Honda CBR 125 - ASBO Therapy

[Fozzie]

Well, my cheap as chips CBR125, 2006, written off, had a good reason to be so cheap.

 

 

Aside from an obvious crash. It's littered in cheap Chinese tat, the bodywork is near as non-existent as it all needs replacing. The tank is particularly battered, I've dredged better condition fuel tanks from the bottom of the sea. You can hear the fuel sensor rattling about inside. It starts, but there's a weird "tickity" rattle noise that is irregular, I'm hoping cam chain tensioner, but already the engine will have to be stripped for a full inspection. 

 

I've offered this option out to another group I'm in. What should I do? Money no object, it's a 125, worst case I'll probably still make back more than half the build cost, and I don't do personal projects like this for profit. 

 

1. Convert it to a streetfighter. Probably throw a big bore kit on it and make it a yobos dream... That they can't insure or ride legally.

 

2. Nut and bolt full resto, keep it clean. Restore old parts where possible, buy new where I have to, make it a minter. 

 

...Feedback welcome... 

[Guest]

I vote 1. Or a new option 3 turn it into a an Uncle Bunt style chopper. 

[Fozzie]

Interesting choice! So far option 2 is edging it, but it's early. 

 

Option 1 interests me as I like doing engine work. It's my favourite "bit" of a project, and making something faster than stock appeals. Option 2 is basically as I feel really sorry for this bike, it seems to have had a senseless (teen) rider who had as much mechanical sympathy as a modern politician morals. So tidying it up into a fresh bike appeals. 

 

 

[John]

I’d say #2. At least you would stand a better chance of clawing back some of your investment with that option.

[GojuRyu5]

I’m always in the option 2 camp on such matters @Fozzie.  Maybe it’s a similar feeling of sadness for a once popular starter bike for someone that has since fallen on hard times, but the old boy almost deserves a chance at being great again.

Edited August 8, 2023 by GojuRyu5

[Fozzie]

1 hour ago, GojuRyu5 said:

I’m always in the option 2 camp on such matters @Fozzie.  Maybe it’s a similar feeling of sadness for a once popular starter bike for someone that has since fallen on times, but the old boy almost deserves a chance at being great again.

 

I had a vote on another group and option 2 won. Which I didn't expect, and was partly looking forward to making some street fighter bits. And breaking out the fibreglass kit.

 

I will do an update when I can, I've stripped the bike back quite a bit. I also got very lucky and bought a frame with a V5 from the same year, and only 2000 miles less showing on the last MOT. The engine had a rattle, which was just the cam chain tensioner, but it feels a bit lumpy. I ordered a full set of bearings to rebuild the engine, but they are long lead items (6-8 weeks). Fortunately parts are cheap, so I've ordered quite a bit, and got a new old stock fuel tank, and a couple of fairings that were in mint condition. It's going to be blue at the end of this process. 

 

I'm about £800 into it so far, and trying to keep it below £1500 as that's where the resale value likely will be. I'm a bit uneasy with selling it, as I worry some yobbo will buy it and thrash the living daylights out of it. I remember being 17, and you could really tell the difference between those who paid for their bikes and the maintenance, and those that had the bank of mum and dad. It was really reflected in the condition of the bike after 6 months!

[GojuRyu5]

Sounds like you’re well into it already @Fozzie. I wish new old stock parts were quite as available on my 1980 project, but I’m managing. The blue sounds like a good choice; very striking colour for a bike.

 

I know what you mean about 17yo newbies. It’s the pointless / cheap modifications that you’re now battling with that are frustrating. All a bike really needs is a regular clean and maintenance to protect its value to make it easier to move to something more enticing as your skill develop. But what 17yo ever made a rational choice in such matters?!?

[Fozzie]

With my Kawasaki project in its last few bits to be road worthy, I need to raise capital for the next phase of those works where I convert it into a scrambler. I probably shouldn't have bought this, but I was slightly inebriated during a break at a Hans Zimmer concert in Manchester, and thought I was getting a cracking deal. I'll probably make back what I put into it, even with restoring it back to stock. 

I've so far sourced an old new stock fuel tank (still in the Honda original packaging), a tail fairing, and two trim fairings. I only spent £150 for all of that, and some mechanical bits, so the bike only owes me £800 currently, and arguably some of the biggest bits are out of the way. 

 

The source of the rattle was easily solved. Just the cam chain tensioner, a £17 fix. But when I dropped the oil, it was just below the low mark, and it's quite obvious an unsympathetic teen owned this last. So I'm going to crack open the engine and have a look. I can live with the top end being worn, but if the crank is gone in addition it will get pricey and stall the job for a while. 

 

Fuel tank came off easy enough, a single bolt, 4 hoses and a fuel sensor connector were dealt with easily.

 

Platform lifts are ace for shifting engines out. I'll be stripping the bike down to bare parts and throwing out what I don't need going on. I destroyed the main cable for the starter though, it wouldn't come off the post. So I zapped it with the gun, and it took the nut off... Also twisted and frayed the cable. I will probably just make another length up, and better insulate the new one. 

Took me a few hours to get to this point, good thing engines are light. I'll be stripping it down in the week sometime and taking the required measurements. As I've bought all major bearings for the engine, if this engine is a bad egg, I'll try to buy good bits from other engines first. I'm definitely stripping the paint and repainting this engine on the rebuild. Fresh clips/hoses as well.

[Fozzie]

Forgot to mention, how do you make a written off bike... Not a written off bike? 

 

You buy a clean frame that comes with a V5. It feels a bit dodgy to do this, so my justification is that the bike and all its mechanical components will see attention that will hopefully leave it in the top 2% of condition against its age and mileage. I will be riding it for some time after the MOT to check there's no teething issues, or any ongoing problems before it is sold. 

[RideWithStyles]

Per

Edited May 14, 2024 by RideWithStyles

[Fozzie]

I've got the V5 for the other frame now, so will swap the engine details and new colour (Blue) onto it. The blue models were actually the least sold colour, but they are also really popular now when they come up on eBay... So will see if this gambit boosts value. 

 

I agree with it having a patina, as long as it's not deep scratches, I'll have it! I'll be doing as much as I can to restore the other components on the bike. Swingarm is a bugger, if the bushings are knackered they aren't replaceable. You need to buy a new swingarm! It's only £150 but bushings would have been what, £15?  

[Fozzie]

Mixed news. 

 

I've measured the crank big end gap, I'm not sure it should be measured in the bike like this. I'm pretty sure it needs to be removed as the crank bearings are pressed into the engine casings, which are in turn pressed and torqued down. So I'm going to slowly pull the engine down to the bare components, and measure it all. But initial reading was 0.3mm gap, the book says I should be seeing 0.4-0.65mm with a max service limit of 0.85mm. Has anyone got any possible narrative on why the clearance is tight? Absolutely no radial play though, which is promising. 

Scuffed piston skirt... Oh dear. The oil level was low. Poor lubrication?

Oh dear oh dear... Nice even cross hatch apart from this face. I know single cylinders have uneven combustion forces, which can contribute to this. But 20k miles? I've ordered a new top end. 

Deep gouges in the cam. The bearings feel ok, but a little rough. Also to be replaced for an all new item. Weird, the valve rocker for this cam lobe was chewed up badly too, the other one is fine. So either the valve clearances were done poorly, or the clearance tightened. Again, insufficient lubrication could have played a part.

 

I've bought enough bits, and paint to refresh the entire engine now. I have all bearings, a top end is in the post, and all other components. I will need to spend a good day taking the engine down to its basic parts, measure up everything that needs it, and repaint the thing as well. Once together and oiled, I'll spin it up on the bench with a drill to make sure it's all spinning freely and in time. Then steadily rebuild the bike with the new frame, will take the chance to rebuild/repaint the forks, and all bearings for the wheels and so on. Always on the look out for the remainder of the bodywork in good condition. 

[RideWithStyles]

Yep

 

Edited May 14, 2024 by RideWithStyles

[Tinkicker]

It's been thrashed from cold and suffered multiple ring seizures.

[Fozzie]

Its been a minute, life has been a bit busy. My other project took priority in the second half of last year, and this year so far I've been able to do very little due to work pressures, and also saving up frantically for a house and last holidays before I lose the fight with my partners body clock :lol:

 

So I've broken down the bike into its basic pieces, disposed of the old frame as I have a new, non-write off one. My garage is small, and a bit messy, but coordinated chaos as I like to call it. 

 

 

Good thing with small engines... Easy to take apart, it took maybe 90 minutes to get here. Fortunately I had the right special tools for various bits. 

I gave it all a very good clean first. All the grime on the outer casings was removed before disassembly as it reduces the chance of any getting into places I don't want it going forward. The lower section of the engine is in good order, the crank I need to get looked at, the conrod looks a little worn on the faces that meet the gudgeon pin. I suspect slight oil starvation still.

I need to recheck the crank tolerances, as I'm hoping the casings were simply pressed together too tight and gave a false reading. But I'm expecting to need to send it off for a new rod, bearing, and being trued up. I've got a new cylinder and piston, as well as camshaft and all associated gubbins. Also have a full set of bearings for the cases, so I should be ready soon to build the engine back up, good as new. And with a fresh lick of paint. 

[Tinkicker]

For your crank rebuild, I would recommend PJME in Wolverhampton.  They have a very good reputation.  They specialise in two strokes, so are very experienced in rebuilding pressed together crankshafts.

[Fozzie]

Been a minute since I've updated this. But a lot happened.

I sent the crank off for reconditioning. New big end roller bearing, and new case side bearings. The chap called me to say he'd done a few of these before, and they aren't very well designed. They were meant to be thrown away and replaced, not reconditioned, so he did his best but there was some distortion. The picture directly below shows the damage, and while the distortion is only 2mm or so, it was enough to stop the engine sitting back together. 

I ultimately ground off the raised lip, which I didn't like doing, but there was no other viable crank I could buy online to replace this one. Then I discovered, even with this issue resolved, the engine wouldn't slot back together. 

I could write an essay here, but after several hours of trying, going away, thinking, coming back and trying various other methods, I couldn't do it. The new bearing, freshly pressed on won't fit inside the left hand casing. The cases came apart relatively easily but in the end needed a 10 ton press to get the new one back in. I checked all numbers on the bearings, and it was correct, and when measured with a micrometer, was dead on. But the casing? Too tight, and I have no idea why. Researched the engine numbers, made sure the right part was bought, and all signs pointed to "All parts correct". Contacted those who raced these, and got some indication that these engines can be difficult (but nothing conclusive). So I chose in the end to give up on it. And buy another engine... I won't share all the outer casings that I painted, I was so annoyed.  

 

The new engine has 35k on it. I worried it would be more worn than the 20k one I had. But, rather happily, it was spotless inside. Apparently owned by a careful owner for its life. I was doing a teaching session with a young lad, so I didn't get many pics, but here is the "after" picture and me replacing the top end and cam shaft/rockers, as I had them anyway. 

 

All done and dusted. 

Fresh camshaft, but old one shows little wear. 

Full assembly, with new rockers.

rings installed, all ready to go back together.

Fresh cylinder, cleaned and oiled the bore before install.

Valves timed up. Old piston also seen next to engine, looks in good shape and it appears original to the bike. Turned it all over a number of times. And no problems. 

 

I've just ordered some rust treatment for the frame, some paint to cover the bits that no one sees (but I want to seal), and I plan on installing what bits I have currently. Wheel bearings, steering stem bearings, and fork seals. Then I'm putting it back together and trying to do the minimum to get it started. If the engine runs sweetly, I will progress, if not, project over, I'll be selling it as a project as I've gone over £1000 into it now. It won't be worth saving if this engines bottom end/gearbox turns out to be knackered. 

 

Edited September 9, 2024 by Fozzie

[peepae]

What did you pay for this bad boy originally?

[Fozzie]

Got it for just shy of £400.

Confirmed it ran, and sank another £400 into it thinking it wasn't likely to cause my issues, then had to get the second hand engine and gets it to £1050 currently. Not including sundries though. 

 

In theory, if I get it done up for £1500-2000, as it's on a fresh frame (no write off) it will possibly pay for itself back.