Author Topic: Early 70’s CB250  (Read 924 times)

Offline AshimotoK0

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Re: Early 70’s CB250
« Reply #15 on: November 03, 2018, 08:58:03 AM »
Member who were around when they first came out  can wax on all day long about them but take it from someone who sold one recently and sold a lot of spare parts ....  in recent years ..... that model is VERY popular. My biggest criticism is that Honda, in their wisdom, omitted  to include a removable plate to gain access to the centrifugal oil filter. This meant removing the exhaust and complete clutch cover to do a routine maintenance job and I guess the average owner, if best,  changed the oil but couldn't be bothered with the hassle of cleaning the filter. I reckon if you rebuild it properly and fit the later modified cam chain tensioner it will a decent project Andy.   
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Andych

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Re: Early 70’s CB250
« Reply #16 on: November 03, 2018, 10:54:55 AM »
Thanks Ash
Yes, the plan is to maintain it to the highest standards etc...and the beauty of forums like this is the knowledge in here to know what needs fixing / modifying or weak points to ensure I build a reliable bike to have some fun with...
1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Bryanj

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Re: Early 70’s CB250
« Reply #17 on: November 03, 2018, 12:00:32 PM »
You are correct Ash, it todays world a nice one will be looked after well and be a good thing but we all remember the lemons from our working days and as they say hindsite is the only perfect science!!

Offline Andych

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Re: Early 70’s CB250
« Reply #18 on: November 22, 2018, 08:44:17 PM »
Still havent been able to get up to where the bike is to collect it.. apparently I am not supposed to be driving long distances at the moment.. something to do with the Pain killers or some such rubbish...

So I have been slowly planning how I will go about this sorting this bike.. which is a bit tough as I dont know the build date / Vin number or condition other than the pics I have posted but... I had in my mind a nice rebuild...certainly not a nut and bolt restoration... and then someone posts a pic on FB of an absolutely gorgeous CL350 in a Candy Red with a wicked high mount exhaust and it gets me thinking.. hmmm how would it look with a CL style high mount exhaust.. retro road / trail tyres and high rise CL style bars?
Hmm maybe it is the drugs...lol But the 70's CL350's are a lovely looking bike.. and I am not sure there is too much difference.. visually anyway.. I wouldnt be worried about lower first gear etc.. just how it looks.
1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Andych

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Re: Early 70’s CB250
« Reply #19 on: February 01, 2019, 07:29:00 AM »
I have finally been able to organise myself into driving 500 odd km to pick the bike up and another 500km back.. apart from breaking a strap early and having to jury rig the broken bits for 20km until I could buy another couple of straps it was fairly uneventful..Having looked over it when I was picking it up I was a bit confused with what I had actually bought..
When I looked for a VIN Tag there was none.. I am not sure what year Australia started to require VIN tags.. but there definitely isnt one on this bike nor any sign of one being there previously.. and.. I know that a couple of other CB250 G5's all have the G5 in the VIN code.. which matches up with the parts book to some extent.. at least for European Direct bikes.. there is nothing about General Export G5 nomenclature other than G5 and K5 Frame and Engine numbers run the same sequence so the G5 in the VIN would make sense..

From what I can gather... I have bought a CB250 K5.. deduced mainly by the Pilot light block as well as the twin leading shoe drum brake.. It appears the tank is also the same for both for General Export..
This is all in a very quick look once I got home.. so I could also be completely wrong.. not that it maters much at this stage.

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1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline AshimotoK0

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Re: Early 70’s CB250
« Reply #20 on: February 01, 2019, 09:01:08 AM »
I think your bike is possibly a CB250G  (the G5 was disc braked). My understanding is that the the old K series bike with disc was the CB250K5 or CB250B in Germany. Could be wrong but as you say ... just enjoy the restoration. That bike was a very early version of the 'G' engine so will have the early problematic  cam chain tensioner issues. I think Common Collective sell a repro of the later modified camchain tensioner.

https://www.common-motor.com/honda-360-engine-transmission
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline billy192

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Re: Early 70’s CB250
« Reply #21 on: February 01, 2019, 12:24:39 PM »
yes its a G5 but as Bryan said change the oil reguly and clean the funny filter and it will run and run. i have done many K on mine with happy smile.

I think the front wheel is not the correct one and as alway high bars from USA. David silver has loads of new spares for these.

Billy
Thanks
Billy

Offline AshimotoK0

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Re: Early 70’s CB250
« Reply #22 on: February 01, 2019, 06:27:50 PM »
I think the front wheel is correct and its a G model not a G5. I bought a 350G front drum brake plate from the States for one of my CB250K0's and it had the 369 part number printed inside ..the only difference between it and the earlier K series was a little arrow cast into it for the brake wear indicator
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline Andych

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Re: Early 70’s CB250
« Reply #23 on: February 01, 2019, 11:18:40 PM »
Thanks for the info.. with no background on it and no VIN tag stating the age of the bike it is a bit hard to properly identify it.. I will trey through the Motor Registry at some stage and see if they have any info..
For now it will go into hibernation next to the CB400 while I finish the little Yamaha SRX 250 / 350 hybrid.. hopefully not too long though, both the 400 and the 250 are longing for some loving...:)
1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Andych

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Re: Early 70’s CB250
« Reply #24 on: February 02, 2019, 08:31:49 AM »
I had the chance today to have a look at the engine parts that came with the bike.. the bottom end turns over ok with no resistance so it will have some oil tipped in and covered up for now.
I really wanted to have a look at the head and valve cover to see how bad it may be... hmmmm.

While everything is pretty grubby and gritty form being in an open shed in the NSW Country (worst drought on record right now) the camshaft is in a bad way.. the bearing surfaces are not too bad (will need to check dimensions and clearances) but the lobes are in a bad way.. as are the rocker arms.. I am not sure how the back of the lobe gets to be so discoloured.. almost look likee its from heat and the tops of the lobes are quite worn and pitted.. so this camshaft will need to be reworked (welded up and re-ground) as will the rocker arms.

I will pay particular attention to the oil pump when I get to that stage and also the cam tensioner.. I see this engine uses a very similar system to the CB400.. does the cam chain tensioner arm suffer similar issues to the CB400 item?
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1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Bryanj

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Re: Early 70’s CB250
« Reply #25 on: February 02, 2019, 10:10:23 AM »
Thats the start of an oil starvation problem

Offline Andych

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Re: Early 70’s CB250
« Reply #26 on: February 02, 2019, 08:58:06 PM »
Yes...its not looking good is it.. there doesnt seem to be too much around in the way of parts for these either..
There is a good looking camshaft on eBay but it is from the UK and pretty expensive.. or is that the going rate for a good one?
https://www.ebay.com.au/itm/1975-Honda-CB-360-250-CB360-CB250-G5-T-engine-camshaft-cam-shaft/352458634331?hash=item52102bf45b:g:ZYYAAOSwRolbj8UT:rk:1:pf:1&frcectupt=true

I will have to check around and see what can be done with mine.. it will probably be cheaper to have it repaired.
1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Bryanj

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Re: Early 70’s CB250
« Reply #27 on: February 02, 2019, 10:00:15 PM »
Problem is they are rare now due to being thrashed to death by inconsiderate UK learners!possibly US for 360 G5 or 360T

Offline Andych

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Re: Early 70’s CB250
« Reply #28 on: February 14, 2019, 12:24:23 PM »
Well, I am glad that the CB360 is basically the same engine.. I managed to pick up what looks to be a really nice Came out of the USA which should be here in the next day or so. All up I paid around A$95 to get it here.. and it can with the advance mechanism as well.. the lobe look pretty reasonable as well as the end bearing surfaces.. the centre bearing surface is a little manky but I will check it out properly when it gets here... plus I am not sure on how good the running surface is for the bob-weights.

I also scored an almost complete CB360 engine for spares.. it isnt in real good condition by the photo but for A$10 plus $32 freight to get it here from Victoria I cant dont think I can lose on it..
The engine arrived today and this evening I ripped the rocker cover off to see if I bough a bunch of scrap metal or not...
Before I even pulled it apart I had well and truely covered my cost.. this engine had a Points cover and points backing plate.. those items alone are over A$120 second hand.. and I think the points plate is over $50 new as a pattern part.

With the rocker cover off.. I had more or less struck gold. The cam looked wonderful, other than the centre bearing.. but it may just be dirty and greasy.. the lobes look to be in great shape.. if so I could have a good spare camshaft...lol
The other bonus is that the rocker arms are really good.. so even if I scrap the rest.. I am well ahead.
The USA Camshaft
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$10 engine opening up
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1975 CB400 - Project
1978 Yamaha SRX250 - Project

Offline Andych

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Re: Early 70’s CB250
« Reply #29 on: February 14, 2019, 12:28:32 PM »
A couple more pics..
I also scored a timing cover in really good condition.. just needs a good polish and the black paint refurbed :)

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Another view of the $10 engine top end

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1975 CB400 - Project
1978 Yamaha SRX250 - Project