Sometimes you wonder...

[GregT]

Among the bikes the unskilled shouldn't own or work on the RC30 Honda is prominent...
I'm pulling one down for a client at present. It's a race bike with some history. The previous owner apparently never got it running - he'd taken it as a trade on a Laverda.
I'm not surprised it didn't run - and pleased he didn't persist.

So far...No alternator rotor retaining bolt. Rear inlet cam is I think a front one and has been timed up on the wrong marks. Yes, the pistons are marked so the inlets on that side are probably bent...There are 3 X 6mm capscrews as head bolts in each cam gear tunnel. All 6 finger tight only.
Those fasteners that are tight are of course over-tight. And it's covered in aluminium capscrews which I loathe and should only be single-use.
I can see three different gasket sealants on the case joint...all to excess.

I'm looking at the bearing shells - particularly the outer mains - and realising I've got to put the crank between centers to check for straight.
Don't like the look of the outers at all.

About par for the course when you're dealing with old race engines....

 

[Nadrol]

Sounds like a nightmare. Some just don't care to do things right!

 

[GregT]

Just an update - the cases had been welded which is why the end mains showed odd wear marks. Looks like a low mileage crank and rods which had been assembled without paying due attention to the mesh of the cam drive to the crank...Luckily it's still usable. Gear on the crank is ugly but passes crack testing.
My biggest problem is identifying just what in it is racekit, the sump probably is and the cams are marked and lightened like kit ones....but lift is stock.

At this point it looks like it'll be rebuilt into VFR750 cases. I suggested going big which is quite feasible with those cases but it's looking like they'll keep it 750 for the "750 formula" class at Philip Island.

I also have an A65 BSA engine apart at present. Thank the gods they don't make them like they used to, LOL. The BSA twin parts take up one more box than the RC30. It's the difference between an engine that was designed - and one which simply evolved.

 

[nvr2old]

RC30's are amazing machines. One just sold at auction with 14 "push around miles" for $90,000. Nice ones still go for 35K and more. I painted one a number of years ago. The hardest paint job I ever did. If I ever do another one I would charge 3 times as much. With how crazy rare and expensive as they are, (although magnificent to race) I would be afraid to put it out on a track.

 

[GregT]

RC30's are amazing machines. One just sold at auction with 14 "push around miles" for $90,000. Nice ones still go for 35K and more. I painted one a number of years ago. The hardest paint job I ever did. If I ever do another one I would charge 3 times as much. With how crazy rare and expensive as they are, (although magnificent to race) I would be afraid to put it out on a track.

Funnily enough it's often the ex Honda dealers who have them with "push around" mileage. I know of one here in NZ who was over the moon when his one arrived, put it on display in the shop and rode it home for lunch a couple of times.....Then the parts fische and price list arrived.
He took it home in the shop van the same day and put it in his lounge where it stayed for years.

 

[GregT]

An update - and minor rant...
The spares kit arrived finally so i was able to move things along a tad. Found a usable valve and refaced it so at least the damaged bit is sorted.
But...Given it's unknown history, we want to replace head and rod bolts. Discontinued, NLA. Head bolts are 9mm - and socket heads - which they have to be as the access to each is via a 10mm hole. Honda...
At this point it looks like we'll be using modified 10mm head bolts BMW/Audi/Merc which have torx socket heads. And retapping the block.
Oh and a mob in the UK have had ARP do a run of head bolts - 47 Pounds each. You need 16 of them...Don't think so, thanks.
Rod bolts - 8mm and unusually long. The Ti rods are a bigger section than steel hence the length. May have scored here, still to check but I think I've found an ARP bolt for a Mitsubishi which is correct

The cams are interesting. There were some stockers in the spares so I could do a comparison. Yes, we have one genuine early kit inlet - and one I'll call a later evolution inlet. Pretty much the same duration and lift but a fraction more area under the curve due to a higher acceleration rate from half lift upward.

So now the neverending plastigage sessions followed by cam drive shimming sessions start...Oh joy.

 

[Buffalo Bill]

Oh boy, not for DIYer racers.
Kawi EX500 race bike makes sense for me.

 

[GregT]

Oh boy, not for DIYer racers.
Kawi EX500 race bike makes sense for me.

A single cylinder 2 stroke is looking like a holiday to me, LOL

I wouldn't like to have to pay a specialist to rebuild this one. I do it as occupational therapy and to supplement the pension. The owner had the choice of sending it to the UK or to me. The bike was in NZ and will be used in Australia so I drew the short straw.
Talking to a known specialist in Aus, they're very keen to find out what alternative parts we use. Their customers are rationing the use of active racing RC30's due to exactly the problems we're finding. There have been some sources for parts in Japan but apparently they're drying up.
We ran into the parts problems earlier than most due to the poor condition of the bike on purchase.
But hey, you take your RC30's as and where you find them. This one was cheap.

 

[steve murdoch]

Thanks for starting this thread, Greg.
It has sent me for a couple Google searches about these gems about which i know little.
I had thought the RC45 was just a replacement for the RC30 but i have found that is not the case.

A guy near me has a NC35 that he imported with great difficulty. Unfortunately i haven't seen it for a couple years.

 

[GregT]

Thanks for starting this thread, Greg.
It has sent me for a couple Google searches about these gems about which i know little.
I had thought the RC45 was just a replacement for the RC30 but i have found that is not the case.

A guy near me has a NC35 that he imported with great difficulty. Unfortunately i haven't seen it for a couple years.

We got quite a lot of the 400's as grey imports. VF's were sold new here but the gear driven cams versions - VFR, NC30, NC35 were greys. Plenty of NC30's but very few NC35's. The first two NC30's in Christchurch immediately hit the track...and both spun rod bearings. I had both apart and fixed before the local agents could source manuals or the parts fisch. I'd had a VF400 apart and realised the shells were the same. Both cranks were undamaged luckily.
The problem turned out to be the one endemic to the V4's - poor finishing on the cranks. Sharp edges on the oil holes. Fine in road use but put some real stress on them and you'd do a bearing. I've had to properly radius the RC30 crank oil holes too....

Rod bolts....Mitsubishi Evo ARP bolts are ordered. Heads are correct, shank OD and unthreaded length is correct, just need to shorten the threaded portion.
Quite cheap too.

 

[GregT]

Patience is a virtue much sought after...

 

[Big T]

Such an intracate motor
No wonder the 2 local ones I know of are on display

 

[GregT]

This thing is turning out to be a trap for the unwary...Mocked up #1 and #2 to set up the gear drive shimming.
It would appear that the block has been decked so far in the past when it's been re-linered that the squish clearance has been almost halved...
Luckily there's a very good machinist in ChCh who can take the required .015in off the piston squish areas.

Bearing clearances were at least OK - one step forward, one sideways...

 

[GregT]

Moving slowly along. I've got the 'flu and don't want to work on it while I'm wobbly....So the pistons are going for machining tomorrow.

The odd inlet cam- a front one in the rear bank - needs modifications too so it can go while i'm down. I did at least manage to establish the correct timing - something I wasn't sure was even possible. Fixed gear drive, no adjustment. It's flipped end for end and running in reverse. But the profiles are symmetrical anyway.
BUT - the oil feed arrangement is into the center of the cam from the RHS. A drilling carries oil through the cam and there are oil holes on the base circles of the lobes. Flipping it end for end would make it run dry...
So the remaining 15mm or so of the center drilling has to be completed then the original open end plugged.
But - Mr Honda said " You're not going to futz around with my cams, sonny !" It's hardened right through..
Luckily a precision engineer of my acquaintance has a range of carbide drills....

I've also got to contact a FIAT specialist. Guy I know who's an internet search specialist has come up with a FIAT head bolt identical to the discontinued OE Honda. Might yet avoid retapping the block...

Talking to the owner's rep today, he's been imagining what it would have cost if they'd sent it to the UK....

 

[GregT]

Pistons in for machining, should be a quick turnaround. Rod bolts hadn't arrived. FIAT parts specialist searching his databases to find the head bolts I want. Could be anything - tractor to industrial motor to car...
Cam bored while I waited and sweated. Try finding another. Carbide drill wasn't much cop but a carbide milling cutter did it eventually.

Now to put me feet up for a couple of days. Actually as soon as I'm up to it there's the usual maintenace work to do here. It never stops.

 

[GregT]

Okay. Feeling a little better so got out and made the shell measuring jig I'd promised myself. Very simple, a 1/2in dia ball bearing welded to the end of a short piece of tubing. Held upright in the vise with a magnetic base DTI coming down onto it from above. The DTI has a good sized dial - 2 in plus - so the divisions are good and large. Works surprisingly well and seems repeatably accurate too.
I've been able to quite easily separate the pile of shells into four thicknesses. Interestingly - and a bit worryingly - the thinnest and thickest shells are both unused greens....

I wasn't enormously happy with the bigend clearances when plastigaged - all were just greater than .0017in. So put those shells over the jig...Two rods didn't have matching shell pairs even though the numbers are the same. Colours are long gone.
I have enough thicker shells of usable quality to redo the bigends and get them down to .0016in where I want them.

Worth doing - and that jig is going to see more work in the future...

 

[GregT]

Moving along. Happy with the bottom end clearances now. Trial assemblies done using #1 and #2 pistons less rings to establish cam timing. Both banks within 2 degrees of each other. It appears that the kit cams lobe centers are the same as the road versions - 100 inlet, 105 exhaust. Not where I'd have put them but there's no adjustment possible. Put in an inlet and exhaust valve and did valve to piston clearances. All good there and checked the high points on the pistons too against the chamber - don't have to trim anything.
I can't build the heads until the new head bolts turn up. Assembly sequence is - spring seats, stem seals, head bolts in. Then put the cam carrier on the head - which traps the head bolts. Then you can assemble the valves - which traps the cam carrier on the head....Honda......

Made a guide plate to put the pistons in the bores. Much better than ring compressors. Worked out which way round the rods go by checking for centrality in the pistons. Once i'd sorted that it was apparent how they were supposed to go. Judging by what little wear marks there are, they may have been wrong way round. The manual is contradictory of course. Happy they're right now anyway. Assembly lube generously spread around and the rods torqued up. New piston circlips of course - suzuki actually, lol.

Washed and inspected the gearbox shafts. They look like new - the dogs are practically virginal. But I had to buff some strange jointing compound off the OD of the bearings. Looked like a contact adhesive. Not Loctite bearing mount anyway.

Cases will go together tomorrow. Then it's the ancillaries, oil pump etc etc...

 

[nvr2old]

It's really refreshing to watch someone work meticulously on such a rare and historically important engine as one of these are. I'm sure your client is grateful.

 

[GregT]

It's really refreshing to watch someone work meticulously on such a rare and historically important engine as one of these are. I'm sure your client is grateful.

As long as that is expressed financially....

Found yet another sting in the tail. Started cleaning the oil pump pickup - which resembles an oyster, only just open - and realised it was half blocked with fabric...You needed to shine a strong light into it to even see there was anything there. Not like our own, familiar, open and easily checked GS pickups....
A LOT of scraping and high pressure solvent washing got it out eventually.
The sump appears to be an aftermarket deep one. It has a baffle cast in behind the pickup - so it can be wheelied without sucking air...Bonus.

I still haven't decided just how it got to this point. Was it a project which got past the owners engineering capabilities ? Was it someone's collection of parts which they decided to loosely assemble and sell when they realised they'd never finish it ? So many questions - and so many mistakes found in it.
The guy doing the chassis has found almost as many problems too.

The primary gear on the crank has a spacer taking up the distance the starter clutch would have occupied with the ignition trigger rotor outside that. The spacer is very loose on the crank so a replacement will be machined up. What's there has at least 1mm clearance on the shaft...

 

[GregT]

The head bolts turned up on Saturday. They are same length and will drop in perfectly. But they use a modern six point splined recess to tighten. Like a Torx - but straight sided splines so not a Torx...Anyway, went to town to a specialist tool shop and found the correct long bit for them. It came in a 10mm hex 1/2in drive socket so it got driven out of that - and will be used in a long 10mm 3/8 drive socket which matches my torque wrench...
Next problem was that the access holes in the cam carrier through which you tighten them were about 8.5mm dia. I machined the hex shank of the trick bit down to 10mm OD- leaving enough hex at the top to engage the socket. Then bored the holes in the cam carrier to 10.5mm...
Those holes are hidden under the outers of the ball and roller bearings the cams run on. Deburred them and I can now look forward to a couple of days building the heads and shimming them.

The end is in sight - for the engine anyway. Last I heard they were still looking for a rear axle - the one in the bike is cracked...