My Week with a ZA50 - Lengthy Notes on Rebuilding

I had some spare moped money sloshing around and wanted a new and challenging project so I decided to dive into rebuilding a ZA50. There is a good amount of literature on Moped Army and other sites, but there's a decent amount that isn't mentioned so I figured I would add to what's out there for posterity.

First I'll say make sure you have the right tools for the project. There is a good list of tools on the wiki, but there are some that aren't mentioned that you really need to do this right.

- Having a vice set up is going to be a huge help, especially when opening up the second gear shaft to change the pucks. It just makes life easier.

- On the subject of pucks, don't waste your time using too small a screwdriver when you're getting those loctited screws out. I stripped the shit out of my first one and had to grab a second. I picked up a 3/8 in. craftsman slotted screwdriver and it made it way easier.

- An impact wrench was really helpful getting the very first nut off. Remember that it's reverse threaded.

- You need a 15/16 deep socket to remove and properly tighten the big clutch nut. I didn't tighten it enough the first time around and it backed off. That made it so I couldn't roll my bike backwards or engage the starter clutch rolling it forward. Tightened it up right and now its golden.

- Don't mess around with rope tricks or funny business - just get a piston stop. It would have made my life a hole lot easier. If you're rebuilding and don't care about the old stock crank, just disassemble the top end and stick a screwdriver in the con rod. Worked for me.

- Get a three jaw puller or a proper flywheel puller to get the flywheel off. Screw rubber mallets.

- Get a good set of circlip pliers. Or at least a big one and a little one. You'll need a hefty set to get the giant circlip out to remove the bearings on the output shaft.

Other than tools I found helpful, I also picked up a lot of tips from friends and from making many mistakes.

- Rebuild this on a clean table with some white contact paper you can write on. Circle and label each little part and place them in the order they come out. This really helped me keep track of everything.

- Returning to the second gear shaft, avoid holding a blow torch on those screws. If you heat the screws to get them out, you're going to melt the pucks and make an awful gooey mess that really isn't fun to clean up. Put it in a vice with a rag wrapped around the shaft and, using the right size screwdriver, see if you can't brute force them out. If you can't, I have heard and read that an impact driver (NOT an impact wrench - they are different) is useful here. I tried that and broke the impact driver. So. That didn't work too well for me. Like I say above, don't both with too small a screwdriver, you'll just fuck it up. Make sure you use blue loctite when you put those screws back in.

- Heating with a blowtorch did, however, work great for getting the old bearings out of the tranny cover and cases. Just be careful and don't ruin anything.

- On the topic of bearings, I know most people heat the bearings and then drop them on the crank or whatever, but for both the crank bearings and the case bearings, I found an actual press (in this case a ten ton press) was much quicker and safer than messing around with heat and mallets and what not. I messed up the bearings trying to get them into the case with a mallet and heat and had to replace them (again). If you don't have a press, which you probably don't, see if you can't find someone who does. My friend and I replaced every bearing in the engine in about 15 minutes. If you press bearings on the crank, make sure you supply adequate support.

- Continuing on the topic of bearings, if this isn't obvious from some of the rebuild guides, with the crank bearings, press the outer races into the case first, and then press the rest of the bearing on the crank via the inner race.

- The bearings and seals on treats are priced crazy high. I screwed up a couple as well as a couple seals because I am an idiot and took a blow torch to one by accident (woops). I live in Allston and there is a bearing shop - Action Bearing Co. - right up the street for me. I went and checked it out with the dimensions of the seals and the numbers of the bearings and sure enough they had everything in stock. The best part was that for three seals and two bearings, it was only $22. I priced it out and that would have been $55 on treats. So try to find a bearing shop around you and save some cash.

- If you get a sealed bearing, pop out the metal or nylon covers and use compressed air to blow out all of the grease inside there.

- I have since added it to the wiki, but don't forget to get a seal for the output shaft. Its 25X35X7 and it wasn't on there before, so I didn't get one. I was trying to force one of the seals from the seal and bearing party on treats and was really confused about why it wouldn't fit. Then I checked the number on the seal I took out and realized. The seal that comes stock in the engine has a metal ring around it. Pop that dumb thing out - your new seal probably won't have it.

- The seals are kind of a bitch to get in. I used my 15/16 socket to gently tap them in.

- The output shaft is held onto the case by a cuff on the exterior. There is a special Puch tool to pull that bad boy off but where the hell are you gonna get that? Other people have suggested a three jaw puller, but none of my three fit. So I said fuck it and tapped on the shaft with a hammer. It came out with no problem. Way easier than messing around with that other junk.

- On the subject of Puch tools, and this is probably obvious, you don't need them

- When I first bolted my engine together and put it on my bike, my starter clutch wouldn't disengage. I messed around with the adjusters to no avail. I opened up the case and dug down to realize that I had attached the spring wrong. The right side of it hooks into that plastic starter pad thing, that's pretty obvious. The other side rests on the left side of the case. There is a ridge about where it falls. I had mine below the ridge - you want it above, resting on it. I clipped the right side in first, then worked the other side onto the ridge. It's not that difficult. Tap the circular part of the spring down with a socket.

- Those seven bearings on the first gear are not hard to get back in like the wiki disassembly guide makes it seem. I didn't need needle nose pliers or a screwdriver. I just held the bearings and pressed them against the springs and they sat right down like good little children. This is probably obvious to most, but in order to get the bearings to sit, you need to put that nut on first. I didn't understand why they weren't sitting and then did a massive facepalm when I realized my error.

- When you take off that first nut, chances are your bearings will stay in place. Remove the nut and all seven bearings so they don't fall all over the place.

- When I first bolted the crank (I got the $150 aftermarket crank from treats) into the case, it was binding something awful. Wouldn't move nice and smooth at all. This was a problem because obviously it meant I was shimmed too tight or something, but I had no shims in - just the bearings. So I doubled up on case gaskets and it solved the problem. It's now nice and free.

- Be careful when you're case matching. I case matched to a 65 metra, but there isn't as much material as on an e50 and you don't want to cut down all of your sealing surface. Don't forget to grind down that stupid nub. Don't get metal shavings in your bearings. No one likes that.

- If you're using the CDI from treats, the red and white wires plug into the CDI box obvi. The yellow wire connect to both your headlight and taillight. The black wire from the CDI box goes to your killswitch. Send that in one end and ground out the other.

I am sure I am forgetting some stuff and I am also sure some of this is self explanatory or already out there or common knowledge or just me being stupid, but maybe someday someone will find this and it will answer a question they are having. If anyone else has any info, definitely share your knowledge. There really isn't enough literature on this subject and its not as hard as people make it out to be. It is fairly expensive though. Google the shit out of stuff - Adam Augustyn has a great blog with tons of info on ZA rebuilds at http://mustachemachines.blogspot.com/ . Search for shit.

Okay. (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

For the output shaft I just used a press, it was hard to reassemble since I took it back home and lacked a press. The bearing for the output shaft popped out easy also but I used some special bearing punch that fit perfectly in the case.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Overpriced Parts /

Doubling the gaskets? Za50 builders don't do that. Many new bearings are not correct size compared to NOS ones. Sometimes machining the /crank/ends/ bushing is a answer . Let us know how it shifts, rides, holds up.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

doubling up on case gaskets....? :P

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Ϫ‡☄ಬ∞ ƀƖḬƝƊ ƤǂƿƎ ∞ಬ☄‡Ϫ - Hoke from Black Pipes Moped Gang /

have you gotten this off the bench and on the road yet?

lets see a video of it running....

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

I read about someone else doubling up case gaskets, and it seemed to work for them. So far it shifts extremely smoothly. Machining the ends of crank wouldn't work - the problem occurs before the tranny cover is ever bolted on. However, I also read about how some of the bearings aren't exactly the same size as the stock ones. Aside from swapping them out, I'd love to hear solutions from other people other than case gaskets. But I'll definitely report back with how this holds up so far.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

yes, the problem.. can be fixed by making the gaskets .016's.. so I used 2 .008 gaskets.

If you don't know your specs.. then its just guessing.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

So, what brand of bearings and seals did you use. SKF FAG OKI INA...

I do not use the anything but name brand and I like to buy older bearings as there made with better metals. imo.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Taking the screws out of the second speed gear is made much easier by an impact driver... not an air impact wrench, but a hammered impact screw driver.

You also need a torque wrench - because your clutch nut shouldn't have backed off. Torques are important in these engines - sounds like you did this rebuild without the manual at all.

I wouldn't clamp the second speed gear in a vice. The outer portion of that gear shaft is a bearing surface - the inner side towards the out put shaft is fine (not on the gears of course) to clamp on. You should be able to get those screws out with an impact driver and flat surface only - I just did one last night even.

Using case gaskets to mess with end play float is fine - so long as the gasket increments aren't more than the tolerance of the end play. Which is .1mm and I doubt your gaskets were less than .1mm. Differing case gasket thicknesses are the only way to get your shimming right without the factory tool - so long as you know how much you're changing the thickness by - else you're just guessing. I think case gasket thickness is more accurate than trying to measure with a straight edge. You have to buy your own gasket material and cut your own gaskets though - doubling up on cut gaskets from treats is NOT ok.

I didn't hear you say anything about transmission shimming... bad. You should at least fix that.

I also disagree about case material... You can match ZA's way deeper than e50's. There's no stupid case bolt right against the transfer. Base gasket surface should be the same too. Disagree.

This will probably run fine for a while, but without proper shimming... I wouldn't expect more than a couple thousand miles out of this motor.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Ryan Piccirillo Wrote:

-------------------------------------------------------

> I read about someone else doubling up case

> gaskets, and it seemed to work for them.

You mean this thread?

https://www.mopedarmy.com/forums/read.php?6,3071110,3071562

Doubling up case gaskets is wrong. Go back into it and do it right. I've had the same issue with 4 or so (out of 8) of the Treats/1977 cranks I have put into ZA's. You have to assemble the cases with the crank horizontal, not vertical and it helps to rotate the crank while you do it.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

This comment is definitely helpful. Like I said, I made a lot of mistakes and am still trying to learn from them, so I appreciate your feedback and hope it too will be helpful to people in the future.

However, if you go back and read my post you'll notice that I am explicitly clear that you should be using an impact driver and NOT an impact wrench (I say exactly this) to remove the second gear screws. Not exactly sure how you interpreted what I said to be the opposite of what I said. In fact, the wiki originally read that you should use an impact wrench, and I have since edited it to change that.

My clutch nut backed off because I didn't tighten it enough and also didn't sufficiently bend up that lock washer. Again, one of the many mistakes I made and corrected. I agree however, that I need to get a torque wrench. The manual was extremely helpful, and I did in fact refer to it often, but thanks for your assumption.

I was extremely careful not to clamp the second gear shaft in a vice too hard - I wrapped it in a heavy blanket of soft rags and only tightened it until I felt a little resistance, and no more. No damage came to it and it worked quite well. But the more methods that work, the merrier.

Just so we're clear, are you talking about the case gasket in the middle of the engine, or the tranny cover? I'd love to learn more about that and how each affects the end float.

Yupp I intend to work on getting my tranny shimming to spec. I haven't run this engine for more than a couple miles and just got it running last night. I still need to do a bit more research and test out the couple methods out there on proper shimming.

I'm not talking about the depth of the case match - I'm talking about how wide you case match it on the gasket sealing surface. My metra gasket template came dangerously close to the outer wall and, had I matched it all the way out, would have left me hardly any sealing surface.

Any reason an engine not properly shimmed would shit the bed after a couple thousands miles? And what would cause this? I am not doubting you, I just think this is valuable information to have out there.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Yupp I tried assembling it with the case horizontal, but to no avail. Everyone really seems to take issue with this case gasket practice. Anyone have any experience with an engine failing because of that method? Or any evidence as to why it would?

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

I've got three different brand of bearings in there that I'm sure of - SKF, NTN, and Malossi.

Is there any reason you suspect older stock bearings are made of higher quality metal, or is that just speculation?

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

I also used a press to get that cuff back on the output shaft. I don't know of another way to have done it, but I'm sure its possible. Getting it off was simple though.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

On the road - I can try to grab a video tonight. I'd actually like some feedback on how it sounds, especially when it shifts. Everything sounds creamy to me and it shifts smoothly, but there are a lot of people here who would know better.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Did they not use metric hardware on the ZA? What's up with these standard sizes?

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

You can use a 15/16 or 24mm socket. But yeah, it's all metric.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Measure a nice and rich aka 77/treats crankshaft.. VS a STOCK oem crankshaft.

You will be amazing how there is different.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

My apologies if I was coarse, didn't see the part about the impact driver - very good - glad you're a fan of that instead of melting the damn pucks all over everything.

Just so you know, I'm not being demeaning, I just want to point out what I don't agree with so that someone reading this in the future has a second opinion - one that I believe more ZA enthusiasts would agree with. You've put a considerable amount of effort into this - much more than many - and you're doing ok!

Torque wrench would be good... even if you over estimate by 10lbs or so without one... measure out a foot on your wrench and try to guess the torque if you absolutely cannot get a torque wrench.

I'm a fan of the right tools - and doing the best you can if you don't as well.

As long as there's no damage on the gear that's all that matters - what I posted above is just my opinion and advice to others. There's no right way or wrong way to do something as long as you get the same result.

I'm talking about both gaskets... These engines have helically cut gears which means that the bearings and surfaces on the ends of the shafts not only provide a rotation point - but also a surface to push against. So when these gears are turning, they push each other away or bring each other closer. When slowing and accelerating, the helical cut gears are going to be pushing in opposite directions. So when you're accelerating quickly, or coming on the gas from coasting a bit, these gears are going to suddenly start pushing in the opposite direction and slam the other direction as they begin to apply force in the new direction. This puts extra stress on your bearings and gears. Just like you wouldn't drop the clutch in a daily driver every day - you're doing the same *if* your shimming is off.

When your shimming is very far off (on the crank and/or transmission) things can start grinding against each other. Hurpdaderp. It sounds like nothing in yours is off that much.

In the crankshaft, the shimming is important because you want to keep the crank bearings in the race riding where they are supposed to - not sliding around or riding where it isn't supposed to on the inside of the race... It helps align the clutches and second speed drive plate as well, so it's important that none of it move around very much.

Here's what I suggest to do to make it right. Get differing thicknesses of gasket material in .1mil increments or as small as you can. You already have a ball park range that's between one and two gasket thicknesses of whatever you're trying now. Try increasingly thicker gaskets until the crank stops binding and rolls smooth. Each time you will need to re assemble the case and torque the case screws down. You will need to go to a gasket supplier for thicknesses that close. Every crank and engine is different, so just because something worked for one person doesn't mean it will work for you.

The transmission is much easier. You'll need some different thickness shims and some plastigauge. You can order the shims (probably enough for two transmissions) from mcmaster-carr. I'll send you the p/n's of what I usually order when I get home. The transmission is easy. Just bolt it together with plastigauge between the race and shim and see if you're within the tolerance and correct if needed - again - tightening all 6 cover screws between each measurement.

You've done a lot to this motor - it'd be a shame to see something happen to it because of something stupid like shimming.

Pucks and case cover bearings are the biggest downfall of these engines - you've got one more biggie to go and you'll have a really nice bullet proof engine!

Riding it until you know where you stand is a risk - you could be fine - but you don't know.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Have you looked into adding material to the case so you can case match that perfectly?

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

I think this might be the most helpful comment I have every read on Moped Army. Just learned a shit load. Thanks a lot man, and I'll be looking into all of that.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad William /

- "Don't mess around with rope tricks or funny business - just get a piston stop. It would have made my life a hole lot easier. If you're rebuilding and don't care about the old stock crank, just disassemble the top end and stick a screwdriver in the con rod. Worked for me."

Universal "pin" spanner.

These are even handier than a piston stop in many cases. Very often you can locate slots or holes with these at rotating points of the flywheel or gears. Better to keep super high torque stresses close to the source

than transferring them through the crank cheeks and wrist pins (possibly forcing the crank out of alignment). (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad William /

"Pucks and case cover bearings are the biggest downfall of these engines"

On any older ZA search out and inspect all the oil access holes that feed the bushings in various spots. Can't recall exactly... there are about a dozen of them in various spots and some are not easy to see such as deep in the gear valleys. ALL of mine were plugged solid with shreddage from my mostly disintegrated pucks and had to be swaged with a fine wire to clear them. I'm assuming that this is the case on many other older ZAs. The passages in the gear valleys are especially important since the gears literally pump oil through them while running.

When I posted this in my own rebuild thread a while back someone basically suggested that it's "nothing to worry about". I'd strongly disagree. (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad William /

"Those seven bearings on the first gear are not hard to get back in like the wiki disassembly guide makes it seem. I didn't need needle nose pliers or a screwdriver."

Not necessary to know, but it helps when trying to visualize the mechanics of this. These seven do not serve as rollers in the most common sense. They're elements of a roller-bearing clutch and only "bear" when motionless (in relation to the rest of the assembly). When they're not engaged in stopping reverse rotation (when in second gear) they are no longer working as bearings, they're just floating against the spring retainers. (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad William /

"There is a good amount of literature on Moped Army and other sites, but there's a decent amount that isn't mentioned so I figured I would add to what's out there for posterity."

Thank you for taking the time. You pointed out some things I hadn't considered.

Unfortunately a lot of the info is scattered and lost. Many (most, all?) of these tips and observations have been posted, sometimes many times over, and then sink into oblivion to be forgotten and later re"discovered".

I know the wiki is not that difficult to negotiate, but there ought to be a more straightforward way to document helpful specific info like what's in this thread. (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad, are you on flat or threaded view?

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Brad William /

Flat view. ....meaning I can see all responses in full and not the "tree" diagram (i think i have that straight anyway)?

I rarely ever contribute/follow in threaded format. Which is good and bad I suppose. Flat view encourages people to either start a new thread entirely or, like in this case, go ahead a little off track in the hope that most people think it's relevant to the topic.

I was aware that Ryan had buttoned up the motor already by the time I'd weighed in, but his aim seemed to have as much or more to do with offering tips "I would add to what's out there for posterity" so I figured I'd add to it as well.

I just get a bit overzealous sometimes:) (edited)

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Definitely add more Brad! You interpreted what I said right - I think the more information everyone shares, and the more information that makes it into the wiki, the easier this will be for others in the future.

Also, OT: I really wish moped army had a threaded view that expanded all of the posts, rather than having to click each individual post. Very annoying.

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

Ryan, go to the top and click on "FLAT VIEW"

Re: My Week with a ZA50 - Lengthy Notes on Rebuilding

I want a flat threaded view. I don't have it. I'm already viewing in flat view.

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