1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Project Early 70's Honda CB250

Discussion in 'Your 250cc Projects' started by Andych, Feb 2, 2019.

  1. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    this all started when I was laying in a hospital bed after having had my left knee replaced and was trolling FB Marketplace.. low and behold.. there was an early 70's CB250 for sale at the el cheapo price of $250... how bad could it be...lol
    So fast forward 3 months and I have finally brought it home.. all the way from Dubbo
    UNADJUSTEDNONRAW_thumb_127e.jpg

    The engine is not completely in pieces but has the head and barrels off.. it needs some work.
    These little engines had 2 weak points.. cam wear.. mostly on lobes and rockers but also on cam bearings.. mine doesnt seem too bad on the cam journals but the lobes and the rockers will need to be rebuilt..
    UNADJUSTEDNONRAW_thumb_1285.jpg

    UNADJUSTEDNONRAW_thumb_1289.jpg

    UNADJUSTEDNONRAW_thumb_1286.jpg

    UNADJUSTEDNONRAW_thumb_1287.jpg

    UNADJUSTEDNONRAW_thumb_1288.jpg

    Yep.. everything needs a damned good clean.. nothing was covered and it was kept in basically an open shed.. lucky that there has not been much rain up that way..lol.

    There are plenty of other parts that I will need to source over time.. side panels.. Air boxes or filter housings I think Honda call them.. one each side of the battery box.
    The tank needs repairing and it will need a new seat.. as well as complete exhaust..
    But.. considering one in a lot worse condition (but with all parts there) and extremely rusty sold for $1650 recently I have got a reasonable starting point..
    And if I cant ind the parts I can always make it into a Cafe Racer... hahahahha... nah.
     
    • Like Like x 1
    • Love it! Love it! x 1
  2. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

    Messages:
    6,397
    Likes Received:
    4,785
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    Ohhh, NOT another good old bike made into cafe crap heap. :lolsign:
    I know you will bring this one back to life. Looks to be a 1974 CB250K5.
    The rocker faces can be reprofiled easy enough but I would be looking for a new camshaft. Seems to be a lot of bits around for these, even Risky has some spares.
     
    • Like Like x 1
  3. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    The Camshaft is a weak point on these engines.. mainly due to oil starvation due to not cleaning out the centrifugal filter...
    Having looked quite a bit last night the only camshaft I can find is on eBay from the UK and while it looks to be OK the nett cost to get it here is nearly $300... I will do some checking on refurbishing my cam for now.. plenty of time to worry about it though :)
    Yep I agree it looks to be a 1974 K5... not that it makes a huge difference.
     
    • Like Like x 1
  4. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    Scored a good condition Camshaft from the US of A for a very reasonable price (under A$100 all up) which also had the advance mechanism on it.. I am missing that as well as the points plate..
    I also have a lead on a pretty ratty looking CB360 engine that is cheap but complete so I can always rat the points mechanism from that and maybe other parts.. the only difference is the barrels, pistons and engine cases.. (for the bigger sleeves). Doesnt hurt having too many spares for these engines.
    I will slowly accumulate bits as I come across them.... :)
     
    • Like Like x 1
  5. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

    Messages:
    6,397
    Likes Received:
    4,785
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    I don't think there is any difference in the cases as it was very popular years ago to swap 350cc barrels into the 250cc cases for cheaper rego.
     
    • Like Like x 1
    • Thanks! Thanks! x 1
  6. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    Hmmm may have to look at that.. :)
    I just checked the parts listing and the upper case does have a different part number between the 250K/G and the 350 / 360K
    If I get the 360 engine it will be easy to measure anyway..different cylinder head as well
     
  7. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

    Messages:
    6,397
    Likes Received:
    4,785
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    360cc engine is a bit different. Don't think it will fit.
     
  8. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    360 and the 250G5/K5 are basically the same...I have checked the Honda parts list. It is all a bit confusing...
    The 250K5 G5 and 360K (UK) 360T (USA) share an awful lot of parts and engine design.. The G5 has this horrible Oil Slinger / Centrifugal oil filter under the clutch cover.. so unless they were serviced by Honda they were mostly neglected.. leading to oil starvation in the head... hence cooked cam lobes, bearings and valve followers.. apparently there is also a modification to the oiling system that improves the flow of oil to the head... To clean the filter regularly meant removal of the exhaust pipe.. clutch cover etc.. I am still searching for details on said modification..
     
  9. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    So a little bit to add onto this thread.. I picked up another early CB250 G5 fro down the South Coast. This guys buys / sells and parts out motorbikes.. turns out this one he bought from the Blue Mountains.. it would have been easier for me if I had seen it advertised...lol
    Anyway... it has been butchered to become a "Cafe Racer" with the rear end of the the frame chopped off and indicators fitted into the raw pipe ends... lol
    There are a few other nasty items.. the gear change is interesting.. I am not sure if I got a good picture of it..
    The wiring has been played with and the tank has been clear coated to keep the "patina".. plus there are socket head capscrews everywhere... plus "joker" style Tappet covers, no front or rear guards, instruments etc.
    The good news is.. I have all of those items on the other bike :)
    The front rim looks to be nice.. not sure about the TLS drum brake.. I might use the single disc yet.
    The Tank looks to be basically Rust and dent free and the engine has good compression so I might even try to get it running soon.. just to see how it sounds.. it might need just a quick tidy up and some paint plus changing out some of the capsrews.

    UNADJUSTEDNONRAW_thumb_132f.jpg
    UNADJUSTEDNONRAW_thumb_1330.jpg
    UNADJUSTEDNONRAW_thumb_1331.jpg
    Note the indicators in the headlight bolts... that will pass inspection....
    UNADJUSTEDNONRAW_thumb_1333.jpg
    UNADJUSTEDNONRAW_thumb_1332.jpg
    UNADJUSTEDNONRAW_thumb_1334.jpg
    UNADJUSTEDNONRAW_thumb_1336.jpg
    UNADJUSTEDNONRAW_thumb_1337.jpg
     
    • Like Like x 1
  10. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

    Messages:
    6,397
    Likes Received:
    4,785
    Trophy Points:
    1,148
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    1937 Royal Enfield 250, CF Moto 250 V5, Honda's XL250, CBR250, FT500 plus a few others.
    I'd be using this as a parts bike to fix your other one.
     
  11. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    Pretty much that is the plan... I will check this frame and if it isnt stolen or written off I might end up selling it and the left overs as a project...who knows... someone will want to do a Cafe Racer project... still plenty of tabs to grind off that frame.
     
    • Funny Funny x 2
  12. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

    Messages:
    4,289
    Likes Received:
    2,504
    Trophy Points:
    918
    Joined:
    Oct 6, 2016
    Gender:
    Male
    Location:
    Albury 2641
    My Bike:
    1987 Yamaha SRX250, Honda 1974 SL125 K1, 2022 Triumph Tiger Sport 660
    I was instructed to tidy up and sort out what I needed to keep (or throw away was the term used) in the main garage so I rearranged the 2 bikes (CB400 and CB250) and then decided to quickly pull the ratty 360 engine apart as I thought it was seized on the crank.. if so it would have been scrap.
    Once I took off the starter and then undid the remaining casing bolts the upper and lower separated easily and much to my surprise it looks to be really good.
    It will need a good clean but the clearance on the big ends feels good and all the gears look really good. The clutch plates will need replacing but all in all a salvageable motor.... apart from the head and camshaft.
    This one is probably at the extreme of the sort of wear and failure seen in the 250 and 360 engines once they changed the clutch cover design making you remove the clutch cover to clean the centrifugal oil filter... earlier 250 and 350 engines had a removable cover so you could service the filter.
    I will need to search out a serviceable 360 head or see about machining the 250 head to match the combustion chamber of the 360.. I should check to see if valves are the same size... I have a spare 250 head... might be worth a go depending on cost but the 360 heads are not cheap either.. and getting one in good condition is very hard.
    end result is didnt throw anything away.. but all the parts are now in boxes and stacked up neatly...

    UNADJUSTEDNONRAW_thumb_134e.jpg
    UNADJUSTEDNONRAW_thumb_134c.jpg UNADJUSTEDNONRAW_thumb_134d.jpg UNADJUSTEDNONRAW_thumb_134f.jpg
    UNADJUSTEDNONRAW_thumb_1351.jpg
    UNADJUSTEDNONRAW_thumb_1353.jpg
    UNADJUSTEDNONRAW_thumb_1352.jpg
     
    • Nice Work Nice Work x 2

Share This Page