Dezdan's Engine

[Enginedoctor]

As discussed in a previous thread, Dezdan has (finally) cashed in on his 'freemium' engine rebuild he bought the parts (making it not really free) and i'm supplying the labor...

This is a test to asses time spent and parts in involved in a legitimate engine restoration. I've done plenty of engines, sure, but none completely for profit. Maybe, this will change in the future.

Dan Totally hooked it up with the parts. no expense spared. ALL honda oem quality, and a couple go fast goodies to go with it. AND, to make it even better, he individually inventoried, labeled and bagged everything along with schematics in highlighter. Bravo. Even if i'd never done one before i think i'd be able to piece it together.

Regardless, normally i do full size pictures, but these are quicker and easier.

This is the engine teardown.
First things first, this isn't my first rodeo. all the special tools, i have. if there are subtle tricks, i might know a few… This teardown took extra time due to the photography of it, but first picture to last i still think is only 2.5 or 3 hours.

This is what the package looks like:


Very nice, i think, in the grand scheme of things. It's an hk0 motor. Splines aren't wiped out, nothing's bent, one dinged thread, one crack in the sprocket cover, all the screws have 'some' head, with the exception of one on said sprocket cover…

Here we go:
Here's the crack in the cover, and the garbage thread is the one in the case half, just below it. Once i got it off, it looked like a hammer has been used on the flywheel. who knows why.


Remove the round clutch cover. it's the long 10mm here: A 9mm then gets off the 3 cam sprocket bolts. I hold the flywheel when i loosen these. an impact helps too if you have one, but you don't need it. just a good socket and some technique.


I used my #3 impact jis on this screw. it's proximity to the head makes it difficult with even the thinnest walled box wrench. if you want you can use the open end, but i just did it this way. Then i whack the lowest (closest to crank) portion of the cam sprocket with the screwdriver and my hand, and it (usually) pops off the cam, allowing for removal of the head.


I'm zoning out… more to come tomorrow AM

 

[Adam-NLV]

Think I'll watch your thread, see how it's done.
Dan's motor seems more worn than the 73 I've started to dismantle.

 

[69ST]

The rusty cylinder can be deceptive, in a good way. I've gone through a number of these motors where the piston had to be hammered free. Some may recall that lovely example I posted that also had seven kickstart pinion gear teeth sitting in the bottom of the crankcase and the head casting cracked around both exhaust studs. What seemed a house of horrors, at first blush, turned out to have a near-mint condition transmission assembly, alternator assembly and crankshaft. A $45 used head casting, new pinion gear and an 88cc bore-up kit later and this thing was literally good-as-new...with a little extra grunt...for just shy of $150 above & beyond the cost of a garden-variety rebuild, including a hotter cam.

A heavily rusted cylinder might require a two, or even three, O/S overbore if it's deep enough. Still, it's just a chunk of dumb cast iron...more substance than style and that works in your favor. The only time top end rust might be a problem is if it's around the valves and deep into the seats. Rotted guides can be replaced. OTOH, if the valve seats have to be cut too deeply to reach clean, solid, metal the head may "exceed mechanical limits" - line mechanic speak for :cc_rip:

My point is that you can't tell what you're getting into, until every part has been inspected. The most likely deal-breakers, imo, are: serious rust in the lower end, broken LH case casting, worn-out 3-speed crankshaft, broken/worn out gears (primary, or secondary side). Rust in the bottom end can mean every part is , the LH case casting has the SN (if that matters to you), cranks are expensive to rebuild, or replace w/NOS (good excuse for a 51mm TB stroker) and gears, especially 4-speed flavor and K0 primaries can be hard to find, when you need them.

 

[Enginedoctor]

The rusty cylinder can be deceptive, in a good way. I've gone through a number of these motors where the piston had to be hammered free. Some may recall that lovely example I posted that also had seven kickstart pinion gear teeth sitting in the bottom of the crankcase and the head casting cracked around both exhaust studs. What seemed a house of horrors, at first blush, turned out to have a near-mint condition transmission assembly, alternator assembly and crankshaft. A $45 used head casting, new pinion gear and an 88cc bore-up kit later and this thing was literally good-as-new...with a little extra grunt...for just shy of $150 above & beyond the cost of a garden-variety rebuild, including a hotter cam....

Excellent points. In fact, the lower end was 'much better' than i thought, after seeing the seized piston as the first introduction to this motor on my bench. We'll get to the bottom end in just a few. it was actually taken apart along with the other disassembly, but last night i was seemingly on a 'mission' and after a couple more coronas (and about half a lime), i felt my ability to post helpfully was compromised. sorry for that, especially to dan, to whom i promised pics of the teardown yesterday.

Regardless, Surprisingly, the cylinder didn't require a hammer to remove. Lots of rust in the top end, sure, but it actually slid out. must have only been the top ring seized to the bore. Luckily, this motor is also going the way of 52mm bore and AL cylinder, so i'll probably repaint it, and let it be shelved for a rainy day.. or maybe a dry day so it doesn't get rusty again :24:

onwards and upwards. here's the cylinder and piston removal, and condition of cylinder, which we're not reusing immediately.


Now time to attack the clutch cover. the Vessel Impacta is coming in handy here. i'm not sure it's as 'sturdy' as a regular impact driver, but it feel it does the job very well. once your hands get oily it's a pain, as with most things. Literally not one of the clutch or case screws required special means of removal. maybe i should play the lottery tonight…. i don't think utah has one though Oh, and notice how clean the screen is. I used the wood end of the hammer to LIGHTLY tap the clutch cover until it came free.


Sorry the pics are out of order. luckily you can probably figure out what comes first. Flywheel time. i used the 17 mm on my little impact. Clean the threads WELL before putting in the puller. then a quick burp with the socket, ready to go. the advancer looked to be non-operational until i freed it with a little fiddling. i'll clean that up before assembly. Pardon the reversal of images.


The stator assembly is very clean. the countershaft sprocket area is not. (anyone surprised?) it appears as though the seal has been leaking for a little while. I popped the screws out, and the cam chain tensioner was also looking good.


Use the impact to remove the clutch outer. this might prove difficult. I cleaned most of the trash (which there wasn't much of) out of the spinner, then popped the clutch special nut off.


yank the primary gear.


Then the 'rooster comb' (auto trans guys??)/ shift detent goodies.



clean the shaft off, then make sure you're clear, and smack shaft til it comes out.


Almost time to split the cases… Don't forget about this one, though….


Back up the cases, smack the screws with the impact, and split away. DO NOT STICK SHARP PRYING OBJECTS IN THE GASKET SURFACE…


here's the goodies. The countershaft stuck in the left case half temporarily, and that wasn't my intention. So the gear sitting at the bottom wasn't there initially.


This is the trans and the sad shift forks. the shiny spots are where the gears contacted the fork (not supposed to happen)


Remove the snap ring on the kickstart shaft (this is the only one you need to remove, it's on the clutch side)
then the oil pump, and oil drive gear, etc.


SO, everything's apart. Remove the gasket with a BRAND NEW razor blade, VERY CAREFULLY…


Okay, the cases are a mess. This is where people go to extreme measures…. DONT blast them. as much as you want to. These parts are going into a hot alkali wash. I don't want to use acid because it attacks metal. This seemed easiest, and least invasive…. the rest is yet to come…

 

[Dezdan]

:4::4::4::4: Thanks TED!

 

[kirrbby]

One of the first things I want to do when I get a new bike or engine, is to get a look at the stator. I LOVE to find them like that. Sucker looks great. Trans... Great. Dezdan, you have a very nice core there.

 

[cjpayne]

One of the first things I want to do when I get a new bike or engine, is to get a look at the stator. I LOVE to find them like that.

X2. They're getting harder to find.

 

[Dezdan]

One of the first things I want to do when I get a new bike or engine, is to get a look at the stator. I LOVE to find them like that. Sucker looks great. Trans... Great. Dezdan, you have a very nice core there.

Stator was one thing I was worried about since there is no rebuild kits for the Mitsub yet. Glad it is clean! I just need to find a decent plug to replace the one currently on it, I think CHP sells them. Overall, it honestly looks better then I expected it too. This engine is non-matching to the frame, seized, and sat with carb off for ~12 years when I picked it up. I was expecting there to be some internal damage - glad it looks good!

 

[69ST]

The top end rust is what happens when an engine sits, untouched, for many years with an open valve. Humid air gets in, moisture condenses onto the surfaces and rust forms; that's why the piston didn't have to be hammered free. Below the rings, everything remained oiled and relatively dry...and rust-free. IMO, there's nothing below the cylinder that's unusual; IOW, this engine is pretty average, as rebuildable cores go - a nice surprise.

Funny thing about the Mitsubishi alternator, it's a better quality design than the Hitachi, again IMO. It's a lot more rebuilder-friendly than its more common sibling.

This project ought to turn out very well and the before/after photos will have stunning contrast.

 

[Enginedoctor]

Okay so i spent the whole month of july running around like a madman, one state to another, mostly driving, making deals, buying snowblowers, fixing cars and one or two busses…. it's been hectic, to say the least.

Like a turd, this engine has been sitting in my garage, more or less ready to build for the whole month. Finally i've decided to knock it out. Today, in a very detailed writeup, we're going to cover the 'case splitting' rebuild, and we're going to prepare a block to be built, including a HV oil pump prep, Rebuild and install a transmission, including new forks and pins on the drum, replace a kick start shaft, two bearings in the block, and then put the cases together. PAY ATTENTION, you might learn something.

First things first, The left side case has a bolt hole absolutely destroyed.


i'm terrible working Aluminum with the Tig, so i showed the danish guy what i was trying to accomplish, and asked him to add some metal for me. This is how it ended up. i'm not super stoked on the aesthetics of it, but i can get this functional.


So, i got out the drill and got to work. I decided to use a 6X1mm insert i had laying around, i figured it was stronger than the soft aluminum it sits in.



And, how i feel about how it looks….


Now we get to dan's box of parts. he went over the top in terms of organization and comprehensive purchasing.



Here's the Right side case. he bought a bigger oil pump, so i need to drill the case out.

This is the closest bit i have to a 2mm, so it's the winner. It's soft aluminum, so i just spun it by hand and got these results:




AND, make SURE you clean out the oil galleys. one goes north and the other east to the clutch…


TRANSMISSION time…. This is the dirty old trans. still has old oil on it. Dan got all the washers and the new circlips. There's a schematic, but if you don't know how a motorcycle trans goes together, GENERALLY the circlip goes towards the gear that is fixed to the shaft (or splined, if ya know what i mean) And the washer goes towards the spinning gear. On the 4 speeds, there's no end washer on the mainshaft. this throws me off EVERY time, and i have to check the schematic… there's none there….


And these are the dreaded shift forks. See the smileys? that's where the gear has contacted the fork… means it needs it.


yet the fork ends still look good. you can still see some of the machine marks.


This is the clip you're removing to pull the pins out of the forks, and thus the forks off of the drum.




Yank that clip, and the pin usually wiggles out. if it doesn't, a tiny pick can persuade it


Here's the schematic and the new goodies, nice and bagged up…



This is the bare drum. look for wear both on the drums surface, and in the 'canyons'… generally, they're unharmed, but when a bike has bean REAL beat, you can see evidence of wear which makes the drum difficult to turn or shift sloppy.


Here's the new pins going in. NOW, these are rarely damaged, and designed to spin freely inside the bore, but you need to make sure the fork is alined with the groove in the drum. then re-install the little clip when the pin is fully pushed in.



Then both forks on the drum


Now for all the clips and washers. on this trans, the gears go big to small, respectively, so the order is easy to keep. if you don't have a schematic, take the gears off one by one and keep them in place with the washers and spacers all still on them.


Here is the countershaft. use a GOOD PAIR of snapring pliers and remove all the rings CAREFULLY, not over stretching them. And dis-assemble. Spend good money on these from a real tool vendor. not the chinese harbor. it will save you the frustration.




If you have a nice pump oiler, put good clean oil in it and be generous on all the contact points.


Now, gear, washer, clip.



Check the dogs on ALL the gears and look for chips or smashing, these ones look great.



More clips, a washer, and another gear. oh and a spacer.


Here it is on the fresh drum.


Putting this bearing in the left side case. Drive on the OUTER RACE ONLY. hitting it lightly every 90 degrees or so.




Now, on the mainshaft, the 1st gear is integral to the shaft, and then 2nd 3rd and 4th go on from there.


Check the condition of the splines. again, these are great.


The 2nd gear circlip is kind of tricky. you kind of have to work around the dogs.


Check with your finger to make sure these spin freely.


Check this groove for garbage or galling.


Circlip, then a washer, and the last gear… And the complete assembly. Lube it, then i drop it in as one.





Be sure to line up the drum with it's respective hole. the rest of it more or less lines up, generally. if it's a 3 speed, don't drop the washer. you might want to use vaseline and stick it into the case before you drop in the trans.

Spin the main shaft and the drum to see if it 'shifts', even though it really won't until it's all together….


Now here's the trash kick start shaft. the splines are questionable, so we're gonna replace it. new clips all around, and a new springy gear thing, so it's essentially a full rebuild of the shaft, reusing the original gear.



I was stingy on the pictures here. take the clips off the shaft. Put the new clip on the gear, new clips, the washer goes on the back (towards the left side case). Install 3 clips. they're all (2) different sizes. then, i slip it in. In the past, i've installed this into the right side case and then put them together, but i don't do that anymore. oh and make sure the spring is in it's groove.



Here's the bearing in the right side case. i tapped it in the same way.


Crank dropped in, ready to go together.


Vesrah gasket installed.


Case ready, gasket surfaces clean…




Here's the gasket's reveal. i'll probably trim it.




So, Ta-da, we've built a bottom end. next time is the shifter, clutch rebuild, seals, spray the covers, and get the bottom all done.

 

[hooter ray]

Your the man!....that was very helpful!...
Would my 71 sl70 be the same?..... Even though I don't for see having to split any cases..... I do however for see a top end rebuild while I take care of some engine noise, probably timing chain. Or valves.... Would really like to do 88cc if not to much more trouble:4:. Bike only has 1400mi Lol!.if so is there a kit all inclusive. On yea probably need to go in rt case and change oil screen and check /refresh clutch.:monkey