Compression/fuel problem

[Phil50]

hi all
Well an update. I had the z900 overbored by0.5mm fitted new pistons/rings etc. Checked compression and it was 150 on 4,3,2, but 1 was 25!!! this was due to my bending a valve (exhaust) due to getting cams in wrong( boy have I learnt now)
anyway, I got a new valve but decided sod it. The head had a missing fin so I got a good Z1000 head (for the 8mm exhaust studs) fitted the Z900 valves as the Z1000 had a few bent ones. reground them all in perfectly. I had this head skimmed and some stainless inserts fitted as the cam caps threads were all loose on torquing up on the exhaust cam.
So all going well tightened down the head got the cam timing perfect and after much battery charging it finally started. Ran it for 10 mins and took it for a short run. Gaskets are new and tested carbs inlet/outlet rubbers for air leaks none found. Cluth bangs a lot though. Perhaps balancing out? That does not explain the choking problem even with air filter out and airscrews out THREE turns.
Well the same problem as always, fuel dumped in the carbs like a waterfall. runs like a pig and the compression is down on all pots. New carbs fitted and checked out by a carb man as OK. Oh plugs changed twice now.
Before I scrap this bike for parts to sell on ebay has anyone got a suggestion (polite)
It cannot be the rebore faulty as the compression was high with the Z900 head on it. The Z1000 head is perfect condition and the valve seats were tested with Industrial pure Meths for leaks, none found. Spark seems OK.
It won't idle well and if revved the revs stay high for a bit instead of returning to lower right away.
Tomorrow I am strippping carbs and inspecting choke slides. after that?????
regards (and hopes)
Phil

[cra-z1]

I would check the carbs. sounds like you have a combinaion of mis- adjusted floats and out of sync carbs. Bench set the carbs first and check the level of the float bowls. If your not sure about how clean all the passages are in the carbs then have them cleaned in an ultrasonic tank. Replace needles and seats which shut off the gas to the bowl.You can make a gage out of some thin plywood to rough set your float height. Or if you have the later style bowls you can use a small length of clear hose attached to the bottom of the bowl with a fitting and held along the side of each carb to see how far the gas comes to the top of the bowl.

[Phil50]

thanks for the suggestion.you are the only one who has replied
I wont complain about my Kawasaki problems any more, I must just pack up me tent go quietly.

[grumpuszed1]

i assume the valve clearances are set correctly? also check the linkage between the carbs, lots of little ball joints that may need some lube.

[knut]

phil50 don,t giv up ,as cra-z1 says check float heights,i,ve similar problem with my z900, it,s fowling 1 & 2 while 3 & 4 are probably too lean,i,ve replaced float valves and air screws and pilots and done float heights ,it,s running a bit better but still not right, i,m running a dyna s with dyna coils setup,what,s yours adjusting air screws make no difference
i,m going to check choke mechanism and also valve clearances next.
there,s no easy fix with these bikes ,zeds are not just for christmas there for life

[Phil50]

thanks knut

I have done the valve clearences and they are perfect. This is the third set of carbs to produce an identical fault. They cannot all be faulty. A testament to mikuni crap if they are )))

The float height is a question that must be solved. I do not have the special tool that is required. A friend does and he is taking the entire bike off my hands next week as I have had enough of it.
If he don't fix it, it goes up for spares. I just don't have the time and money to keep throwing at a machine that seems un reparable depspite the new parts fitted at great cost.
I understand what you say that a big ZED is for life. But I ain't spending my life trying to get it to start up and run. I must say i haven't actually seen another Z900 on the road for years, perhaps there arn't any and I am in some twighlight zone trying to go bankrupt? )))))))

I have had 4 others, the last in 1984.
I have to say I have never had a single problem with any of them before, perhaps it is just a fact of age and I should just buy something new.

I just don't like the plastic poorly profiled things they sell today.

I am about to fit a Boyer ignition on Sunday with new boyer coils as this may be a factor for sure, and I have paid for them. I decided on Boyer as they have a nice long 5 year warranty and are made in England.
Being that Electronics is one of my few real qualifications in life I decided afetr careful investigation and that Boyer was on my last ZED that was flaweless, this was the route to go.

So I shall shut up for a fortnight and see what happens.
Thanks lads for the support
Phil

[chrisNI]

It's always hard to tell the difference between an electrical problem and a carb problem when the bike's running like a bag of shite. Fitting the ignition should at least remove that aspect of the equation, as if you've fitted three sets of carbs it's unlikely to be them.

The airscrews don't do that much anyway - if you balance the carbs and get them even then the factory manual says at that point set each airscrew to the highest tickover point then set the tickover to the proper level with the main tickover adjustment screw but you can screw then in and out without noticing a hell of a big difference - they will never make the difference between it running like a pig and running like a clock. Carb balance can though.

Is your fuel tap clear round where it goes in the tank? Are you running an inline filter? Simple stuff I know but I once spent months chasing a carb problem which was a nerlly completely blocked tap. I wouldn't worry at this point about compression being a bit lower with the new head if it was even between all four - or is it still off on 1?

It's fairly easy to make a float height tool especially if you've got a spare carb drain plug.

[cra-z1]

Don't give up. Make sure you run filters between carbs and tank. You can try many carb banks,but if there not set up correctly they will all give you problems. Take your time to go through the carbs.

[knut]

hi phil, i used a clear bit of air hose 6mm stuck into a soft rubber insert thingy and just removed drain plug and got it to thread in a little bit,not very pretty but it works.