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Project Kwak Z400F

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.Chris.
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Joined: 09 Jun 2007
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PostPosted: 22:32 - 31 Mar 2016    Post subject: Reply with quote

Haven't updated this in a while. A bad back stopped play for a while. But.... the bike is now on the road!

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/20160331_163038_zpsf9nxxmja.jpg

In the end I managed to use some tweezers to remove the mystery O-ring from the choke plunger housing, which obviated the need to remove the end cap.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC08508_zpssmo6ylvo.jpg

This allows the choke to return fully home on all four carbs. For the time being I've also repaired the diaphragms with some glue. As a consequence they're now airtight, but the rubber has hardened with age, which means there's quite a bit of resistance at one point in the carb piston travel, where the rather cardboard-like rubber has to crumple. When the carb tops are not fitted (and thus not holding the diaphragms down) the pistons move freely, so they're not binding in the bore. I suspect this is what's causing some of the running issues.

After putting everything back together, I fitted the carbs to the engine. This is not a very pleasant job as it requires a huge amount of force to get the carbs into all four rubbers simultaneously. Nevertheless I eventually managed it, and also fitted the air filter housing, complete with new filters. This job was much easier than it had been before as I've replaced the carb-to-airbox rubbers. The old ones had gone completely hard, which meant the only way to fit the airbox was to tilt the engine forwards to create space. With the new, very much more flexible rubbers, it's possible to fit the airbox without doing that. At about £40 for the set the rubbers weren't exactly cheap for what they are, but they're definitely worth it in terms of the amount of hassle they save.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC08524_zpsw7x9rqrh.jpg

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC08527_zpsy7rbrndu.jpg

Fortunately the small side panels hide the side of the airbox where it's been taped up!

That all done, the bike starts and runs better than before, although it's still not perfect.

My attention then turned to other matters. I sourced and fitted a replacement headlamp lens to replace the one I dropped and smashed when I dismantled the bike, got all the electrics working, fitted the bodywork, etc. In common with the other rubber parts on this bike, the cush drive rubbers seem to have shrivelled slightly, allowing some play in the rear sprocket, despite the carrier bearing being fine. This was fixed by padding out the rubbers to take up the play. A bit of a bodge but it'll do for now.

The next problem was the front brake. Despite repeated bleeding, the lever was still somewhat spongy, and if you pulled hard enough it would come all the way back to the handlebar. I suspected dodgy master cylinder seals so thought I'd get a rebuild kit.... no chance. The part has been discontinued by Kawasaki and I can't find one from any of the aftermarket manufacturers. In the end I pinched the master cylinder off a GPZ550, which has solved the problem.

That all done I took the bike for an MOT test, and it passed! Only two advisories - there's a tiny bit of play in the swinging arm, and the rear brake drum is slightly oval. It's great to finally be able to ride the bike, and despite the imperfect carburation it does ride pretty nicely.
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Chris
1985 Kawasaki Z550F
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UnspeedySam
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Joined: 26 Nov 2009
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PostPosted: 22:34 - 02 Apr 2016    Post subject: Reply with quote

Congrats. Bet you're glad to be back on the road. I do love 80s bikes; if I ever have more time I might take on one as a project (in addition to my bros 400 daily ride).

Did you ever check the valve clearances? If they're as hard to adjust as you say I wonder if they've been ignored for a while.
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Riding: Does an Audi estate count?
Fixing: Honda VFR750 RC36 '94 and MZ ETZ 251 '90
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01,Honda Bros NT400 NC25 '88
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.Chris.
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Joined: 09 Jun 2007
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PostPosted: 17:20 - 03 Apr 2016    Post subject: Reply with quote

It's great to finally be able to ride it. Valves are still on the to-do list!

You're probably right that they've been neglected - the Kawasaki handbook that I have for the bike is quite insistent that they need to be checked every 3000 miles (Shocked) but says once set they'll rarely need adjusting. That sounds a bit too much like a ready-made excuse for not checking them. There is also a very slight ticking sound from one point of the top end once the engine is fully warm, which may be a wide valve clearance. My plan is to run it for a couple of hundred miles so that everything settles down after such a long time unused, then check the valves, as well as doing another oil and filter change.

Cams out may not actually be too much of a bother, as it looks like the head may need to come off anyway. It seems that the gasket is weeping a small amount of oil Rolling Eyes. Compression is fine, so for now I'm going to clean it up and see if it reappears, but if it does it'll need replacing at some point.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC08676_zpsebqkg45q.jpg
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Chris
1985 Kawasaki Z550F
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.Chris.
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Joined: 09 Jun 2007
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PostPosted: 12:06 - 03 Jul 2016    Post subject: Reply with quote

So, as discussed in another thread, I'm finally getting around to doing the top end. The valve clearances are as follows:

Exhaust (spec. 0.15 - 0.25)
0.18 0.15 0.15 0.19
0.15 0.14 0.11/2 0.16
Inlet (spec. 0.10 - 0.20)

They're all within spec, but the middle two exhaust valves are right on the limit and no. 3 inlet isn't far behind. If it weren't for the oil leak requiring the head to come off I'd leave them as-is for the time being, but given the cams are coming out anyway I might as well adjust those three.

With all that measured I removed the cams and head. Strangely two of the three small bolts that hold the head down around the front of the timing chain housing were missing. There is evidence of a small oil leak from that area but nothing terrible.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC01454_zpscxgobzvq.jpg

The state of the head gasket itself is a bit of a mystery - it seems to have some rather rubbery gunk on it in the area around the timing chain tunnel. I'm not sure if this is just deterioration and delamination of the gasket itself, or if someone's been in here before with the dreaded instant gasket.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC01458_zpsvdulinj0.jpg

At the edges of the head are the O-rings that I reckon are the culprit for the oil leaks. Both have gone completely hard, and there's evidence of oil leaking in their vicinity.

https://i31.photobucket.com/albums/c390/chrisd87/Z400F/DSC01455_zps9ij1c5tk.jpg

Next job is to remove the tappets and see what shims are in there.
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Chris
1985 Kawasaki Z550F
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Meatybeaty
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PostPosted: 12:35 - 03 Jul 2016    Post subject: Reply with quote

Just caught up with your resto,but looking good Thumbs Up
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.Chris.
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Joined: 09 Jun 2007
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PostPosted: 21:33 - 03 Jul 2016    Post subject: Reply with quote

Measured the shims...

EX
2.25 2.45 2.45 2.45

2.00 2.50 2.55 2.05
IN

Slightly concerning is No. 1 inlet valve, which already has the smallest shim available (from Kawasaki, at least) fitted. The clearance is spot on at the moment but once it wears by another 0.05mm, then what?

Looks like 2.40mm shims are needed for the middle two exhaust valves, and another 2.50 for No. 3 inlet. Fortunately I've already got a 2.40 and a 2.50mm shim that I can rob off a spare GPZ550 head, so I only need to buy one to complete the adjustment this time.
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Chris
1985 Kawasaki Z550F
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UnspeedySam
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Joined: 26 Nov 2009
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PostPosted: 20:46 - 11 Jul 2016    Post subject: Reply with quote

Good job. Need to do this job on my ratty Bros 400 in the near future. No shims to worry about on that though.

Not sure what to suggest on the smallest shim available issue. Surely someone must be able to supply one in the right size, or maybe a bit of machining is required.
____________________
Riding: Does an Audi estate count?
Fixing: Honda VFR750 RC36 '94 and MZ ETZ 251 '90
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01,Honda Bros NT400 NC25 '88
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