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Discussion Starter · #1 ·
Hey all! It's spring, and that means it's time to figure out whether the CM450C works! Aside from some standard things (it needs an oil change, the battery is low, etc.), I have one major concern this spring, and that's the puddle of oil (?) under the left side of the fork. The drain bolt was definitely oily, but I don't see anything else I can definitely say looks like anything was leaking. The puddle is pretty small... maybe a tablespoon or so of oil, I'd guess. The right side looks fine, though if I'm going to do one I might as well do both.

So: the Clymer manual suggests there's no good way to check the fork oil level without completely dismantling the forks. Is that accurate? It also suggests you need a special tool from Honda (a "fork seal driver"). Is there some other common tool that will substitute?

I'm unemployed for the moment, so I'm running on a shoestring budget. Buying new fork oil and o-rings is going to be painful enough. Adding a new single-purpose tool will likely put the project on hold until I've got a job.
 

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You don't need any special tools. If you don't wanna disassemble forks you can just drain the oil and refill from the top. Be careful removing the top bolt/cap(the spring can send bolt flying.
 

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Discussion Starter · #3 ·
Thanks! I probably ought to rebuild, but I may just drain and refill for the moment. And, obviously, keep an eye on it to make sure it doesn't start leaking again. If it does, well, time for a rebuild.
 

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I have had good success using old fork seals to drive in new fork seals. After the new seal is in place, place the old seal on top of it (around the fork tube like it's normal position) and whack it down with a length of scrap wood, the wood won't scratch your fork tubes.

Cheers.
 

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Discussion Starter · #7 ·
Thanks. I don't know for sure that's where the leak is, but if it's an option I'll just replace the washers on principle.

After poking at it yesterday, I also remembered that the throttle cables are sticky, so I'll need to pull those and check them out. That doesn't look too hard, though, and as long as they just need to be clean and lubed I already have all the parts and tools.
 

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If leaking from the bolt and it isn't obviously loose the copper sealing washer might need to be replaced, costs like 2$ at any motorcycle shop.
You can also anneal the copper washer(heat it until it's red hot then let it cool naturally) and save yourself $2.
 

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Discussion Starter · #9 ·
That wouldn't have occurred to me, but thank you! That'd be a good incentive to get my metalworking vise mounted on the new bench, so maybe I'll do that.
 

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https://images.cmsnl.com/img/partsl...-front-fork-cm450ac_bighu0184f0c0801_4688.gif

Being unemployed sure sharpens your skills and "adaptability". Fit your vice to your bench as its gunna come in real handy. You have dumpsteres where you live? These =can be a real good source of raw materials for stuff, like tubing to tools to make it easy to fit the new seals etc.. A make do and mend and recycle type mind set, thru necessity. Any fool can cheque book there way out of trouble.

Find out where the oil is coming from.

Do your research, you have a clymer and now know of cmsnl for the exploded views, and get a shop manual for your bike, there will be one on here i suspect.

Oil from seal, for drain bolt or from damper rod allan bolt, the "hidden one".

Be carefull about the small mudguard fender bolts in the alloy forks, they can shear off dead easy if corroded in, but do you have to take the alloy section of the fork off to drain the fork oil and refill??

As said, be carefull about the top chromed large nut AND the thin hex drive top "ring" and the spring underneath. An old flanged 14mm bolt is an ideal base for a tool for removing and refitting this hex ring. Make one, you have a welder?? Make the tool long enough for easy useage, a "T" handle. The thin hex ring is easy to cross thread refitting, and so much easier using a long t drive flanged hex head tool rather than a clumbersome allan key. Its well worth making the tool as you will find out.

CORRECTION, yours has air forks and circlips etc, but be carefull about the spring as a circlip in the eye is bad. You may need an assistant removing the circlip.
 

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Discussion Starter · #11 ·
Thanks, drydreamer! I'm definitely finding new uses for a lot of junk in my garage. Where we are now (Western Massachusetts) there's not a lot of dumpsters, and they're less useful than a lot of places: people out here are good about keeping usable stuff out of the waste stream.

It definitely looks like the oil was coming out around the drain bolt, though I can't say for certain. There was oil all the way around it, though, and everything else was pretty clean. Fortunately for me, the motorcycle is a hobby, not critical transportation, so if I'm looking at a lot of parts I can just set it aside until I've got a job again. I'll be annoyed (all this great riding time, wasted!), but better annoyed than riding with a damaged suspension.
 

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Correct soft annealing of copper and its alloys involves a quench while still heated to dull red...
Slow cooling will re-harden it....Quenching in a Boric acid "pickle" will leave the copper clean and bright......

Ferrous materials (iron and its alloys) are the opposite...Quenching hardens them.......
 

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Thanks, I was thinking of steel in regards to annealing.
 

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Hello - I have a CM450A ('82) and thought I had a leaking fork but found that the brake reservoir had leaked from top seal when the wheel was turned while sitting idle. Recommend checking that as a possible source of the fluid. I now keep it on the center stand and monitor the brake fluid level.
 

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Discussion Starter · #15 ·
That was actually the first thing I checked, since I had to rebuild the front brakes last year. I figured "I did it wrong" was a better first guess than "my forks developed a spontaneous leak." The brake reservoir is still full, though, and I couldn't find any evidence of leakage anywhere except around the fork drain bolt.

Thanks for pointing it out, though! That could have been annoying if I'd missed the problem that way.
 

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Discussion Starter · #16 ·
Update, in case anyone is curious:

I've drained the fork that looked like it was leaking, and it was quite low on fluid. The manual says 220ml, and I'm guessing there was less than 100ml. Unfortunately, the top bolt is stuck tight: enough force to almost rock the bike off the center stand isn't enough to budge it. After looking at the diagrams it appears that the air port on the top bolt goes to the same place as the oil, so I'm cobbling together an adapter that should let me pour the new fluid in that way. It'll be slower, but it should work, at least.
 

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I tried that and it was a PITA and I ended up eventually figuring a way to remove the top cap. I would suggest maybe trying a syringe or something to inject the fluid, trying to pour it in just didn't work.
 

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Discussion Starter · #18 ·
Good to know, thanks. I've got a funnel and hose hooked up to a tip that's a tight fit in the air port (with the screw adapter removed), so I'll give it a shot, but I expect I'll have to do something different.

At least now I've got warning that it's not likely to work!
 

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Discussion Starter · #19 ·
Further update:

I had exactly the same problem Rscottp had, and now I know why. A 5' wrench extension (the shortest pipe of the right diameter I had handy) opened the top nut with no trouble at all. The reason the nut seemed to be so stuck was, of course, the fact that a big spring was trying to force it out of its threads. If the spring weren't there, it would have been easy to remove. And the reason I couldn't get my funnel/hose/adapter to work is that there was nowhere for displaced air to go. If I'd drilled a hole in the end of the cap nut, it all would have worked fine. I decided I'd probably want to drill the hole where it couldn't drop bits into the fork, though, so I took off the nut instead.

So the forks have both been drained (neither one had anywhere near 220ml of fluid in them, and what there was was thick, black sludge), somewhat flushed with fresh ATF, and then refilled. So, as soon as I can reattach the handlebars, the bike will be rideable again! What's that? Why didn't I reattach the handlebars instead of coming in and writing this? Well, because the combination of 36 year old bolts and a cheap torque wrench added up to two sheared off bolts. I'm gonna have to go buy some new ones and extract the broken off bits before I can actually attach the handlebars. Oh, and test the torque wrench to make sure it's not too far off.


Life with old equipment, I guess!
 
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