71K0 just brought out of a LOOONNGG storage.

[Coastal Redneck]

Hmm, guess I should reiterate my intention to buy a new motor for my FrankenBike, after hearing alla youse heroes... I want to put a bigger & better 4-speed motor in my bike, and Mr. Bombardier may have a connection to pull that motor swap. However, if not, I'm gonna try to put a larger motor on that bad little offroad rocket without wasting a fortune, 10? Otherwise, I'll do it myself later AFTER my Wild West Monkeybike Tour, though I'd rather have the 125cc, 140cc, or MFing Hardcore 160cc motor on my bike during the HELLER EXPEDITION, LOL.

 

[cjpayne]

You got it CJ. They're not goin anywhere. And you know, if you're vouchin for him, his credit is good here too. Good to hear he likes his new old bike. Are you gonna put the 4 speed in his motor or into your spare? His I'm guessin, since that's the one that's chunkin.

Thanks. Kevin does like his new old bike. He was pretty excited. Yes, the 4speed is for this bike and I told him the CS sprocket would at least need changed. I also told him who I had in mind(haven't asked him yet.lol) to do the tranny rebuild and the shipping. I'm not comfortable doing a firstime full rebuild on this original motor.

Kevin has a restored '72 Chevy that is a real looker/runner that does get out of the garage. He said he can't wait to put that K0 in the back of the bed and take it to a car show somewhere. It would be cool to tool around on that bike looking at other cars/trucks too. How much you wanna bet the bike gets more attention than the truck! lol.
http://lilhonda.com/webboard/showthread.php?t=15191&highlight=


BTW, Kevin said he was diggin' around for something and found some vintage license plate mount/reflectors and is going to put them on the bike.

 

[cjpayne]

I was thinking and remembered that some months ago I acquired a 6volt Z50 motor from the local MC shop. I'm wondering if it has a good tranny. Since those Z50's are alot easier on the tranny, I'm thinking it probably is in good shape and would make a good donor. Hmmmm........

Here's the motor I was talking about. No idea what year/model. There is no set screw for the chain tensioner, so I'm guessing it's from a hardtail Z50. Someone has definitely been into it before. It's a Z50 engine, but it has a 72cc jug on it. The head, in some area's, looks ike it was painted black at one time. It also doesn't have any date/casting numbers. Stator and flywheel are in decent shape though



Don't know if this clutch cover is original. Looks to me like the type that goes on an old 3wheeler.



I was very discouraged when I opened it up. No oil or water found, but rust. I don't think the tranny is any good:12:



Maybe the gears can be cleaned up(blasted) and some other stuff salvaged. Maybe the shiftforks too,......hopefully.

 

[mikejana]

honda50.com used to have a great identification chart for engine serial numbers. I can't access it. Hopefully someone has an archive to the site.

I'm thinking that was 1970ish?

 

[cjpayne]

I'm thinking that was 1970ish?

That's what I was thinking too.

While tearing this thing down, I finally did find a casting number. Also, this combustion chamber looks to be a 72cc, Was suprised to find it uncorroded. I'm starting to think that the clutch cover, jug, and head are from a ATC70. Didn't find any of the O rings that should have been there either. Didn't find any trace of oil leaks in the head,

 

[cjpayne]

honda50.com used to have a great identification chart for engine serial numbers. I can't access it.

I can't either. Just gives me a blank page.

 

[cjpayne]

Here's the motor I was talking about. No idea what year/model. There is no set screw for the chain tensioner, so I'm guessing it's from a hardtail Z50. Someone has definitely been into it before. It's a Z50 engine, but it has a 72cc jug on it. The head, in some area's, looks ike it was painted black at one time. It also doesn't have any date/casting numbers. Stator and flywheel are in decent shape though

View attachment 30665View attachment 30666View attachment 30668View attachment 30667

Don't know if this clutch cover is original. Looks to me like the type that goes on an old 3wheeler.

View attachment 30669

I was very discouraged when I opened it up. No oil or water found, but rust. I don't think the tranny is any good:12:

View attachment 30670View attachment 30671View attachment 30672

Maybe the gears can be cleaned up(blasted) and some other stuff salvaged. Maybe the shiftforks too,......hopefully.

Got it opened up and the tranny is alot cleaner than I thought it would be. The bearings in the crankshaft seem to be fine and roll smooth.

 

[cjpayne]

Got it opened up and the tranny is alot cleaner than I thought it would be. The bearings in the crankshaft seem to be fine and roll smooth.

View attachment 30679View attachment 30680

Need some advice from you guys with tranny experience. I'm thinking this tranny assembly will work fine. What clips, pins, ect., do I need to replace with new OEM? I have new gaskets and 1 new primary gear snap ring.

 

[69ST]

Considering the amount of water-inspired rust inside this motor, I'd want to check the contact surfaces of the gears, forks & drum assembly. Looks like the rust is superficial and will clean off with a good wire-brushing. All that scouring, however, will require a thorough scrubbing afterward. Odds are high that the shift forks & pins have noticeable wear...in which case they should be replaced. As for Circlips, any that get removed should be replaced with new...cheap insurance.

 

[cjpayne]

There's a little bit of surface rust on the shift drum that looks like an easy cleaning. The inside of the motor appears it was laying mostly on the clutch cover side when the water started coming in. I spun the countershaft while using the shiftstar back and forth. It spins/shifts fairly easy. Of course it all needs to come apart for cleaning/inspection. I really don't see any rust on the gears, just some tarnish grime. What kind of Locktight is used for the shiftstar screw?

 

[69ST]

There's a little bit of surface rust on the shift drum that looks like an easy cleaning. The inside of the motor appears it was laying mostly on the clutch cover side when the water started coming in. I spun the countershaft while using the shiftstar back and forth. It spins/shifts fairly easy. Of course it all needs to come apart for cleaning/inspection. I really don't see any rust on the gears, just some tarnish grime. What kind of Locktight is used for the shiftstar screw?

The only rust that matters is any which is on contact surfaces. The rest is cosmetic. Look for wear on the shift fork pins; they should have a uniform, single, diameter. A visible "step", means they're worn.

Use blue Loctite, clean both threads (drum & screw) with brake parts cleaning solvent first.

 

[cjpayne]

Thanks for the "visible Step" tip. I've seen shift forks before with a round scrape on them and I take it there shouldn't be, for reuse anyway, when I take this completely apart. Would you happen to have a handy pic of what the fork tips should look like in reuseable/good/new condition?
Like I said before, someone has been in this motor at some time. The inner case gaskets came off with little effort. I have to cautious and assume there may be some parts missing that I'm not aware of. Think I need to find a copier somewhere and run off OEM parts fiches.

 

[69ST]

Might not be second nature to you but, there's really nothing terribly remarkable, or complicated, inside these motors. There are a few tips & tricks that make life a little easier. Still, a little extra patience & diligence can go a long way toward overcoming lack of experience. Specifically, with shift forks, if you see contact (witness marks) anywhere but at the contact pads on the fork tips...a.k.a. the old, dreaded, "smiley faces"...the forks are toast.

When in doubt, ask questions and post photos.

 

[cjpayne]

Definitely not 2nd nature in my brain.lol. The smiley faces is what I was referring to in my previous post about the round scrapes I've seen before. Does that mean they are simply wore out(high mileage), badly abused, crash damage, or all of the above? I've already contacted Kevin via text and was hoping he could bring the bike today, but he was busy with throwin' a kid's birthday party. Would have went and got myself, but my health has been down for a couple weeks. I can barely drive around town,lol, but I'm extremely bored and am able to fart around in my little shop for breif amounts of time. Been suffering from vertigo just from walking and get exhausted easily. Last week I was REAL bad, but I've been improving s-l-o-w-l-y. As long as I'm still, I'm basicly OK. Anyway, when I get a chance, I'll get some pics and start getting things cleaned up. Talked to Ray(Deoodles) today and he said he's got some spare new parts for the tranny's that he's done, such as the circlips and pins, ect. So should be covered there.

 

[69ST]

It only means that the metal has been worn-down. Most of them will still measure within wear limits but...you're into softer metal, from this point forward. Heat-treating only goes so deep. Unless you know the complete history of the motor, the cause of the wear is pure guesswork. Worn parts are what they are, in need of replacement, which is clear enough...y'know?

Speedy recovery, CJ...being sidelined is less than no fun.:7:

 

[cjpayne]

It only means that the metal has been worn-down. Most of them will still measure within wear limits but...you're into softer metal, from this point forward. Heat-treating only goes so deep. Unless you know the complete history of the motor, the cause of the wear is pure guesswork. Worn parts are what they are, in need of replacement, which is clear enough...y'know?

Speedy recovery, CJ...being sidelined is less than no fun.:7:

Wont be any smiles from me if I see "smiley faces".lol.
Yes, being sidelined has been tough. Doc gave me some different meds again today and another week. Probably wont get to cleaning/inspection until sometime tomorrow. At least the weather has been great here in NEA, Ok lately.

 

[cjpayne]

I tried to get the best pics I could, so you may have to enlarge to get a good idea. I went ahead and looked for smilies, broken teeth, ect., before cleaning. The rest of the shift fork tips all look the same and I don't see any smilies. Fortunately, the only rust on the whole assembly is just on the outside round part of the shift drum/forks. Was very light, mostly like babypowder. Some of the rust powder easiy mixed with oily parts when I started moving things around. Needs thoroughy cleaned. Basicly came off just from my handling it. Got lucky there. Shafts, pins, circlips, and gears, all appear rust free.

 

[OLD CT]

The side you posted, #1662 #1665 #1666 pics appear to have enough wear to warrant changing them. They aren't smiley yet but it wouldn't take long.
Seems like it's a good time, to do it right the first time. Having fun yet?
Now you know how much time and cleaning all the parts, really takes.
Not to mention sending out a cylinder to be bored or a machine shop
''back and fourth'' to cut the valves. Not worth it for me to do any more.

 

[69ST]

X2 on the shift for replacements. I see significant wear...and pitting. Where service longevity is concerned, that's a bad combo. Break out the magnifiers and check the contact surfaces on the gears, where the shift forks hit. If the gear faces are pitted in these areas, they'll grind-down shift forks in a hurry. Only bright spot, under that scenario, is that 3-speed gears are usually in decent shape and a dime a dozen. Any 49-72cc tranny is a potential donor, if you need `em.

Shift fork & pin replacement is easy, while the tranny is on your bench. Like Pat said, the worst part of an engine rebuild is the scrubbing[SUP]3[/SUP] required.:43:

I'll never do my own cylinder boring, "a man's got to know his limitations". It'd take more years than I have remaining to recoup the 5-figure equipment investment. It's not that big a deal to farm-out and there's always new aftermarket in your choice of standard or bore-up flavors. Valve jobs, including seat cutting & lapping, are something I learned while the K0 was the latest & greatest model. If you need assistance, I'm just a PM away.:3:

 

[cjpayne]

Thanks guys. My franken K1 engine has a rebuilt tranny in it. I might just use it. It worked and shifted fine the last time it ran.