Flat height settings 1996 bandit 250 (GJ77A)

[imthatguy]

Does anyone happy to know what the correct float height is for the later model bandit 250's (GJ77A model), mine does not want to start and I suspect it may be related as Ive tried literally everything else..

[F5 Dave]

That won't affect things enough to make it fail to start, unless perhaps fuel is pouring out the overflow pipes.

Give it a squirt of ether (startyabastard or equivalent), or brake cleaner in a pinch, down the airbox (filter removed). Report back.

Oh yeah, have a rag handy to smother any backfire flames. Just in case.

[andrej168]

Would start with the basics
Check for spark and compression. If you have that, Dave's advice will make bike cough couple of time and maybe start.
How has bike been sitting?

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[imthatguy]

I just realised I wrong flat not float height, sorry about that!

Ok so some background would probably be helpful, this has been a problem bike for about 5 months now and Ive never managed to start it off the starter button ( It WILL bumpstart fairly easily ). Compression is ok, around 120psi over the 4 cylinders, if you squirt some carb clean in the bike will clearly stutter and cough like it wants to start but thats about it.

When I first picked the bike up it had no spark, narrowed that down to a missing resistor in the ignition, and finally the gapping of the crank sensor, now we have consistent (although relatively weak) spark at all times when turning over. All other electrical systems on the bike check out.

As too the carbs, Ive gone over them with a fine tooth comb and cleaned / reset them, fitted new washers etc etc. Float height is a bit hard to set, but as you say, and I assumed, it shouldn't really stop it starting.. All the jets are clean, emulsion tubes clean, no tears in the diaphragms, mixture screws set at 1.5 turns out (though Ive tried anything from 0 - 5 turns out.

Bike had been sitting for about 6 months before I picked it up.

Edit: If you bumpstart the bike it will run, although fairly badly, definitely needs tuning but that would logically come after being able to start it

Edit 2: Have replaced the plugs before anyone suggests that

[Akzle]

vacuum leaks

[F5 Dave]

OKfor giggles, bump start it then put a meter over that battery and see what voltage it is putting out. 13.5-14.7 ok. Above or below =bad.

Check the heat in header pipes when it first starts. Do some pipes get hot and some not?

[imthatguy]

vacuum leaks

Nope, nothing connected past the carbs and near new carb => block rubbers, all hoses replaced

[imthatguy]

OKfor giggles, bump start it then put a meter over that battery and see what voltage it is putting out. 13.5-14.7 ok. Above or below =bad.

Check the heat in header pipes when it first starts. Do some pipes get hot and some not?

Reg / Rect isn't connected at all atm but when connected getting 13.8v

They are all warming at roughly the same temp, also when its running its does idle evenly, its not missing

[Akzle]

Nope, nothing connected past the carbs and near new carb => block rubbers, all hoses replaced

ya so, grasshopper

[FJRider]

Edit: If you bumpstart the bike it will run, although fairly badly, definitely needs tuning but that would logically come after being able to start it

Edit 2: Have replaced the plugs before anyone suggests that

The ability to bumpstart it suggests a bad battery. The starter motor is sucking all the power. Try first putting jumper leads from a good battery power source and try the starter motor again.

Small bikes are easily affected by small things .. so check plug gap. Check all power connections are clean and tight (including battery terminals).

[imthatguy]

ya so, grasshopper

Well Akzle, whereabouts would you suggest I look for a vacuum leak?

[imthatguy]

The ability to bumpstart it suggests a bad battery. The starter motor is sucking all the power. Try first putting jumper leads from a good battery power source and try the starter motor again.

Small bikes are easily affected by small things .. so check plug gap. Check all power connections are clean and tight (including battery terminals).

Have actually run seperate wires for the ignition system to eliminate the loom so its not that, swapped out the bike battery for a big ass car battery today for the lol's but the issue persisted. It sounds keen to start, its intermittently kicking but its never catching for long enough to be self sustaining.

Plug gap was checked when i swapped the plugs..

What effect would tight valves have? I had another bike awhile back that was incredibly hard to start and ran like shit until the valves were opened up a bit, but it did at least start..

[Akzle]

Well Akzle, whereabouts would you suggest I look for a vacuum leak?

everywhere.

i might also suggest (based on "it runs rough" and "[you've] done 'literally' everything else")
that you're running way too lean with no airbox, and that the either: the carbs arent even close to balanced (did you bench set them?); or there's one or more pots not doing what it should.

also, weak spark outside, will probably equal no-spark under compression.

[Akzle]

. It sounds keen to start, its intermittently kicking but its never catching for long enough to be self sustaining.

got choke, nigga?

[Drew]

If you can see spark, it's normally ample. However that is not always the case. If you've buggered around with the pulse generators, the issue may well be there and in the timing.

How have you got it wired up? Could be a shit connection breaking down with the wires you have.

I once experience similar issues with a bike, and it turned out to be broken wires in the loom at the steering head. Fuck did that take some time to find.

If there is good compression, I reckon it's not valve clearance.