Richard's ZR750C1 Restoration Project

Document your ongoing rebuilds and restorations here
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Eddie
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Joined: 28 Oct 2017, 19:46
Location: Reading Berkshire

Re: Richard's ZR750C1 Restoration Project

Post by Eddie »

Great work, especially on the tank, I remember doing a Suzuki tank some years ago now , so I know what a big/difficult job it is to get right :) .

lovely Ohlins forks too, can't wait to see them fitted, actually thinking about it I want some now!! :lol:

cheers eddie
92 Kawasaki Zephyr 1100
78 Kawasaki Z1000a2
10 KTM 990 SMT
76 Yamaha XT500 supermoto
80 Honda Z50R Monkey
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Richard
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Joined: 24 Aug 2017, 14:35
Location: Zeewolde NL
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

Thanks!

The forks will be fitted later, intent to ride my bike often this summer ;)
And I also need some professional help in manufacturing a new triple piece...
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

So after 9 months (winter period and 2 months sick leave...) I finally went for a ride yesterday visiting my son at some 100 km distance. Bike runs fine, still needs new pilot jets, but I did have a weird issue. Been riding @120 kph for a long time without issues but suddenly it felt like all power was going away. Throttling up did almost nothing anymore, it felt like I was running out of gas, shifting down helped to get some more revs and suddenly all power came back and all seemed normal again. Then on another road I had to stick to 60 kph also for a longer period of time and then the same happened. I stopped and the engine stopped running by itself :shock: Restarting it felt like it ran on 2 cilinders or something and I had to throttle quite a bit to keep it running. So I let it cool down for some 10 minutes or so and lo and behold the engine acted normal again :?: :?: :?:

I have no clue what happened, must be a carburation issue but what could be causing this behavior?

There was no fuel leaking out of any bowl and I checked the fuel tank for any vacuum (not the case). Selecting prime mode did not make a diff.

Now what?
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

This afternoon I went for a test ride staying near home ( I live in a polder with long strait roads) to see if I would get the same error like a week ago. Kept the revs in the high range and yes after some 15 minutes the engine just stopped so I had to park it, glad it wasn't a highway though... :mrgreen:
2018-06-16 15.47.32.jpg
At first it starts to run rough with almost no reaction on the throttle :cry: , it does still accelerate somewhat though, but after 2 minutes running rougher all the time it just stopped. I felt the exhausts and #1 was stone cold, 2 and 3 were hot and 4 was somewhat less hot. This does point to an ignition problem, I'm using new ignition coils but it wouldn't surprise me if I have a flaky one :evil:

After cooling down for a 10 minutes or so the engine started again, #1 exhaust hot but #4 cold initially. Drove to the next exit and the roughness was completely gone. Was able to ride home without any issue 8-)

Next will be a test in my garage, applying some heat to the left coil and see if I can reproduce the problem :roll:
David Richard
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Joined: 04 Sep 2017, 20:21

Re: Richard's ZR750C1 Restoration Project

Post by David Richard »

hi that's a sod when you have put so much work into it ,I had the same with a c3 I would check the fuel tap or its inside the carbs as been said before open the drain valve on the carb put it on prime see what comes out its worth a look ,I have just been doing carbs on a zir im fed up with them but they have to work right ,david
Freddy
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Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Richard's ZR750C1 Restoration Project

Post by Freddy »

Richard wrote:I'm using new ignition coils but it wouldn't surprise me if I have a flaky one :evil:
From your description I reckon you are on the money. If you still have the old coils why not just stick one on em back on and see how it goes?
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

thanks guys for thinking with me. Primary suspect is the coil but I will do some testing later this week to check it out. No sure if the old ones are still around :roll:
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

Well that last update seems ages ago, so much has happened since... :roll: For more info read viewtopic.php?f=2&t=454#p3381

Anyway the problem described above was a real stupid error but apparently easy to overlook. It was caused by an almost blocked fuel filter :o . I fitted that one earlier when I found rust particles from the tank in my carb bowls. Obviously over time it will become clogged and the fuel flow is minimized. I was stil able to ride a few km's until the cilinders cut of one by one with indeed two cold down-pipes but the other two were still hot. After 10 minutes pausing the bike would start normal again until it was stopped again. I never ever suspected the filter to be the cause of this. Yes I did check the pet cock but did so before the filter and not after it :?

Anyway, with the newly sealed tank I simply removed the filter completely and the bike was back in business again :mrgreen:
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

Well, again over a year has gone by since the last post, corona stroke and I stayed at home as much as possible. I've got my first vaccination and it looks like we're finally getting some of our freedom back...

A month ago I went to check the bike and all it did when starting was a loud click and a dimming headlight :roll: Further investigation revealed the dreadful fuel lock occurred again :o
It seems my petcock is still leaking fuel, I did overhaul that one earlier so did not expect this to happen again. As the bike was parked on its jiffy cylinder 1 and 2 were (partly) filled with fuel. I simply removed both spark plugs, covered the heads with some clothing and hit the start button to get rid of it. So the bike would now turn over but it didn't start no matter what I tried.

I stored the bike without draining the petrol from the tank which was at least half full. Now with the modern fuel there is the problem of methanol which is hygroscopic and I sort of expected the fuel by now was bad and most probably there was water in the tank which sinks to the bottom. So I guess I've tried starting the engine on water :roll:

Today I removed the carbs and cleaned all of them thoroughly and used compressed air to get rid of the water that was everywhere inside the carbs and jets. I reinstalled the carbs, used a jar with fresh fuel connected with a hose to the carbs and the bike started immediately being it only on Cylinder 3 and 4 and somewhat later number 2 kicked in. Number one did have a dead spark plug, replaced it and now its running on all fours again :D

Recorded a view video's

Here it's running on 2 cylinders: https://www.youtube.com/watch?v=9V-dSmnvyzY
[youtube]https://www.youtube.com/watch?v=9V-dSmnvyzY[/youtube]

And here with new spark plug in #1 running on all fours: https://www.youtube.com/watch?v=wVlVofU0DFA
[youtube]https://www.youtube.com/watch?v=wVlVofU0DFA[/youtube]
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Richard
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Re: Richard's ZR750C1 Restoration Project

Post by Richard »

Changed oil today as it was contaminated with fuel. Warmed the engine and tapped it off in an oilpan, let it drip for an hour or so. Replaced oil filter and filled it up with 3.5L, not visible in the oil level glass so poured some more, oil level visible but sank down quickly, poured some more and same happened. I've now filled it up with 4L, should be 3.6 max for an empty machine.

Where does the oil go???
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