Topic: Texas Barn Find - 1974 CB750K4 - HELP ME OUT!!!

[carnivorous chicken]

Perhaps a little late, but here goes... Getting dirt in your cylinders is potentially a buzzkiller of a problem, and I hope that didn't happen. At this point, I'd carefully thread those plugs back in, tighten them down (not too tight, but finger tight and a little more with a wrench), and wash the hell out of the plug area. Get that #$%* outta there and don't be afraid to use a strong and steady stream or compressed air. Then let it dry completely before backing those plugs back out. But unless you're actually dripping something into the holes, you should have the plugs in or some kind of cover so that mud daubers don't decide to build nests in your cylinders. 

[Funkenstein]

Perhaps a little late, but here goes... Getting dirt in your cylinders is potentially a buzzkiller of a problem, and I hope that didn't happen. At this point, I'd carefully thread those plugs back in, tighten them down (not too tight, but finger tight and a little more with a wrench), and wash the hell out of the plug area. Get that #$%* outta there and don't be afraid to use a strong and steady stream or compressed air. Then let it dry completely before backing those plugs back out. But unless you're actually dripping something into the holes, you should have the plugs in or some kind of cover so that mud daubers don't decide to build nests in your cylinders.

Man, I'm hoping it didn't happen too. Just glad I took a better look before I went to town with the fluids. I put the plugs back in and washed the area thoroughly. Found another nest under the taillight. Thankfully my garage in Austin is mud dauber free! Thanks carnivorous chicken!

[calj737]

If you're overly concerned about the infiltration of mud, remove the exhaust, remove the plugs, and hand rotate/kick the motor over after drizzling in some gas directly into the cylinders. The fuel will ultimately wash past your rings and contaminate your oil, but you'll be changing your oil anyway. The cycling of the pistons will purge the mud and and fuel mostly through the exhaust ports and spark plug holes.

Afterwards, add some MMO and repeat to re-lube the cylinders and cycle a few more times (about a dozen kicks). Then drain and change your oil and filter.

[Stev-o]

If you're overly concerned about the infiltration of mud, remove the exhaust, remove the plugs, and hand rotate/kick the motor over after drizzling in some gas directly into the cylinders.

Believe the motor is still stuck, Cal.  The top end may need to come apart to replace rings?

[70CB750]

Nice progress.

I am not sure what I hate more - daubbers or stink bugs. We have both in Virginia.

[calj737]

If you're overly concerned about the infiltration of mud, remove the exhaust, remove the plugs, and hand rotate/kick the motor over after drizzling in some gas directly into the cylinders.

Believe the motor is still stuck, Cal.  The top end may need to come apart to replace rings?

d
Ah, sorry, had lost track of the status of the motor. In that case, just flush the cylinders heavily with fuel to clean the dirt. Then do the ATF-Acetone tick to unstick the motor possibly. But avoid adding oil to the cylinder while mud/dirt may be there. It will become a bigger mess to clean out.

[Restoration Fan]

With a stuck motor and it still in the bike, I highly recommend you put it in 5th gear and rock the bike back and forth.  To me, that is BY FAR the easiest way to unstick a stuck motor. 

[greenjeans]

While were on the subject of stuck pistons - With mileage that low, I'd soak it for as long as you can stand it.  Then try the 5th gear trick.  Rings can rust stuck, but after seeing the rest of the bike and the lack of serious rust, I'd bet you can get them free.  The plugs (which look great) were in, and the carbs & airbox are still in place - that is a huge difference from a bike stored outside with out an airbox/carbs etc.   Once you get it free and running I'd bet it runs like a top.   You might consider having the carbs cleaned by harisluv, making sure to keep the original jets and needles in there.    I be shocked if the timing and valve tappets weren't still dead-on.   Check them anyway.   

Great hearing they are still out there. 

[754]

 If you had dirt on the plug threads you would probably feel it threadingthem in, and certainly feel crunchiness, as it hit the seal... if a bit of dirt falls it it will probly blow out the pipe...plus the mud duaber grit might not be highly abrasive.

[mrbreeze]

Vacuum it out!

[apehanger550]

 I just want to caution you about electrolysis on that pretty tank. The foam and bubbles produced from the process pukes the carrier which is a very strong detergent on the paint and that can cause a stain. I thought I had that problem covered by oiling the tank with motor oil, but it still stained it.

 Actually, I doubt if all the brown powder we are seeing is rust. It probably is crystallized varnish and lacquer thinner will dissolve the hard stuff perfectly. Just do not get the lacquer thinner on the paint. When it does become time to remove the rust, I saw this stuff at the All Ohio Show and it is available at Home Depot. It is supposed to be kind to paint, but I have not used the product. The process it uses is chelation and there are no strong acids involved
http://www.homedepot.com/p/Workshop-Hero-1-gal-Metal-Rescue-Rust-Remover-Bath-WH290487/203247483.

 If that tank were mine, i would use lacquer thinner on it first and then the metal rescue. Before using the metal rescue on the tank, I would test it by cleaning a part [not a bike part] with both paint and rust on it.  That tank is probably in fantastic shape even on the inside.

[mrbreeze]

I did a tank last summer with prep & etch that I thought was gonna be a goner due to the appearance of rust inside. It turned out great and no pinholes.

[mrbreeze]

Vacuum it out!

Seriously!! You can make up a small hose with reducers on a regular vac cleaner and run it through the spark plug hole. Unless you have access to a boroscope you won't be able to see if it's clean but you could alternate the vac with short blasts of compressed air and get a good deal of the crap out of there.

[754]

Yeah it sounds like giving it the old shake, with nuts and bolts and sharp goodies, may get a lot of what you see.. Remove petcock and screen, make a plug.. I used a bottle cork, trimmed with a knlfe and sanded and filed....took some effort but fit good enough for gas.
 Solvent is safer, dont use gas indoors.
 Sit on a chair, shake, move tank a bit..shake,move tank and shake, change position. For around an hour.. You can pour the liquid out now and then..use about a quart or so, you will see it get cleaner as the tank clears.
 I used a suction device to try to suck out most of the debris with the fluid , on side away from  petcock. You may not get it all but if some is behind, it has to jump up about a 1/4 inch or more to get in the petcock screen.             Good luck, hope you save it.
 

[Restoration Fan]

 Actually, I doubt if all the brown powder we are seeing is rust. It probably is crystallized varnish and lacquer thinner will dissolve the hard stuff perfectly. Just do not get the lacquer thinner on the paint. When it does become time to remove the rust, I saw this stuff at the All Ohio Show and it is available at Home Depot. It is supposed to be kind to paint, but I have not used the product. The process it uses is chelation and there are no strong acids involved
http://www.homedepot.com/p/Workshop-Hero-1-gal-Metal-Rescue-Rust-Remover-Bath-WH290487/203247483.

Good advice.  Just FYI to you.  I have used Metal Rescue and it does everything they say.  Safe on paint.  Safe on rubber.  Even safe on stickers but it eats away rust like noone's business.  I'm convinced that they actually have pieces of ground up genies in the stuff because it works like freaking magic.  I keep a couple of gallons around at all times for such type work.  It is indeed the miracle product they claim it to be.

[Stev-o]

Where are you with this Funk? 

[Funkenstein]

Tonight...... It started. For the first time in 45 years. It took me 4 years longer than I wanted. I moved it from Texas to Oregon in pieces. But tonight... She was banging!! I'll post a lot of follow up pics and the resources I used (thank you SOHC4 & hondaman!!!) very soon.  So excited to have it start tonight! Thanks y'all!!

[Stev-o]

She lives!

[MauiK3]

Another vote here for keeping the points, use Hondaman ignition module if you feel you need to.
Specifically, don't rely on the hex nut at the points to turn the engine, it's fragile.
You will likely find most of the rubber to be hard, fork seals, shifter seal, etc. Plan on some leaks there.
Your rubber brake lines might be pretty stiff, new ones would be a good idea.
Hondaman did my head and cylinders on my K3, outstanding job, I asked for a "solid stock" head" , not a hot rod, he did a great job and he's not that far from you, I had to ship mine from Maui. Ouch
He will also do your swing arm.
Careful with the carbs, stick with stock Honda brass, other brass is pretty sketchy.
There are lots of good sources for parts, Yamiya and David Silver Spares are top shelf.
If your spokes are corroded, Buchanan sells great stainless kits.

Wow, what a great find, very lucky. If you hadn't taken pictures it would be hard to believe.
Congratulations