Preliminary steps and preparation
**This motor is already done and I’ve been riding the bike around without any problems for the past little while, so you can trust the assembly guide. The engine pulls nice and hard came out very nicely with no leaks, noises or issues.
**This is simply the step by step assembly guide and not a guide on how to plan your build or modify ones motor.
***DISCLAIMER***
This guide will be a step by step walkthrough on how to get your engine from a pile of parts into a functioning motor. It will NOT cover installation onto the bike as bikes vary from one another, even Cubs themselves. If you can handle the motor assembly, then you will have no problem installing the motor on your bike, trust me.
Now before you get all excited to build yourself a new shiny motor, you need to step back and make sure you follow these important points.
1. Don’t rush things. The faster you rush, the more issues you’re going to encounter.
2. Always keep things clean. If you’ve got any kind of junk on your hands, wash it off. If your work area gets dirty, clean it up. If your parts spend any amount of time outside, wash them off throughly. Being clean is the biggest single thing you can do to ensure you end up with a successful rebuild.
3. If you don’t know, don’t go. If you find yourself saying “Mm, I think that’s right.” or “I don’t know but, let me try…” STOP. Go back and study or familiarize yourself with any specific procedure before you continue.
Follow these basic guidelines while you rebuild and you’ll have a good experience, or at least, a more successful one than if you didn’t.
BEFORE WE BEGIN
First thing is first, I’d get the following things to assemble the motor.
A little squeeze bottle filled with clean motor oil. Assembly lube is not required in the least bit on these motors nor is greasing of parts required beforehand, just oil and priming the motor with the starter for 5-10 seconds.
A bucket of a very specific size, roughly 45-50 cm in diameter. You’ll see why.
2 rolls of paper towels at least. I use a ton of paper towels (sorry trees!), but I justify this because of all the CO2 I am not putting in the air by using a Super Cub over my car often times.
2 or 3 cans of brake cleaner or carburetor cleaner.
A very clean workspace. I go over my table, chairs and floor at least 3 or 4 times with cleaner and a hand towel to make sure there’s no trace of anything hanging around.
Feeling excited? No? Alright then,
More to come, updates, pictures and the rest of the guide.
Things to come
How to rebuild a Honda Super Cub (Series 84) motor
First thing is second…I mean first.
Pressing the bearings into the case, NOT HAMMERING. Don’t hammer, just…don’t do it. It potentially risks cracking your case and damaging your bearings. Don’t try it.
To properly HAND PRESS bearings in with NO HAMMERING, follow this method.
What you need to do with either “bake” your case in the oven for 20 minutes at 140 C, or place it over a gas fire for 3-4 minutes. If you start to smell burning, you’re getting too hot already.
When your case is hot, take the bearing you are going to install and hold it like so.
Be ready to act quickly because you only have a 2 or 3 second window to slip the bearing in before it heats up and expands. Now, as best as you can, lower the bearing right near it’s slot and, while making sure it’s straight, push it into place. It should slide in with very little effort.
Repeat with the 2nd bearing, and then repeat the same process with the other case.
To better show how it’s done, here is a youtube video that I think works. My first time using teh internetz like this, so forgive me if it’s terrible.
Alternatively, if you don’t like the “fast track” approach, the oven approach works in another way as long as you make sure the bearings are dry. To ensure this, dump your bearings in a container of petrol and swish them around thoroughly. Make sure the oil (packing oil if new, or remaining oil if used) is completely washed away and the bearing is dry. Air dry the bearing until no petrol remains.
Now place bearings loosely in the case over their respective housing on the case and put the whole thing in the oven at 200 C. Over 5 minute intervals or so, keep trying to encourage the bearings to “fall” into their slots with chopsticks or something. If they don’t easily slide in, wait until the case heats up more. If you still can’t get it in after 20 minutes or so, the bearing housing might be either dirty or damaged. This is why I like to remove the bearings in the oven as well, because if they simply fall out in the oven, then I know they’ll “fall in” when I rebake it.
If you’re really in a pinch and the heat method doesn’t work for you for some reason, but fine, use a hammer and socket and pound the OUTSIDE race into the case. Be careful though, these bearings are fragile as is the case. Hit it wrong and you can ruin either one.
Now that the bearings are in place, let the cases cool down. It takes about 20-30 minutes before I touch them again.
In the meantime, get the bucket out and put some paper towels under it. Clean your workspace too if you can.
The reason I said to get a bucket about 40-50 cm in diameter is because of this.
You can place your engine on it like a stand and have the crankshaft stick through.
Speaking of crankshaft, get your assembly and insert it now.
Make sure the timing gear is on the “back” and the splined and threaded side towards you, like so. Also ensure the connecting rod is not hitting the case.
Gearbox time.
Here is the input shaft “exploded”.
Here is the output shaft exploded view
And here are the end “washers” or spacers that go on each shaft.
Output
Input
You may wonder why the input shaft is partially assembled. It’s because most of the time they are assembled this way when purchased new, so little assembly is required. However, if you are interested in modifying your gearbox and swapping in new ratios, here’s what to keep in mind in general for assembly and installation.
If the gear is a “cog”, meaning it rotates with the shaft (it is physically attached to the shaft), no copper “syncro” is required, or no copper washer is required to retain it. Only a circlip.
If the gear is a freewheeling gear, then a copper syncro/spacer is required AS WELL AS a circlip/snap ring.
Here is the complete “box”.
And here is with the gear selector installed. Note that the gear pins are facing you. It is entirely possible to install it backwards, so take note.
Orientation of the shift forks.
When installing the gearbox, simply pick it up in the palm of one hand and hold the engine case up so you can slide it in sideways. A little wiggling is needed, but it should slide into all it’s housings (there are 3) very easily. No pounding, smashing or pressing (hydraulic press) is required at all.
When installing the shift pins, take note that if you have either a 3 or 4 speed, one of the pins will be much shorter than the rest. Install a long pin in each hole until you find which one. It will be obvious as it doesn’t fit.
Installing the kickstart. The kickstart simply slides in, the spring going in the recess. No washer required on the end of the kick start going in.
Make sure the fit is flush and…
DO NOT FORGET THIS WASHER. Your kickstarter will not function without it.
This is what the finished gearbox should look like as of now.
Installing oil pump drive. THIS HAS TO BE DONE NOW AND CAN NOT WAIT UNTIL LATER. THERE IS NO GOING BACK IF YOU FORGET THIS.
Slide the oil pump drive in threaded side “down” or away from you, but don’t let go. Simply slide it through the hole. In the other hand, hold the oil pump driver gear and feed it through the timing chain side. You have to make sure that the gear is installed the correct way. If you install it backwards, it was not align with the timing gear HOWEVER, it will run just fine. I am picky though, so I like to make sure the gear is in near perfect alignment with the timing chain gear like so.
Sorry for the lack of more pictures, if you need a clarification, email/PM me is fine.
If at any time you need to stop with the cases still open, please pack with paper towels to prevent dust getting in.
Place the guide pins here…
and here.
Now install the case gasket. If you somehow managed not to get a case gasket, then use threebond non hardening sealer and remove the 1st gear thrust washer from the output shaft to provide adequate clearance. Seriously though, just buy a damn gasket, they’re everywhere.
Now you’re ready to slide on the other half of the case. Gently lower it over all the shafts and with a little wiggling here and there, the case will simply fall into place, even without bolts.
BEFORE YOU BOLT ANYTHING DOWN, check to see if the
Crankshaft freely rotates
Transmission freely rotates
Kickstarter engages transmission (turn anti clockwise)
Gear shifter freely rotates. Sometimes it might bind, that is okay. Wiggle the transmission input shaft or rotate it a few times WHILE rotating the gear shifter. The gear shifter should make it through a wide range of shifts without any dragging. Occasionally abrupt binding okay while shifting okay, but resistance or drag is bad.
If all mechanisms free rotate and no binding is detected, then bolt down the case and check again. If all checks out, well done!
Now you can remove the engine off the bucket and set it on it’s own two…feet?
Pressing the bearings into the case, NOT HAMMERING. Don’t hammer, just…don’t do it. It potentially risks cracking your case and damaging your bearings. Don’t try it.
To properly HAND PRESS bearings in with NO HAMMERING, follow this method.
What you need to do with either “bake” your case in the oven for 20 minutes at 140 C, or place it over a gas fire for 3-4 minutes. If you start to smell burning, you’re getting too hot already.
When your case is hot, take the bearing you are going to install and hold it like so.
Be ready to act quickly because you only have a 2 or 3 second window to slip the bearing in before it heats up and expands. Now, as best as you can, lower the bearing right near it’s slot and, while making sure it’s straight, push it into place. It should slide in with very little effort.
Repeat with the 2nd bearing, and then repeat the same process with the other case.
To better show how it’s done, here is a youtube video that I think works. My first time using teh internetz like this, so forgive me if it’s terrible.
Alternatively, if you don’t like the “fast track” approach, the oven approach works in another way as long as you make sure the bearings are dry. To ensure this, dump your bearings in a container of petrol and swish them around thoroughly. Make sure the oil (packing oil if new, or remaining oil if used) is completely washed away and the bearing is dry. Air dry the bearing until no petrol remains.
Now place bearings loosely in the case over their respective housing on the case and put the whole thing in the oven at 200 C. Over 5 minute intervals or so, keep trying to encourage the bearings to “fall” into their slots with chopsticks or something. If they don’t easily slide in, wait until the case heats up more. If you still can’t get it in after 20 minutes or so, the bearing housing might be either dirty or damaged. This is why I like to remove the bearings in the oven as well, because if they simply fall out in the oven, then I know they’ll “fall in” when I rebake it.
If you’re really in a pinch and the heat method doesn’t work for you for some reason, but fine, use a hammer and socket and pound the OUTSIDE race into the case. Be careful though, these bearings are fragile as is the case. Hit it wrong and you can ruin either one.
Now that the bearings are in place, let the cases cool down. It takes about 20-30 minutes before I touch them again.
In the meantime, get the bucket out and put some paper towels under it. Clean your workspace too if you can.
The reason I said to get a bucket about 40-50 cm in diameter is because of this.
You can place your engine on it like a stand and have the crankshaft stick through.
Speaking of crankshaft, get your assembly and insert it now.
Make sure the timing gear is on the “back” and the splined and threaded side towards you, like so. Also ensure the connecting rod is not hitting the case.
Gearbox time.
Here is the input shaft “exploded”.
Here is the output shaft exploded view
And here are the end “washers” or spacers that go on each shaft.
Output
Input
You may wonder why the input shaft is partially assembled. It’s because most of the time they are assembled this way when purchased new, so little assembly is required. However, if you are interested in modifying your gearbox and swapping in new ratios, here’s what to keep in mind in general for assembly and installation.
If the gear is a “cog”, meaning it rotates with the shaft (it is physically attached to the shaft), no copper “syncro” is required, or no copper washer is required to retain it. Only a circlip.
If the gear is a freewheeling gear, then a copper syncro/spacer is required AS WELL AS a circlip/snap ring.
Here is the complete “box”.
And here is with the gear selector installed. Note that the gear pins are facing you. It is entirely possible to install it backwards, so take note.
Orientation of the shift forks.
When installing the gearbox, simply pick it up in the palm of one hand and hold the engine case up so you can slide it in sideways. A little wiggling is needed, but it should slide into all it’s housings (there are 3) very easily. No pounding, smashing or pressing (hydraulic press) is required at all.
When installing the shift pins, take note that if you have either a 3 or 4 speed, one of the pins will be much shorter than the rest. Install a long pin in each hole until you find which one. It will be obvious as it doesn’t fit.
Installing the kickstart. The kickstart simply slides in, the spring going in the recess. No washer required on the end of the kick start going in.
Make sure the fit is flush and…
DO NOT FORGET THIS WASHER. Your kickstarter will not function without it.
This is what the finished gearbox should look like as of now.
Installing oil pump drive. THIS HAS TO BE DONE NOW AND CAN NOT WAIT UNTIL LATER. THERE IS NO GOING BACK IF YOU FORGET THIS.
Slide the oil pump drive in threaded side “down” or away from you, but don’t let go. Simply slide it through the hole. In the other hand, hold the oil pump driver gear and feed it through the timing chain side. You have to make sure that the gear is installed the correct way. If you install it backwards, it was not align with the timing gear HOWEVER, it will run just fine. I am picky though, so I like to make sure the gear is in near perfect alignment with the timing chain gear like so.
Sorry for the lack of more pictures, if you need a clarification, email/PM me is fine.
If at any time you need to stop with the cases still open, please pack with paper towels to prevent dust getting in.
Place the guide pins here…
and here.
Now install the case gasket. If you somehow managed not to get a case gasket, then use threebond non hardening sealer and remove the 1st gear thrust washer from the output shaft to provide adequate clearance. Seriously though, just buy a damn gasket, they’re everywhere.
Now you’re ready to slide on the other half of the case. Gently lower it over all the shafts and with a little wiggling here and there, the case will simply fall into place, even without bolts.
BEFORE YOU BOLT ANYTHING DOWN, check to see if the
Crankshaft freely rotates
Transmission freely rotates
Kickstarter engages transmission (turn anti clockwise)
Gear shifter freely rotates. Sometimes it might bind, that is okay. Wiggle the transmission input shaft or rotate it a few times WHILE rotating the gear shifter. The gear shifter should make it through a wide range of shifts without any dragging. Occasionally abrupt binding okay while shifting okay, but resistance or drag is bad.
If all mechanisms free rotate and no binding is detected, then bolt down the case and check again. If all checks out, well done!
Now you can remove the engine off the bucket and set it on it’s own two…feet?
Last edited by AE86 on Wed Sep 02, 2015 1:39 pm, edited 2 times in total.
Reckless driving cucumber - 成
The gear shifter slides right in. Make sure the shifter spring slides over the black pin sticking out of the case. Sorry for no picture, but you’ll see what I mean as long as the shifter is installed like so in the picture. It will automatically line up over the “pin”.
Position the arm like so on the gear shifter drum so the pins sit inside the arm.
Install gear star (only fits one way)
and bolt, hand tighten only.
Go to the other side of the motor and get this 10mm bolt, beveled washer and install it on the other side of the shift drum.
Now with a 10mm socket on one side and a 10mm socket on the other, tighten both sides down.
While I’m here, I like to install the selector contacts in this orientation. Oil them slightly for ease of install.
Don’t forget the bracket
And lastly, plonk this seal in like so. I usually add some threebond to it to be safe, if you do so, make sure the black plug AND metal surface is sqeaky clean if you do add sealer. If it’s not clean, you may actually CAUSE an oil leak.
Kickstarter spring
Install the spring onto the notched piece and then slide the starter onto the kickstart shaft like so.
Pull the spring over the notch in the case.
Install the snap ring
I like to test if the kickstarter functions by attaching the lever on loosely and giving it a few turns. Also rotate the gearbox to see that it’s clearing the kickstart, not dragging.
If all is good, continue to the gear selector and attach the shift drum spring?
Seals, I like to lube both the exterior and interior bits with a small bit of oil.
Simply press them into place although this will take a bit of effort. If you must, get a socket the size of the seal and tap it in GENTLY.
Same with the output shaft seal but don’t push it too far in. Push it just until it clears the edge of the lip like so.
Timing chain tensioner arm.
Install the arm with the 17mm bolt (make sure it rotates freely, even after the bolt is tightened) but don’t install the wheel just yet.
Now comes the timing chain, then the wheel.
Loop the chain over the crankshaft FIRST…
…then you can route it out the timing chain slot in the case. Now you can also simply slide the timing chain wheel on the tensioner arm. Be careful though, since it’s not fastened it can easily fall off if you’re not paying attention.
If you need to stop at this point for any reason, be sure to pack up your motor with paper towels.
More to come…
Position the arm like so on the gear shifter drum so the pins sit inside the arm.
Install gear star (only fits one way)
and bolt, hand tighten only.
Go to the other side of the motor and get this 10mm bolt, beveled washer and install it on the other side of the shift drum.
Now with a 10mm socket on one side and a 10mm socket on the other, tighten both sides down.
While I’m here, I like to install the selector contacts in this orientation. Oil them slightly for ease of install.
Don’t forget the bracket
And lastly, plonk this seal in like so. I usually add some threebond to it to be safe, if you do so, make sure the black plug AND metal surface is sqeaky clean if you do add sealer. If it’s not clean, you may actually CAUSE an oil leak.
Kickstarter spring
Install the spring onto the notched piece and then slide the starter onto the kickstart shaft like so.
Pull the spring over the notch in the case.
Install the snap ring
I like to test if the kickstarter functions by attaching the lever on loosely and giving it a few turns. Also rotate the gearbox to see that it’s clearing the kickstart, not dragging.
If all is good, continue to the gear selector and attach the shift drum spring?
Seals, I like to lube both the exterior and interior bits with a small bit of oil.
Simply press them into place although this will take a bit of effort. If you must, get a socket the size of the seal and tap it in GENTLY.
Same with the output shaft seal but don’t push it too far in. Push it just until it clears the edge of the lip like so.
Timing chain tensioner arm.
Install the arm with the 17mm bolt (make sure it rotates freely, even after the bolt is tightened) but don’t install the wheel just yet.
Now comes the timing chain, then the wheel.
Loop the chain over the crankshaft FIRST…
…then you can route it out the timing chain slot in the case. Now you can also simply slide the timing chain wheel on the tensioner arm. Be careful though, since it’s not fastened it can easily fall off if you’re not paying attention.
If you need to stop at this point for any reason, be sure to pack up your motor with paper towels.
More to come…
Reckless driving cucumber - 成
Fantastic. Don't be put off by the lack of replies. People are just waiting for it to finish!
pew, pew, pew, pew!
Sorry, I have been slow to getting this completed. The engine has been done for a long time, I just didn't get around to the write up.
Install this bit, wide side towards the crank bearing side.
This gear usually slides on fine, but sometimes low geared Cubs have a bigger gear, thus necessitating the installation after the clutch spacer thing.
Circlip
Check to see that there is no contact between the gear and engine components.
Install the drive pinion and thingy in the middle. I have no idea what to call in English.
Oil pump installation.
New gasket is always nice but old gaskets are useable as well as long as not damaged. Notice how of the three bolt that one is longer than the others. This goes in the "raised" side of the oil pump (bottom right).
I personally like to "prime" the oil pump with a few drops of oil. It's the only part I really don't like to run dry.
Gasket goes in this orientation, only one way possible.
The oil pump needs some rotating and "working" to get it to sit right. Don't try to bolt the pump down before you get it to sit perfectly flat.
Not seated.
Seated.
See the long bolt mentioned earlier? Goes here.
Move the oil pump drive wheel to ensure no binding. Should rotate easily with one finger.
Clutch installation. For actual clutch pack disassembly I might do a write up later, but for now just treat the pack as one unit (which it is).
To get the clutch to properly seat, you need to align the gear teeth in the grooves here. Slide the pack onto the crankshaft and make sure it seats properly.
If you happen to try and upgrade your oil pump to a high capacity version, be sure that the cover screws are the thin versions and don't stick out far like these. If you install fat screws on a fat oil pump, it will collide with the clutch when you try and shift and make a horrible grinding.
Pictured are the fat screws, but the oil pump is the thin (low capacity) type, so clearance is no issue
Install the lock washer I think it's call
These little tabs correspond to the grooves in the crankshaft.
Make sure those tabs go into these slits.
Belleville washer, make sure "OUTSIDE" is facing, well, outside.
Install this bit, wide side towards the crank bearing side.
This gear usually slides on fine, but sometimes low geared Cubs have a bigger gear, thus necessitating the installation after the clutch spacer thing.
Circlip
Check to see that there is no contact between the gear and engine components.
Install the drive pinion and thingy in the middle. I have no idea what to call in English.
Oil pump installation.
New gasket is always nice but old gaskets are useable as well as long as not damaged. Notice how of the three bolt that one is longer than the others. This goes in the "raised" side of the oil pump (bottom right).
I personally like to "prime" the oil pump with a few drops of oil. It's the only part I really don't like to run dry.
Gasket goes in this orientation, only one way possible.
The oil pump needs some rotating and "working" to get it to sit right. Don't try to bolt the pump down before you get it to sit perfectly flat.
Not seated.
Seated.
See the long bolt mentioned earlier? Goes here.
Move the oil pump drive wheel to ensure no binding. Should rotate easily with one finger.
Clutch installation. For actual clutch pack disassembly I might do a write up later, but for now just treat the pack as one unit (which it is).
To get the clutch to properly seat, you need to align the gear teeth in the grooves here. Slide the pack onto the crankshaft and make sure it seats properly.
If you happen to try and upgrade your oil pump to a high capacity version, be sure that the cover screws are the thin versions and don't stick out far like these. If you install fat screws on a fat oil pump, it will collide with the clutch when you try and shift and make a horrible grinding.
Pictured are the fat screws, but the oil pump is the thin (low capacity) type, so clearance is no issue
Install the lock washer I think it's call
These little tabs correspond to the grooves in the crankshaft.
Make sure those tabs go into these slits.
Belleville washer, make sure "OUTSIDE" is facing, well, outside.
Reckless driving cucumber - 成
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