Honda-SOHC
SOHC.co.uk Forums => Project Board => Topic started by: MRA464 on January 19, 2021, 01:01:34 PM
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Hi All
Thought I would introduce myself and have a go at posting with photos, fingers crossed, here I go.
I have been riding and maintaining dirt bikes for many years and due to Covid have decided to get myself a project.
Using a well know auction site I have picked up a very tired 1981 CB250Rs in black.
The bike had been used as a spares / donor bike and had been stored under a tarp outside for many years.
The important thing for me was that it ran and sounded ok even with a blown exhaust.
Let the strip down begin.
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Welcome,
I'm looking forward to seeing your photos as the strip down progresses.
Any distraction is to be welcomed during this boring 'lockdown' period.
Good luck
Skoti
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Yes, good luck with the project. I rode down to Sicily and back on one of those in the early 80's. I thought about buying one myself recently to do up as you have, so I'll follow your progress with interest.
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Looks like you've got your work cut out on that one given initial condition.
Think Honda hit the bullseye on it when released, a light fast and good looking 4 stroke single. Interesting to see it progress.
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I loved my one, very good little bikes, well loved by despatch riders
Sent from my SM-G950F using Tapatalk
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So the work started.
I will try and catch up over the next couple of posts, as I have got a long way into the disassembly and the issues I have encountered.
After a more detailed look around the bike it was obvious that certain items were not correct or were damaged past there best, but all nuts and bolts although
rusty were stock Honda issue.
The items that stood out were;
Wheels need a new spokes and rims will need dressing.
Rear shocks were wrong and need replacing
Front brake seized
Forks badly pitted and rusty.
Blowing Motard Exhaust and flaking chrome
Battery was shot
Chain and sprockets worn out
right side panel split
Missing frame info plate.
plus general poor paint and rust everywhere.
[attach=1]
Knowing that these bikes suffered from worn cams and cracked heads, I was keen to take the engine out of the bike to take a look inside the head, before doing too much else.
So out came the spanners.
Seat assembly removed along with tank. This gave me my first real view of the hidden parts and look what I found, some one had made home.
[attach=2]
The tank had issues which I will return to later on. I continued with the strip down, all the fixings came out some with ease and others with a little more work. Taking lots of photos as I went as my memory is not as good as it was.
Battery box was intact with some rusting, air box was good along with good supple rubber boots it even had the original filter still intact.
Rear end was all good apart from odd indicators and more rust.
[attach=3][attach=4]
The rear end parts piled up and I was soon ready to start the front.
[attach=5]
More to follow.
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You can get replacement shocks from TEC and they look the same as the originals.
Piki (Reddice on here) makes the decals for the rear shocks as well as the DID decals for the wheel rims. He also made the decals for the rear cowl, front mudguard, sidepanels and the Honda wing badges for the tank as well as the black warning inserts for the alloy footrest hangers.
Keep the photos coming.
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Looks like you have your hands full there, shame as once upon a time it must have been someones pride and joy but that's what "men in their sheds" (and women) are there for. I must admit that I really liked those bikes and was tempted by them.
Glad to see that you are taking lots of photos, photos and zippy bags helped me loads when I was stripping mine down.
Cheers
Dennis
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Mice seem to like motorbikes for building their homes. Especially under seats. I know they can cause huge damage but I kinda like the thought that something has made a nice comfy nest in a bike.
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Considering the state of the bike you may want to check the frame alignment before undertaking big work and spending serious money. The last three bikes I have restored (400/4, Morini 350 and CB250RSA) were all checked. two of them had the steering head angle out by up to 1.5deg. It cost £70 to check a frame by the guy I used in Croxley Green, Bucks (Viking Motorcycles) and for the 'tweak' to be undertaken. You need the frame with the swing arm and shocks still attached with the engine installed (can just be the empty cases) and the back wheel in. Well worth it considering how much you could spend only to find it wobbles like a jelly!
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Same with my 1970 Triumph. I had that bike since 2007 and had stripped all the paint off it by hand and repainted it using spray can primer and finish coat. Had it for years and one day I stuck the swing arm back on and the rear wheel only to find that the wheel was about an inch out (25mm for the youngsters on here). Never thought about the frame being bent....never entered my head. I had it put on a jig and straightened - £150 as it was so bad !
Good advice on here from Laverda Dave.
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Thanks for the reply guys, frame alignment was not something I had thought about.
Once the frame is sand blasted I will carry out an inspection for welds and then get the frame checked.
I might even get it to work and build myself an alignment frame to check it against.
The strip down continues.
More rust and debris, but not too many major issues. Front headlight rusty bezel and outside of reflector.
[attach=1]
Full Harness removed along with clocks and all the bracketry. Not sure if this is correct but one wire not connected, may be someone could advice.
[attach=3]
Forks show pitting and chrome damage, we will look at the damage once cleaned.
[attach=2]
As I said before the general idea was to get everything off the bike ready for a top end engine inspection. Parts are set aside ready for inspection and reworks at a later stage.
The only major issue was whilst removing the Carb the inlet boot fell apart -oopps. Apparently these are impossible to get so I will be looking at a repair of some kind.
[attach=4]
The bike had a seized front brake, so after removing the caliper and brake line it was obvious that the master cylinder was at fault. It looks like it has a seized piston, so another job for the list.
[attach=5]
After several hours work and a pile of parts, I got it down to just the frame and engine.
So this will be the next post, as this did not go as planned, my first real issue.
More to follow
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The extra wire is an earth for 3 terminal flasher can, as for intake perhaps modify something like 400 four
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There have been a couple of the inlet manifolds new on ebay but sold expensive put the part number, 16211471000, into a search and save it
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The extra wire is correct, the flasher unit on the RSA only has two terminals. You can get the headlight from DSS and a few others, they were used on a few models.
I gave up trying to repair the master cylinder on mine despite buying a repair kit. I found it impossible to separate the fluid reservoir from the main body to allow access to the piston assembly. I bought a new pattern part in the end and it was actually cheaper than the repair kit!
You can get a stainless brake piston, seals, boots and bleed nipple from Powerhouse, they will overhaul your existing caliper and repaint it if you want them to.
Renew the balance chain whilst the engine is apart, it works hard and is prone to stretching. Don't buy a genuine replacement at £250+, a DID gold heavy duty go-kart drive chain is better quality once you cut a few links out.
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Thanks all for the 3rd wire info and all your advice.
Do let me know if my posts get too boring.
So my first real issues, I had a stripped out the frame and I was left with a seized centre stand tube and more of a worry the engine with a seized lower rear bolt, all others were free and left loose.
Try as I might I could not remove the stand, so I concentrated on the engine mount bolt.
It was the typical steel corroding in aluminium with added salt and general road dirt.
I tried the usual methods, lubrication, heat, force, time, more lubrication etc not to no avail. Fortunately for me after several attempts I managed to get the unthreaded part of the bolt to move,
So I again tried to get the bolt undone but all I was doing was causing it to twist.
A new plan was undertaken, lucky for me the engine case is two lobs rather than being completely enclosed. This gave me access to the bolt so with a dremel and small cutoff wheel I managed to cut most of my way through the bolt with out touching the case. Now the bolt was weak, so I just sheared it off using a socket on the head, happy days one side off.
I now cut through the protruding threaded side as close to the frame as I dare, ready for it to be drilled out.
[attach=1]
Carefully I centred a drill and drilled enough of the bolt away to allow me to remove the engine with no damage. I then continued to drill the bolt and eventually with a drift it came loose and popped out, Result.
[attach=2] [attach=3]
The center stand was cut out of the frame and will be modified or replaced in a later post.
Now I could strip the engine to see if I had a good one.
[attach=4] [attach=5]
Oil looked like caramel sauce, fingers crossed, as it was running.
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So now the engine was out I could take a look at its internals.
I had read in various posts that the threads easily stripped, so I had allowed the bolts to soak with oil overnight before attempting the disassembly.
Luck was on my side and they all came out easily with no issues ,moment of truth off came the cam cover.
[attach=1]
All looked good to me, but I am happy for your comments please. The rocker pads were clean with no pitting or damage the close up photos just show the wear lines in the surface and makes them look worst than they do visually.
[attach=2]
The bearing surfaces looked good again with no damage. So next to be removed was the cam chain, never stripped one of these so out with the manual, after some hassle I eventually manged to pull up the cam chain tensioned and pinned it in place. I had measured the tensioner are at approx. 7/8mm so I may change the cam chain on rebuild along with the balancer chain as advised by you kind gentlemen.
Cam sprocket was removed and out with the cam shaft, again it looked ok, bearing surfaces were good and the lobs showed some wear, closer examination with the camera showed some small imperfections, are these acceptable?
[attach=3] [attach=4] [attach=5]
At this point it was time to check the next know issue with these bikes, cracked head.
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The only issue I had removing the head was trying to undo the top sunken 14mm headed bolts, after breaking a 1/4 drive socket, I managed to find an old 3/8 drive socket that I could fit inside the recess and after some force it came loose and all was good, no breakages or damage threads.
The head was eased off and I turned it over to see what I had, HAPPY DAYS all looked good no obvious cracks. Even looked like a good combustion colour
[attach=1] [attach=2] [attach=3]
Now had it had a rebore?
The piston looked ok with no apparent slop although it looked oily. On cleaning I could see no marking so I assume it is original.
The bore was also very good with no steps or scoring, so it looks like I have been lucky and picked up a usable engine. ( hoping your comments don't dash this hope.)
[attach=4] [attach=5]
I will carry out the engine work New piston /Rings, Cam chain, Balancer Chain and a general good clean as part of the rebuild.
It needs the output shaft seal changing as well, not sure if this can be done from the outside or if it needs the cases split.
I will also change all the other external oil seals as I go whilst I am in the mood.
So lets get started on the rebuilding of this little classic. Lots of parts to order and find.
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As you note, it's not quite the same looking at a photo compared to having the parts in front of you.
But the cam and rocker faces show considerable wear, the right side cam profile in particular looks like its been running with no clearance as the wear is complete round the base circle. Also the oil has not been able to protect the surfaces as it should either through age or fuel dilution. There's characteristic and noticeable "pickup" from the two metal surfaces being unsupported by oil film which has given the wear marks experienced.
It's not completely trashed itself, but more hanging on with grim determination.
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I agree with Nigel, the cam looks like it's begining to break up on the lobe.
These cams are made from chilled iron, replacements are virtually non-existant and very expensive if and when you can find one. The rockers also look as though they have started to pick up due to dirty or lack of oil.
I would send both the cam and the rockers to Newman Cams in Kent, they will advise if the cam can be saved. They will weld new pads to the rockers and grind them to match. Your biggest problem though wil be getting the rocker arms out of the head. The rocker shaft is held in the head by a dowl, they are an absolute pig to get out, they will break if you do what they Haynes manual tells you to do, grind a notch in the dowl and use a screwdriver to attempt to lever them out! I found someone who spark eroded mine out called Peter Lovell Developments, he's in the midlands. He may do yours, he may not as he said mine were a real pig. He only did mine becuase another company gave me his number! He does have a website though. You can still get the dowls from Honda.
What are the cam bearings looking like in the head, if you can feel any groves with your thumb nail that's not good news either.
As for a replacement piston, see if you can get a genuine Honda piston and rings if you can, they are available sometimes. I had to use a brand called IMD, no problems at all (second time round!). Make sure you only get it rebored by someone who sticks to the Honda specifications, I learnt the very hard way what happens when so-called experts do what they think is right and not what Mr Honda designed!
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Yep, the valve gear looks a bit tired.
I notice the tappet adjusters show also signs of pitting, are the valve stem ends OK?
I've seen worse though, but I suppose it would run on a bit longer in that state if you didn't want to throw extra cash at it.
Most of my recent projects have suffered "mission creep" where I've spent much more that I intended to, and more than the bike was probably worth...
Good luck though and please keep the photos coming.
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You will have to split the cases to renew the output seal. Only buy a genuine seal from Honda, the one I had was part of a kit of seals for the engine, it tore and the oil poured out on start up, oh how I laughed :'(. I am always really careful when I put seals on, plenty of oil on the lip, make sure it doesnt turn in on itself etc and still it tore (a tiny nick but enough to allow the oil to spurt out under pressure). When I compared the genuine item next to the pattern part it was obviously inferior, the rubber was very soft.
Splitting the cases now you have got this far isn't a big deal, you can keep all the gearbox shafts in the case. You will need three hands though when you renew the balance chain as the crank and front balance shaft is in one half on the case but the rear balance shaft is in the other case, you have to feed the balance chain around all three. I did it on my own but do yourself a favour and have a couple of trail runs before going for the real thing to give you the feel of it. To make it more of a challange you need to mark the balance chain links in three places with a bit of paint to ensure the links match the timing marks on the balance shafts. It is difficult but rewarding when you get it right.
Don't forget to use Hondabond on the crankcase joint after your practice runs and when you go to join them for the final time, a very thin smear will do.
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Oh dear guys that was not the news I was expecting, thanks for your replies, this is going to be a big learning curve.
It sounds like this build could get expensive.
This bike as a project was really just to get me out of the house and the bike back and running, rather than rusting in someone's garden.
As the bike is not going to win any shows and is likely to be run very occasionally, do you think I need to get the cams and rockers done straight away? I guess that it will just get noisy over time? I will defiantly get the bottom end split and do the internal work plus piston and rings, but might hold off on the head work and do it at a later stage, thoughts please.
I have also just bought another one in blue which is in much better overall condition and is also a runner, so I will split that one at some point. I hope that if all is well with it, I will get this up to a higher standard and keep it for investment.
I will continue to collect parts and see where we get.
Again thanks for all your comments and advice.
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If it ran before it should run again albeit noisey and not at full output, only problem is you might take cam and rocker beyond repair but that shouldnt happen if plenty of good oil present
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Take the rocker cover off the one you have just bought and check the condition of the head, cam and rockers. If better than your original engine it could be a case of mix & match to get a good one, very common back in the day when these were throwaway bikes.
I think Newman Cams charged me £27 per rocker and £56 for the cam reprofile about four years ago, so allow for a £100+ spend if you go this route. Try Peter Lovell developments first though to see if he can get the two dowls out. Have a go yourself first with plenty of heat and long nose pliars, you might be lucky and they might come out, you have plenty of time on your hands and its a learning experiance so worth a try, dont give up yet, plenty of help and guidance here so plough through it ;)
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As Bryan indicates, it's been running and we've seen worse.
To separate, obviously a route through to fully fix as described by Dave with recent experience of exactly the same is the most desirable to bring it back to technical quality. In that, you've a well researched route and recommendations for suppliers too.
To run as is, if it were for me, I'd want to redress the rocker and cam surfaces to remove (as much as possible the peaks without taking off base material) just to give them better chance of stopping pickup, one material transmission to the other component, and run with some consideration in allowing for it's recognised condition.
It appears that both the oil condition was compromised, and it's run with nil clearance on one of the tappet too.
Running with clearance set at maximum tolerance should assist it's future lifing.
The oil, obviously new is going to be used. But I'd use a specific type, VW diesel specification with code 501.01 as it was formulated for their series of engines that had conventional material in the valve train along with very high loading. Essentially it coped with this by using a tightly defined oil package that's of use here. It's particularly good at avoiding this problem.
If you're not certain about cleaning the tappet and cam surfaces, I'd offer to do that if you could get them to me.
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Thanks Guys for all your inputs.
I will get a price for the reworks and go from there, as stated I am in no hurry.
I believe these bike will become in a few years the next collectable so best to invest now.
I will upload pics of the new bike once I get it, I will then get the cover off that one and see what its like.
I may have two that need repair !
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The good news is they are already becoming 'collectable' but I dont think they will reach giddy heights in terms of investment.
I rode mine to the Critch tramway event a couple of years ago just after I completed it. One of the stewards offered me £2,750 for it there and then! He wanted it because he was finding it difficult to kickstart his Vincents! Even though mine is a kickstart model he still wanted it, he really did want to do a deal there and then! I did offer to swap it for a Vincent though ;). Even £2,750 would not have come close to the money it cost me to restore it. The simple fact is if you are intending to restore it to make it investment grade you really will have to spend a serious amount of cash and you will not get the money back unless you put the bike into dry storage for 20 years! I restored my bike to ride it and to have fun on and it does that in bucket loads, it always produces a big grin as it feels like you are going fast even when you are going slowly!
My advice is to restore it, ride it, change the oil every 500 miles (it's only 1.3 litres), clean it properly and have the fun on it that it was intended for. If you make a few pennies after a few years you'll be laughing, you won't make a fortune but you would have had heaps of fun along the way :)
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Going back to the cases and replacing the balancer chain. The two photos will give you an idea how the cases can be split leaving the crankshaft and gears in the lower crankcase. The front balancer shaft is in the top crankcase half.
The second photo shows the new balancer chain fitted and its route between the two balancer shafts and crankshaft. The paint marks on the balance chain are there to ensure the timing marks are matched as it is easy to just be one link out and the balance will be all over the place!
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Thanks Guys for all your inputs.
I will get a price for the reworks and go from there, as stated I am in no hurry.
I believe these bike will become in a few years the next collectable so best to invest now.
I will upload pics of the new bike once I get it, I will then get the cover off that one and see what its like.
I may have two that need repair !
I recommend checking the splines for any backlash, on the gearbox output shaft, for the drive sprocket. Splines were completely shot on my resto project!
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Thanks again for all the reply's.
I am now in possession of the blue rs that came free with some parts I had ordered ( that what I told the wife!) again its a runner and has been dry stored. Condition wise its showing its age but oily not rusty.
I have only glanced over it quickly , but it all looks reasonable. The kick start is badly worn, which has caused damage to the peg and brake lever, wheels are painted along with the spokes, which don't look rusty so hopefully I can recover them unlike the ones I have on the black bike.
[attach=1] [attach=2] [attach=3]
So my plans are now to keep this one for another day and continue with the black one. I will use it as a reference to check for originality as I don't know if the black one is right.
My next plan is to get the engine completely stripped down and replace the worn out parts.
Piston & rings, Cam chain, balancer chain and all the o rings. Do you guys have recommendations or have definite don't buys.
Will I need to buy a cam chain tensioner? how do I tell if its worn, the chain is defiantly worn. 9mm upper limit.
[attach=4]
My first task is to remove the pins securing the rockers in place. My plan is to weld a rod or threaded bar to the top of the pin and ease it out with slide hammer or pull it out using the threads in a fixture. Fingers Crossed.
I will continue to clean up and replace where necessary all the other parts and get them stored away ready for the future rebuild.
I will update as I go.