Goose starting problems...

[Majik]

Thursday was a day full of grimy hands and shouting in the garage. However, a solution (of sorts) has been obtained.

After the new choke cable was put in, she was starting reasonably reguarly, but still needs some pretty long turn over to get going.

As for the revs maxing out at 5500-6000? Replacing the original airbox cured this completely. WooHoo! Of a kind... See, the whole point of this was to not only release some extra ponies, but also to get rid of the bloody ugly thing so I could take the side panels off, relocate the battery from under the seat and get a lovely looking trellis frame effect posing off the back of the engine and the space under the seat. So although she's now going fine, I'm trying to decipher why the cone filter prevent her reving out. I'm making an educated guess that it's due to the way the CV carb works and it needing some kind of "still air" or pressure to raise the diaphragm.

Help? I want rid of this bloody airbox...

[guest27]

So do you still need the needle on the lowest ring and crank her on 30 - 40% open to get her to start, or is the needle back as per spec?

It may be that the flat spot with the cone filter is due to the mix being too weak on the needle?  Maybe it will need the circlip raising rather than dropping - as you had to start it when the choke was to pot?

R

[Majik]

Nope - I've put her back to spec now. She's starting, but irreguarly again. Driving me nuts! Someitmes she'll burst into life after 30 seconds of trying (and yes, I still need to go 30-40 percent and then chuck it back to closed throttle for her to have a chance of catching).

I've got a final theory I may test tonight with a spare battery - the higher revs is are making the spark stronger, and therefore the battery isn't in good enough nick to start her from no throttle turnover...

[guest27]

Used to have a CB250 that needed 30% throttle or there abouts and lots of spinning to start - but then she had a pair of exhaust valves with splits in them so would not hold any compression...  Have you got compression?

Still sounds a little like the pilot jets are causing probs and not letting enough fuel through - just guessing mind
What is she like to start when warm?

R

[Majik]

If I go for a start within a minute of her being turned off, she's fine. Anything more than five minutes and chances have increased, but she's still a bitch.

[guest27]

Mmmm - still sounds like a pilot jetting problem - maybe I am stuck on a single solution.  Warm engine with a bit of fuel still in the tract etc will start, (ie within 1 min or so) let the fuel evaporate off - 5 mins or so - bitch to start - sounds like low throttle fueling - or a weak spark as you have thought.  Any luck with the battery? - it is 12v? can you not run some jump leads from a car to see if this make a difference?

R

[Majik]

DId the battery test last night - absolutely fine. Have ordered a new pilot jet for her from Allans. I'll let you know

[Majik]

New pilot jet went in - starting is no better Had ordered a slightly bigger pilot alongside the standard one to be sure) no dice on the starting (although she's picking up faster through 3-6000 revs).

I'm becoming convinced that my carb is not the problem.

Could the starter not be spinning fast enough? The starter speed increases with the throttle, so could the starting sequence of 30% to no throttle be carrying starter speed through to the correct carb settings (i.e. no throttle) to start her up?

Coil problem?

I'm a luddite on electrics...

[Steve H]

DId the battery test last night - absolutely fine. Have ordered a new pilot jet for her from Allans. I'll let you know

Did you replace the battery ?. I use an old battery out of a diesel and jump leads to check if the battery is border line.

[Majik]

Yep - jumped off a good diesel battery as well. All good.

[guest27]

Does that mean that it started well from a jump battery or that all the starting problems remain?

Does it have a decompressor and is this working / stuck open?

R

[Majik]

Sorry - unclear. Same problems. Same effect as battery on it;s own. No decomp lever - have been thinking about this - there must be an auto decomp somewhere, right? Working off a cam or something? Where would I look to see if it's broken/stuck?

[Majik]

Sorry I haven't been keeping y'all updated, but the bloody thing totally died on me. I can only assume it's all related, and I'm now looking at a bike with no spark...

SO far I've:

 Replaced the coil/plug
 Replaced the reg/rec
 Replaced the CDI (at GREAT expense...)
 Gone through the loom as best as my limited knowledge will allow me to check for continuity.
 Checked the sidestand / clutch / kill switches.

Nothing. Occassionally (as in once every week or so) I'll get a big fat blue spark on the first push of the button. If I keep the starter going, it'll keep sparking. As soon as I stop, the next push will produce zip, and she'll be down for ages. No rhyme or reason to when she'll give me a spark again.

For the love of God, help me...

[guest27]

All at sea on this one but it sounds like something somewhere is breaking down when the lekky pixies run through it.

No idea what though and could be totally wrong - usually am

R

[KirriePete]

I see no mention of replacing plug cap & lead .... maybe?  Also, it's not unknown for spark plugs to be duff out of the box, even being sneaky little beggars and sparking OK against the head, but failing when under pressure.

HTH