Mystery starting and running issue.

[Gibbotvr]

I have a the most peculiar issue that is kind of driving me crazy.
What I've done:
Boysen Bransden electronic ignition kit with resistors and 2.2ohm Dyna Coils.
Full set of genuine inlet rubbers.
New plugs.
Good leads.
Rebuilt fuel tap.
Second/third set of carbs. All clean with good pilot flow and the set I have now has air correction kit fitted.

The bike will start from cold on choke and then will run off choke sounding quite good and revving.
Then it starts spitting back through the carbs as if its running mega weak. And then revs up unevenly.
If I then stop it I cant get it started again. If I check the plugs they are NOT wet even on multiple attempts as if there is no fuel.
If I drain the carbs I get plenty of fuel out. The float levels were within the manuals setting.

It almost seems there is a lack of vacuum. I've tried it with the tank cap off and also on prime.
All the air take off's are blanked apart from the fuel tap vacuum pipe. Is this right?

I haven't checked the tappet clearances but I would be surprised as it spits back through all of the carbs.
I haven't tried to set the ignition a 5k as advised, as TBH it doesn't run well enough to keep a regular engine speed. It is just set to the middle on the stator as recommended on the fitting instructions.

Am I missing something stupid?? or is it me being stupid?? I don't care which I just want to get the fecking thing running and mot'd.

Please help!!!!

[Mr Bump]

Hi,

Just a bit of a brain dump of questions I'd be asking myself:

stating the bleedin' obvious, it does have fresh from the pump fuel, yr not filling it from a can you've had under yr bench for two years?

What exactly is the bike? I assume you've got standard z type mikuni, not cv carbs? You should have two breather pipes open.

From the spitting back description it sounds like yr running pod or no filters. Have you an airbox you can put on it for comparison?

Does it still have a spark after its been run for a while then won't start?.

Have you ever had it running right, and what's changed since then? For example, is the boyer ignition new and it ran ok on points?

I found that the dyna coil supply 12v terminals can get very close to and even arc out on the bit of metal sleeve that spaces the coils off of the frame, so i used plastic fuel injector pipe bits as spacers instead. Could this be happening?

If you squirt brake cleaner down the carb intakes while turning it over after it cuts out does it try and start again? Go steady with it, watch it doesn't spit back a sheet of flame at you!

Hope this sparks a few fresh ideas.

Olly

[Gibbotvr]

Hi thanks for your reply.

It's a Z1000J 2.
I bought as an unfinished project without a spark so I have never had it running until I got my mits on it.
The fuel is fresh Super Unleaded.
It is BS34's CV carbs.
It is on pods but it has the Ledar air correction inserts.
I bought some after market inlet rubbers that were shite but I'm now on genuine Kwak's.
I like the coil idea, they have been spaced off the frame with some metal tubing and the connectors are close.

If it didn't start and run initially, it almost feels like the firing order is wrong. Like when you get the leads on the wrong pots and it runs unevenly and spits back.

It's just strange how I'm not soaking the plugs when trying to restart almost like the inlets are closed when the fuel should be going in.

The electronic ignition is meant to sort all the retard and advance etc I read in the bumf.

I going to have to back and start from the beginning.

[Mr Bump]

Just another thought - Have you tried running it from a dummy tank rather than going through the tank tap?

[rickm]

It does sound like it could be a fuelling problem. As I'm sure you're aware, CV carbs are notoriously difficult to get running well on pods (even with air corrector kits). I appreciate that may not be much help unless you can source a standard airbox from somewhere (rare these days).

This one's cheap, but it does have a couple of bits missing: inlet rubbers (which you can still buy), top cover which secures the filter (much harder to find but you could probably "work around" that).
https://www.ebay.co.uk/itm/Kawasaki-Z10 ... SwcMNee4fE

[Gibbotvr]

When I was having the paint done I had a dummy tank but it was similar. TBH though that was on a different set of carbs and with some rubbish inlet manifolds so I might give it a try.

The coil short may of been there as the rev counter is behaving now.
I will try it again with the coils mounted differently I think just as a tick box.

[Gibbotvr]

Sorry can I just check on BS34's CV carbs, the vacuum take of pipes as suggested two should be open?
I appreciate one goes to the fuel tap. I have three blanked at the mo.
I have seen some pictures of these being linked but not sure where they go from there. Without an airbox do they just go to atmosphere.
They obviously feed directly into the inlet tract after the butterfly, would this not cause it to run even weaker?
Or does this help with the vacuum?

The BST34's flat slides I was messing with had two take off's that required just a pipe going to the atmosphere but they did not feed directly into the inlet tract they went into the casting first.

[rickm]

On Euro versions there should be one vacuum pipe connected to the fuel tap, and the other 3 are blanked off. Yes, leaving them open will allow extra air into the inlets and cause lean running.
I think some of the US versions had the pipes joined up and other bits and pieces for emissions purposes.

[Pigford]

Boyer ignition is NOT the best!!!!!!!!

The standard ignition on a "J" is much better...... or use DYNA.

[oldzed]

You mention that you have a boyer ignition.
Worth checking that the magnets on the rotor are still strong.
I have one here that will not give a reliable spark as the rotor has "demagnetized"

http://vintagebikemagazine.com/technica ... -shooting/
See the third or 4th image.

You could check if its a problem with the ignition pickups or control unit overheating by heating them with a hair dryer as soon as you get it running.
May be something totally different of course.

[Al]

Is the Boyer a magnetic or an optical system?
AL

[Al]

With BS 34 CV carbs, if you suspect that there is a fuel restriction which is not solved by leaving the fuel filler cap open, removing any aftermarket inline filters etc. you can check the re-charge rate of the float bowls in real time by attaching a piece of clear plastic tube to the float bowl drains and cable tying it to the carb body so the open end is level with say the carb tops.
Run the engine, open the drain screw and it will be immediately apparent if there is sufficient re-charge to float bowls. This does not necessarily mean that there is sufficient flow to re-charge when its running on the road on extended fuller throttle openings but its an easy place to start.

There are some tiny domed fuel filters in the bottom of the carb bodies which sit above the float valves and stop the smolge from the fuel and tank reaching the float vlaves. They are tiny and very restrictive with only a tiny amount of crap on them. If its flakes of paint or other non soakable debris then fuel flow can become intermittent. Getting them out usually does more harm than good since you need to remove the float spindles and this often ends with a snapped post!!!! I cant see a way to back flush them but you can 'brace' the posts with a piece of 1 or 1.5mm flat steel plae with two slots cut in it.

Are the pod filters covering the tiny jet openings in the carb mouths?

AL

[Gibbotvr]

The Boyer is the Micro Digital version. I was recommended to use that one over a Dyna!!

During my sleepless night last night I was thinking that the spark has never looked really meaty and sharp.
I was going to re-step the installation process. I have the 2.2ohms Dyna coils, Boyer recommend that anything under 3.0ohms needs a 1.0ohms ballast resistor which I fitted.
In the old days Ford Escorts used a ballast set up sooner than a straight 12v coil. And used a lower voltage which I believe was rated at 9v through the resistor.

The Dyna coils are not designed to be used with a ballast resistor, could this be making the coils try and work at below 12v.

I know the filters on the float seat insert, I changed the seats and needles on my other set of BS34's and luckily didn't snap a post.

I will check the fuel flow albeit the new carbs I have come off a recently running well bike.

[Pigford]

Dyna S is proven & approved by most of the Z1OC community (Boyer does work but not as easy or robust).

Dyna S will need 3 ohm, or get a good standard "J" ignition and use the 2.2 ohm coils.

Check the supply volts to coils when engine running.

[Mr Bump]

Might be worth checking that the coils are properly earthed to the frame through the mounting bolts, rather than the bolts and washers only contacting paint or powder coat. Same, but much less likely goes for the engine mounts themselves. There needs to be a good earth route from the plug threads back to the coil core.