Z1OwnersClub GB

Just a quick recap My bike is a Z1B which is totaly standard with the exception of carbs from a Z1R. The problem is the bike has a slight missfire when accelerating at 6000 rpm and a reluctance to rev cleanly please refer to my recent post {first ride update}. At first I thought the problem may be ignition / fuel starvation related however I have fitted the carbs from my brothers Z1B and the bike runs perfectly so on this basis I can rule out all ignition components and fuel tank breather/ starvation.
The carb details are as follows,
Model VM28SS
Mains 115 {standard 107.5}
Piolts 15
Jet Needle 5CN15 3rd position
Fuel delivery rate 1 min 35 secs per litre
Brand new Dyna S, new coils /leads/plugs
Just for extra info the pipes are showing a slight straw colour and the plugs seem ok I am desperate for advice to cure the problem surley the carbs work on the Z1R so should work on a Z1B. Is it a jetting issue ?,too small/too big mains . At 6000 rpm do you switch from pilots to mains and there is a missmatch in jet sizes ? All sugestions welcome don't know what else to do.

I`ll do this from memory but pilot affects 0 - 1/8th opening

Throttle slide cutaway affects 1/8th - 1/4 opening

Emulsion tube and needle 1/4 - 3/4 opening

Main jet 3/4 to full throttle.

There is some overlap between these so some experimentation is required but personally I would try and change settings of what you have before buying other components.

I think a colourtune or Dyno test would help a lot and save money in the long run.

Or buy some Z1B carbs

The carbs are set up to deliver more fuel as the z1r has 100 cc more to cope with, your main jet with deliver an over rich formula with 115 and may cause some popping and banging on throttle off, go standard carbs if the engine is standard expect the problem to be there if you dont,

i think your main jet slightly blocked .Iam running z1r carbs on my z900 a4 with 150 main jet kn filters and it runs very well

Paul u cant be serious, i bet u are using more fuel than you need to,
I only used 150 main on my drag bike with a 1260 kit, i must be doing sumut wrong,

it seem to be okay on fuel i went to donington on saturday and it must be seventy miles for me and i put seven pounds in the tank to fill up .I also brought myself a coltune and with a little bit of ajustment it runs great

Sound then mate, if it works then let it beeeeeeeeeeeee,

The mains are spotlessly clean along with the emulsion tubes [ all items inspected with a jewlers magnifing eyeglass} when you say go standard do you mean standard for the Z1R i.e 107.5 mains or standard Z1B carbs.
Not many suggestions coming forward please guys read the thread and make a suggestion as I am lost without help/ideas.

I`ve heard great things about the Colourtune.

Takes out the guesswork !

If you're happy with your carbs.... rubber manifolds..... get it on a DYNO


2nd is suspect ignition/electrix. Hows all electrix.. connections... coils.... over 12volts?

Hows valve clearances...... is head correctly torqued down.

Cracks in cylinder head.... leaky head gasket....

As for jets, the larger slotted & smaller hex are not rated the same. The 'Amal' type (hex) have a higher value and a 150 = about 113 in the slotted jet. So running a 150 Amal will be equivalent to a 115 Slotted

The HEX (Amal) has its fuel flow calibrated in the 'wrong' direction of flow. - ie@ from threaded end to the orifice, & the number is cc of petrol thru jet from clibration direction from a hgt of 500mm. As this is opposite to operational flow, it does NOT correspond to the number stamped on it!!!!

The slotted or button jets are also known as reverse jets, coz the flow is the same from either direction. Therefore the number stamped on it relates directly to the flow - unlike the hex/amal type.

Well done Piggy ... you never fail to amaze me

Alan, I have a spare set of z1b carbs available at very reasonable money if you need them?They have not been used for a while but are free moving and not seized. I can send you photos if you wish. I am looking for £70 plus postage. Gez

very interested
regards
Alan Roscoe

gez635 I have sent you a pm
regards
Alan Roscoe

mark iam using 150 slotted main jets .Alan said his bike was running fine when he used his brothers z1b carbs it was only when he used the z1r carbs that a problem occured . alan you need to get yourself a colourtune and they are easy to use, you don,t need to be a mechanic to use it, there 26 pounds on ebay this will tell you whats wrong with the carbs .Otherwise were all just guessing. Ive spent weekends trying to fix carbs on my own bike waste of time this will tell you the answer in minutes 14mm you need hope this helps