Author Topic: The slow and unsteady progression of a bike named Lucy, a CB750 built 08/72. (Read 11701 times)

rickmoore24 · « **on:** September 27, 2009, 01:07:29 PM »

Hi all! Noob forum lurker, first time poster. Back story; found a CB750 on CL in Laguna Beach. Picked it up for $100 to do a full teardown and rebuild to a mild cafe of sorts. It was missing a lot of things, didn't start but the engine wasn't locked up (tried the kick start) and it apparently sat in a barn in San Luis Obispo since shortly after she was laid down in the late 70's by the original owner (ODO shows 19,549 miles). This was where the bike was raped over the years for parts until being bought by the fellow I got her from in Laguna. Got her in the truck and back home but couldn't work on it right away due to other obligations. I'm not a mechanic but I am mechanically inclined, don't own a lot of tools and don't have a great work area set up for the build. Nor do I have a lot of money to throw at the project to make it go. I've had the bike for a month and have done some work already. I'll post photos up to my current progress. I'm at the point where I need to be held accountable for this bikes ressurection. Please feel free to chime in.

rickmoore24 · « **Reply #1 on:** September 27, 2009, 01:57:52 PM »

Turns out I needed to split the case because the alternator was broken off of the tapered end on crankshaft. Didn't see that until I took off the stator cover. Boo! $:-\$ I got an extra bottom end with the purchase of the bike so that was nice. Still missing a lot of odds and ends though. I'll be replacing the Big End and Main bearings, all oil seals and gaskets. Gotta clean up the pistons and put in new piston rings. I'll also be replacing the alternator since the one that came with the extra motor was rusted to poop.

More progress photos:

rickmoore24 · « **Reply #2 on:** September 27, 2009, 02:34:18 PM »

Split the case and put in the new-used crank, cleaned up the pistons with a simple green bath and installed the new rings. I noticed the tops of the pistons were previously cleaned with something that scratched the crap out of them. I was wondering why the carbon deposits were so prominently placed on certain areas. I'll need to polish the tops off so the deposits don't stick to the scratched areas so easily. Any tips on that?

More progress photos:

rickmoore24 · « **Reply #3 on:** September 27, 2009, 02:54:36 PM »

This forum rules!! I've learned a ton of stuff about these bikes from the people on here. Especially the Old Timers, I hope to get there one day. This post gets me to my current state on the build. I have the first set of things I wanted powder coated back and am gearing up for the next set of odds and ends. I'm super lucky to have an aquaintance who media blasts and powdercoats for a living who charges me next to nothing. I went with a satin black. My next deal is cleaning the finned areas of the motor. I'm thinking simple green bath, a quick hot water rinse and alcohol rinse. Is that crazy or is there a better way? Media blasting maybe? I gotta mull that over. Also, still waiting on several parts before I get to button up the bottom end.

more progress photos:

rachet · « **Reply #4 on:** September 27, 2009, 03:01:04 PM »

Well you are off to a great start Rick! Slow and steady will get the job done and you'll be riding Lucy in no time!

Keep it the great work!

Rachet-

rickmoore24 · « **Reply #5 on:** September 27, 2009, 03:14:49 PM »

Thanks Rachet! I just need to stay motivated and not get complacent. A little bit at a time, slow and steady is right on.

KB02 · « **Reply #6 on:** September 28, 2009, 03:29:17 AM »

Um... those pistons don't look stock. Take some measurements and let us know what you have there. Looks like a non-stock piston that may have been ground down (Badly) to make them fit the combustion chamber.

rickmoore24 · « **Reply #7 on:** September 28, 2009, 07:29:43 AM »

Thanks KB02, I will check that out. But here is where my inexperience steps in; what measurements? Length top to bottom, diameter? Are there any markings I can find on the piston itself depicting it as a stock 750 piston or otherwise? $:-\$

KB02 · « **Reply #8 on:** September 29, 2009, 04:33:08 AM »

Quote from: rickmoore24 on September 28, 2009, 07:29:43 AM

Thanks KB02, I will check that out. But here is where my inexperience steps in; what measurements? Length top to bottom, diameter? Are there any markings I can find on the piston itself depicting it as a stock 750 piston or otherwise? $:-\$

Top to bottom, yes.
Diameter, yes.

You see how those pistons have reliefs for three valves? Where as your engine only has two?

Could be a "cheap mod" the previous owner did. Check out the diameter first to see if the engine has been bored out at all.

rickmoore24 · « **Reply #9 on:** September 29, 2009, 08:45:53 AM »

Oh, wow!

I didn't even notice that, or know to look really. I simply assumed that the pistons were stock and the scratches were due to a previous (harsh) cleaning. I'm thinking this set has to go. I have a set that came with my spare motor but they need a good cleaning first and I'll be sure to measure the cylinders to see if they still fall within tolerances. Thanks for the heads up KB02. Thank goodness for this forum!

rickmoore24 · « **Reply #10 on:** November 01, 2009, 05:21:32 PM »

Man! No one warned me about the endless bits and pieces i'd have to end up replacing (J/K, I knew what was coming). Sometimes locating them can be a chore in itself. I've got a few more parts on order and got a bit more work done on the bike. I got those measurements for the pistons and cylinders. Everything fell within specs. I ended up replacing the pistons mainly due to the excessive scratches on the crowns, even though they were within tolerences (I failed to take pics, I was on a roll

. Got the top end buttoned down and waiting for some new bolt/flanges for the top end. I wish I had more money and skills, I would have done more to spruce up the motor. I attached some pictures of the revamped wheels, carbs cleaned and rebuilt by TheHun, a powder coated triple tree I might be selling later and the current state of the motor (not yet cleaned). I'm hoping to have a rolling chassis within the next few weeks. Then it's on to electrics, YIKES!!

rickmoore24 · « **Reply #11 on:** December 07, 2009, 09:14:29 PM »

I finally got my engine back into the frame. I tried to clean it up as best as I could but she's not meant to be a show bike so I didn't go to town with the toothbrush and engine paint. I do hope to build my spare motor with all the bells and whistles and swap that in when it's done, that one should be prettier. I also, got some rear shocks from partsnmore. I can't really tell much about them other than they don't fit very well. None of the bushing they came with fit the top shock mount on the frame properly and the top mount on the shock isn't as wide as the stock one so there is a grip of play there. Same goes with the bottom clevis that connects to the swingarm, lots of play. Nothing some washers and a search for the proper bushings won't fix. It's what's to be expected for the price I guess but they sure look a lot better than the rusty stockers and I'm sure they perform better too. She's starting to look something like a bike again and that getting me re-motivated to move forward. Thanks for stopping by.

Retro Rocket · « **Reply #12 on:** December 07, 2009, 09:38:10 PM »

Looking good mate, did you ever find out what those pistons were?

Mick

rickmoore24 · « **Reply #13 on:** December 07, 2009, 10:15:19 PM »

Thanks Mick. You know as far as I could tell they were stockers. They had a Honda stamped next to where you insert the pin and if my memory serves me right the number 302 on the opposite side. I can't recall for sure, in any case those are gone now in recycle heaven.

rickmoore24 · « **Reply #14 on:** December 10, 2009, 06:22:09 PM »

I got a little more work done on Lucy and a few more little odds and ends on order. The front end is back on, I'm not really feeling the headlight ears, I'm gonna get rid of those or maybe save em for a future project. I actually like the stockers better than those. I still need to clean up the upper forks some more, honestly I think that's why I want the stock ears back on, just to hide that discoloration since those fork tubes can get pricey. At least she looks like a bike again, I'm happy about that.

rickmoore24 · « **Reply #15 on:** December 10, 2009, 11:07:20 PM »

I had to back out some sheared bolts from the stator cover and now I'm doing battle with the tappet cover from hell. I mean come on, seriously? I shot the thing with WD40 for almost a week after I nearly rounded off the hex. Now I've drilled it crossways to torque it off and you can see what happened. Time for the dremel tool...

rickmoore24 · « **Reply #16 on:** December 18, 2009, 09:26:01 PM »

I'm going to chop that rear fender, maybe go without a rear fender and tuck this light under the seat. It got a few options in mind, possibly something a little wider as a light. Man, if it's not one thing its another, still it's so much fun to do.

rickmoore24 · « **Reply #17 on:** January 19, 2010, 08:25:22 PM »

I'm getting a lot of inspiration from the guys doing their builds on here. Really amazing stuff everywhere. I'll be really happy when I get mine back on the road for a while before a proper full cafe build. Still working on bringing her back from the dead. I've got compression again, around 140psi on all four. Shes got oil in her and I'm kicking her over everyday to get things on the way to seated and lubricated. I'm on to the electrics. I still need to rebuild the MC and front caliper. Chopped the rear fender and got a new integrated tail light mocked up with one of my dads plates from the 70's off of his old CB750. Also, picked up some HM341's, gas tank and side covers. Almost there and almost time for a battery.

Retro Rocket · « **Reply #18 on:** January 22, 2010, 01:13:40 PM »

Gday Rick, what seat is that you are using? Did you try tapping that tappet cover nut tosee if that would help with getting it off? Some times a couple of taps will break the seal that holds them on...

Mick

bert96 · « **Reply #19 on:** January 22, 2010, 01:25:15 PM »

where did you take your seat!?

Bert

rickmoore24 · « **Reply #20 on:** January 22, 2010, 01:42:02 PM »

Hello RR. The seat is a slightly modified cafe style seat that I ordered from Hondaclassic31.com, I got it from his store on ebay (hondaclassic31), very helpful and nice guy; he made some design adjustments for me before he built and shipped mine. He does work here in Irvine, Ca and his production is done in Vietnam. I'm pretty happy with the seat, my only complaint is the seat lock studs on the pan are a bit off but I can fix that pretty easily. As far as that stupid tappet, I had to cut it out with my dremel tool, I still can't figure out why the thing wouldn't come off (and I tried everything!), but it's off now....

I've attached a photo of the hack job I had to do on it to get it off. BTW, I got the seat for $252.48 shipped from Vietnam and I'll still be able to ride two up.

heyjones · « **Reply #21 on:** January 22, 2010, 05:28:45 PM »

This project is awesome! It's giving me a lot of great ideas, looking forward to seeing the finished product.

rickmoore24 · « **Reply #22 on:** January 22, 2010, 06:57:20 PM »

Hey...thanks heyjones

This site has all the inspiration anyone can handle and I'm with you; I neeed to get her done soon. I see you're in Ventura, I surfed up there last weekend, I'm from Oxnard originally. We'll have to ride sometime when our bikes are dialed in.

rickmoore24 · « **Reply #23 on:** January 22, 2010, 08:58:32 PM »

Retro and Bert, if you're interested here is a photo of the underside of the seat to show that the hinges did line up nicely and the quality of work is pretty good.

Also, a photo of the HM341's I'll be tooling around with. I've always liked these over the 4 into 1's for some reason.

Retro Rocket · « **Reply #24 on:** January 22, 2010, 10:34:27 PM »

Thanks for the seat pics and info mate..... looking good

Mick

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Author Topic: The slow and unsteady progression of a bike named Lucy, a CB750 built 08/72. (Read 11701 times)