Topic: Senior project for high school - 78 CB750K

[calj737]

Answer to your question: soda blasting is quite and will normally remove the gasket material too. As for blasting the head, I'd leave the valves in place and blast. This protects the seats while cleaning the chamber.

The only issue with soda blasting is the need to clear the residue from the oil passages. Denatured alcohol or Mineral Spirits works well for that. Or even a parts cleaner is fine.

If you are painting the cases at home, after cleaning/degreasing (whichever method you opt for) preheat the cases in the oven. 20-30 minutes on 350 is enough. This will help drive the impurities from the alloy. Then wipe down with Acetone or Dentaured Alcohol (my preference as it completely evaporates) before spraying. You'll get a better bond and the paint will flow just that little bit better.

Return to oven cure paint after no longer tacky.

[Restoration Fan]

Answer to your question: soda blasting is quite and will normally remove the gasket material too. As for blasting the head, I'd leave the valves in place and blast. This protects the seats while cleaning the chamber.

The only issue with soda blasting is the need to clear the residue from the oil passages. Denatured alcohol or Mineral Spirits works well for that. Or even a parts cleaner is fine.

If you are painting the cases at home, after cleaning/degreasing (whichever method you opt for) preheat the cases in the oven. 20-30 minutes on 350 is enough. This will help drive the impurities from the alloy. Then wipe down with Acetone or Dentaured Alcohol (my preference as it completely evaporates) before spraying. You'll get a better bond and the paint will flow just that little bit better.

Return to oven cure paint after no longer tacky.

Great advice, cal.  Does the oven make the house smell really bad or is it pretty much odorless when it's oven curing the paint? 

[calj737]

Sorry, wife will hang you by the shortest of hairs left on your body. Best to do whilst she's away shopping or visiting a sick Aunt.

You could always clean the oven afterwards and claim it's the cleaner that's stinking up the house 

[Restoration Fan]

She's out of town until Sunday for work, so I'm hoping we can get this thing buttoned up this week and prepped for painting.  Otherwise, it'll wait until she's travelling again.  But that may well be next week.   If so, we're golden. 

[SOHC4 Cafe Racer Fan]

What's that new and interesting aftertaste to the roast?

[calj737]

Hickory smoke, dear 

[Stoli]

I've never noticed the smell to linger. Seems like it is always gone within an hour or two. 

[SOHC4 Cafe Racer Fan]

I'm sure you will get some residue on your food for a while -- maybe not enough to taste it, but enough to ingest it.  Think of eating baked paint! Hey, most of us lived through the 70's and 80's so this probably won't kill you!

[grcamna2]

I live alone and I've done it in my oven many times  . I open the windows while it's baking and then close them later;the smell disappears that way,especially w/ a fan in the window.

[toytuff]

I live alone and I've done it in my oven many times  . I open the windows while it's baking and then close them later;the smell disappears that way,especially w/ a fan in the window.

Remind me to "skip" dinner at your house.

 

tt

[70CB750]

I live alone and I've done it in my oven many times  . I open the windows while it's baking and then close them later;the smell disappears that way,especially w/ a fan in the window.

Remind me to "skip" dinner at your house.

 

tt

Ever observed your wife opening dishwasher - and all wooden stock parts from 1916 SMLE slide out? 

Dishwasher is excellent for removing Cosmoline.

[Restoration Fan]

Today....is a good day!!!!!
Of course, my granddad always said that any day above ground is a good day...so that should have been obvious.

But, we got the cases split.  We built a little homemade stand to hold the cases so that the studs don't get broken.



As a tip for someone else doing this, we found it much easier to get a grip on the lower case half when we stuck screwdrivers through the holes that hold the pins that go through the frame to hold the engine in the frame.


And, voila!  We are now able to get to the kickstarter spring to finally try and determine what's wrong with it.




HOWEVER, we do still have one nemesis.  This little bastage kick spindle stopper pin.  The manual says to rotate the pin to enable removal.  But I'll be doggoned if we can get the thing to move.  We tried channel locks, vice grips, needle nosed vise grips, a screw driver and pretty much anything else we could think of.  Is there some secret trick, like you have to keep your tongue in the left side of your mouth or something?

[calj737]

Propane torch and flat blade screw driver in slot.  Blade perpendicular to pin and just turn it while hot. It'll come loose.

[toytuff]

Put it in the oven!

You have until Sunday. 

tt

[Restoration Fan]

Put it in the oven!

You have until Sunday. 

tt

LOL. Well played, sir.  Well played!

[danyo]

I soaked that pin in pb blaster overnight and used long nose vise grips to wiggle left and right and pulling up. I believe torch method should break loose that pin quicker

[70CB750]

Better to use vise grips to squeeze the pin than wedging screwdriver in it.   Heat would help - as the last resort - but the bond between steel and aluminum can be broken by knocking on it gently with a hammer.

[toytuff]

350 degrees for one hour or until golden brown.

 

I'm dying here....lol!

tt

[Stoli]

Just use some wire cutters like in the picture you posted. Vise grips won't work. Put something between the case and the cutters to protect the case and that will act as a fulcrum. Grasp the pin with the wire cutters and that's your lever. You will be able to rock the pin out a little at a time. Heat is good for things that are corroded in place but that pin has sit in oil it's whole life. You just need the right force to move it.

[Restoration Fan]

I have a question about something neither Logan nor I understood last night.  The kick starter gear itself.  When the engine is assembled, it connects to the oil pump gear.  Shouldn't that kick starter gear turn all the time to make that pump work?

But when we manually spin the final drive gear there (the one connected on the other side to the front sprocket), there seems to be nothing tying that gear to the kick starter gear.  Am I just misunderstanding how that works?

[Stoli]

The gear does turn all the time when the engine is running. But it does not have a direct linkage to the kickstart shaft that it is mounted on. The linkage between the kickstart shaft and that gear (presumably you have a problem with yours) will only engage when you turn the shaft by "kicking" the bike over. Sort of like pedaling a bicycle  -  the rear wheel will keep turning even after you stop pedaling.

Do you understand why the wirecutters work to remove the pin while vice grips and pliers don't? The cutting edge of the wire cutters dig into the sides of the pin allowing enough of a grip to "pull" it out of the hole. Anything else you use will tend to slide on the pin because it can't get enough traction. You will wind up with small dents in the pin where the cutters dug in but the pin can be reused (although it should be pretty easy to find a replacement).

[Restoration Fan]

Do you understand why the wirecutters work to remove the pin while vice grips and pliers don't? The cutting edge of the wire cutters dig into the sides of the pin allowing enough of a grip to "pull" it out of the hole. Anything else you use will tend to slide on the pin because it can't get enough traction. You will wind up with small dents in the pin where the cutters dug in but the pin can be reused (although it should be pretty easy to find a replacement).

Yeah, I understood exactly what you meant when you posted it last night.  We're going to try it later this afternoon when I get home from the office.  At that point, we should be able to remove everything from the inside of the engine cases and get it ready to go be soda blasted.

I contacted the guy yesterday about the dry ice blasting and he said that he receives about 8 - 10 calls per week from people like me wanting to know if he does it for motorcycle & car restorations but they're primarily industrial and don't have a brick & mortar shop.  I told him I didn't mind driving to wherever they're set up because the idea of using steam or fine dry ice instead of baking soda seems advantageous since there would be no residue to clean up...the moisture just evaporates.  He was definitely interested and said he'd get back to me but I think for this build, I'll just go with trying to find an established person who does the soda blasting and has done quite a few.  Gonna take the cylinders, head and both parts of the engine casing to be soda blasted before we start the cleaning, "cooking", and repainting process.  So any suggestions for someone in the Atlanta area who does soda blasting would be much appreciated.

As far as the gear, thanks for the explanation.  We examined the teeth of the gear last night and they appear to be fine.  I suspect it's the flange underneath the spring that's the problem but we won't know that until we can get the pin out and remove the gear and shaft to get underneath the spring.

[Stoli]

I should also mention that there is no "direct" linkage  between the final drive and that gear. Otherwise, when you were at a stop with the engine running, the oil pump wouldn't be turning and the engine would seize. The kickstart gear is turned by the main shaft before the clutch interface with the final drive. The rate at which it spins is directly proportional to the engine RPM, which is why oil pressure goes up and down with the tach and not the speed.

[calj737]

I'd still opt for dry ice blasting if available. Virtually impossible to do harm to the cases with either media. Less clean up is all with the dry ice. You could have the case covers soda blasted as a test between the two. Or have him dry ice the side covers, then decide if you want to proceed with the cases.

[Stoli]

... I suspect it's the flange underneath the spring that's the problem but we won't know that until we can get the pin out and remove the gear and shaft to get underneath the spring.

It should be obvious if it is broken or not when you remove it for inspection. It is impossible for me to explain how it works without detailed pics and/or video. There are two things in there that could cause your problem - one is the mechanism that engages the one way connection between the "hub" of the assembly to the gear itself. That consists of a tooth on a spring - I imagine it is what you would find if you took apart a socket wrench. The other possibility is the splined section of the shaft that the hub mates to (the same type of deal that you see mating the various levers (kickstart, gearshift, rear brake) to their respective shafts) . If that was stripped, the shaft would be allowed to spin without turning the gear.

Both of those things seem like very unlikely candidates to just break during normal wear. Did you say that there was blue gasket material between your cases? If so, my guess is that a PO put it back together wrong. For instance, if the splined area on the shaft and hub look good, then they might have forgotten the small spring that engages the aforementioned tooth. Not to be confused with the large spring that moves the kickstart lever back to the "up" position which you can see is installed correctly in your pics.