Is this goodbye for my NC35?

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Foxy400
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Is this goodbye for my NC35?

Post by Foxy400 » Mon Sep 03, 2018 11:58 am

Don't use the bike as often as I should..the new Bonneville has had priority lately. However it's been regularly started (weekly) and run until it's hot and the temp. needle has moved. A week or so back it produced a lot of exhaust and was clearly burning oil. It hadn't been professionally serviced for 3 years (I've done oil&filters etc. myself in that time) and I think it's good to have paperwork to back up servicing (in case I sell it), so I booked it into Weston's Motorcycles near Runcorn. They've got a very good rep and I trust them.

Just had a chat with their main man. It's wasn't running properly on cylinder 3. They've replaced the plugs and stripped off the end can and collector to check for excessive carbon in the headers. The situation is that he suspects the oil-scraping ring (or whatever it's called) on piston 3 is stuck in it's groove and not cleaning oil off the bore (therefore letting it past, hence the smoky exhaust)... or the ring is broken :( .

He tells me that if the bike isn't run often enough then the ring(s) can get gummed up and stuck. He's is going to run the bike over the next few days (not continually!) and see if it frees-up :pray: .

If it doesn't then things get serious. Apparently it's an engine-out job and partial strip down to get to the pistons, to replace rings. This is mega-expensive as you will know and he said in the region of £1500-1800 :shock: !!!! Why did Mr Honda make it so fucking complicated?
This is half the value of the bike and I can't afford it. So I'm asking for advice and opinions please.

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CMSMJ1
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Re: Is this goodbye for my NC35?

Post by CMSMJ1 » Mon Sep 03, 2018 1:39 pm

Get it out for a ride. It will sort itself out, or it won't and then you can sell it me for scrap?

compression test should identify if rings are knackered?
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Tim400GB
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Re: Is this goodbye for my NC35?

Post by Tim400GB » Mon Sep 03, 2018 1:50 pm

Unfortunately if it is the rings it is a rather involved job, I'm not sure rings are available anymore, the issue could however be valve stem seals which 'only' requires the head to be removed.

You could cheapen the bill by removing the engine yourself.

Like CMSMJ1 says a compression test/leak down test should give a better diagnosis

Foxy400
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Re: Is this goodbye for my NC35?

Post by Foxy400 » Mon Sep 03, 2018 11:11 pm

Thanks for your replies. Both of you mentioned compression. I forgot to say that he checked it and said it was good...so there's hope?
Removing the engine myself is certainly a possibility. Did it on my old Yamaha air-cooled twin..even got it back in! But the NC35 is just a tad more complicated. Something to bear in mind though.

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Re: Is this goodbye for my NC35?

Post by CMSMJ1 » Tue Sep 04, 2018 9:08 am

Have you not ridden it then? If you have good compression then your rings are in a good place? Getting it under load, and all nice and hot will either cure it, or fuck it up* - either way - you then know.

As much as you "trust" these guys, really - oil scraper ring, no evidence other than soot and it runs rough? It would run just fine, but be smoky? What does the airbox breather look like? messy as hell?

it doesn't add up (to me, not a mechanic at all, but I think sensible enough to get how these work)

1: you have compression (they said so) (and if it does, then it "should" run nicely
2: it's been sat ages - so get it out for a run - as it is probably fuelling and not fundamentals such as compression.
3: spark plugs? they do die, as I am sure you know.


*it won't fuck it up...honest - they are tough**
**if you kill it, then removing engine is easy
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Re: Is this goodbye for my NC35?

Post by saltysealion » Tue Sep 04, 2018 9:34 am

It's interesting how bikes break drown from lack of use!

I feel like this could of been avoided with some moderate use rather than just warming up on the stand still.

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Tim400GB
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Re: Is this goodbye for my NC35?

Post by Tim400GB » Tue Sep 04, 2018 4:27 pm

could this just be as simple as some fresh fuel and new plugs.....

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Re: Is this goodbye for my NC35?

Post by moforockband » Thu Sep 06, 2018 5:17 pm

Possibly a 20+ year old valve stem seal completely fallen apart, and lying in the head?
You could also run some engine strip through the engine for 1/2 hour, and then change the oil and give it a good thrashing to try and break the gumming up on the oil rings?

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Re: Is this goodbye for my NC35?

Post by Foxy400 » Wed Sep 19, 2018 12:38 pm

Thanks for the suggestions. I've been in France for 2 weeks and the bike shop is closed today (just like much of France most of the time). I'll keep people posted with the news when I call them tomorrow. If the Gods have smiled on the bike while I've been away then I promise it will get used a lot more often and the Bonnie and NC29 will just have to take their turn.

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Re: Is this goodbye for my NC35?

Post by NGneer » Thu Sep 20, 2018 7:47 am

For my 2p worth.

We all know that just starting the bikes up and not actually running them can kill the spark plugs. You have been doing this and IF that had killed the plug in cylinder three you would then be getting un-burnt fuel coming through the exhaust - thus excessive smoke.

I am very much in the same place as Timon here, and suspect some fresh fuel, new plugs and a good run on it will solve the problem. :peace:


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