kawasaki Z1100R1 - 1984 troubles

[kawagek]

Hi everybody, thx for letting me becoming a member of the forum first of all.
I am currently restoring a kawasaki Z1000R1 , so with the gpz1100 unitrak engine in it. But man, i have troubles, on trying to synchronize the carbs, i do not have enough vacuum to make the gauges react, the engine backfires trough the carbs, and keeps hanging in high rpm when throttled to 5000rpm, i've checked the valve play, repositioned the camshafts as in the manual, you know, 44teeth , checked the igniter, nothing seems to cure the disease. oh yes, and i have rebored the cylinders, and the bike has new pistons and rings.
any suggestions are more than wellcome, because i am out of solutions for the moment, thanks to you all in advance

[z1bman]

have you done a compression test ?

[kawagek]

yes i've done a compression test, low compression on all cylinders, 70 psi on 1 and 4, 65 on 2 and 3. of course the test was done with a cold engine, and new pistons and rings. done a leak test to, but no extreme leaks, all valves close well i think, the only thing i can think of is a wrong camshaft timing, but i've done it as described in the kawasaki service manual, so,????

[chrisu]

thats very very low. way below service limits. i assume you did this with the throttle WFO.

timing or possibly a bent valve. you did have the rings set 120 degrees apart ?

does oil down the bores improve the readings ?

[kawagek]

A bent valve??, i did the valve check with fuel in the combustion chambers, and there is no leak, and yes i did the cold compression check without carbs, so throttle more than wide open.
i have put in the piston rings as mentioned in the instruction leaflet, so i really don't know what i can do more, to cure this problem

[needaz1100r]

A bent valve??, i did the valve check with fuel in the combustion chambers, and there is no leak, and yes i did the cold compression check without carbs, so throttle more than wide open.
i have put in the piston rings as mentioned in the instruction leaflet, so i really don't know what i can do more, to cure this problem

You are waaaay in front of yourself trying to balance the carbs with the engine in this state.

You NEED to check all the things suggested to you, you cannot think that you have just done them so they are correct.

Have you done a leakdown test?

Piston ring end gap and piston to bore clearance? It's not unheard of for the boring to be wrong.

Unitrack engine, did you get pistons for a unitrack engine?

Did you use the cams from the unitrak engine?

[Taffus]

Valve angles in the head are different on unitrack, pistons may need to be milled to stop them interfering with the valves
Zed1015 or Al can advise you here

[z1bman]

i would double check the cam timing or take some photos & put them on here so we can have a look

[Al]

Post Author: z1bman » Wed Jan 26, 2022 5:38 pm

i would double check the cam timing or take some photos & put them on here so we can have a look

This first....... and i would make every effort possible to check what the situation is when removing the cam cover although i realise that it is easier to get the cam timing wrong on the J motors than it is right and so it is when removing the cover.

Cam timing in particular and some types of cam profile have a significant effect on cranking compression pressure. The revs where you would test compression ratio and carb balance.

Pistons will be Unitrak / Z1100R1 because if they wern't, they would be 17mm wrist pins in an 18mm rod and be a bit rattly

If youre purposefully using performance cams or if you are hell bent on radical cam timing AND are using 'Morgan Carbtune balancers' then you can turn them upside down when the vacuum does not register because it is too low.

http://www.carbtune.co.uk/

Registering low vacuum / getting low compression pressure readings and revs 'hanging' are classic symptoms of not standard valve timing.
You will need to see approx.21cm of vacuum to know that all is in order.

I guess you have glued the carb rubbers to the head and they are in serviceable condition?

AL

[kawagek]

Thanks for all the advice, but until now, i ve learned nothing new.
I don t wanna be mister wise guy, as some mombers suggest, so i Will post here if there is any improvement

[kawagek]

Yves, i use carbtune synchroniseren, but also tried old vacuum meters, and they won t work either

[kawagek]

Post Author: z1bman » Wed Jan 26, 2022 5:38 pm

i would double check the cam timing or take some photos & put them on here so we can have a look

This first....... and i would make every effort possible to check what the situation is when removing the cam cover although i realise that it is easier to get the cam timing wrong on the J motors than it is right and so it is when removing the cover.

Cam timing in particular and some types of cam profile have a significant effect on cranking compression pressure. The revs where you would test compression ratio and carb balance.

Pistons will be Unitrak / Z1100R1 because if they wern't, they would be 17mm wrist pins in an 18mm rod and be a bit rattly

If youre purposefully using performance cams or if you are hell bent on radical cam timing AND are using 'Morgan Carbtune balancers' then you can turn them upside down when the vacuum does not register because it is too low.

http://www.carbtune.co.uk/

Registering low vacuum / getting low compression pressure readings and revs 'hanging' are classic symptoms of not standard valve timing.
You will need to see approx.21cm of vacuum to know that all is in order.

I guess you have glued the carb rubbers to the head and they are in serviceable condition?

AL

[z1bman]

as all cylinders are low on compression its a classic symptom of incorrect valve timing

[Al]

Do you have something which does this job?

AL

[kawagek]

no, i don"t, does this help to set the camtiming correctly?????