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1994 Honda CB250

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merryck
Derestricted Danger



Joined: 11 Jun 2011
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PostPosted: 16:54 - 11 Jun 2011    Post subject: 1994 Honda CB250 Reply with quote

Hi all,

New to the forum, new to biking on the roads, on my third Honda.

The first was a 50cc Express, the second a 185cc scrambler of unknown origin. The third is a 1994 250CB, oh what fun it is.

Basically I rode it to it's MOT last week and have never seen **Dangerous** printed on a fail certificate. It failed on the chain being too tight, the headlight being loose, the brake pedal switch not turning the light on and what was the other one? Oh yeah, nothing big, steering was just a bit loose...

Good fun. Sad

While i was riding it over there I realised that it wouldn't go uphill easily. I had it in second gear with the clutch half in trying to get up a hill at 20 and it would only get up to 50 downhill. It felt like a blown head gasket would in a car..

My question is thus. The bike was free, and I can't afford to buy a decent one but I can do most of the work myself. Is it worth doing this bike up? Is the power loss a common thing with these engines? Am I looking at a new engine or just a rebuild, or is this just how powerful they are?!

I know you can't answer very easily without looking at the engine etc. but if there's some fault with CB250's whereby they become crap at 35,000 miles then I'd rather know now before I sink a load of money into it!
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Moo.
World Chat Champion



Joined: 11 Jan 2009
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PostPosted: 18:09 - 11 Jun 2011    Post subject: Reply with quote

To be honest, doesnt sound like it would be too costly..

Tight chain.. take it off, wash it in parafin, and lube it in old engine oil, stick it back on and tighten it up till theres about 1.5cm up and down play.

Headlight.. just tighten up the side bolts..

The brake light, theres a big spring that returns the pedal, and a little spring that turns the light on when the pedal is pressed down. Is this still attached? If not, pull it back round the big spring and it should work.. if not the switch might have gone.. (i might have one somewhere..)

Steering.. did he say the bearings were gone? Or just loose?

Might be worth picking a manual up for it, or looking for a free one on the net Very Happy

Power loss.. is it smoking or anything? Bogging down? Air leaks? Or any oil leaks?

If its smoking, rings could need replacing, bogging down, could be something in the carbs.. Need a bit more info Very Happy
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Teflon-Mike
tl;dr



Joined: 01 Jun 2010
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PostPosted: 20:01 - 11 Jun 2011    Post subject: Reply with quote

1994 CB250 is actually a Benley. Honda had a wibble with the badging! Anyway, its the CD / CM engine, and it ought to have a single 26mm carburettor, which along with a restrictive two branch inlet manifold, and soft camshaft is why they don't make much power. Book, they make I think 19bhp, only a tad over current Learner-Limit.

Though 50mph sounds a tad poor.

Headrace bearings, about £25 if you need to replace them. If that bad, probably worth it.

Rest sounds like adjustment & lubrication.

Motorwise.... ? Question ? Question ? Question

Pretty tough lumps. Most likely carburation / exhaust. Ignition is fixed CDi system normally pretty reliable.

Start by doing service items, from the manual.

Change the oil: Pull the primary drive cover off and clean the oil strainer.. (there's no filter) again, another item oft never touched. (Thread on her by my O/H on how to do that one if you use search). One of the few things that can 'kill' a benley engine, letting them starve of oil, and first rule when you get one, this.

Next; Cam chain is not self adjusting, and adjuster is 'hidden' under inlet manifold. Possible its never been touched! Do the tappets at the same time.... while the rocker cover off, give the camchain tensioner blade a 'rattle' as you adjust tensioner, to make sure its not 'sticking'.

Clean / replace spark plugs.

See how that helps.

If not hugely better, then pull the carb strip & clean, pull the fuel hose, and blow through / replace, but important one, pull the fuel tap out the bottom of the petrol tank, clean tank out and make sure tap and the fuel filter on the pick-up pipe are free of silt and sludge.

Functionally, they are a useful, post test 33bhp restricted licence 'commuter' bike. Not exiting, but they are economical. Value wise, they don't often fetch very much money... as proved by yours being a gift. Occasionally seen a Dealer manage to punt one for around £800ish, though top book is more reasonably around £500 for a 'good' road worthy bike in serviceable condition.

If you completely overhauled everything, new rear shocks, swing arm bushes, steering bearings, fork seals, brake shoes & pads, new brake hoses, new chain & sprockets, bit of engine work, maybe some new exhausts, you could spend best part of a grand... picking the important stuff, realistically you'd have to try hard to spend more than £500.... BUT done have a good solid bike under you... BUT value would be from using it, and enjoying that 80mpg ecconomy...

I mean for similar work, and similar money, if you wanted to muck around fixing something up, there are other bikes that could offer a lot more performance, or be more valuable for the effort. BUT if you can get value from use, YES, worth the doing of.
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merryck
Derestricted Danger



Joined: 11 Jun 2011
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PostPosted: 22:52 - 11 Jun 2011    Post subject: Reply with quote

See this? This is why the internet is amazing.

15 years ago I'd have had to have joined a club and gone to a good few meetings before I even got half that information, that or go pay a mechanic for his time and advice!

Well tomorrow I'm going to have a play, I think the bearings do need replacing. They're not too expensive, so I might replace them for peace of mind.

The issue with the power loss, after riding it up and down a slope in my garden for a while I think it's tuning. There was power there at low revs. I'll whip off the carb and clean it up tomorrow.

I think most of it is going to be cleaning up and making it nice and tidy. I'm wavering between tearing the whole thing apart and doing a complete rebuild or just getting it tidy for the summer.

decisions decisions!

Another thing i need to do is the electrics, They're a bit untidy as at some point someone has cut off all the plugs from in the headlight. Had to rewire all that bit already. eurgh.
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thomp1983
Crazy Courier



Joined: 05 Feb 2011
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PostPosted: 23:34 - 11 Jun 2011    Post subject: Reply with quote

get it tidied up and ridden, the summers short enough as it is without shortening it with a full rebuild, patch it through the summer enjoy it then rebuild over the winter

chris
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Teflon-Mike
tl;dr



Joined: 01 Jun 2010
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PostPosted: 12:29 - 12 Jun 2011    Post subject: Reply with quote

HOW2: change Oil & CLean strainer (Small Honda's +)
HOW2: Overhaul Clutch (Small Honda's +)
HOW2: Make a Cornflake Paket Gasket!
How2: Fit Head-Race Bearings - Photo-How-To
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Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'
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nighthawk250
Renault 5 Driver



Joined: 26 May 2011
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PostPosted: 10:02 - 29 Sep 2011    Post subject: Reply with quote

The original steering bearings are imperial ball bearings, should only cost a couple of quid, I replaced mine, retaining the existing cups and everything was fine.
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pepperami
Super Spammer



Joined: 17 Jan 2010
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PostPosted: 16:58 - 30 Sep 2011    Post subject: Reply with quote

Teflon-Mike wrote:


These are VERY good Thumbs Up Thank you Mr TM and mrs ST Thumbs Up
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chris-red
Have you considered a TDM?



Joined: 21 Sep 2005
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PostPosted: 17:06 - 30 Sep 2011    Post subject: Reply with quote

Moo. wrote:
To be honest, doesnt sound like it would be too costly..

Tight chain.. take it off, wash it in parafin, and lube it in old engine oil, stick it back on and tighten it up till theres about 1.5cm up and down play.

Headlight.. just tighten up the side bolts..

The brake light, theres a big spring that returns the pedal, and a little spring that turns the light on when the pedal is pressed down. Is this still attached? If not, pull it back round the big spring and it should work.. if not the switch might have gone.. (i might have one somewhere..)

Steering.. did he say the bearings were gone? Or just loose?

Might be worth picking a manual up for it, or looking for a free one on the net Very Happy

Power loss.. is it smoking or anything? Bogging down? Air leaks? Or any oil leaks?

If its smoking, rings could need replacing, bogging down, could be something in the carbs.. Need a bit more info Very Happy


1.5cm is too tight for most chains, most say at least 2.5cm and my TDM says 5cm. Taking it off to clean it is overkill IMO.

What is too costly about it everything he listed could possibly be fixed for nothing.

Loosen off the chain, tighten the steering head bearings, tighten the headlight adjust the brake light switch. Power loss could just be a gummed up carb.

IMO you should give it a full service, new filters oil plugs etc. check the valves cleaner the carbs grease/loosen/tighten everything and it may well be fine.
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