell ? (maintenance free )

carn Gos...you know
all mudderboike batteries are supplied dry...hence dry cell

its a case of...just add water

[photomike666]

Plugs are all a good colour and not wet.

the surface in the pic the the underside of the air box lid, the wet side goes above the carbs, the dry side above the air filter. Fluid smeels like petrol, but after two days it still looks wet and I expect petrol would evaporate off. Valve clearence has not been done in a while, perhaps 6 track days, nor has be carb balance.

[Gosling1]

.......Dry cell batt ordered.

The wetness in the airbox is a wet film on the inside of the lid right above the induction ports.....

Dry cell ?? Like a big pack of D-cell batteries ??

do you mean Gel-cell ? (maintenance free )

carn Gos...you know
all mudderboike batteries are supplied dry...hence dry cell

its a case of...just add water

I always add acid to new batteries mate, not water ! - but I have never heard of a normal wet-cell bike battery being called a dry-cell......even if they are dry in the box, they get filled before you use them.

[photomike666]

http://www.allpurposebatteries.com.au/p ... ucts_id=11

[Smitty]

aaahhh...all is revealed
sealed NOT DRY CELL

[photomike666]

"*The liquid-free design..."

[oldman]

Gas sputtering back through the carbs is not normal. You might want to run a compression check. You might have smoked intake valves. It could be adjustment also. Too bad it wasn't Jim Beam.

[IsleofNinja]

Sorry Mike - what year is the trackie??
Reason I ask is because this 95 I'm resurrecting is behaving very similarly.though somewhat worse !?

Have stripped , cleaned and preliminary set carbs etc.
Next step is the coil packs / HT side ten ignitor/ stator etc depending on how quickly I find the issue!?

Nb: The staining on the airbox lid is a combo of intake pulse 'reversion' or blowback through carbs combined with a bit of engine blowby I would say. Sorta thinking the engine might be getting a bit tired going by the pic perhaps? How many km?

[photomike666]

Bike is a 1999 CBR600 with 76,000Km - last 4000km have been all track.

[IsleofNinja]

Bike is a 1999 CBR600 with 76,000Km - last 4000km have been all track.

Has to be said ... It's a bloody Hooonda !!

think Dave is pretty spot on re farkled battery. have you tried it since replacing the battery? Might also be related to the o-heating / fan issue ie undervoltage to actuate;)

If no good , think you are on the right track re carb synch / valve shims & running a tad lean too perhaps.( if it comes good with new plugs) .. As you know , carb sych plus insufficient valve (ie inlet) clearance will make it a bit off song down low in particular.

I would tend to go for a magneto set up rather than the total loss you mentioned (no matter what your battery is like you have nice clean fat sparkies!)
Running a maggie deletes the charging coils so you will need to re-charge the (smaller/lighter) battery each meeting for starts. Another good idea is run a mini 'Anderson' plug under the ducktail for charging / pit start ups warm ups (jump start) so you don't kill the onboard battery.... just ideas
(P.S I'm no racer - just a mechanic's point of view here)

Had a think about the airbox thing , prob is breathing a bit of oil but in a track situation you kinda expect it too a little bit . I think the 10's burn a bit on the track too!

see how you go