1981 CB750K, Let's do this.

OK! Finally some pics. Sorry for not getting these up sooner. Without further ado, here she is!


I've already taken off the seat and fitted pods, so no completely original picture, although i'll try to find one.



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Here are all the tools I have. Man i need some ratchets. Gonna look in some pawnshops/garage sales and online tomorrow.


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I just started disassembling one piece at a time. Eventually I got to this!


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Sorry for the picture quality, Its rainy and some lights are out in my rent's garage :(


How on earth am I going to get this engine out!?
 
I used one of my most favorite tools, a Harbor Freight 2 ton hoist ($129). Man, that thing is as invaluable as a Dremel Tool. I bet the DOHC engine weighs a good 250 lbs. But, I got it in and out of the frame twice without as much as a scratch!

P.S. A lot of guys lay the bike on its side and remove the engine that way. Also a good way to avoid scratching the frame.
 
It's easy to pull the motor. There is a section of the frame that you can take out to make it easy on you. Also, if you're going to be tearing it all the way down, alot of guys use the method of laying the bike on it's side when it's just an engine and frame and lifting the frame up away from the motor. If you do run into jetting problems, I can most likely help you. My Brother has an 80 CB750K that is cafe'd out and he is just doing the fine tuning on re-jetting his. He runs pods and a Kerker 4 into 1 on his bike. :)
 
biker_reject said:
P.S. A lot of guys lay the bike on its side and remove the engine that way. Also a good way to avoid scratching the frame.
Click to expand...

Ah you beat me to it! lol
 
I think im going to need to invest in a dremel for polishing. Any ideas where to pick one up cheap? I'm in uni so this is going to be as low budget as possible. On the bright side everything I make over living expenses is going to get dumped into this bike. I'm going to take as much as i can out tonight. I think the valve cover is leaking oil too :(. Will I have to take all the fluids out of the engine before removal?


Thanks for the quick replies! really awesome community
 
Etchasketch said:
I think im going to need to invest in a dremel for polishing. Any ideas where to pick one up cheap? I'm in uni so this is going to be as low budget as possible. On the bright side everything I make over living expenses is going to get dumped into this bike. I'm going to take as much as i can out tonight. I think the valve cover is leaking oil too :(. Will I have to take all the fluids out of the engine before removal?


Thanks for the quick replies! really awesome community
Click to expand...


I think you would be better off with a bench grinder style buffer for polishing. Harbor freight can hook you up there. IF/When you go to replace the valve cover gasket, only use the Honda gasket. Others WILL leak. I learned that one the hard way.
 
Yeah, big grinder/buffer for big stuff and Dremel for detail work. I had a Craftsman rotary, burned it out after years of use, and found an entire kit (case + acc) on ebay for like $50. Dremel bits fit Craftsman rotaries.
 
Almost done with dissasembly, hit a hurdle though, the chain got stuck :(


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More pics of the rusty/ gummed up bike.




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Is that the right order?






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I'll worry about cleaning out the muck later. How can i get that chain out?!
 
You could put it in gear and remove the front sprocket, or grind off a link. I ditched my OEM chain because I planned on a new one anyway. That half moon looking thing in the third pic is a "washer". It looks to be in the way. Remove that.

That corroded piece, is it the swingarm pivot?
 
Sorry i'll label the pictures from now on.(First pic is the front sproket, second is the exhaust, third is is front sproket again fourth is the rear axle and last is the exhaust just before it join 2 into 1.)

I think ill just take off the front sproket. what kind of torque wrench do you guys use for reassembly?
 
I jammed a chunk of wood in my drive sprocket and used a ratched to unbolt it. When in gear, all I did was turn the engine over...
 
I used a BAH torque wrench on my front sprocket, AKA, a Big Ass Hammer. Seriously, wrench it down, grab a socket and a pull bar, and whack away. Once your arm gets tired, it's tight enough. As for removing/installing the engine, sit it on a cinder block. Seriously, a single square under the oil pan, and a double under the oil filter (protect it with a couple shop towels/rags). Slide the frame over the engine and put the long engine bolts in. I put my engine in, by myself, in under 3 minutes, and it was already right side up! I just got done rebuilding my 79 DOHC, so if you have any questions, myself and a lot of others have rebuilt the exact same bike.
 
Garage Rat said:
I jammed a chunk of wood in my drive sprocket and used a ratched to unbolt it. When in gear, all I did was turn the engine over...
Click to expand...
I've had to stick a 2x2 or my jack handle and wedge that between the mag spokes and swing arm on my sport bikes. I guess you could also leave the bike on the ground and loosen the bolt then lift the rear with a stand if you didn't want to wedge something between the spokes.
 
Alright! Progress! i managed to remove the front sprocket and get the chain out. From there it didn't take me too long to get the engine out, tipped it on its side on a mattress with a tarp over it and with that piece of frame that unbolts it came right out with a little fidgeting!


Now the good stuff. It is clear that the engine will need to be fully cleaned as it is FILTHY. grease everywhere. From looking at the way the frame sits with the front forks its also clear that im going to have to drop them 3-4 inches to get closer to that flat cafe style. Also gonna look around for some bars. Still between Clubmans and Clip-ons, Leaning towards Clip ons. Need a tank as well, thinking about the cb650 tank as seen in another thread.


No pictures today, but tomorrow i'll get some up of how she looks naked.


SO, any preferences on what I start into first? Engine or Aesthetics?
 
If you are going to lower front end that much, be weary of fender clearance in the front. If you plan to use a front fender. Mine is lowered a bit in the front and I actually ruined my original front fender from the horn getting in the way. I smashed it after having to do a panic stop. ::) You can get progressive fork springs for the DOHC CBs and make adjustments and whatnot so you can a: get the exact type of handling you're looking for and b: so you can save your front fender from dents! haha. I think yours will look good lowered that much. Those era CBs kind of have the high riding stance up front anyways. Also, alot of clubman bars won't fit because of how wide your triple tree is. They do make clubmans that will fit, but I just wanted to give you a heads up so you didn't buy a set and have them not fit.
 
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