'71 cb175 take 3!

jag767

Over 1,000 Posts
Hey all,

Long time lurker and first time poster. I figured what better way to introduce myself than with a double bike build! Been building hot rods for years, and finally decided to take the plunge into something new. A friend and I are currently elbow deep in the crank case of a 1975 cb550f, which we plan on making a wild beast out of. So far everything has been cleaned and measured, just about half way done on the port/polishing on the head. Once its complete in the next couple of days motor should be going back together. The goal on this build is to get a little more spring in her step, while making a real wild custom ride.

As for the rest of the bike, everything is completely broken down, frame and tank went out for media blasting, and all the smaller aluminum components were blasted in our media cabinet. Still not sure if we are going to bring them all back to a high polish or going to go with a unique matt finish look yet, but as my partner in the build is a pipe maker with amazing ability to bring things down to a mirror finish, we're gonna have to weigh out the time vs reward on that one. Once I get some pictures up I'm sure some of you will really be in love with his work on the head cover. He's about 85% done cleaning up every nook around the tappet covers and bringing the whole thing to a mirror finish.

Now for the 175:

As the 550 is at my buddys shop, My garage was looking real lonely. What better way to give yourself a headache than to get another bike going at the same time! Picked up a 1972 cb175, definitely paid too much, but this one is for me, and i wanted this particular bike since i love good things in small packages.

The original plan was to just do some bolt on mods and call it a day, but, well, we all know how that goes. Long story short the parts lists now includes new controls, switches, bars, grips, throttle, cables, led halo headlight, tires, mirrors, rectifier/regulator, probe digital ignition, sparck wire harness, coil, seat, rear suspension, led tail light, digital tach, exhaust, rear controls, and im sure there is more I'm forgetting.

So once I looked at this mass of new shiny stuff, I decided theres no way I cant break this bike down to the frame and give it the love it needs to be in showroom condition. Bike will be broken down the rest of the way this weekend, frame and tank are getting blasted, then going to my friends body shop for some tlc. Going to keep the fork covers on this one since I really dig the look, also going to keep the plastic covers under the seat. Gives me more canvas for custom pinstriping. The fenders, signals, and electric start are all going buh bye.

As for the paint scheme, I'll be drawing a little inspiration from the hot rod world. Tank, air box covers, and fork covers are going matt black, and the frame will be Impulse blue metallic, same color my '04 gto was. The pinstriping will be in that same blue to give that old school chopped top hod rod look on a beautiful matt canvas. Since I'm going for a very simple/clean look, all the welds on the frame will be cleaned up, and a little body work will be done to smooth them out for finish paint. Fingers crossed my buddy will let me lay down the paint myself, I really want a show quality paint job on this one. Plan on sanding down to 5000 to really get that perfect finish.

The motor on this one is good, will just be polishing it up real purdy. As for time frame, I recon the 550 is about 30-45 days out, and with any luck I'll be riding this 175 before christmas and will be looking for another project bike for the new year.

Special thanks to Matt at Sparck Moto for being so helpful with all my questions on this project!

All the pictures for both of these are on my phone, will be putting them up very shortly.
 
Re: '75 cb550 and '71 cb175 double build!

Got caught up in all the work. Here are a few shots of the 175. sorry for the low quality shot of the paint it's from the painter in a text. I have a lot of polishing to do this weekend, then reassembly will start. The front forks are done being polished, Just about everything else to go!
 

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Re: '75 cb550 and '71 cb175 double build!

forgot the legs!
 

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Re: '75 cb550 and '71 cb175 double build!

And some early progress of the 550. There's been a lot done since then, have to take updated pictures. all those sandblasted parts have since been polished.
 

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Re: '75 cb550 and '71 cb175 double build!

Santa came early!
 

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Re: '75 cb550 and '71 cb175 double build!

I DIG the 175.
I bet you'll be able to lean that sweet little bike over enough to drag your ear!

-Sherm
 
Re: '75 cb550 and '71 cb175 double build!

Bigsherm said:
I DIG the 175.
I bet you'll be able to lean that sweet little bike over enough to drag your ear!

-Sherm

Haha thanks man. Got a fair amount done tonight. Motor went back in, and I successfully put two 1 inch gashes in the paint on the left side right on the bottom of the frame by the motor. Thankfully it will never be seen, and i had the paint shop give me the leftover paint. I will mask off the area and airbrush it back in. It wont match perfect but itll at least protect the two spots from rust. Needless to say im still pissed about it.

I also put on the front brake cable, headlight, grips, throttle, levers, and continued polishing the motor. Its about halfway done, still have to do the top end. Tomorrow the plan is finish polishing it up, continue sanding down the side covers to raw alumium and polish, and get every buttoned up.
 
Re: '75 cb550 and '71 cb175 double build!

Well not much to report. Bike is all wired up, probe ignition is installed, rear brake all finished up, power switch is mounted (dont need no stinkin keys!) and i drilled out the screws holding the starter in. The previous owner managed to strip almost every screw, which has been oh so much fun. Cant find my snap ring pliers so i will have to pick up a set tomorrow to remove the starter and then plug it. I purchased the plug for a 350, which appears to be the perfect size.

I also made the bonehead move of drilling them out with the side covers off the motor, and now have a few metal shavings to get out. Was thinking to wipe it all out, drench it with motor oil, then wipe it out again. If anyone has a suggestion how to be more thorough Im all ears.
 
Re: '75 cb550 and '71 cb175 double build!

Here's a couple of shots of tonights progress:
 

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Re: '75 cb550 and '71 cb175 double build!

Well all the sanding on the engine components has caught up to me- hands are killing me. So as I am putting that to the side for a couple of days i tackled a few odds and ends-

Separated the headers from the stock muffler, much easier than I expected. Now I just have to make a bracket for the new shortys.

Finished up the front and rear brakes, and took apart the stock carbs. Man they are ugly. Really really bad. I decided to cut my loses, so I ordered 2 mikuni vm20's. I read these take a little convincing to get in correctly, and I am already dreading the nightmare of tuning with a shorter less restricted exhaust, large cone filter, and having to get the timing right on my probe kit all at the same time.
 
Re: '75 cb550 and '71 cb175 double build!

Still waiting on new carbs. The list is definitely getting shorter. I have a lot of detailing to do, especially in the motor area. Still have to figure out the seat, but I think I have a plan.

As it sits now:
 

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Re: '75 cb550 and '71 cb175 double build!

Does anyone have tuning input for the vm20's on this bike? I've done a ton of searching and have found no specifics other than jet recommendations from dime city. They will be here today so my goal is to have them in working order as well as get the timing sorted by tonight.
 
Re: '75 cb550 and '71 cb175 double build!

Check out the "father son rose from the ruins CB200" build by Texasstar. He's running VMs but had to chop a little off the down tube to get velocity stacks to fit. Not feeling too confident about a cone filter unless you have a tube to get it past the center pillar.

Bike is looking GREAT btw.
 
Re: '75 cb550 and '71 cb175 double build!

1sttimer said:
Check out the "father son rose from the ruins CB200" build by Texasstar. He's running VMs but had to chop a little off the down tube to get velocity stacks to fit. Not feeling too confident about a cone filter unless you have a tube to get it past the center pillar.

Bike is looking GREAT btw.

Thanks will do!! I can see how with velocity stacks you would need to do that. Well my plan is to use silicone hose to extend past the frame, and have it make a 90 degree turn on each side. Then I will mount an aluminum tube between them, and add a large cone filter to the center of it. The silicone will have a larger diameter end where the aluminum goes, prolly around 50mm. This will give me plenty of air between the filter and the carbs, in theory!!! Haha.

I actually got them mounted without a problem yesterday, just waiting on the smaller pilot jets from dime city then I will change the mains to 135 and pilots to 17.5 since that was what they suggested. All I had to do was increase the diameter of the holes on the intake runners between the carbs and the engine, use a skinny stainless screw with some large washers. Probably not the perfect solution, but they are very secure so I'm pleased. I also made a custom mounting bracket to mount the seat, and decided to have a local upholstery shop make a new one for it once I narrow the pan a hair. I also made a mounting bracket for my tail light, but I'm not sure I love it just yet.

The bike is actually down to the short list, although 2 of the items left are going to be a pain for sure:

Change out the main and pilot jets
Put on the chain
Install fuel lines
Touch up a couple of small paint chips
Lube the cables
Detail the crap outta it
Kick her over, set the timing for my probe unit, and adjust the carbs all at once.
Go for a long, long ride.
 
Re: '75 cb550 and '71 cb175 double build!

Still waiting on jets for the carbs, hoping they come soon. In the mean time I plumbed the fuel lines, and tackled the seat. I found a local upholstery shop I will be using, but the last thing I wanted to do is just bring the old seat and try to describe what I wanted them to do with it. So..... I took the cover off, and took the big hunk of foam down to the shape I have in my head.

I got it down to about 90% of a finished product, so now I can just show it to them and ask for basically that, just in new foam. Figured there's less chance for error this way. And btw wow does that foam make a mess!
 
Re: '75 cb550 and '71 cb175 double build!


jag767 said:
Still waiting on jets for the carbs, hoping they come soon. In the mean time I plumbed the fuel lines, and tackled the seat. I found a local upholstery shop I will be using, but the last thing I wanted to do is just bring the old seat and try to describe what I wanted them to do with it. So..... I took the cover off, and took the big hunk of foam down to the shape I have in my head.

I got it down to about 90% of a finished product, so now I can just show it to them and ask for basically that, just in new foam. Figured there's less chance for error this way. And btw wow does that foam make a mess!

Would you mind posting the links where you bought your jets? Using the stock Keihin 20 right?
 
Re: '75 cb550 and '71 cb175 double build!

1sttimer said:
Would you mind posting the links where you bought your jets? Using the stock Keihin 20 right?

Nope, went with mikuni vm20's. My keihins were in sad shape once I opened them up, really didn't have a choice.
 
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