Topic: My 76 CB750 Project "Crotch Bobber"

[cbr500]

Hello I am somewhat new here but just wanted to show off a bit on my project. It should be on the road this spring. It is a 76 CB 750 mated with a few select parts from a 2008 CBR600rr. Part bobber project part crotch rocket.

[sangyo soichiro]

I see CBR wheels and a front end.  

Now you're going to have to give us some details on that front end swap.    I'm very interested.  More pictures too.  


Also, are you sure you want to call this project "crotch bobber?"  Think about it....  



You might find this thread interesting.
http://forums.sohc4.net/index.php?topic=63784.0

[Geis32]

What type of swingarm is that?? I'm thinking about going that route with my 75k.

[cbr500]

I will post some more pic of the bike. The front end almost bolted right on. I used a set of CB750 steering stem taper bearings. The new front end stem is the same diameter as the old one. it is about a 1/4" longer though. I made a spacer to take up the extra 1/4" and bolted it on.

The rear swingarm I made myself. I used .120" wall 1.5" DOM tubing. I bent it to shape and welded that to the origonal pivot that i cut from the stock swingarm. I then carefully cut the rear wheel mounts and adjusters off the swingarm and notched the tubing so they would fit snug and welded those on. I did have to mill the ends to fit the bigger diameter wheel bolt too. I did buy a 10mm offset drive sprocket and flipped the rear sprocket for chain alignment.

It was a bit of work but overall not bad. The best part is the bike tracks straight down the road on my test runs.

As far as the project name thats just my sense of humor.

[cbr500]

Some more pics.

[fastbroshi]

  This is TOO cool!!  Very clever swingarm.  What are your rake and trail numbers with the new front end??  How's the clearance lock to lock?  I don't know what your plans are, I hope you get it all sorted and tear it all apart to paint and finish everything.  It would look so killer.  Not that it won't be bada$$ finished the way it is though.
 

[cbr500]

Thanks for the compliments!

Most of the fab work is done at this point except the seat. Once that is done I will be tearing it down to clean up my welds and have the frame powder coated. I plan on a few engine upgrades as well. The paint will be mostly black and flat black with some gold accents. I just need spring to get here so I can paint again.

I havent done any measurments as far as rake and trail but the bike seems to handle pretty well so far. I live on some country back roads and have had the bike to about 90 so far with no handleing problems.

[hoodellyhoo]

Sweet looking bike!

Got anymore pics of that suzuki triple I see in the back?

[J.Webster Designs]

what size rear tire is that?  I like what you have done with the bike. I have a 1000rr front end in the garage waiting to go on my bike. i am planning on making my own swing arm as well to fit a 180 rear tire. I will probably be making my own frame to get me to the steering geometry specs that I want.  If you wouldn't mind, can you take the rake and trail measurements off your bike so i can see how much of a difference there is between bolting onto the stock frame and building my own.

I will probably be sending you a PM here in the next day or so to see if you can answer some questions that I have.

[traveler]

Cool little hot rod!

Are you going with a cafe style seat?

~Joe

[cbr500]

The rake and trail are approximately 25 degree rake and about 4.0 inches of trail. thats just a quick couple measurements. That is with about 1.5 degree on the horizontal seat tubing. The back sits up a bit with the current shocks and springs. If I shorten the rear springs a little I should be able to get a little more rake in it if necessary.

The front is a 120/70/17 and the rear is a 180/55/17 tire.

The steering clearance is great the handle bars and stuff all clear the stock tank. I will probably get the thing a little closer once its done to get maximum turning lock to lock but thats just hitting the stock steering stops with a grinder for more turn.

I will be going with a pretty much flat thin seat that turns up in the rear. Pretty minimalistic.

I do have more pics of the 73 GT550 I will only post one since this is a CB forum. Good eyes btw.

[cbr500]

Well after being sidetracked a little I have resumed work on the project. I finished the frame it is being powder coated gloss black. I have disaasembled the engine and cleaned up most of the parts. Found an old repair. It looks like at one time the bike threw a chain and cracked the case. Luckily a friend at work used to do small engine repair and is pretty good at tiging aluminum. He touched up the old repair and the case looks great. Anyway I have powder coated most of the engine parts. I should be reassembling the engine by next week. Hopefully the frame will be done around the same time the engine is done.

[cdoggy81]

NICE!

[Alan F.]

Very well thought out build.

[J.Webster Designs]

any updates?

[cbr500]

Well the motor is back together. I still need to degree the cam and set the valve lash then i can button up the valve cover. All of the parts I powder coated are done. Just waiting on the frame and I will be starting final assembly. Here are a couple engine pics.

[fastbroshi]

Motor looks good.  What color are you going for the tank and side panels?

[75cb550 (kyle)]

it does look good. i like this project

[RustyOlive]

AWESOME!!! I was just day dreaming the other day if gsxr rear wheel would fit.. and if the chain line would still work?? on my 550 mind ya.. but.. this build gives me hope... =)

can't wait to see more!

[rippy154]

Well the motor is back together. I still need to degree the cam and set the valve lash then i can button up the valve cover. All of the parts I powder coated are done. Just waiting on the frame and I will be starting final assembly. Here are a couple engine pics.

Is that some sort of tach block off you made or did you buy it??  Very cool build, also what kind of tubing bender do you have mounted in your shop??

Thanks Stephe

[cbr500]

Thanks for the compliments. There wont be any side covers due to the new oil tank. I will be painting them a very dark blue. Havent quite decided on the exact color yet. I want it to be dark enough to almost look black until the sun hits it. The tach block off is made by Joker Machine. Thay have some pretty neat stuff.  I purchased a JD Squared Model 3 tubing bender. It works pretty well. I have already used it way more than I thought I would have.

[RustyOlive]

DUDE!!!! any progress on your bike???
wanna see more.. LOL

[rippy154]

yeah I wanna see any progress as well .... super cool build

[zzpete]

  Can"t wait to see it run!!

[cbr500]

Sorry I havent updated in a while. I have been busy working on the bike. I finished painting the tank (minus the emblems and the pinstripe), I got the frame back from being powder coated, the engine is in the frame and its a roller again. I still have alot to do yet like wiring, cleaning the carbs, and other odds and ends. My biggest problem is the bike has been turning out so good (way better than i thought it would at least) that I cant stand to see all the old hardware go back on, it sticks out too much. I have been slowly working on getting together all the hardware I want to replace. The rest I will use some black touch up paint to hide the years of wear and tear.

The tank is two tone with a very dark midnight blue pearl on the sides. It looks pretty cool depending on what angle you look at the tank it looks black but in the sun light it is a bright blue.

Here are some pics of my progress.