Carb Replacement!

[greenlaningxt]

Been trying to sort the carbs back fireing, but not having much luck.

Anyone point me in the right direction of a modern set of carbs to replace the ones on a Z1000A2 engine thats in the Harris.

Need a set of inlet rubbers as well to fit these carbs.

I hear the 750 GSXR carbs fit?

Can someone tell me the inside size of a standard inlet rubber, carb side. I have 40mm ones for the carbs that are on there now, carbs are big smooth bores and have always needed a lot of tender care.

Time to change me thinks.

[Pigford]

Backfiring thru carbs is often too lean mix

GSXR carbs have same spacing as Kawasaki. Gotta check the float bowls will be fairly level when fitted to your bike

If they are CV carbs, don't bother...... dead hard to tune properly

Wanna sell the smooth bores then

[london calling]

Piggy,what is it with you and carbs

[Pigford]

Jack-M-Laddo, I'm on a life mission to crack the "Carb Secret"

Always liked tinkering with (tuning ) bikes so it was a bit unavoidable really

Trial & error is always the best way to learn....

[london calling]

Stick to the IRONING BOARD and keep Lady Pigford happy

[greenlaningxt]

Pigford,

I know backfire is a sign of it running lean, although adjusting the mixture screw it gets worse, should try new pilot jets I guess.

What gsxr carbs are not CV?

The smooth bores may be for sale if I get this sorted

[Pigford]

I think its only the Older Slabby GSX's that were flatslide or similar....

You'd be best to get a decent set off a similar Zed thats been running with them on & already set up or it'll take a bit of sorting

A nice set of 34 or 36mm Mikuni RFS would go well..... All you'd need to do is fit some "J" OR "GPZ" manifolds

[Rich]

Slabside GSXR!!

Spitting back or backfire??????

Spitting back
Check fuel height. Raise the fuel levels 1mm to give you more scope with the mixture screws. Check valve clearances.

Backfire
Check ignition timing.

[Pigford]

To raise the FUEL level, you have to drop the floats which means a lower "float height" as measured with the bowls off & carbs inverted (upsidedown - Mikey )

You may already know that, but just in case.......

As the bike is non standard you'll probably need larger pilots & mains...... as with any K&N filters & 4:1... etc.

Whats the full engine spec then

[greenlaningxt]

Lots of fun here!

Carbs do need sorting, but went a stage further today.

Checked the compressions this morning, strange but the clylinder giving the problem had the highest reading, then the two that seem to be running well were well down.

Just as well its a Harris, engine out in under 30mins!

Head off, exhaust valves all a bit shot, 2 with the low reading well shot.

All bit strange 2 cylinders wet and 2 running hot, paired by which coil they were connected to, would suggest a coil, but changed them a while ago to see if they were a problem.

I am running a Electronic Ign, did pop and bang a bit before with points so not that.

Engine not done a mass of miles since it was rebuilt, some of them were hard though when its was in Spain for a few years of its life and only got used when out there.

Bores are in great nick, and no seapage past by petrol down the bore, and rings seem good as I took the block off as well.

Any ideas fokes, before I order loads of expensive stuff.

Anyone seen the drag head on ebay, would it use the cams I have and would it be a reasonable replacement.

All in all an expensive lunch hours work!!!!

[Al]

Checked the compressions this morning, strange but the clylinder giving the problem had the highest reading, then the two that seem to be running well were well down.

You didnt mention what that problem was unless you meant spiting back?
Most importantly; what colour are the exhaust ports and the first inch of the inside of the headers?
Black, white, somewhere in-between?

Head off, exhaust valves all a bit shot, 2 with the low reading well shot

What is the octane rating of fuel in Spain?

All bit strange 2 cylinders wet and 2 running hot, paired by which coil they were connected to, would suggest a coil, but changed them a while ago to see if they were a problem.

Did you dynamicaly time one pickup and assume that the other was 180 degrees away?

Are you running all the air screws at the same number of turns out or are they specific to that particular pot?

I am running a Electronic Ign, did pop and bang a bit before with points so not that.

Mine are dynamically times 180 degrees apart but do not appear diametrically opposed on the baseplate!

Engine not done a mass of miles since it was rebuilt, some of them were hard though when its was in Spain for a few years of its life and only got used when out there.

Was it left with the old fuel in it and started with new on top or drained down and re-filled?


Have you tried listening to the induction hiss with a straw, stethoscope or piece of tubing. If its clean you will know immediately and if its stuttering then that will be obvious too.
I think i'm right in saying that the air screws (if thats what they are) have no impact on mixture per-sey beyond a certain number of turns out from fully closed. Different for different bodies and screw condition / age and profile. ie have you reached the end of their useful effect at the position in which you now have them.

Just guessing that the drag head although i have not seen it will have been breathed on.
Its not just a question of cams, it may not be compatible with your bore size, compression ratio, piston height above the pins, etc etc etc.

Likely to be a whole heap of heartache and expense when you have to reverse engineered your set-up or upgraded your configuration to match its specification.

What cams have you got and what engine are we talking about?




AL

[Rich]

To raise the FUEL level, you have to drop the floats

Don't do fuel heights by tipping the carbs upside down and measuring the float height. Do it by the service fuel method as described in the Kawa manual. Needles, floats and pivots will all be slightly different especially in a set of carbs that are probably 25 years old.

[Pigford]

By chance, I have a very tidy standard "J" head for sale

[greenlaningxt]

Zorded,

Spitting back from the high compression cylinder, also seems to be running rich on the same cylinder.

Also getting backfires from the exhaust, bit harder to tell which cylinder.

Have been thinking a bit more about this, its possible there is a electrical problem (feed to coils), but from what I remember there both share the same possitive feed.

Its done quite afew thousand miles since it came back from Spain, including a one day quick ride to Sweden (almost 1000miles) where it went with no problems.

The exhaust ports colour two black one fairly good and one brunt white.

Cams none standard but could not say what they are, been a long time since they were fitted.

[Al]

Guesses and no more.

Spitting back from the high compression cylinder, also seems to be running rich on the same cylinder.

This is the cylinder with the mis-fire. Its unable to burn the fuel from two cycles and chucks some down the exhaust and turns the rest into carbon.
That is why it has the highest compression ratio.
It is also like to be the one with the cleanest looking bore from fuel washing.

Very likely that this cylinder has no valve clearance on the inlet.
If this cylinder shares a coil with the other cylinder which appear rich then it is coil or dyna components. If it is a different pairing it is plug or lead.

Also getting backfires from the exhaust, bit harder to tell which cylinder.

Its the one above which appears to be running rich!

Have been thinking a bit more about this, its possible there is a electrical problem (feed to coils), but from what I remember there both share the same possitive feed.

Dont know dont do electrics specially not with a crystal ball.

Its done quite a few thousand miles since it came back from Spain, including a one day quick ride to Sweden (almost 1000miles) where it went with no problems.

Tempted to say that this is different fuel but really dont know why.

The exhaust ports colour two black one fairly good and one brunt white.

Two black on the same coil??? If so timing out or feed to coil intermittent.

What does 'one fairly good' consist of? If you mean dark~ OK

'One burnt white'. Low fuel level, incorrect valve clearances, leak at inlet manifold, leak at exhaust manifold fuel bypass screw to far closed or blocked.
Assuming that the 'one fairly good and the one burnt white, are the same coil i would suggest that the timing overall, or for that pair only, is / are retarded.

Cams none standard but could not say what they are

If you dont know i sure as shit dont

I hope this helps. If this ever goes to court i will naturally deny that i said any of this.
Let us know how you get on or if any of this makes any sense for your situation.

What were the valve clearances when you took it down? What motor is this by the way and which cylinders and pairs of cylinders are you referring to? It would have been much more help to others looking to help if you posted details and / or pictures of the situation but its not too late.



AL