Back again... WHEN WILL THIS END!

[asantirims]

Hello everyone,
OK so i have still not been able to get my bike started,
Could somone please tell me, i have a SP model gk73a 89, if at some point of the bikes life somone changed the CDI and they had changed it to the normal GK73A CDI and not the SP CDI, could that affect it starting, i mean the bloke who sold it to me drove it to me without any problems, although it did stall at slow revs and was very hard to start up?
My bike is temperamental, it sometimes sparks and sometimes dosent, i have checked the coils and the wiring and they seem fine, me and my uncle have exhausted most options and i'm starting to wish i had never bought this bike, as beautiful as it is!
My compression rate is pretty low 6.5 on all cylnders, but when i do have a spark it is pretty strong to to be honest it started before i started fiddling with it!
ANY help is apreciated!
Regards Jake

[Variablevalves suck]

Hi,
Dont think im having a go but you say it started before you messed with it, you need to take a step backwards and look at what youve done. There is a parts list in the manuals section that will allow you to cross reference sp and non sp numbers. If the spark is inttermitant then there has to be a fault, have a good look at the trigger pick up as these can give this type of fault, it should give a reading of between 95 ohm and 110 ohm.

[asantirims]

Hello again chris,
All I have played with is I changed the starter solenoid, changed oil filter and oil, new spark plugs, new o-rings in carbs and cleaned them, and a few other cosmetic things.
If i'm honest i think the bloke flogged the bike off to me because there was something wrong with it and he did not know how to fix it.
Is the pick-up trigger located to the right of the starter solenoid at the back neat the battery?
Jake

[chris_psmith]

Did you get it started after changing o-rings and spark plugs, if you did have you balanced all the carbs and set the mixture screws?

Chris

[Variablevalves suck]

Hi Jake, trigger is under the nearside engine cover, you will see the wires coming out the rear corner of it, they can brake at this point. Follow the wire up to near the battery and test between the two wires.
If the cdi still has the part no. on it post up and i will compare it to my 73a sp's.
@ chris until the spark is good it's pointless looking at any thing else.

[chris_psmith]

This is how my bike was when i got it:
http://youtu.be/34DLFpRqCUg
Random sparks, but turned out to be an issue with the choke not coming on full, fixed the choke and bike ran fine.....then the igniter box packed up, maybe it was an early warning.
Anything like yours?

Chris

[asantirims]

Thanks for the replys guys,
OK so i checked and the trigger seems OK, it was about 100 ohms. Unfortunately the CDI part number has worn of, its a 12 port but there's only 10 wires connected to it.
Also the bike is sparking now but its just backfiring, I thought this might of been a timing issue, but then again i don't think the bike will start with bad timing and i alos hadn't fiddled with it?
RE: Chris_psmith, I had changed the spark plugs and it stopped working for a while (no spark), and then i sorted the carbs out with new O rings and set the float heights and it started again, which was strange. and its been doing that ever since, not sparking then sparking. And now it wont start at-all it just backfires.
How did you find out that the choke wasn't working correctly?
I'm dumbfounded by this bike and i dont know what to do apart from seek help!
If anyone knows how to post photos i have taken some and can post them on here if its any help.
Jake

[chris_psmith]

Best way to post photos is to get an account on photobucket and put links on here.
I will give you a potted history of my one in case it helps:
Very bad starter, sometimes backfire then eventually bang into life, as soon as it started you could stop it and it would re-start immediately no problem....drove me mad!
Checked for a spark, random as you can see from the youtube clip. New spark plugs, new HT leads. No better.
Took carbs off, cleaned them and checked them, one had trapped diapghram, check all the open ports for balancing have a rubber bung on them, changed o-rings, re-built, set mixture screws all to 1.5 turns, one was fully in so thought that may have been the issue as it would have only been running on 3! - no different.
Balance the carbs, they were miles out.... no different.
Checked for air leaks on intake by squirting easy start on joints when running, two carbs were leaking at manifiold so tightened them up...no different.
Did some head scratching, thought might be bad battery not turning it fast enough, new battery...no different.
Had a look at the fuelling, tap was leaking and flooding carbs, new tap.... no different.
At end of patience.... checking if choke was working, it was pulling the slide over, for some reason i grabbed the end of the slide and pulled it, the slide moved another 10mm over.... pushed start and it started! Turns out the choke cable had a bent tube on the end that was pointing upwards, so when choke lever moved it would only pull half way before cable was tight and wrong angle to move it any further
Well after all that, bike was running brilliant, put it away for 3 weeks, all dressed up for a run and it wouldn't start! No spark....... Measured pick up resistance, fine, measured coil primary resistance, fine, measured secondary and couldn't get a resistance.... bought another set of coils off e-bay, fitted them, nothing. Measured resistance and same thing no secondary resistance so since decided never to bother trying to measure that again!
At limit of patience and unwilling to spend about £50 on another 20 year old igniter off e-bay, changed 4 capacitors in igniter, bike like new again

No idea if any of that helps, but at least you know you are not alone in these issues..... first issue was over about 3 week period and included 2 sets of spark plugs at about £45 a set as the first set got damp, ht leads about £5 O-Rings about £14, battery £50. Second issue about 2 weeks - coils £9.....capacitors £2.96

Chris

[asantirims]

Ah sounds a-bit like mine, But once its starts and you stop it it wont start again (or not easy anyway)
Unfortunately, I cant find any SP specific CDI's, just ones the GK73A .
I have just just checked the choke, and it seems fine, I'm going to take the rocker head of tomorow to check the cam timing and to see if the valves are OK. I will also take the nearside cover off to check that its all aligned correctly.
If that brings no joy im going to triple check the carbs, could the float heights if set incorrectly stop the bike from running?

There was a Black wire in a kind of braided material and that was really screwd, I pulled it out and it was freayed and corroded so i sorted that out and reconnected it, could that of caused any problems? When i pulled it out , it turned the neutral light off and when i plugged it in it turned it on.

Thanks for your help guys ill keep you updated! Jake

[chris_psmith]

If it is an earth wire then it could play all sorts of funny games with the bike, check all your earth's are good. Float height needs to be right but unless a couple of them are out it probably wont be the issue, did you check mixture screws and balance the carbs?
I doubt it is anything 'mechanical' if it will run ok sometimes.

Good luck,

Chris