The NC30 Thread

[K2-K6]

It's been a busy but productive weekend in the garage. The bike is now completely apart with the engine now sitting on its own on the bike lift as I removed the frame today.
Prior to indulging in some heavy degreasing I thought I'd strip the fork legs. Somebody has been in there before me and has managed to completely mangle the head of the hex socket bolt holding the damper rod. Nothing fits what is left of the rounded head.
Has anyone else come across this before and if you did how did you get the bolt out? I think I might have to resort to drilling it out but that is going to be risky considering the head of the bolt is set so deeply in the recess. It's only going to take a slight deviation of the drill and I'll go into the alloy of the fork leg. I was going to try to hammer a torx headed socket in there but knowing how tight those bolts are I can't see the torx head having enough grip in the socket head.
Any ideas would be welcome 🤔.

I do that for some, works well on softer materials to get good flank drive.

However, with steel hex internal knackered, the "spline" drive bits (think some call them triple square) bits are usually most successful in getting good drive from the butchered item.
Tap in with lump hammer,  remove to clean swarf etc. Tap fully home, then first attempt with decent potency impact gun will usually see them yeald quite easily.

Emphasis of the prep and fully home/engaged to give first strike bite and highest chance of straight removal.

[Laverda Dave]

Thank you both for the suggestions.
When I get home later I'll get togged up and go into the garage with a lump hammer in one hand and a drill bit in the other and see how it goes.
I'll report back in dispatches with an update 🤞

[Laverda Dave]

Success 👍. Nigel's method worked at the first attempt and the bolt moved slightly........until the impact driver cracked the driver bit😤. Luckily I was able to extract the extractor bit from the mangled head of the bolt. On to Bryan's method of drilling the head off the bolt and it worked.
I was expecting the same scenario with the second fork leg but no, the bolt put up no resistance at all.
Both legs are now completely apart ready for a big clean and new bushes.
As always, this site and the knowledge contained by the members is the best.

[Laverda Dave]

An update on the NC30.

First the good news, the wheels and various other parts are currently undergoing blasting and powder coating. I’m collecting all the BZP and yellow passivated parts tomorrow (one week turnaround and £60 for everything in the photo).

I took the frame, bare swing arm and footrest hangers etc for vapour blasting to R D Cox in Reading. Doug advised me not to vapour blast the frame as it is anodised and a vapour blast finish wouldn’t look good on the side beams. He told me to use steel wheel cleaner and a stiff brush. Looking around I came across an alloy wheel cleaner made by Bilt Hamber so ordered some. It was excellent; it cleaned up the castings and the beams really well. It was so good all I needed to do was to use some solvol on the two side beams and they are like new!

And the bad news, I thought the engine was all good and wouldn’t need anything more than a good clean and service. Checking the valve clearances revealed one missing valve shim, oh dear. Looking as best I could down the drive gear tunnel with a torch I couldn’t see anything. The thought of a shim floating around inside the engine fills me with dread so it was off with the sump to hopefully find the shim sitting in there. No luck although it did give me a change to clean out the sump pan. When I took the oil pick up strainer off I found a chewed up piece of metal although not a shim lodged inside (see photo). I have no idea what it is/was. I looked inside the engine from underneath with a torch but no sign of a shim.

Next I removed the cams and the cam gear drive from the front cylinders where the shim was missing from to check if it had lodged in there; it was clear so all that went back in...slowly and keeping an eye on the valve timing marks.  I did notice though some score marks to the underside of the casing looking down from the now empty cam gear tunnel (photo). Something has defiantly been floating around the engine at some point doing some minor damage.

Next up will be to remove the engine side covers to see if the shim is in the clutch area or the alternator. If it’s not there I can only assume it may have been flushed out during an oil change at some point in its past. I know from speaking with Rick Oliver the checking of valve clearances on the front two cylinders is notoriously difficult unless the two radiators are removed first and even then it’s so tricky to change the shims a lot of these engines never get checked. Maybe they were checked at some point and the shim was not properly placed and was spat out when the engine was started.

I have to say though it is a real jewel of a bike, build quality is immense.

[Bryanj]

Sorry but if it was mine i would have to go all the way to check every possible piece that may be damaged

[Laverda Dave]

I thought you'd say that Bryan. Well I know there's no damage to the front two cylinders valve gear and drive gears. I'll check inside the gearbox, alternator and clutch sides.
The piece of metal looks like the top of a dowl, it's very thin like a shaving of something and it's very small, about 8mm in length (before it was bent double!). It's definitely not a piston ring, it's much too thin. Could it be part of a three piece oil ring, but where's the rest of it?
I have my doubts if this engine has ever been opened to any great extent because the valve clearances are well below what they should be with really tight clearances, every valve was well out of spec. The sump gasket was original Honda and had never been off which makes me think the engine has never been out of the frame.
I'll dig deeper and report back.

[Bryanj]

Are there dowels between rocker cover and head, or cam cover and head? If so could it be one of those.
Dowels are frequently "rolled" metal so could be, that pic was a bit blurry.

Possibly leave top end alone and just check lower end for any damage, cant help much as never layed hands on one at meads

[magpie114]

That's a great price and turnaround for the zinc plating! I thought the plater I use was unbeatable on price but nowhere near that.
Bad news on the engine, as you say it does look like the remains of a dowel, can't think of anything else. Hopefully will become clearer as you dig further.
BTW there is an as new YSS rear shock on eBay if you are looking to replace the original.

[Laverda Dave]

I'll give it all another go in the next couple of days. Just waiting for the replacement shims to arrive before delving deeper.
I saw that YSS shock Alan but at the time I was going to get the original shock rebuilt but now knowing it's going to cost somewhere between £250-£300 and some parts such as the actual damper rod are irreplaceable I went to bid on the YSS shock only to find it had been sold😕. I won't think about the suspension now until I know what I'm potentially in for with the engine!

[Johnwebley]

I'll give it all another go in the next couple of days. Just waiting for the replacement shims to arrive before delving deeper.
I saw that YSS shock Alan but at the time I was going to get the original shock rebuilt but now knowing it's going to cost somewhere between £250-£300 and some parts such as the actual damper rod are irreplaceable I went to bid on the YSS shock only to find it had been sold. I won't think about the suspension now until I know what I'm potentially in for with the engine!

I fitted mine with a Yss shock from Wemoto, not to expensive

Mine had previously been fitted with a CBR600RR unit, but the spring was far too soft,

Back end went down far to much


The damper travel is very short on NC30, so needs a stiff spring



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[Laverda Dave]

That's what I was told John, the rear spring will easily bottom out.  Same with the front, the standard springs are based on a 10 stone Japanese rider, not a 12 stone Englishman! I've already bought a set of uprated front springs from Rick Oliver to fit when I get the fork bottoms back.

[Laverda Dave]

Some excellent news to report regarding the shims  .

It appears I cannot count, or at least be trusted to write things down before I come indoors for dinner!
Long story short, when I was measuring the valve clearances and removing the shims to replace with the correct sizes and writing down the calcs in a notebook I tried swapping one from one valve to another to test the idea. It was the perfect size and in my success a) I was called indoors for dinner and b) I hadn’t written down what I had done. The result of this was the next day I went back out into the garage to continue and counted I only had 15 not 16 shims on the bench forgetting I had used one the evening before! This is why I though one was missing from the motor and I stripped the sump, cams and cam drive out trying to find a shim that wasn’t actually lost.....oh dear .
Anyway it gave me a chance to look deep inside the engine and find that sliver of metal in the strainer. But looking right through the motor there was absolutely no sign of any damage to the gears etc. All the dowels are where they should be as well (in the front cylinders anyway).  The metal shaving is too thin to be a dowel. I’m going to use my camera in the spark plug holes to check for any cylinder scoring but the motor wasn’t smoking when I ran it up for 40 minutes before the strip down.

I have cleaned the frame using Bilt Hamber alloy wheel cleaner and really pleased with the results. It got a five star review in tests and it really does work.

I have now prepared the front and rear discs ready for painting the carriers, what a boring job spending three hours with masking tape and a scalpel! I'll spray them with VHT when it warms up and cure them in the oven when the O/H goes to work.

It hasn't all been bike restoration I did undertake a domestic chore and cleaned the dishwasher whilst the wife went shopping. I cleaned the dishwasher first using the two stage process reccomended by Bryan. This involves putting a complete wiring loom in there first on a 65c wash. This was followed by using a dishwasher cleaner to do the real work and hey presto an immaculate dishwasher is the result

[Johnny4428]

I take it the dinner dishes weren’t in there at the time!😂 Nice work Dave, what a pain looking for something that wasn’t there in the first place. Done a few of these disc centres and they are a right pain to mask.😡 if only you could separate the parts.

[magpie114]

Great news on the shim and it did lead to the discovery of the unidentified fragment.
I haven’t the courage to use the oven or dishwasher for parts, more than my life’s worth!


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[K2-K6]

Good that you've found the "missing " shim Dave, that would be quite a chunky piece to have floating around unconstrained.

Those little camera / scope are great for inspection of bore etc, we used one on my son's car to very good effect. With very good view of cylinder walls etc from side facing lens, all ok and with aluminium bore at 140,000 mls too  also its a 40 valve in total, although hydraulic tappets fortunately  that's in my role as Technical consultant and general grease monkey 

He used the camera too on his friends car with suspected head gasket failure ..... to find two cylinders leaking around the gasket. Saves so much time by being able to look inside an engine like this.