New project bike (Honda CM250C)

[OutlawStar]

Saw a listing on craigslist for a "project bike" for $425 and kinda made an impulse purchase. I was looking for a little project to get me in the garage over the winter and this may be the ticket if the weather stays colder and I don't want to ride my other bike. Its a 1982 Honda CM250C. Seller said he's downsizing his house and wanted to get rid of a few hobby projects, time will tell if he knew something was truly broken and expensive, or telling the truth. Its my first project bike and its older than me so no real electronics to mess with, but its all ancient tech and parts. Seller said eBay (yuck) is flooded with bike specific parts. I already know even in immaculate condition these bikes only sell for $2500, okay driver condition are $1500-2000. I'm not looking for a flip on this, I wanted a project and maybe something to knock around town with its silly 14 horsepower. But if I can stay within a "profit zone" on this bike that wouldn't be so bad.

Not so great:
Came with a rusty unpainted gas tank
New seat but no way to bolt it down
clutch cable detached but NOS Honda part included
Rear tail light is a used LED unattached
Something isn't right with the clutch. I can take the side cover off, but the clutch lever on the case will not move the clutch. I can't even push it in which makes me think something is jammed up.
Tree lock appears to be keyed incorrectly; I took apart the tumbler this evening and 1 or 2 leafs sticks up with the key in. Lock guys will know.
Just rolling it down a ramp, the front brake could slow the tire, but man these drums don't give me confidence yet.
Something isn't right with the carb, but I can't tell what; its my first carb and I know it'll take some effort to make it right again; the linkage brackets just don't seem right.
Kinda crummy rattle can black on the frame and engine fins, who knows if high temp paint was used; it looks oily when clean and dry.
Old plug wires and starter motor wire.

Not so great, but not bad and maybe even good:
All factory wiring is still working: Key on to aftermarket speedo works, headlight and front turn signals work. Horn doesn't for some reason, but there are numerous wires simply disconnected flapping in the breeze. Some other exposed connections, wires, and questionable prior installs would make me panic if there was a quick splash or rain while riding though.
Came with a Haynes manual, so that saves me $40
Starter motor works, engine turns over and it sounds like it has compression.
Tires are fresh, chrome wire spokes look great, headlight is new.
No rear fender and the frame now has a rear "hoop" around the back, no idea if I can still attach a rear fender or what.
New battery with a drain hole I managed to splash on myself already
New side gaskets
Bike even came with some Harbor Freight Bike lift and a weird stand/ramp combo thing that already helped keep me from getting a hernia moving it from my van.
New Chinese chain in box, new sprockets
New NGK spark plugs

Took a few things apart just to spend an hour or two in the garage and so far I've got a bad ground lead, clutch hasn't healed itself but it will shift from 1-n-2 with the engine off, Battery is fresh, tree lock may be deleted, and 95% of the parts are with the bike. Now I just need to install and make it all work!

If anyone has any guidance for the clutch that would be very much apricated. I figure I'd try to get the clutch cable installed and sorted before disassembly of the clutch pack since I have a phobia of springs ejecting themselves from assemblies.
Same with the carburetor; there are multiple blades that seem like they should work together, but maybe theres some vacuum wizardry I'm not familiar with.

Let me know if theres any interest to follow along with the restoration too, no sense in posting for nobody. And yes, I did haul the bike sideways in my minivan with a ramp and jack in there too haha. So much easier than a pickup truck with the lower deck!

 

[deemus]

Cool! Great price. I’ve had several project bikes used to teach my son how to work on bikes. Most of ours were dirt bikes.

By the time he was 8 he had a driveway hustle. Every kid in our neighborhood was paying him to fix bikes. Now he’s doing that with his son who is 6.

Have fun!

 

[jetcycles]

That's a SCORE!

Sent from my Pixel 6 using Tapatalk

 

[jrbfishn]

It has been many years since I have touched one. Sounds like the clutch pack is frozen or the push-rod assembly is put together wrong. Can you post a pic of the carbs? They have to be suncronized if there is more than one. I was no great fan of Hondas. Had a 350-4 at one point though. I prefered Kawasaki or Yamaha. Loved my Triumph.

Sent from my SM-S906U using Tapatalk

 

[OutlawStar]

It has been many years since I have touched one. Sounds like the clutch pack is frozen or the push-rod assembly is put together wrong. Can you post a pic of the carbs? They have to be suncronized if there is more than one. I was no great fan of Hondas. Had a 350-4 at one point though. I prefered Kawasaki or Yamaha. Loved my Triumph.

Sent from my SM-S906U using Tapatalk

Just the 1 carb on this lil 250cc engine thankfully so I don't have to mess with carb syncing and balancing and a special tool just to do it. I can open the throttle blade, I know the black thumb screw is the idle adjust. But on the opposite side of the throttle (where the air filter would go) theres another blade that doesn't seem to link up with anything and doesn't open up all the way like the throttle blade. A little headscratcher but I also haven't referenced the manual or internet yet.

This is the clutch mech, like I said gripping the gears or pulsing the starter everything rotates with the engine, but the pin I'm holding that the clutch lever assembly on the case cover is supposed to push simply isn't going in. I've got the haynes manual so there isn't an easy fix I was going to simply remove the clutch, disassemble, and then do the opposite. But if someone knew of a common mistake from the seller I could go directly to that'd be ideal. The lever/arm on the crank case looks and feels good, the specific orientation may not be correct because I'm not sure where to attach the clutch cable to.

 

[OutlawStar]

Well bad news on the carb front: it appears to be missing an accelerator pump linkage to move 2 other flappy bits internally, I can't find a clear diagram how they even assemble even if I did find the parts which are simply unavailable on most parts websites outside of England. Assemblies in England are $80, plus international shipping of about $80-100. Or I can just buy a NOS good carb for $400. Yikes.

eBay feels super confident about some generic 50-300cc engine carburetors for $30, I'm more inclined to try that before shelling out as much for a single part as I did for the entire bike. Similar story for a good gas tank if I can't find a suitable replacement considering the rust inside.

I've taken off those 4 bolts on the clutch and unfortunately don't' see anything wrong after watching several videos, studying parts diagrams, and several other sources so maybe its a matter of installing the clutch cable and housing and seeing if that works before disassembling the entire engine and clutch with tools I don't yet have, however I need a roll pin for the lever too.

Parts are surprisingly expensive and hard to find considering they made a billion of these parts over about 10 years and complete bikes are relatively cheap. Not discouraged yet; I'll get the chain on, and investigate rear fender and other bits before defeat.

Wish I had more time to really dig into everything, holidays, new girlfriend, work, when is a guy supposed to get some quality time with a pile of decades old grease?

 

[OutlawStar]

So I've got the chain on today and that was an adventure in grinding pins away. The tank should be a good fit, seat should be easier than I thought to mount, electrical works but found a bad ground strap (hole in insulation) so thats on the way. Figured I'd get them more sorted and routed so I don't have a few pigtails flopping around on hot parts next.

The tank has rust on the inside; current plan is to fill it with vinegar, let it sit overnight, toss in some nuts and bolts to agitate, and rinse out the rust with water. The bike came with a tank sealer kit so if the vinegar works I'll try that before buying a new tank. If anyone has a secret trick to removing rust inside the gas tank without resorting to $25/gallon chemicals, I'm all ears.

The carb issue still has me worried; found another one for sale that looks very similar but even the seller admits "got the engine running, but it wasn't running how I like" and at the tune of $200, I'd rather not throw cash at it hoping it'll work. I messaged him asking him what alternate carb solution he went with in the hopes he used something modern and good, pending a response. All else fails I'll offer him $50 to ship it from Nova Scotia. I'm open to suggestions if any of you guys had some carb insight: my feelings won't be hurt if I just have to buy some modern chinese unit. Hell if there is a modern known good idiot proof unit for $200 I'd go for that as well.

The clutch is keeping me up at night. Without disassembling the entire basket assembly, I can't see anything wrong with it. (I don't have the tool to remove the castle nut) The clutch lever on the side of the engine case just wont' budge it at all. I also have no idea where to mount the clutch cable; theres a nearby bracket but its about 4" in the wrong spot.

tl;dr
Need tips for in-tank rust removal
How do I replace a carb?
Does the engine need to be on with oil for the clutch to operate normally?

 

[digger]

tl;dr
Need tips for in-tank rust removal
How do I replace a carb?
Does the engine need to be on with oil for the clutch to operate normally?

OXALIC ACID is what you seek

Amazon product ASIN B0147GM7CQ

 

[OutlawStar]

OXALIC ACID is what you seek

Amazon product ASIN B0147GM7CQ

I'll do some research into it: I had about a pint of CLR I dumped in there I'll let chooch all day today. I can already see chunks of rust floating as I rotate the tank every couple hours. I have about 1.5 gallons of vinegar I'll try all day tonight and tomorrow with some nuts/bolts to act as an abrasive. The bike came with a tank sealer kit that I barely glanced at until this morning; it comes with a rust remover solution I'll try as a final attempt. Worst that happens is I've wasted half a bottle of CLR I never use anyway, and about $6 of vinegar before just buying a used but good tank.

The gentlemen in Nova Scotia of all places on ebay replied back saying he just used some generic chinese carb ($40) and had to modify another throttle cable to get it to kinda work. I think I have an idea of what he did but I'm not super enthusiastic to try it. He used something very similar to the pic below: the "throttle value" I think is just a pull for a throttle like you'd see on a piece of lawn equipment that is either at idle, or at operating speed. Not something I really want to dink around with modifying and getting a special cable to work on a motorcycle. Current plan is to either spend $150 on his "used, but didn't run right" carb, or a fairly similar kawasaki KLR300 (clone) carb because the throttle arm is on the correct side and the intake/outlet ports are fairly close in size, along with a 300cc engine probably being fairly close in air/fuel to a 250.

So far I'm still enjoying this project because I haven't spent much on everything and little bits/bobs only take about 1-2 hours at a time to mess with. Learning new stuff before I take on a larger project like a car or truck that isn't running.

 

[OutlawStar]

Got a chinese carb in that is nearly a clone of what came on the Honda, same dimensions, similar throttle arm. I still need to figure out how carbs work, but have to fix the clutch before filling the engine with oil and trying to fire it up.

KBS tank sealer is done. Vinegar inside for about 5-7 days was effortless other than rotating and shaking the tank a few times a day. Went from plenty rusty to now it has a hardened petrochem coating on the inside. A couple before/during/after shots for the audience. I used some wine corks as the stopper on the bottom, broke 2 off and had to open this tank of fine wine. Hair dryer to dry it out between rinses of the chemicals, flash rust isn't flashy. A little bit of trimming of that hard coating where the petcock screws in with the pickup tube; just the way the excess dripped out prevented the tube from being inserted, not a big deal.

 

[kbaxter60]

I'll do some research into it: I had about a pint of CLR I dumped in there I'll let chooch all day today. I can already see chunks of rust floating as I rotate the tank every couple hours. I have about 1.5 gallons of vinegar I'll try all day tonight and tomorrow with some nuts/bolts to act as an abrasive. The bike came with a tank sealer kit that I barely glanced at until this morning; it comes with a rust remover solution I'll try as a final attempt. Worst that happens is I've wasted half a bottle of CLR I never use anyway, and about $6 of vinegar before just buying a used but good tank.

The gentlemen in Nova Scotia of all places on ebay replied back saying he just used some generic chinese carb ($40) and had to modify another throttle cable to get it to kinda work. I think I have an idea of what he did but I'm not super enthusiastic to try it. He used something very similar to the pic below: the "throttle value" I think is just a pull for a throttle like you'd see on a piece of lawn equipment that is either at idle, or at operating speed. Not something I really want to dink around with modifying and getting a special cable to work on a motorcycle. Current plan is to either spend $150 on his "used, but didn't run right" carb, or a fairly similar kawasaki KLR300 (clone) carb because the throttle arm is on the correct side and the intake/outlet ports are fairly close in size, along with a 300cc engine probably being fairly close in air/fuel to a 250.

So far I'm still enjoying this project because I haven't spent much on everything and little bits/bobs only take about 1-2 hours at a time to mess with. Learning new stuff before I take on a larger project like a car or truck that isn't running.

Ha ha! "Transparent Oil Cup".
At least it should not freeze up.

 

[popper]

Wet clutch frozen up. Soak in kerosene.

 

[OutlawStar]

Wet clutch frozen up. Soak in kerosene.

Can't really call it "frozen up". As its installed (I've unbolted everything and removed the disc pack) I can rotate that assembly, engine will turn over with the starter without issue, according to the neutral sensor I can shift gears 1-n-2. Pulling on the lever on the crank case, the clutch doesn't move. I think its "pushed in" but just can't figure out if its just assembled incorrectly (its right according to 3 youtube videos and the haynes manual) or what. In Post #5 that pin in my fingers doesn't push the clutch in.

 

[popper]

Do the plates move in the basket? Better put, when disassembled, do the plates move freely? They will stick together if oily. Lok for burrs on the basket fingers or bent center. The plates don't move very far anyway. And the rod may be too short.

Your carb probably is full of rust from the tank.

 

[BBL]

Man, oh man, jealous. (in a good way).
Sounds like a fun project.
I bought a similar bike in a similar condition last year but have not had a chance to work on it yet. Not gonna restore it but modify it. Hoping to get to it this spring.
Please do post progress of your project. It motivates many of us.

 

[OutlawStar]

Do the plates move in the basket? Better put, when disassembled, do the plates move freely? They will stick together if oily. Lok for burrs on the basket fingers or bent center. The plates don't move very far anyway. And the rod may be too short.

Your carb probably is full of rust from the tank.

Plates feel like they move mostly freely, once everything is sandwiched in and bolted its a little snuged up but the individual plates I can wiggle around by finger. The lever on the crank case is making contact but nothing budges. I have the cltch handle on the bar and a cable, but the cable is a bit long and I'm not fully certain where its supposed to mount; there is a bracket nearby but it ends up maybe 1/4" from the clutch lever on the case. Unless the lever on the handlebar gives way more mechanical advantage and this clutch is super stiff, I'm just a little stumped.

Carb is clean (see post #5) however missing several linkages, theres binding on some valves, and a bunch of really expensive parts; a "used, might work?" unit on ebay is $400, same price I paid for the bike. Its why I got a similar chinese clone for $40 with the hopes it'll work. Seller said he put brand new jets in it and there hasn't been any fuel sent through this, so I at least might have factory sized jets if this no-name unit doesn't idle.

Man, oh man, jealous. (in a good way).
Sounds like a fun project.
I bought a similar bike in a similar condition last year but have not had a chance to work on it yet. Not gonna restore it but modify it. Hoping to get to it this spring.
Please do post progress of your project. It motivates many of us.

So far I'm having a bunch of fun. Was hoping it'd be simpler in terms of "just bolt everything together" but in terms of a restoration project it was only $400 for the bike. I've had to buy a couple simple tools I simply didn't have and a handful of jellybean parts for a grand total of about $145. It also came with some cheap ramp, bike lift, and what the seller thought was nearly everything else including chain, new tires, new seat, neat speedo, new headlight, and haynes manual. It was probably a 95% all there sale to get it running. So $550, and I know I probably need to spend another $100 to make it complete enough to bop around town, I'd be thrilled to ride a $650 bike. I also wouldn't be opposed to selling it! haha

I know on the horizon I'll have to fab up some sort of bracket to bolt the seat to the frame so probably another $15. The tail light that came with it doesn't give me a whole lot of confidence, but at least I can wire it up and see what it looks like for now. I'll need a license plate holder bracket and those often come with decent tail lights so maybe $60-80. The front forks feel like they're a bit collapsed. No idea if thats because this is a tiny bike and I'm an overweight American, or if the forks need to be replaced. Wiring feels okay but is original, even if I replaced it with a universal kit, thats still just another ~$75. Remaining questions are what to do with this gas tank; sand it down, primer and rattle can it for $20, and sourcing side panels and rear fender after the prior owner kinda chopped and lowered it for a cafe racer look. Side panels are confusing me but such a low priority I'm almost not even worried about them currently. I would like to cover that battery and there are $20 units on alibaba, or $400 units specific for this bike. I might try the cheap route, but it won't be until spring.

Its my first restoration of anything significant beyond a failed leaf blower or bench vise but a ton of fun. I can think about it for much of the day, then for 60-90 minutes put on a podcast and make a mess in the garage for a bit. If your project bike is rusty, crusty, and overall neglected the easiest thing you can do is simply take a part off, polish or clean it, bolt it back on. The worst that happens is you find what is absolutely broken and cannot be re-used, best case scenario you made a part look brand new again and can re-use it.

 

[BBL]

Cafe racer or scrambler would work well with this bike. Depends on what you like.
You can google something like "Honda CM250 scrambler" or "Honda CM250 cafe" and see if you like what others have done. It might "tickle your fancy" and your "I'll just fix it for $100" idea will turn into a $4,000 custom build. Don't ask how I know!

I have two scrap bikes in my mower shed (no joke) and already have a pretty good idea on what to do with one. No idea on the other, I don't even know if the motor turns over and the wiring has been ripped out so I gotta rewire the whole thing. Of course no fuel tank, no seat, no handlebars, it's just a roller, that's all. A "trashcan" of a motorcycle, if you will. Yay for fun projects!
Now hopefully I made you feel better about your options by comparison. You're welcome.

 

[OutlawStar]

Some good news:

Got this generic carburetor in, bolted on, and it only takes 1 throttle cable but operates just fine. Opens all the way, closes to where it should. If I WOT on the bars it'll slowly start to close and get stuck before returning to idle. Its all very smooth, that throttle blade spring doesn't have the power to pull the cable. I'm going to stick with this, hopefully this 250cc engine doesn't kill me because I don't remember to "close" the throttle on the grips. Doesn't feel like a safety hazard [yet] but also doesn't feel dangerous [yet]. Plus this bike will probably never get over 45mph for a while.

I had my wisdom teeth removed and about a week later I went to the garage and had a couple pints and sat at the healing bench on my thinking stool. Found a bracket that doesn't appear to be listed anywhere in the Haynes manual I physically have and thought it'd look exactly like something I need. Took a chance and bought it from eBay for $17 and sure enough its the exact bracket for this engine and clutch. Got the cable on there, and while the grips bar is a little worse for wear, it all just works! At least it feels good before I get the engine started.

Speaking of clutch, during my pints I took it off again and while staring at it (and my beer) and started digging around both the Haynes manual and the internet. According to the manual the seller of the bike had 5 clutch friction discs in place, and 6 normal discs. Looked fine to me but halfway through my pint discovered some bikes have 5/6 discs, some should have 4/5. I simply took one out then reassembled and now the clutch levers/arms move!

The shortlist:
Engine/trans feels like its ready to be started BUT I ordered some 5/16" fuel tubing, plugged it into the new carb and discovered I have a 1/4" petcock and fuel filters. Waiting on a brass-barbed adapter and the 1/4" fuel tubing.

Took the nut off the top of the fork and theres just old oil film on everything. I'll pickup a quart of ATF fluid and oddly enough its very specific about how much goes into the forks and it doesn't look like 5 ounces would fill up those tubes but what do I know?I have no real intention of removing them from the bike and "rebuilding" them, but just sitting on the bike the front forks go down a little too easily, I'm hoping the ATF fluid helps dampen it.

Shopping for tail lights and license plate holders makes me realize everything is made in china in the same dumb factory for about $3 and when the price is $30 its partly because shipping and probably 10 hands it changes. I have a crappy LED strip that should work, but I'm really just not happy with it and have to replace it. Double sided tape brake lights are not the play.

And finally, I need some miscellaneous bracketry to experiment with where my license plate will go. The bike doesn't even have that and while I'm sure local PD would give me a stern talking to once, they wouldn't think the bike is so cool they let me never register and insure it. Sure wish I had my childhood erector set still, I'd just use a couple of those pieces! Even for mounting the seat; I'm thinking I'm going to Lowes for some really small U-bolts, brackets, and using this piece of sheet metal (I don't have tin snips) to secure the seat to the frame.

So close, and feels like just in time for decent weather for starting and scooting around town. Thanks for coming to my TED talk, heres a couple pics

 

[OutlawStar]

Once it can start and I take it for a couple victory laps around my neighborhood, I'm probably going to spend a couple hours double checking bolts and screws. Seems like every time I get out to the bike and mess around for an hour, I find a bolt or screw I have never touched and its barely finger tight. Grab another socket/wrench/driver and tighten what I can as I catch it.

The front cables feel way too long, especially since the fender guide is broken. I'm just low speed straight line they're just fine but lock to lock the cables sometimes touch the tire. I'll have to get creative with how they're routed so they're not flapping around as much, I tried tucking them and that just bound up the brake a little, no bueno.

 

[mroper]

get some muffler hanger strap. same as the erector set stuff.