1980 CB250RS Project.

[AshimotoK0]

Picked up a 1980 CB250RS Single this week. Always fancied one since I saw the restored one in Classic Mechanics a few years back. Been off the road since 1991 and spent the last few months under a tarp outside. Taken off the road  because it had burned out a valve and done 50k miles. A bit of a change for me as my latest year model bike is a '75 CB400F .. But I had to save it! 

Like most of my bikes I got the silencers before getting the bike and had these made directly by Brituro, rather than from David Silvers.  We literally chucked the bike in the back of my mates van on Thursday and I won't have chance to fully asses it until I go to my mates warehouse (where I do my painting) on Wednesday. Even though the bike comes with a spare head, in unknown condition, I bit the bullet and bought a NOS head with valves inlet rubber etc, plus a NOS cover with the rockers etc. fitted and NOS cylinder barrel. This should hopefully save me a load of grief. I picked up these bits today near Easingwold York and the seller included a surprise freebie pair of wheels and a spare seat. The bike comes with a spare set of wheels (and CDi) but I suspect that these freebie wheels are in better nick and the spokes with replate fine at home. I bought a lovely crank and gearbox/selector parts from DK but the b*ggers have lost one parcel with the gearbox bits in it It is shown as being in transit via DHL but oddly no tracking given. They refuse to discuss this over the phone and will only communicate via eBay messaging. I wanted them to ship everything together but they refused, saying one part may possibly damage the other in transit.

The great thing about this model is that there is hardly any chrome on it and I now feel confident enough to paint it myself in pearl blue original colour. Piki on here is kindly supplying the decals although I am going to paint the stripes myself.

Laverda Dave has been a  fantastic source of help to me on this model and has some spares to trade. Thanks Dave !  If anyone else has decent parts then I will pay a decent price.

I bought a late version of the parts book for £20 in fantastic condition and I hope to scan it sometime and share with others in my Dropbox links. It  covers the early and later e-start models.

Feast yer eyes on these NOS top end parts ... they don't come along every day of the week ! Cost ££££ but it's only money. Pics of the bike to follow but be warned it's not at all pretty 

[Laverda Dave]

Congratulations Ash on a very wise purchase. Those NOS parts are gold dust especially the head and rocker cover. Where did you get them, it couldn't have been eBay?
I'm looking forward to reading about the rebuild with plenty of photos👍

[philward]

Sounds a great project Ash - good luck

[AshimotoK0]

Congratulations Ash on a very wise purchase. Those NOS parts are gold dust especially the head and rocker cover. Where did you get them, it couldn't have been eBay?
I'm looking forward to reading about the rebuild with plenty of photos👍

Facebook Marketplace .. they were amongst a load of other used RS parts as a job lot but other parts sold quickly. Nobody apart from muggins here would offer a decent price for the NOS parts. I just gave him my top figure ..deal or no deal and he accepted. Cos I didn't muck him about,  I think he included the wheels and seat for free ... which was a real bonus.

[K2-K6]

Interesting project Ash, and bit of a find to get those nos bits.

[McCabe-Thiele (Ted)]

Nice bike Ash, at the Station  where I worked a young PW used to commute on her learner motor cycle.
She turned up after passing her test on this single cylinder Honda it was a 250 RS aside from splashing out on a new bike she would wax lyrical about how nippy & economical it was compared to my 750GS. It had a good turn of speed in traffic iirc methinks it had a disc brake being a strangely skinny bike for a 250 - multi valve possibly as well - it was a long time ago!

Just looked at your photo 4 valves in one cylinder. Have you taken a before photo or was it in too many parts?

[AshimotoK0]

I met the guy I got the RS from in the pub Monday night and he gave me three bags of spare parts. Evidently, he had a donor bike at one time. Some useful stuff including three cylinder heads and cam covers, CDi etc etc. They don't look bad in terms of the camshaft bearing surfaces and the rockers look OK too but two heads have one valve seat insert removed. Not sure how you would obtain and replace a valve seat but my mate Graham Curtis is bound to know. I have NOS head and covers complete anyway and that's what I will be using along with the NOS barrel. There is also a spare cylinder barrel plus the one on the bike. Among the spares were a couple of the cam chain tensioner main assemblies (evidently rare unobtainium NOS) and one looks to be in great condition and I reckon I will be using it plus a few cam-chains, one of which I suspect may be unused but I need to investigate this further to be sure. Also a set of clocks, which are much better than the ones on the bike.

We unloaded the bike at my mate Rogers warehouse today, photo'd it along side it's temporary mate .... a Beezer C15 and then completely stripped it, apart from removing the swinging arm from the frame. Removal of the swinging arm  is going to cause me problems I suspect because I think the bushes are seized...certainly the long bolt won't turn, although I haven't  put too much welly on it yet, as I didn't have a full hex impact-gun type socket where I was working today. Surprisingly none of the fasteners both on the bike and already taken off by the P.O. were chewed up and should replate fine ....  It has the hex type screws instead of crosshead JIS screws an the case covers (as favoured by Oddjob on here).

There was no air filter fitted but Mickey and his mates had attempted to make one  .

One surprise was the state of the fork stanchions.. a quick rub and they look pretty good .. I was budgeting for a rechrome but I don't think it will be needed now.

Overall, the frame looks fairly solid as the rear end was caked in grease as was the swinging arm ... I believe these can rot quite badly.
Not sure what happened to the headlamp unit ... it's probably still with the fairing in the pub blokes garage that I still need to pick up (has broken screen ... not sure what type of fairing it is ), I won't be refitting the fairing anyway or the engine protection bars. I did get the headlamp frame though, in the bags of spares and the indicators too.

One bit of damage is a crack in one of the front  alloy footrest hangers, so I need to find one or get it welded.

I got a super condition crankshaft assembly and gearbox etc from DK but they lost the gearbox and decided to refund me after 10 days. However, it was bought on my wife Cathy's eBay account and she pleaded with them for me and it mysteriously turned up the day after they were going to issue a refund.

I only found one camshaft in the spares ... One lobe has a pit and the the flanks look a bit worn but the journals look to be OK. Maybe a job for Newman cams or find a decent replacement. IMD sell a new one for just under £100, made in Japan but its for the XL250 and pretty sure that the profile will be wrong for the RS.

The bike didn't have any exhausts (he may find some once he searches harder but bound to be grotty I reckon so not too bothered if he finds or not ) but my new replacement silencers, which Brituro made me have arrived at work and look to be excellent quality and faithful repro's of the originals. I think I will get him to make me a set of downpipes, as they already make those as well.

I got a spare front wheel c/w disc  (and a front wheel from a BSA Bantam ? ) with the parts but the pair of wheels I got with the NOS cyl.head etc., as freebies, look really nice and the spokes will replate great I reckon so I will be using those. They have nice tyres too that look like they have never been used. I was about to cut them off and bin them both until I looked at the date codes, which are late 2019.


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[McCabe-Thiele (Ted)]

It will be interesting to see the project progress.👍👍👍

[Laverda Dave]

I think the seat has been recovered at some point Ash as it should be quilted with a heat welded pattern but overall it sounds and looks like you have a really decent basis of a bike there especially with the spares you have gathered. The alloy wheel rims were known to rot from inside out so maybe worth taking the tires off to check the rim. I had stainless spokes fitted to my original rims after getting them vapour blasted and the hubs blasted and powder coated gloss black. I tried to rebuild the master cylinder but it never worked properly and it proved impossible to separate the white plastic reservoir from the base so I bought a reproduction reservoir without the white plastic part. Piki makes the vinyl insert for the cast footrest hangers.

[AshimotoK0]

I stripped the master cyl last night Dave and managed to get the clear reservoir part separated and the bore on the alloy body doesn't look bad on it. It has  an O-ring that retains it and pretty tough to separate. I also got a spare pattern one without the clear plastic section in it, which looks fairly new apart from on the outside brake fluid has leaked and stripped some of the paint.
Yes the seat cover is not original. I have another seat with about half of the original cover fitted so i know what the cover should be like.
Thanks once more for all of your help. !980's bikes are new territory for me   

[Sesman]

Good luck with the build, Ash. I’ll be logging in occasionally by satellite to check on progress….something for me to look forward to.👍

[Bryanj]

When they were new and i worked at Meads we had an insurance job where some scroat undid the 2 headlamp mounting bolts a cut EVERY wire going into the headlamp.
Damn near wrote the bike off with what we had to get new plus had to make the two earth wire nuts inside as Honda couldnt supply

[AshimotoK0]

The left hand alloy footrest hanger plate is broken on this project ... lots of RH on eBay but LH hard to find.
My mate bid on one in Japan and won for 200 Yen = £1.07 

Also the air filter holder thingy is absent. Laverda Dave put me onto one on Ebay UK at £39 but before buying that one, I needed to see the P.O. in the pub on Monday to check if he still has it, as he had the bike from new. Anyway,I  found one in Japan and got my Man-in-Japan to bid on it and won it for 1,000 Yen = £5.40   . His mate is coming back from Japan in a months time and is fetching my stuff back in his luggage.

I stripped the original style Master cyl. and brake caliper and the alloy parts look serviceable so order repair kits for both and S.S caliper which have arrived already as well as two cans of PJ1 satin black paint. Mater cyl white plastic part was a bugger to remove ... retained with a rather expensive (£6) O-ring .... I also have a spare caliper with a bloomin big allen cap screw tapped into the front face ... presumably to extract the piston. Neat job but just doesn't look right. Pretty sure I saw another one on somebody's post on here recently on a caliper piston body. I also gota pattern M/cyl with the bike in good shape (needs re-painting) but not the standard CB250RS design

I wondered how DK have parts for this model but the Japanese writing on the label on the alloy hanger they have (wrong side for me)  gave away that they must also import bikes to break from Japan.

Pics of parts my Man-in_Japan got.

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[Laverda Dave]

Japan is the place to get the bits Ash if you have the contacts. They had the CB250RZ over there, the tank and side panels were pin stripped and gave it a real classic image.
There was a CB250RSA on sale at Kempton Park yesterday, 18k showing but the top end was covered in oil, looked like it had a blown head gasket, leaking rocker cover gasket and the classic oil weep from the ends of the rocker spindles. He wanted £650 for it but it was rough, full of rust below the paintwork (the paint is very thin on the tank, built to a price). As you have a complete, brand new rocker cover the spindle ends shouldn't leak but if decide to refurbish the spare be careful putting the rocker spindles back in as it’s very easy to tear the very thin O-ring on the end. Triumph unit twins had the same issue and you can use a special tool for those to seat the O-Ring without damage, probably worth making one up for the 250 as its only a bit of hollow and tapered tube.
Did you get the main stand spindle out in the end? I used heat on mine and it eventually relented. From memory I don’t think Honda fitted a grease nipple on the tube (cost cutting again) so probably worth doing when you put it back together.
The front brake calipers come up often on ebay, I dont know if it was used on another model, I think it was made by Tockio and not the usual Honda Nissin. Are the four rubber boots intact and not split, if they are you can get them in an overhaul kit.

You are making a lot of progress very quickly, it could be on the road by Christmas Day

[AshimotoK0]

The kit for the Tokico caliper came with all of the seals/dust seals/bleed nipple Dave. I just intend to use all of the NOS top end parts .... somebody has gone to a lot of trouble and expense to fit everything  to the head and rocker cover even a NOS inlet rubber and valve decompressior mechanism. I noticed there were quite a few of the Hondastyle nose fairings for sale on Yahoo Japan .. even a NOS in bag one. Mine had a fairing (not sure what style) but the PO said the screen got broken  .. he still has it and said he will dig it out  for mebut TBH I probably wont fit the fairing. Thanks again for your  kind help with this bike!