Author Topic: CB250Rs Rebuild  (Read 4373 times)

Offline MRA464

  • Newbie
  • Posts: 14
    • View Profile
CB250Rs Rebuild
« on: January 19, 2021, 01:01:34 PM »
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.
« Last Edit: January 19, 2021, 01:28:04 PM by MRA464 »

Offline Skoti

  • SOHC Expert
  • Posts: 320
    • View Profile
Re: CB250Rs Rebuild
« Reply #1 on: January 19, 2021, 01:14:19 PM »
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
« Last Edit: January 19, 2021, 04:31:13 PM by Skoti »
Motorcycling is Life, anything B4 or after is just waiting...


1976 Honda CB750F1

Offline cooleronthecoast

  • SOHC Expert
  • Posts: 307
    • View Profile
Re: CB250Rs Rebuild
« Reply #2 on: January 19, 2021, 03:35:05 PM »
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.
Now where did I put that 10mm socket?

Offline K2-K6

  • Grogu
  • *
  • Posts: 5236
    • View Profile
Re: CB250Rs Rebuild
« Reply #3 on: January 19, 2021, 03:52:06 PM »
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.

Offline UK Pete

  • SOHC Jedi
  • Posts: 2696
    • View Profile
Re: CB250Rs Rebuild
« Reply #4 on: January 19, 2021, 08:15:48 PM »
I loved my one, very good little bikes,  well loved by despatch riders

Sent from my SM-G950F using Tapatalk


Offline MRA464

  • Newbie
  • Posts: 14
    • View Profile
Re: CB250Rs Rebuild
« Reply #5 on: January 21, 2021, 12:50:36 PM »
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.

[ Guests cannot view attachments ]

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.

[ Guests cannot view attachments ]

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.

[ Guests cannot view attachments ] [ Guests cannot view attachments ]

The rear end parts piled up and I was soon ready to start the front.
[ Guests cannot view attachments ]

More to follow.







Offline Laverda Dave

  • SOHC Jedi
  • Posts: 2531
  • Health is wealth
    • View Profile
Re: CB250Rs Rebuild
« Reply #6 on: January 21, 2021, 05:15:38 PM »
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.
 
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

Offline Spitfire

  • SOHC Master
  • Posts: 1769
    • View Profile
Re: CB250Rs Rebuild
« Reply #7 on: January 21, 2021, 06:55:23 PM »
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
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8206
    • View Profile
Re: CB250Rs Rebuild
« Reply #8 on: January 21, 2021, 07:11:22 PM »
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.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Laverda Dave

  • SOHC Jedi
  • Posts: 2531
  • Health is wealth
    • View Profile
Re: CB250Rs Rebuild
« Reply #9 on: January 21, 2021, 09:19:26 PM »
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!
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

Offline MCTID

  • SOHC Pro
  • Posts: 608
    • View Profile
Re: CB250Rs Rebuild
« Reply #10 on: January 21, 2021, 11:33:32 PM »
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.
Now: 2008 CB1300S, CB750K4, 1970 Bonneville. Various other 1960's 650 Triumph T120's/ TR6's/ TR6C's (all in bits...many, many bits unfortunately). Previous: 2007 CB600FA, 1976 CB500 Four. BMW F800ST. GS750E. ZZR1100. CB1300 (2). ZXR1200S. VFR800. CB750 Nighthawk. CX500. XS500 Yam. Suzuki GT500. BSA A10. Various Lambrettas. Zundapp Bella (honest).

Offline MRA464

  • Newbie
  • Posts: 14
    • View Profile
Re: CB250Rs Rebuild
« Reply #11 on: January 25, 2021, 02:49:20 PM »
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.
[ Guests cannot view attachments ]
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.
[ Guests cannot view attachments ]
Forks show pitting and chrome damage, we will look at the damage once cleaned.
[ Guests cannot view attachments ]
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.
[ Guests cannot view attachments ]
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.
[ Guests cannot view attachments ]
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
« Last Edit: January 25, 2021, 02:54:47 PM by MRA464 »

Offline Bryanj

  • Grogu
  • *
  • Posts: 10695
    • View Profile
Re: CB250Rs Rebuild
« Reply #12 on: January 25, 2021, 03:07:48 PM »
The extra wire is an earth for 3 terminal flasher can, as for intake perhaps modify something like 400 four

Offline Bryanj

  • Grogu
  • *
  • Posts: 10695
    • View Profile
Re: CB250Rs Rebuild
« Reply #13 on: January 25, 2021, 03:19:31 PM »
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

Offline Laverda Dave

  • SOHC Jedi
  • Posts: 2531
  • Health is wealth
    • View Profile
Re: CB250Rs Rebuild
« Reply #14 on: January 25, 2021, 04:23:35 PM »
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.
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal