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Z900 A4 fuel leak any ideas please? (semi solved)
Moderators: chrisu, paul doran, Taffus, KeithZ1R
Re: Z900 A4 fuel leak any ideas please?
Valid points Warren/Marmck will check them upon arrival as you say no good if they dont read the same. To be fair they may well be rubbish but as long as you get a reading thats the same for all 4 ill be happy, think the plugs will make a big difference too as no idea how long theyv been on the bike and originally 1 was sparking 1/2 the time to the side rather then between electrodes, did swop it but reasoned if ones gone others 3 may not be far behind.
Tried new Tacho today turns out the tickover at 1500 on my original is only a 1000 on the new one, problem is new one has a different sized metal tray underneath, so you have to trim bracket to get it to fit snugly, also original illumination lamps wont fit either, why dont they make the pattern ones the same size!!!! On the plus side it doesnt stick and no vibration needle wobbles so worth it.
Another box ticked.
I also turned airscrews to 1.1/4 rather then 1.5 turns out, still runs the same, pickup from tickover still seems to stall before revving.
I left it ticking over fully warm and squirted the easy start around the carb rubbers, made no difference so assume no leaks there.
I also removed airbox lid and fitted a rubber draught excluder to the lid then re fitted it, its a much tighter fit now so def no leak there now either.
Next i will check timing once strobe light arrives.
Update : First of all decided to re check cam timing as reasoned if this a tooth out then no matter how much i fettle itt will never be right, so off with cam cover (not easy in frame, why on earth not 5mm more clearence?) Set pistons 1 and 4 at TDC and alligned T mark (see photo) checked position of exhaust camshaft, then counted 29 from Mark (yes i know it says 28 but after reading loads of posts it starts at 0) so by my reckoning looks ok. Whats your thoughts?
I found a post stating look at cutouts in camshaft that they should be level with head mine are (see photo)
Before moving on will await replies.
Thanks
.
Tried new Tacho today turns out the tickover at 1500 on my original is only a 1000 on the new one, problem is new one has a different sized metal tray underneath, so you have to trim bracket to get it to fit snugly, also original illumination lamps wont fit either, why dont they make the pattern ones the same size!!!! On the plus side it doesnt stick and no vibration needle wobbles so worth it.
Another box ticked.
I also turned airscrews to 1.1/4 rather then 1.5 turns out, still runs the same, pickup from tickover still seems to stall before revving.
I left it ticking over fully warm and squirted the easy start around the carb rubbers, made no difference so assume no leaks there.
I also removed airbox lid and fitted a rubber draught excluder to the lid then re fitted it, its a much tighter fit now so def no leak there now either.
Next i will check timing once strobe light arrives.
Update : First of all decided to re check cam timing as reasoned if this a tooth out then no matter how much i fettle itt will never be right, so off with cam cover (not easy in frame, why on earth not 5mm more clearence?) Set pistons 1 and 4 at TDC and alligned T mark (see photo) checked position of exhaust camshaft, then counted 29 from Mark (yes i know it says 28 but after reading loads of posts it starts at 0) so by my reckoning looks ok. Whats your thoughts?
I found a post stating look at cutouts in camshaft that they should be level with head mine are (see photo)
Before moving on will await replies.
Thanks
.
Re: Z900 A4 fuel leak any ideas please?
As both gauges and timing light have arrived which will be next steps.
Thanks
Photo of new cam position.
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Re: Z900 A4 fuel leak any ideas please?
See the image from the workshop manual.
You may find that when the exhaust arrow is lined up with the head, the inlet one may be slightly pointing down due to cam chain wear.
If you are a tooth under (27) then the inlet cam arrow would be one tooth up.
The only way to be sure is to remove the top roller and count the number of links.
Hope this makes sense.
You may find that when the exhaust arrow is lined up with the head, the inlet one may be slightly pointing down due to cam chain wear.
If you are a tooth under (27) then the inlet cam arrow would be one tooth up.
The only way to be sure is to remove the top roller and count the number of links.
Hope this makes sense.
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Keyster rebuild kits & carburettor spares - airscrews, jets, needles, starter plungers & gaskets.
Also petrol/ethanol proof float bowl gaskets. IMD pistons preferred seller.
- warren3200gt
- Hardcore
- Posts: 2753
- Joined: 13th Jun 2014
- Location: Dartford Kent
Re: Z900 A4 fuel leak any ideas please?
Can't see the position of the exhaust cam mark as its hidden behind the cam cap on your picture.
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
Re: Z900 A4 fuel leak any ideas please?
I’m not convinced. The position of the visible cam sprocket bolt on the exhaust cam looks out of position to me and lacks symmetry with its opposing bolt head on the inlet cam. A careful re count and re check is definitely the way forward.
Looking forward to hearing the pin count.
Looking forward to hearing the pin count.
Re: Z900 A4 fuel leak any ideas please?
I think I would also strip out the points and either replace them or strip them down to clean and check them along with lubrication of the moving point pivot shafts.
If the points are so corroded the moving point arms could be sluggish.
I’d check them for sure.
If the points are so corroded the moving point arms could be sluggish.
I’d check them for sure.
Re: Z900 A4 fuel leak any ideas please?
Ok thanks for replies Guys, i will re check exhaust cam tomorrow and take photo of its position, trying not to get the cam bucket in. Was trying to use 1 photo for both but maybe better close up of each cam separately. Im pretty sure they are directly opposite each other but will re confirm.
As for points yes did notice that myself, it was over a year ago when i originally stripped it, and had a move in between, although it was wrapped in a blanket and then a nylon over cover its possible damp has found its way in. Will strip down and clean and lubricate, if in.poor condition will replace them.
Keep you all posted
As for points yes did notice that myself, it was over a year ago when i originally stripped it, and had a move in between, although it was wrapped in a blanket and then a nylon over cover its possible damp has found its way in. Will strip down and clean and lubricate, if in.poor condition will replace them.
Keep you all posted
Re: Z900 A4 fuel leak any ideas please?
You’re working really hard on this bike and I for one want you to get it sorted and ride the wheels off it through the summer!
Keep going, you’ll get there!
Keep going, you’ll get there!
Re: Z900 A4 fuel leak any ideas please?
The inlet bottom cam shell seems to have been bent slightly as its pointing outward a bit where the shells meet by cam cap, have to zoom in to see it.
More importantly the top idler mount bolt on the right is loose and not tightened down!!, you dont want this coming loose.
For the points you can rub some 600 grade wet/dry (use dry) folded over so both points are sanded a little which can take any high spots you get on the contacts from arching then set the gap. Next do timing with strobe.
More importantly the top idler mount bolt on the right is loose and not tightened down!!, you dont want this coming loose.
For the points you can rub some 600 grade wet/dry (use dry) folded over so both points are sanded a little which can take any high spots you get on the contacts from arching then set the gap. Next do timing with strobe.
Re: Z900 A4 fuel leak any ideas please?
I'm not sure if its some form of optical illusion but, as Zed9 says the lower inlet cam shell appears distorted or not supported (can be seen in the first/top photo).
It almost looks as tough some of the casting is missing?
It almost looks as tough some of the casting is missing?
- warren3200gt
- Hardcore
- Posts: 2753
- Joined: 13th Jun 2014
- Location: Dartford Kent
Re: Z900 A4 fuel leak any ideas please?
sean_rfi wrote:I'm not sure if its some form of optical illusion but, as Zed9 says the lower inlet cam shell appears distorted or not supported (can be seen in the first/top photo).
It almost looks as tough some of the casting is missing?
??? Gasket obscuring the cap foot?
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
- warren3200gt
- Hardcore
- Posts: 2753
- Joined: 13th Jun 2014
- Location: Dartford Kent
Re: Z900 A4 fuel leak any ideas please?
It looks to me like you've counted the first pin as the the one the mark is pointing to. It should be the one above the mark. This would rotate the inlet cam anticlockwise by one tooth which would make the sprocket bolts on the inlet cam a mirror image of the exhaust cam as they should be.
And as previously advised the rh idler sprocket bolt looks loose.
And as previously advised the rh idler sprocket bolt looks loose.
Last edited by warren3200gt on Thu Apr 18, 2024 8:46 am, edited 1 time in total.
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.
Re: Z900 A4 fuel leak any ideas please?
sean_rfi wrote:I'm not sure if its some form of optical illusion but, as Zed9 says the lower inlet cam shell appears distorted or not supported (can be seen in the first/top photo).
It almost looks as tough some of the casting is missing?
That's the shell location tab which prevents it from spinning in the journal.
The "missing" casting is the machined recess for the tab.
Re: Z900 A4 fuel leak any ideas please?
Ok Rob - I can see it now...
Re: Z900 A4 fuel leak any ideas please?
Thanks for reply Guys and good info, got plenty to go at today.
Firstly Zed9/Sean you are correct about both cam cap and loose idler bolts this is as i had removed it to accurately count the chain links and havn't fully re tightened as may need to come off again, needless to say it will be correctly torqued down before cover goes back on.
As Zed 1015 says the cut out is a machined part of the cam cap, so assume should be there, there def isnt any damage to it that i can see.
I will re check the inlet camshaft position and re count the links in case its 1 out, how much does this 1 tooth effect performance? When i took it for its 1st run it was sluggish at low revs but once over 2.5k i thought it pulled quite strongly, of course i've nothing to go on as never had one before. If i compare it to a modern injected bike its def not as powerful but then its only got 83bhp as opposed to my Blackbird with 160 so no comparison really.
Points will be removed cleaned and re gapped and all parts lubricated.
All ordered parts have now arrived so got the 4 brand new Denso plugs to be fitted. Gapped to 28 thou
The Vac gauges have also arrived so again the carb balancing can be done. When doing this, i appreciate you connect a tube to each cylinder using the take off port on each carb stub, start bike and warm up, leave it ticking over at 1k, but what exactly do you adjust to get them all the same, is it the Air screw on the side of carbs or do you remove tops off all 4 and adjust the 4 slide screws ones with locknuts on top?
The strobe light has also arrived so again will be able to check ignition timing and verify the advance mech is working correctly.
I have to say im a little apprehensive, know all the theory, read plenty of manuals of how to, but never actually done it myself. My concerns are i may make it worst, or end up where it wont start again, at least now its running but not right, its a dilemma im sure many have faced.
I know ill not be 100% happy until it runs as it should though.
Close up photos of cams
Note top guide roller removed so can count links, also there is a faint mark on back side of exhaust cam this is about 1mm below cam cover gasket face, i then counted 28 links from link above that mark and it is on the white mark on inlet, in both cases the notches on the cams themselves centres (ie same amount showing on both above and below surface) are level with head face ex facing forward and in facing backwards, the long part of cam cog y piece bolt is about 1mm above face on exhaust the T mark is spot on.
Thanks
Update lifted cam chain off cog could faintly see an arrow etched into cog dead centre of chrome bolt hole, marked it with a white marker, re fitted chain again keeping it taut, set it to T mark then checked alinement of white mark with head face ( yes did lift gasket 1st) it was about 1mm below face. Next counted 28 from link above white mark, this was spot on with mark on inlet cam. Re fitted top idler wheel temp then Rotated engine 360 re checked still spot on.
Spoke to Warren who confirmed it seemed ok, so pretty sure that is now as it should be. No adjustment was needed so it was ok when originally set, but better safe then sorry!
Firstly Zed9/Sean you are correct about both cam cap and loose idler bolts this is as i had removed it to accurately count the chain links and havn't fully re tightened as may need to come off again, needless to say it will be correctly torqued down before cover goes back on.
As Zed 1015 says the cut out is a machined part of the cam cap, so assume should be there, there def isnt any damage to it that i can see.
I will re check the inlet camshaft position and re count the links in case its 1 out, how much does this 1 tooth effect performance? When i took it for its 1st run it was sluggish at low revs but once over 2.5k i thought it pulled quite strongly, of course i've nothing to go on as never had one before. If i compare it to a modern injected bike its def not as powerful but then its only got 83bhp as opposed to my Blackbird with 160 so no comparison really.
Points will be removed cleaned and re gapped and all parts lubricated.
All ordered parts have now arrived so got the 4 brand new Denso plugs to be fitted. Gapped to 28 thou
The Vac gauges have also arrived so again the carb balancing can be done. When doing this, i appreciate you connect a tube to each cylinder using the take off port on each carb stub, start bike and warm up, leave it ticking over at 1k, but what exactly do you adjust to get them all the same, is it the Air screw on the side of carbs or do you remove tops off all 4 and adjust the 4 slide screws ones with locknuts on top?
The strobe light has also arrived so again will be able to check ignition timing and verify the advance mech is working correctly.
I have to say im a little apprehensive, know all the theory, read plenty of manuals of how to, but never actually done it myself. My concerns are i may make it worst, or end up where it wont start again, at least now its running but not right, its a dilemma im sure many have faced.
I know ill not be 100% happy until it runs as it should though.
Close up photos of cams
Note top guide roller removed so can count links, also there is a faint mark on back side of exhaust cam this is about 1mm below cam cover gasket face, i then counted 28 links from link above that mark and it is on the white mark on inlet, in both cases the notches on the cams themselves centres (ie same amount showing on both above and below surface) are level with head face ex facing forward and in facing backwards, the long part of cam cog y piece bolt is about 1mm above face on exhaust the T mark is spot on.
Thanks
Update lifted cam chain off cog could faintly see an arrow etched into cog dead centre of chrome bolt hole, marked it with a white marker, re fitted chain again keeping it taut, set it to T mark then checked alinement of white mark with head face ( yes did lift gasket 1st) it was about 1mm below face. Next counted 28 from link above white mark, this was spot on with mark on inlet cam. Re fitted top idler wheel temp then Rotated engine 360 re checked still spot on.
Spoke to Warren who confirmed it seemed ok, so pretty sure that is now as it should be. No adjustment was needed so it was ok when originally set, but better safe then sorry!
Last edited by Gray17 on Thu Apr 18, 2024 1:47 pm, edited 2 times in total.
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