Honda CB250 G5

Lerch · L Plate Warrior Joined: 27 Oct 2008 Karma :

Hi all, this is my first project, an old g5. It had been in my pals garden for 5 years covered by an ASDA carrier bag! anyway, this is my first post, so heres a few pics. Cheers.

bmwsport · Nitrous Nuisance Joined: 25 Oct 2008 Karma :

welcome, plenty to be getting on with there! Very Happy

NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

i had a couple of these when there was still plenty of them on the road...

they came in 3 or 4 flavours that i remember, 250 and 360 G5 then there was the CJ250/360...

the G5 was twin exhaust and 5 speed box and the more common of the two styles/models

the CJ had a 2 into 1 exhaust and a 4 speed box (5th was just blanked off in them so could easily be converted to 5 speed)

there was slight styling differences between the two as well

i put 360 guts in the 250 cases back then (250 learner laws) for the extra bit of power, had to open up the mouth of the top case if i remember correctly (also did the same with the earlier 250/350 K4)

front suspension and brakes could be swapped between the K4 and G5 if needed (twin leading drum on the K4) but the fork legs would accept the caliper hanger etc out of the CJ and vice versa

i liked those old bikes and would have another one any day as a run around toy, whip off the right hand case and clean out the "spinner/centrifuge" oil strainer, change the oil regularly as it'll eat the cam and cylinder head if you don't, and those parts will be difficult to find in good condition now

check the cam chain tensioner works freely or you'll smash the roller and guides and eat your way out of the camchain tunnel (seen that happen)

the rest of the engine is almost bullet proof and very simple to work on

you decide to part with it i'd possibly be interested Smile

____________________
it ain't broke...

i ain't fixed it enough

Lerch · L Plate Warrior Joined: 27 Oct 2008 Karma :

A few more pics.......
(the g5 has a 6 speed box?) Very Happy

NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

i had a g5 and it was a 5 speed, with the worst disc brake ive ever come across, i swear the back drum was better than the front disc.

here was mine as it stood last year Very Happy

https://i58.photobucket.com/albums/g257/hmmmnz/DSCF0275Medium.jpg
https://i58.photobucket.com/albums/g257/hmmmnz/DSCF0274Medium.jpg

good luck with it... hopefully you dont have to replace too many valves,

make sure your tappets are tight, and when you do valve clearances, make sure you use loctight glue..

have fun, they are good wee bikes, if a bit prone to eating themselves,
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chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

Do the flames make it go faster?
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NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

thye k4 was an over all better bike, they were a genuine 100mph bike, unlike the g5 which tops out at around 80mph,
all though i did manage to get my knee down and grind the pegs on it Very Happy

____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

mine ate a rocker arm or 2 Very Happy

and a few tappets and a valve
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

from what i can see it's also eating the bearing surfaces Sad

____________________
it ain't broke...

i ain't fixed it enough

satelliteone · Nitrous Nuisance Joined: 08 Feb 2007 Karma :

agreed, the cam shaft needs some tlc. been running shit oil perhaps, or a comtamination in the oil.

If ya can get the cam out. clean up the bearing surfaces. Complete flush of all the oil out of that engine. Might be worth a complete strip down, see what the bottom end is like. Have you a book on the bike?
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NiteMare · Spanner Monkey Joined: 12 Sep 2008 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

yeah the top end is definitly a weak point,
its just that the cam eats it way though the head,
although the pics above look bad, it wasn't that, that caused me any problems, it was the valve stems kept breaking, along with the rocker arms,
not a huge deal, but a pain in the arse thats for sure,
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

Lerch · L Plate Warrior Joined: 27 Oct 2008 Karma :

How do...........
Ive just tried to turn the engine over using the kick start and it jams up???
It moves freely when the clutch is engaged and the crank turns freely,
I'm pretty sure the kick start mechanism is all correct.
Any ideas??
Cheers.
Tom.

MaybeGuy · Super Spammer Joined: 12 Mar 2007 Karma :

Lerch · L Plate Warrior Joined: 27 Oct 2008 Karma :

Gettin there.....

Big Rab · World Chat Champion Joined: 20 Jun 2008 Karma :

I had one of these in 1975, the 250g5 model.
The 360 was a better engine with a bit more power.
Looks like you are doing well with the restoration Thumbs Up

Lets see it when its done.

Rab