Very cool. Walnut shells work good too, that's what was used to clean my ST1100 wheels a couple years ago.
1970 Honda SL100
- Thread starter bmcdonau
- Start date
I dropped the cylinder, head and left case at the machine shop on Monday. He said the bore looked iffy so we'll see if I need a quick hone or a honest to goodness overbore. The valves are good, but I'm having the clearances checked, valve seal (only one) replace and valves lapped. There is only one valve seal, on the exhaust valve. Weird design.
There was a guy in there with a crank from a Ford 460 and he recognized the head right away as he was a certified Honda mechanic in another life. He said there was only one valve seal because the inlet valve was cooled by fuel and didn't need a seal. I guess when you are building these little bikes you have to cut costs every where you can to make a profit. How much does a valve seal cost? Multiply it by about a million world-wide and you're talking about real money.
There was a guy in there with a crank from a Ford 460 and he recognized the head right away as he was a certified Honda mechanic in another life. He said there was only one valve seal because the inlet valve was cooled by fuel and didn't need a seal. I guess when you are building these little bikes you have to cut costs every where you can to make a profit. How much does a valve seal cost? Multiply it by about a million world-wide and you're talking about real money.
Here it is installed, you just turn it and it pulls the rotor off the crank.
once the rotor was off, you have to take the woodruff key off the crank.
There's nothing behind the rotor and stator except the cam chain tensioner.
After the tensioner is out all you have to do is take the case screws out and split the cases.
That was another exercise of pure joy. Not! More stuck screws. This time I used a big easy out and didn't worry about it breaking or the heads coming off the screws.
The crankshaft. The left case pulls off and the tranny and kickstart shaft stay in the right half.
Kickstart
Transmission.
the left case and cylinder and head are still at the machine shop. they should be back this week. Regardless of what I found out about the cylinder, piston and rings, I'll be able to put the bottom end back together this week.
I'm at a bit of a standstill right now. I use Clay's machine shop on South Presa in San Antonio and they do a great job. Its a bit of an old fashioned place as it looks like machine shops I visited with my dad. They have one guy who does the motorcycle work and he's been sick. Hopefully he'll be back next week.
In the mean time I picked up a parts bike with two engines in Ft. Worth today. I needed the frame and handle bars, but I think I can probably build another engine out of the two.
In the mean time I picked up a parts bike with two engines in Ft. Worth today. I needed the frame and handle bars, but I think I can probably build another engine out of the two.
DixieFlyer
Terry Melton
Dennis,
Great job. Thanks for taking the time to post a thoroughly detailed description of the resurrection of your SL100. I know it's a lot of effort and time consuming to post the step by step process of bringing it back to life and, I for one really enjoy seeing the progress you're making. I followed your posts of the restoration of the XL350 a while back, and always look forward to reading about your projects. Thanks again for sharing with us. Good luck and I hope you have smooth sailing on the re-assembly of the SL.
Best regards,
Terry
Great job. Thanks for taking the time to post a thoroughly detailed description of the resurrection of your SL100. I know it's a lot of effort and time consuming to post the step by step process of bringing it back to life and, I for one really enjoy seeing the progress you're making. I followed your posts of the restoration of the XL350 a while back, and always look forward to reading about your projects. Thanks again for sharing with us. Good luck and I hope you have smooth sailing on the re-assembly of the SL.
Best regards,
Terry
I finally got the parts back from the machine shop today. All good news, the piston is reusable and the bore is good and stock size. The exhaust valve seal was replaced and the valves lapped. I'll be painting the cases and rebuilding the bottom end this week. I ordered new standard size rings and some misc parts I need to finish the motor. Hopefully I'll be done in a couple weeks.
The cases are done.
I used Eastwood two part urathane engine paint in aluminum. It looks a little darker than the Honda silver, but it looks good! Its good to 650 degrees.
I'm in the process of replacing the bearings now and have one side finished. I heated the cases to 250 degrees and froze the bearings then drove them home with a large diameter socket.
I'll take the transmission and kick start apart and clean them and reinstall in the new cases.
I used Eastwood two part urathane engine paint in aluminum. It looks a little darker than the Honda silver, but it looks good! Its good to 650 degrees.
I'm in the process of replacing the bearings now and have one side finished. I heated the cases to 250 degrees and froze the bearings then drove them home with a large diameter socket.
I'll take the transmission and kick start apart and clean them and reinstall in the new cases.
When the engine was apart, I inspected all the internal parts and didn't end up replacing any bearings or gears. The gears looked good and the crank feels good. The crankshaft is a pressed up affair and it's expensive and complicated to disassemble the crank and rebuild it. I'm hoping everything is as good as it looks and feels.
I put the bottom end back together and I have all five gears and neutral so it looks like I'm good to go.
I had to replace the bearings in the crankcase halves since I took them out when I blasted and painted the cases.
I heated them to about 300 degrees and put the bearings in the freezer. Supposedly they will drop right in, but not this time. It took a little pressure to get them to seat. I used a socket the same size as the race and tapped them in with a hammer. You're not supposed to, but what you gonna do? Don't let your wife catch you doing this!
A little bit about transmissions, at least a late 60's Honda tranny. There are two shafts and a drum. In the picture below the shift drum is on the lower right, the main shaft on the lower left and the countershaft on the upper left. The shaft on the upper right is the kickstart shaft and the shaft in the center aligns the three shfit forks.
The copper colored contacts on top of the shift drum is the neutral switch. When the drum is in the neutral position, this switch makes contact with the neutral switch and provides a ground to turn on the neutral light. On some bikes it also allows you to engage the starter motor.
The shift drum engages three forks which do the actual shifting by moving one of three three gears up and down the shafts. Different gears are engaged by engaging dogs on one gear into recesses on another.
Here's a good picture of the shift forks engaged in the shift drum.
Here's a picture of the other end of the shift fork engaged in one of the gears. This is a good picture because you can see the dogs on the top and bottom of the gear engaged by the shift fork and the gear above and below which are engaged for different ratios. 4th on top 5th on the bottom. The transmission is in neutral so no gears are engaged.
I reinstalled the kickstart, gearshift, and countershaft seals into the cases.
Then I started by assembling the transmission and kickstart, using assembly grease to prelube the parts and hold some in place.
The two transmission shafts assembled.
The kickstart ratchet. This one has the newer kickstart shaft which is the same diameter all the way to where the kickstart lever attaches. The older type necks down at the end and is prone to break.
Putting the cases back together is surprisingly easy and just a little bit fiddley. All the shafts are different heights inside the cases and have to line up with ball bearings or plain bearings. I found it easier to insert the transmission, kick start and and crankshaft in the left case, then twist the right case to line up the tallest shaft, then the second tallest and so on. You can push the cases most of the way together by hand if everything is lined up. You need a rubber hammer to fully seat the crank bearings in their races.
Back together!
I used stainless steel allen head button screws to secure the cases.
Before inserting the screws I coated them with this.
Next came the stator, as you can see from the picture below, the plastic sheathing is in bad shape as is the connector.
First I wrote down the color codes of the wires in the connector then snipped it off the wires and removed the hardened plastic sheathing. That's the neutral switch attached to the green and red wire.
I tinned the ends of the wires getting the new connector.
Then I installed the new terminal. I crimped and soldered them so they shouldn't come loose.
I had ohmed out the stator before I started and it tests good. I retested after I put the new conector on.
Its pretty easy to test a stator if you have the manual to tell you where you should have continuity and where you shouldn't.
On the right side I reinstalled the shift linkage, clutch, oil pump and oil slinger.
First the oil filter.
Two o-rings.
The oil pump itself.
The driven gear
The cover.
The shift linkage was next. That's the end of the shift drum sticking out there and a small tab that engages the gear shifter.
I forgot to take the next couple pictures. A shift cam plate goes on next then the stopper which keeps you from going through two gears at once. Then the shift shaft just slips into the case and engages thebcam which engages that tab to shift. I'm not sure why the shift shaft doesn't move in and out since there is nothing securing it. I guess the shift lever itself keeps it in.
Then the clutch, it just slips on and is held in place by a circlip you can see in the middle. The springs sit on those four shafts and are held in place by four bolts.
The oil slinger.
This washer goes underneath the nut which holds it on. They don't want you to put this on backwards.
Tightening up the nut with the special socket.
The cover goes on next with a new gasket.
The finished crankcase.
I've still got to paint the head and install the cam tensioner, piston, rings, and cam and points which I hope to do next week.
I put the bottom end back together and I have all five gears and neutral so it looks like I'm good to go.
I had to replace the bearings in the crankcase halves since I took them out when I blasted and painted the cases.
I heated them to about 300 degrees and put the bearings in the freezer. Supposedly they will drop right in, but not this time. It took a little pressure to get them to seat. I used a socket the same size as the race and tapped them in with a hammer. You're not supposed to, but what you gonna do? Don't let your wife catch you doing this!
A little bit about transmissions, at least a late 60's Honda tranny. There are two shafts and a drum. In the picture below the shift drum is on the lower right, the main shaft on the lower left and the countershaft on the upper left. The shaft on the upper right is the kickstart shaft and the shaft in the center aligns the three shfit forks.
The copper colored contacts on top of the shift drum is the neutral switch. When the drum is in the neutral position, this switch makes contact with the neutral switch and provides a ground to turn on the neutral light. On some bikes it also allows you to engage the starter motor.
The shift drum engages three forks which do the actual shifting by moving one of three three gears up and down the shafts. Different gears are engaged by engaging dogs on one gear into recesses on another.
Here's a good picture of the shift forks engaged in the shift drum.
Here's a picture of the other end of the shift fork engaged in one of the gears. This is a good picture because you can see the dogs on the top and bottom of the gear engaged by the shift fork and the gear above and below which are engaged for different ratios. 4th on top 5th on the bottom. The transmission is in neutral so no gears are engaged.
I reinstalled the kickstart, gearshift, and countershaft seals into the cases.
Then I started by assembling the transmission and kickstart, using assembly grease to prelube the parts and hold some in place.
The two transmission shafts assembled.
The kickstart ratchet. This one has the newer kickstart shaft which is the same diameter all the way to where the kickstart lever attaches. The older type necks down at the end and is prone to break.
Putting the cases back together is surprisingly easy and just a little bit fiddley. All the shafts are different heights inside the cases and have to line up with ball bearings or plain bearings. I found it easier to insert the transmission, kick start and and crankshaft in the left case, then twist the right case to line up the tallest shaft, then the second tallest and so on. You can push the cases most of the way together by hand if everything is lined up. You need a rubber hammer to fully seat the crank bearings in their races.
Back together!
I used stainless steel allen head button screws to secure the cases.
Before inserting the screws I coated them with this.
Next came the stator, as you can see from the picture below, the plastic sheathing is in bad shape as is the connector.
First I wrote down the color codes of the wires in the connector then snipped it off the wires and removed the hardened plastic sheathing. That's the neutral switch attached to the green and red wire.
I tinned the ends of the wires getting the new connector.
Then I installed the new terminal. I crimped and soldered them so they shouldn't come loose.
I had ohmed out the stator before I started and it tests good. I retested after I put the new conector on.
Its pretty easy to test a stator if you have the manual to tell you where you should have continuity and where you shouldn't.
On the right side I reinstalled the shift linkage, clutch, oil pump and oil slinger.
First the oil filter.
Two o-rings.
The oil pump itself.
The driven gear
The cover.
The shift linkage was next. That's the end of the shift drum sticking out there and a small tab that engages the gear shifter.
I forgot to take the next couple pictures. A shift cam plate goes on next then the stopper which keeps you from going through two gears at once. Then the shift shaft just slips into the case and engages thebcam which engages that tab to shift. I'm not sure why the shift shaft doesn't move in and out since there is nothing securing it. I guess the shift lever itself keeps it in.
Then the clutch, it just slips on and is held in place by a circlip you can see in the middle. The springs sit on those four shafts and are held in place by four bolts.
The oil slinger.
This washer goes underneath the nut which holds it on. They don't want you to put this on backwards.
Tightening up the nut with the special socket.
The cover goes on next with a new gasket.
The finished crankcase.
I've still got to paint the head and install the cam tensioner, piston, rings, and cam and points which I hope to do next week.
Looking really good.
AARRRRRRRGH
After some delay to do some maintenance on the other bikes I was able to get back to the SL100.
The rings I ordered came in and I was ready to put the to end on the engine. Wait a minute, the wrist pin is really loose in the crank. Lets look at the old piston and pin and see what gives.
Well, not only is the wrist pin larger, the piston is too! After some measuring and thinking and more measuring it seems like I have a 125 crank and piston in the 100. Unfortunately, the original cylinder was no good and I obtained a 100 cc replacement on e-bay.
And finally some good news, one of the cylinders that came with the engines I got with the Fort Worth frame apparently has been bored out to 125 cc. I'll have to get the cylinder and piston checked by a machine shop and order 125 cc rings so it's a minor setback in the scheme of things.
After some delay to do some maintenance on the other bikes I was able to get back to the SL100.
The rings I ordered came in and I was ready to put the to end on the engine. Wait a minute, the wrist pin is really loose in the crank. Lets look at the old piston and pin and see what gives.
Well, not only is the wrist pin larger, the piston is too! After some measuring and thinking and more measuring it seems like I have a 125 crank and piston in the 100. Unfortunately, the original cylinder was no good and I obtained a 100 cc replacement on e-bay.
And finally some good news, one of the cylinders that came with the engines I got with the Fort Worth frame apparently has been bored out to 125 cc. I'll have to get the cylinder and piston checked by a machine shop and order 125 cc rings so it's a minor setback in the scheme of things.
Now that's funny right there. After I sold my SL100, I acquired an SL125 motor and stuck in for the kid who had purchased it. That was in Cincinnati, tho. Complete motor in that case so it said 125 on back of the cylinder.
Well crap, I've got four cylinders, three which say 99 CC and one which says 124 CC and three out of the four have the same sleeve diameter.
Which won't fit in the cases I have.
This is beginning to piss me off. None of the cylinders will fit the good cases I have. I have to get a piston and rings to fit the crank in the good cases or find an SL100 crank with the right diameter wrist pin to fit the piston I have. Either way, its a crap shoot because I am to the point where I don't know whats what.
More interesting stuff, here's the piston from the 125, Something bounced around in the combusion chamber.
Here's the piston out of one of the 100cc heads, its got a big ding in the side of the piston.
oh well...
Which won't fit in the cases I have.
This is beginning to piss me off. None of the cylinders will fit the good cases I have. I have to get a piston and rings to fit the crank in the good cases or find an SL100 crank with the right diameter wrist pin to fit the piston I have. Either way, its a crap shoot because I am to the point where I don't know whats what.
More interesting stuff, here's the piston from the 125, Something bounced around in the combusion chamber.
Here's the piston out of one of the 100cc heads, its got a big ding in the side of the piston.
oh well...
Throttlejockey
Padden is my hero
So, someone sleeved the 99cc cylinder that won't fit to fit a 125cc case?
You could get the sleeve machined on the bottom so it fits into the cases. Or bore the cases if you take it apart to change the crank.
You could get the sleeve machined on the bottom so it fits into the cases. Or bore the cases if you take it apart to change the crank.
Running changes in the production over the life of this model bike? Honda is pretty good about documenting such in the front of the shop manual, even to saying exactly what the change was. OTOH... doesn't do ya much good without the original wrapper for each part.
At this point, might be easier to get another good motor. Somewhere. Cheap.
At this point, might be easier to get another good motor. Somewhere. Cheap.
Three options:
1. Bore out the 100 cc cylinder to fit a 125 cc piston an use one of the pistons I have, I'D still need rings
2. Have the cases bored to accept the 125 cc cylinder
3. Get a 100 cc crank with a 100 cc rod
I chose number 3 and found a good crank and rod. The 100 cc rod has a diameter of 14mm and the 125 rod has a diameter of 15 mm so I had the seller measure the rod. Should e good to go.
1. Bore out the 100 cc cylinder to fit a 125 cc piston an use one of the pistons I have, I'D still need rings
2. Have the cases bored to accept the 125 cc cylinder
3. Get a 100 cc crank with a 100 cc rod
I chose number 3 and found a good crank and rod. The 100 cc rod has a diameter of 14mm and the 125 rod has a diameter of 15 mm so I had the seller measure the rod. Should e good to go.
I got the parts I needed to put the motor back together as a stock SL100 unit and finally had some time this week to work on it a little.
This is how I check the ring end gap, slide it into the bore and measure the gap. This one has to be between .006 and .035" so its a pretty big spread.
I bought a new wrist pin and clips. There wasn't any spec in the manual so I thought better safe than sorry. The new one was exactly the same as the old one though.
I stuck a penny into the gears to stop the crank from spinning while I worked on it.
A single is sure easy to work on. I put the rings on the piston and slipped this hose clamp over it. Then, while looking down the bore, I lined up the piston and gently tapped on the cylinder with a rubber mallet. The cylinder sleeve pushed the hose clamp down the piston and the rings slipped into the bore. It only took two taps then I just pushed the cylinder down until all the rings were in the bore and the hose clamp was around the piston skirt.
This is an oil passage on next to one of the studs.
The oil runs up the shaft the stud runs thorugh into the head. There is a small o-ring here to seal the shaft between the cylinder and the head. A dowel pin also goes here, but it wasn't instaled when I took the pic.
I was having trouble fitting the cam back into the head so I stopped for tonight, there is very little clearance between the cam and cam journal and if you don't get it lined up just right it binds. I'll give it another try tomorrow night.
This is how I check the ring end gap, slide it into the bore and measure the gap. This one has to be between .006 and .035" so its a pretty big spread.
I bought a new wrist pin and clips. There wasn't any spec in the manual so I thought better safe than sorry. The new one was exactly the same as the old one though.
I stuck a penny into the gears to stop the crank from spinning while I worked on it.
A single is sure easy to work on. I put the rings on the piston and slipped this hose clamp over it. Then, while looking down the bore, I lined up the piston and gently tapped on the cylinder with a rubber mallet. The cylinder sleeve pushed the hose clamp down the piston and the rings slipped into the bore. It only took two taps then I just pushed the cylinder down until all the rings were in the bore and the hose clamp was around the piston skirt.
This is an oil passage on next to one of the studs.
The oil runs up the shaft the stud runs thorugh into the head. There is a small o-ring here to seal the shaft between the cylinder and the head. A dowel pin also goes here, but it wasn't instaled when I took the pic.
I was having trouble fitting the cam back into the head so I stopped for tonight, there is very little clearance between the cam and cam journal and if you don't get it lined up just right it binds. I'll give it another try tomorrow night.
Did ya remember to take the clamp off the piston skirt?? 
opcornDid ya remember to take the clamp off the piston skirt??
Yeah, the cylinder won't go on with that hose clamp there!
AARRRGH, part two. The **** cam tensioner won't fit!
You can see here the adjustment arm won't line up with the mounting hole. The 1970-71 had a one type of cam chain anadjuster and it was replaced with a different type for the 72-73 model year. The cases I bought are for a 1972 model ergo my cam 1970 chain adjuster doesn't fit. If this frickin motor didn't weight 50 lbs I'd throw it down the driveway.
Here's the two types. The pictures are the same for all models, but the numbers or the newer adjustment mechanism on the right are not on the 1970 fiche. The older adjustment mechanism on the left are. I looked at the 1973 model and the situation is reversed.
Here is a good picture of the vertical castings in the case that the new type cam tensioner moves up and down between. The other case don't have them. I can't figure out what keeps the rotor from hitting the tensioner, but I'm thinking the stator must hold it flush against the inside of the case. Its not like a cam chan tensioner moves a whole lot.
I checked my spare motor and it has the case I need, but I don't want to split the cases yet another time. Besides, I'd have to blast and paint the other case anyway. Honda doesn't sell all the parts I need for the 1972 cam adjuster, but I found most of them on e-bay. I've ordered the main components and will source the misc hardware from Honda. Another delay.
Here's the cam going in before I figured out what I should have already known.
The cam goes in here, the head is the bearings, there are two oil passages, one on the journal on each side of the cam. The cam runs on that thin film of oil.
I found out the problem was my valve tappets weren't loose enough and the cam followers were interfering with the fit. I was too tired the other night and didn't notice it.
the cam going in.
The sprocket installed.
and two pictures of the new hardware holding everything together.
It cost a few extra $$ for new hardware, but it really makes a difference in how the bike looks.
You can see here the adjustment arm won't line up with the mounting hole. The 1970-71 had a one type of cam chain anadjuster and it was replaced with a different type for the 72-73 model year. The cases I bought are for a 1972 model ergo my cam 1970 chain adjuster doesn't fit. If this frickin motor didn't weight 50 lbs I'd throw it down the driveway.
Here's the two types. The pictures are the same for all models, but the numbers or the newer adjustment mechanism on the right are not on the 1970 fiche. The older adjustment mechanism on the left are. I looked at the 1973 model and the situation is reversed.
Here is a good picture of the vertical castings in the case that the new type cam tensioner moves up and down between. The other case don't have them. I can't figure out what keeps the rotor from hitting the tensioner, but I'm thinking the stator must hold it flush against the inside of the case. Its not like a cam chan tensioner moves a whole lot.
I checked my spare motor and it has the case I need, but I don't want to split the cases yet another time. Besides, I'd have to blast and paint the other case anyway. Honda doesn't sell all the parts I need for the 1972 cam adjuster, but I found most of them on e-bay. I've ordered the main components and will source the misc hardware from Honda. Another delay.
Here's the cam going in before I figured out what I should have already known.
The cam goes in here, the head is the bearings, there are two oil passages, one on the journal on each side of the cam. The cam runs on that thin film of oil.
I found out the problem was my valve tappets weren't loose enough and the cam followers were interfering with the fit. I was too tired the other night and didn't notice it.
the cam going in.
The sprocket installed.
and two pictures of the new hardware holding everything together.
It cost a few extra $$ for new hardware, but it really makes a difference in how the bike looks.