Bikemonkeys ZXR400L4 project

Here's a chance to show off your zxr400, so get them digital cameras out and show us some piccies.Rebuilding your bike or modding it then let everyone in on it.

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bikemonkey
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Thu Mar 09, 2017 1:09 pm

Big update, not done one this week so far as well I haven't.

Monday night I did barely anything as I'd just dumped all my gear and a crashed NC30 in the garage on Sunday night and it all needed sorting out.

Tuesday I turned my attention to the front brakes. Fitted them and tried to bleed them up but the lever was always coming back to the bar...

So I had a better look at the calipers and pumped them out to clean them up. Whilst doing this a couple of the pistons dust seals tried to make a bid for freedom out of their recesses, so I decided upon a full strip and rebuild. Which after looking forlornly at the broken NC got pushed back to last night.

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So I stripped them apart and was greeted by a bit of a mess.

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Out came the brass wire wheel on the dremel which makes cleaning out the crap in the recesses so easy. Downside is they shed brass bits so you have to very thoroughly inspect the halves and make sure you get it all out.

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After that I cleaned up the seals and pistons, which came up really nice and put it all back together with a good bit of red rubber grease.

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After putting them back on they still won't give a good lever. I've left them overnight with a cable tie holding the lever back to the bar, see if that works...

Last thing last night I changed all the mankiest carb screws with good used ones and blocked off the carb heating circuit a bit better than previously.

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Then I fitted them up to the bike with the synchronisers in place and filled up the cooling system.

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However, the bike would not start for love nor money last night.

After looking at the PDF manual earlier I think I know why. I've got the pump and coil plugs mixed up and plugged them into each other. Moron.

I'll switch them over tonight and hope she fires up as I need to balance the carbs and burp the cooling system to get a proper pressure test out of it to find that leak.
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Re: Bikemonkeys ZXR400L4 project

Post by banner001 » Thu Mar 09, 2017 1:31 pm

your carb heating pipes can just be removed, they just send a small amount of hot coolant into a sealed recess in the float bowl...will be easier to work on the carbs with them removed.

all you need to do is make sure to block them off where the coolant feed pipe is on the cylinder head (or barrels, cant remember where the spigot is), and block it off from the radiator cold pipe...

as for brakes your gonna need braided lines, and a new set if you currently have old ones, are you using the brake splitter near the horn, or do you have a 2-line banjo bolt attached to your front master cylinder? i wouldnt rule out a master cylinder rebuild kit either, also i always reverse bleed my brakes on the zxr when changing calipers or lines...has always been the easier way for me.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

bikemonkey
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Thu Mar 09, 2017 2:22 pm

Ace, I'll get those pipes off tonight. And now you mention it I missed blocking the cylinder head off, no wonder I thought the carbs were leaking last night...

I have the standard splitter and very tired looking braided lines, so I guess they will need to be changed for a two line set up first. If that doesn't work I'll rebuild the master cylinder.

I spent ages trying to get a good lever. It was getting annoying as all other brakes I've bled have been pretty easy.
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Thu Mar 09, 2017 10:48 pm

First off tonight I switched the plugs to where they were supposed to be, and in doing so the loom does look proper now.

Then I removed the carbs (doddle compared to the NC) and removed the carb icing pipe-work from the underside.

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I looked for the cylinder head outlet for the icing circuit but could not find one for love nor money.

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So I cranked the engine over a bit to see if any coolant would be forced out. It wasn't so I left it.

Plonked the carbs back on and set about getting it fired up and balanced.

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Bike fired after a couple of cranks which was nice. What was not too nice was how loud the micron can is. Probably has never been re-packed ever.

Finding the previously mentioned coolant leak wasn't hard as it pissed out of the pipe with the T-piece connector on it once everything got warm.

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Split in the small hose from the pump to the T-piece was the issue. Remedied by a bit of a bodge....

As the split was so close to the end of the hose I just cut the hose down to where the split was and re-connected the pipe up. There's still slack in the pipe before anyone says anything so it's not under tension.

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After that I ran the engine up again after having some trouble starting it while it was hot (I see it's a common problem) to test the fix and it held nicely.

Finally I stuck the tank, pillion pegs and rear fairing panels back on (loosely as they need a bit of work) ready for a short shakedown run next week.

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Front brakes still require attention, as does one of the front indicators. The hot starting problem I will delve into next week.
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Re: Bikemonkeys ZXR400L4 project

Post by Ewetea » Fri Mar 10, 2017 10:47 am

Have a look at the photo of the inlet ports with the blue balancing pipes. The blue pipe going to the No. 2 port (second from left) meets a short black hose. At that junction a curved line can been seen just below. That is the boss for the carb pipework, which should have a small pipe screwed into it to complete the de-icing circuit. If it isn't present, then there is the possibility that the engine has been changed, as the rest of the pipework for the circuit is present. I assume that the small bore pipe from the T section has been plugged. Bikes without the de-icing circuit have a complete pipe from the lower port on the rad to the water pump.
That was bad news about the race bike. As I recall it was a wet weekend.
Oh - it might be worth checking the engine number with the V5. The number is on the front of the crankcase just behind the downpipes.

bikemonkey
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Fri Mar 10, 2017 9:15 pm

Thanks for that, I couldn't find any boss whatsoever, and no fluid came out anywhere so I'm guessing it probably has had an engine change. The rest of the system is removed/blocked so it'll be left at that. I'll check the V5 next week.

The frame also has a breakers marking on it and one of the engine bolts was in the wrong way round, so it's definitely had a history!

Yeah it was practically a monsoon at Cadwell last Sunday, looking back I shouldn't have bothered until the rain at least slowed as the track was practically a lake.
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Wed Mar 15, 2017 2:46 pm

Not a lot was done on Monday, didn't have much time so I faffed about assessing the bodywork and fitted it to look at how it all lines up and where needs repairing/strengthening.

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A few bits need attention, both lowers have cracks that need to be sorted. One of the seat panels has a crack, and the front tank bit job thing could do with a bit of tlc.

Tuesday I wanted to get on top of the hot start issue and high beam not working. So I had a look in the starting issues section and saw the list of things to check. Starting with the first I got a silly resistance from the primary coil windings. Then realised just how much corrosion/crap had built up on the connectors so cleaned that off.

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The result after was a solid reading of 3.2ohms for each coil and a bike that started and ran better, but ultimately started on the button when hot! Another issue though is that after I rev the bike it doesn't settle to idle, it settles to about 2k rpm and only goes down after fiddling with the idle adjuster. The revs otherwise are constant without input so I'm sure it's not an airleak.

Solve one issue another arises. After turning the bike off the lower coolant hose coming out of the pump decided to burst quite dramatically. Luckily I was at the other end of the garage at the time.

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It seems the hose has simply had it. So I've ordered a length of hose without the t-piece business as it's not needed.

Lastly I got onto looking at the high beam issue. So I checked the relay, it was fine, checked the bulbs and they were fine. But where didn't I look? The bloody fuse. That had gone, so nice easy fix!

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Next I'll sort the bodywork as I'm waiting on parts again. But the end is in sight!
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Re: Bikemonkeys ZXR400L4 project

Post by banner001 » Wed Mar 15, 2017 3:27 pm

i was going to say, that as you have removed the carb heating circuit, you dont need the metal T piece, and can just go with a straight tube from one bit of tube to the other, or a continuous bit of pipe...
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

bikemonkey
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Thu Mar 16, 2017 9:31 pm

Last night and tonights work.

Bodywork all prepped, strengthened and given me a headache. Damn fibreglass resin.

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A well keyed and cleaned surface is the best bet for a strong repair and this proved itself tonight as I looked at the dried panels. All structurally sound now!

Then today the 2 line brake lines turned up so I fitted them and bled them up.

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Did it give me a good lever? Did it bugger.

Master cylinder rebuild next I think.
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Re: Bikemonkeys ZXR400L4 project

Post by banner001 » Fri Mar 17, 2017 11:46 am

If you still don't get a good lever with MC rebuild kit you might need a new MC...They don't last forever.

Also are you making sure to get the air fully out of the high point where the two brake lines exit the MC? I usually do this by going full left lock, tilt the bike over on the side stand and lightly squeeze the brake lever, this will bring up any bubbles that are pooling there.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Fri Mar 17, 2017 10:31 pm

I could try the bleeding like you say, I have reverse bled the system too but it's worth a try.

If that fails I've been reading up and have seen that a slightly larger M/C may be a good way to go.

Only up to 5/8ths (16mm ish), to give more power and hopefully not come back to the bar. One from a zx6r should do nicely and can be had at less than the cost of a rebuild kit. Speaking of rebuild kits I reckon the M/C has been rebuilt recently as the internals look exactly like those in the kits and look fairly new.
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Thu Mar 23, 2017 9:49 pm

So after a while waiting the new coolant hose turned up.

However, the walls of it are a lot thicker than the original so cue a trip to Halfords to get some bigger hose clips.....

After that I fitted the hose and bled up the system.

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So after that I allowed the bike to run up to temp and took a short video.

As you can see and hear the revs like to hang for a second around 2K before dropping to idle. Also after a very short spin around the garages on the bike it became apparent it does this even more so whilst on the move with the clutch in.

https://www.youtube.com/embed/IBHTVXsgk3E

Plus when I turned the bike off I out of interest tried to start it again to confirm the hot starting fix.

Well it wouldn't start until it'd had 5 minutes cooling down. So I repeated this a couple of times with the same outcome.

More tests on the coil packs I think, can't think what else it might be.
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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Wed Mar 29, 2017 5:30 pm

So back to the hot starting issue.

I took some more readings of the coil packs and found both were within spec on both primary and secondary windings.

So to recreate the fault I heated them up with my heat gun and tested again. No change, so it's not the coils themselves.

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For peace of mind I cleaned up the connections in the HT leads, plug caps and coils again. Then I had a better look at the loom connections. They weren't in the best shape, apart from the right hand side coils earth. The resistance had built up and had started to blacken the loom wiring.

So I stripped back the wiring and replaced from the start of the good bit and added a new connector. Convinced I'd fixed it I put the airbox etc back on and ran the bike up to temp. Turned it off, waited 30 seconds and tried again. Engine started first time! To make sure it wasn't a fluke I tried again 3 more times and again the bike started. Winner.

I also bought a used ZX6R 3/8ths master cylinder too. Plonked that on, reverse bled and still wasn't getting much of a lever. Leaving it overnight with the lever held back to the bar with a cable tie and the reservoir cap off gave me the result I wanted. A nice firm lever that doesn't come back to the bar at all.

So aside from a good test ride round the private rounds I have access to, all that's needed now is an MOT!

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Re: Bikemonkeys ZXR400L4 project

Post by bikemonkey » Wed Apr 05, 2017 12:15 pm

Well I managed to get the bike out on the private roads and all went reasonably well.

Niggles were that the locating pin for the right hand switchgear came out when I strapped the bike down to the trailer, so the throttle was all kinds of weird to operate, I had put too much coolant in the overflow tank so that started emptying itself out the top, and it took ages to start cold.

Got it back to the garage, drained some of the fluid from the header tank and sorted out the switchgear. The cold starting is weirdly instantly solved by turning the ignition off and on again, then the bike fires, don't understand it myself but I can live with it.

MoT is now booked for friday morning!

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Re: Bikemonkeys ZXR400L4 project

Post by banner001 » Wed Apr 05, 2017 1:08 pm

looking reasonable there, was never gonna be a showroom head-turner, but not ment to be either...good to get another one back on the road in useable condition!

have fun :smt003
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

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