Honda Helix CN250

[Jimo]

It’s been a while since I renewed clutch and rollers on my Helix, the main problem left is to eradicate the horrible vibration at all speeds on the road - also while on the centre stand, I thought it likely to be the engine hangar bushes or such so have a good cond unit got from the States - where else? BUT the bike has been standing (fortunately on the lift platform) for about a year while I got partly sorted out at hospital (Bladder Cancer ! ) I started the CN yesterday then noticed it had bled most of its new oil onto the lift platform, quite obviously the crankcase is leaking oil somewhere so it now becomes a complete tear down to sort the probs..... next thought is to replace WHOLE ENGINE with oil tight working unit! ???

If I can find one, any offers or suggestions would be appreciated....because at approaching 83 combined with medical probs I’ve lost my appetite for stripping engines, but I don’t want a LEAKER!

Jim

[Deleted User 4154]

My experience of the CN motor is that they rarely leak oil, Jim, even when completely knackered. If yours has expelled that much then there must be a pretty fundamental problem IMO. It also concerns me that you say yours vibrates at all road speeds - my experience has been that there's a very narrow band of vibes over 2-3mph somewhere between 45-55 mph. This seems to be borne out in conversations I've had over on the American Helix forum. Unfortunately, this does all suggest that there's something badly wrong with yours... sorry to be the bearer of bad news.

[GrahamH]

Did the oil leak out before you started it or when it was running? It could easily be something trivial and much easier to fix than a used engine with unknown provenance. Clean and degrease the engine thoroughly and look carefully for where the oil is coming from. Once a problem is identified you are halfway to fixing it.

[Jimo]

Short of setting up camp besides the sodding thing and watching where the oil comes from at the moment I don’t have a clue except that it seems that the quantity of oil leaked is way in excess of the contents of the final drive unit - indicating that IT MUST be from the engine.... so of course I need to strip it all again to look see, because the engine runs on ball races, both shaft and big end, there is necessarily low oil pressure compared to that associated with white metal bearings, my thinking is that a previous user could have run it with low - or no oil and ruined the bearings, during my earlier replacement of clutch shoes, rollers and belt there was plenty of evidence of neglect by mr ‘Ham-fist’ most of which is now sorted..... I’ll have to strip off the Tupperware again, replenish the engine oil and watch for the leak to show, all very disheartening especially in my present medical condition! Sod it!

The vibrations come at all engine speeds while it is on its centre stand, when I last took it on the road it was noticeable at speeds of up to 50, beyond that I haven’t tried.
I’m hoping to get a stethoscope around the engine to listen for rough bearing races etc and hope something can be identified.

Thanks Jaz for your interest, appreciated.


Jim

[Jimo]

Graham, I must agree with you - if only I can locate the point of leakage, it didn’t occur when the engine was run - it was there after standing for months on the lift platform. I must also agree with you re a replacement engine with no provenance, it would be a CHANCE of course! - I’m not even sure that said action would be an easy option in my circumstances.
Thanks a lot for your interest, I appreciate it.


Jim

[Deleted User 4154]

Thanks Jaz for your interest, appreciated.

I really hope it's not, Jim, but I really do think that vibration all the way across the rev range suggests, as you suspect, main bearing failure. It'll be really bad luck if it is, as I've come across a few horribly abused CN motors in my time and none had bottom end issues. That said, I can't think of anything else that might cause those symptoms.

As you say, the stethoscope is a good next step. Fingers crossed...

[Jimo]

Another Helix has just come up on fleabay https://www.ebay.co.uk/itm/Honda-cn250- ... 4455300140
It is off the road and open to offers, some sketchy details suggest more is wrong than meets the eye, prob go for over 1000 but seems risky, don’t think I’ll chase it, have spent too much on mine plus two new Bridgestone tires.

Jim

[Deleted User 4154]

Another Helix has just come up on fleabay https://www.ebay.co.uk/itm/Honda-cn250- ... 4455300140
It is off the road and open to offers, some sketchy details suggest more is wrong than meets the eye, prob go for over 1000 but seems risky, don’t think I’ll chase it, have spent too much on mine plus two new Bridgestone tires.

Jim

I don't think that one will make a grand; it's pretty tatty, has no MOT, caliper will need rebuilding, missing bits. If you're thinking of having a punt on it, I would ask if he still has the original carb, as the shiny new Chinese one he's fitted is a badly-made copy which would be better suited to use as a doorstop. I reckon it'll go for about 500.

[Whatsisname]

1st registered 1990, MOT date "UNKNOWN" so no MOT history. Been off the road a while then.

[Jimo]

The sun doesn’t always shine on the righteous but it has this time! After trolling the web for several weeks looking for an engine or a crankshaft yesterday my luck changed and I found an 85-88 CH250 crankshaft/con-rod assembly at a very reasonable price so I jumped at it!

The CH250 Spacy and the Helix each share a bore of 72mm and a stroke of 60mm. The CH250 Spacy (Elite in the States) shares the same vertical engine as the Helix on its early models 85 - 88, after that the CH250 used the new horizontal engine of the same 244cc capacity, this latter horizontal engine can also be found in Honda’s FES250 Foresight also believed to use the same crankshaft.

Jim