Ignition advancer

[clacker]

Hi guys.My gpz1100b1 refuses to rev cleanly off idle on a constant throttle.Tickover is fine and over about 3k it goes perfectly.Ive checked nearly everything and all i can find is that the mechanical advancer is not moving until i get to around 3k revs, where it flies round.If i remove one of the springs the advancer will open and the bike seems a whole lot better.So i put a new one on from z-power but that one still will not advance.Would the failure to advance cause spitting and misfires at low revs and am i missing something as to why a brand new advancer would fail to work.

[Al]

If you remove the cam from the advance unit there should be a thin spring steel shim behind it. If there is take it off and save it somewhere. They have been known to split and jam the cam and prevent it moving freely. Equally important with the new one because if it is not opening correctly it probably means the drive nut (washer i think they call it) is pinching down on the end of the cam and slowing it down. The springs / weights / cam should open progressively through the range you mentioned and be fully open by between 3,250 and 3,550 rpm depending on the start point you have set. If you know that it is not opening 'till after that point then you are using a strobe so it will be easy to tell when it does. Is the centre fixing bolt damaged or bent and is the unit spinning eccentrically? Is there any sign that the lobe on the cam has been rubbing the fixed pickups?

AL

[clacker]

I have put feeler gauges between the lobe and pickups and there seems to be equal clearances.I will try removing the shim and see what happens.As you say il check the nut and bolt as well.There is clearance between the shaft and pinch nut.A bit of a head scratcher this one.A problem ive been trying to sort out for a very long time. Thanks Al.

[Al]

Not sure this follows exactly but i guess that if its the standard advance unit it must then have the standard pulser coils and therefore the standard IC igniter?
If its popping and miss-firing and spitting at low revs i would be taking a look at the IC igniter. Could be nearly 40 years old now. That does not explain why the two advance units will not operate correctly though unless, and this is really clutching at straws, you have the wrong IC igniter. It is a strobe youre using to determine the operation of the advance unit isnt it? Might have dreamed this but had the thought that one of them has the advance curve built into it electronically!!!
I take it that the advance units' centre bolt and (so called) washer / drive nut are as standard and the bolt is 8mm x 63mm?
As an aside, mine was dreadful when i first got it. Wrestled with all sorts of erratic issues and in the death it came down to the tiny drive peg in the end of the crank. It must have been over on its RHS at some point and the case advance unit etc had been obliterated. All had been replaced and a Dyna 'S' fitted and the tiny drive peg replaced with a cut down roll pin. Unfortunately they had missed the fact that it sits in a milled tapered ramp on the rear of the advance unit but they had left the end square. After filing it to a shallow angle all was well and has been ever since.
On the subject of spitting and popping at low revs, again, my CV carbs were entirely to blame here or perhaps more correctly i should say the Ram-air filters gave the CV's a very difficult job.

[clacker]

I will check through all that you mention.I know the roll pin has a flat edge.It could be that it is preventing the advancer to fit to the crank correctly.If i find the answer i will post on here.Thanks again Al.

[johny brando]

Not sure this follows exactly but i guess that if its the standard advance unit it must then have the standard pulser coils and therefore the standard IC igniter?
If its popping and miss-firing and spitting at low revs i would be taking a look at the IC igniter. Could be nearly 40 years old now. That does not explain why the two advance units will not operate correctly though unless, and this is really clutching at straws, you have the wrong IC igniter. It is a strobe youre using to determine the operation of the advance unit isnt it? Might have dreamed this but had the thought that one of them has the advance curve built into it electronically!!!
I take it that the advance units' centre bolt and (so called) washer / drive nut are as standard and the bolt is 8mm x 63mm?
As an aside, mine was dreadful when i first got it. Wrestled with all sorts of erratic issues and in the death it came down to the tiny drive peg in the end of the crank. It must have been over on its RHS at some point and the case advance unit etc had been obliterated. All had been replaced and a Dyna 'S' fitted and the tiny drive peg replaced with a cut down roll pin. Unfortunately they had missed the fact that it sits in a milled tapered ramp on the rear of the advance unit but they had left the end square. After filing it to a shallow angle all was well and has been ever since.
On the subject of spitting and popping at low revs, again, my CV carbs were entirely to blame here or perhaps more correctly i should say the Ram-air filters gave the CV's a very difficult job.

Very good points raised by Al & this draws me to reflect on prior very reliable & good info that I kindly got from ' Rob ( zed 1015 )' he provided & confirmed to me... that Z1000 J1-2 & GPz 1100 B1-2 ignition pick ups whilst looking the same a Z1000 MK2 Cdi pick ups ........are in fact different & non compatible !!!!!!
I'd like to know here please & get closure....as there was no conclusion here for people following this thread - Was it the I-C Ignitor box, or incompatible ignition pick-ups causing the problem ?? ..... or was it the crank peg - Advance pin engagement or a restricted or pinched advance / retard cam ...not being able to rotate & and advance properly as it should have ??????? please share the final outcome ,so we all can learn from it ! Thanks, Johny B

[clacker]

well i put a new peg ,bolt and nut on,along with the new advancer but its still spitting and missing.Im leaning towards replacing the pickups with dyna s, as i understand i can do away with the igniter.

[8 Valve Mark]

hi clacker, have you eliminated the ignitor? pick ups? as per the factory manual test procedures?? m

[Al]

As above from Mark but in the short term or longer term you are likely going to have to go the Dyna 'S' route anyway.
Dyna 'S' is simple, effective, inconspicuous, reliable, compatible and cheapish if you consider the price of NLA original components or the grief of having it not play ball.
AL

[z1bman]

i dought whether the iginition system is at fault. i would be looking at the fueling ? has it still got the injection system or has it been converted to carbs

[clacker]

I have checked the pickup coils and they seem ok with a meter.Although im not the best with electrics.Since its only past tickover to 3 thousand revs im not sure it would show up on a ohmmeter.It has a brand new set of rs34s on it.The bike was bought as a part restored non runner so any history of what the previous owner had done im in the dark about.The advancer does move now as i increase the revs,but the problem still persists.I think il go the dyna s route just so i can eliminate the pickups and igniter.I will have a final look over the bike just to make sure i havent missed something ,then order the dyna s.As ive mentioned before i will post the outcome,its just that its had me stumped and continues to.I thank you all for your advice.

[8 Valve Mark]

save money and just fit air correction jets clacker, they'll smooth out the low end lumpyness!I

[rickm]

While Dyna S is a great bit of kit and a good long-term option, I'd be looking at checking and setting up the carbs. I'm not a carb expert, but there are several threads on here with folk saying that carb size is crucial to smooth take-off (RS34s are pretty big ?). Hopefully someone with more knowledge will chime in, but if big carbs are not set up spot-on then you can get these sort of symptoms.

[Al]

RS 34 is about right for a standard bike. Original CV's on J models etc. are 34mm. RS carbs work more or less spot on straight out of the box for a range of engine formats and states of tune / cc etc. Apart from the tendency for them to overfill (see recent threads on this subject) it normally only needs the main jets to be fine tuned. Do you know which 34mm cabs yours are? I think its D-21 K but that may be the suffix for 36mm i cant remember.
Having said all that, when i bought mine fairly recently i took them to bits immediately and found a few small anomalies including a giant piece of brass swarf blocking one of the pilot air jets!

AL

[rickm]

I thought RS34s could flow more air than the standard CV34s ? (at least at the top end)