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Old 08-24-2010, 05:54 PM   #1
sailah OP
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Joined: Aug 2005
Location: Turning expensive metal into scrap
Oddometer: 5,759
1972 CT-90 rebuild

First off to the traditionalists, this is not a museum piece. I didn't match the color or keep the rack chrome. If you can live with that, read on...

So I bought these 2 CT90's (yellow is a 1970 I think, orange is a 72) on a whim for $300. I had no idea what one looked like or what was missing. I figured it would be a part swapper marathon and kick it to life. The more I got into the project, the more I was interested in restoring it.

I knew from the outset that it was missing the entire airbox, battery cover and a bunch of other stuff.

The status of the mechanicals was not great. Piston was rusted to the cylinder and had to get whacked with a hammer to free up.

Head wasn't much better.

So there goes the idea of just a tune up. Decided to strip it all down and see where I stood.

Engine out

Frame and forks

Parts, hope I remember how this all goes back together

Started to polish the covers

Cylinder after I honed it. Wasn't going to go with new rings but just ordered a 20 over piston kit and going to get it bored out.

Lapped the valves and got a good seal. The engine bore guy said to hold the valve in with my finger and spray brake fluid. If you get any leaks, redo. Seems to be holding great. Not bad for my first time.

Getting deeper

My first attempt at lacing wheels. Wish someone told me that the spokes are specific to the inside/outside Think I did each one 5 times.

Think this will hold?

Tried polishing an entire cover. I think this will end up being a nightmare to keep clean and polished. Messy to do as well..

I had 3 fenders. 2 bad frames and one bad tin. So I swapped the tin over and pop riveted it.

Hard to tell the difference on the old vs new wheel but I polished the chrome rim, and sanded each and every spoke. Nightmare. Wheels will get new bearings and have Michelin Gazelles as I won't be off roading. I bought another set of rims I will put some knobs on

Clutch rebuilt with new fiber discs, steels were fine.

I'm going to paint the engine cases semi gloss black. Read on to see what I did with the covers...

New exhaust, the old one was completely shot. The guards are in pretty decent shape, so I'll reuse.

Well look what Santa brought us

Powdercoating is sweet. I had the the orange pieces powdered orange obviously. The skid plate & rear rack were done in chrome powder with a topcoat of clear. Looks more like silver really. Oh well, at least it is consistent.

The engine covers and gear/brake stuff were done in silver. The center stand and footpeg bar was done in semi gloss black.

Really happy with the way it came out, not cheap, but the time it would have taken to really clean that frame out vs sandblasting and coating was worth it.

I'm going to assemble the engine with SS button socket screws from Fastenal. The soft stockers were all pretty much junk when I took it apart. I think I used the EZ out more than a screw driver.

Also putting in all new bearings for the engine save the crank bearings. By the time I washed the cases 100 times, I was getting a little grit in the smaller ones. Also got new bearings for the wheels. New oil seals and the engine should be ready to go.

Engine should be done next week, then I get to reassemble. I have a bunch of loose ends like speedo cable, seat recover, POR the tank, new wiring harness, battery box & cover, frame cover ($$$$), decals, new cables, brake lever.

This is my inspiration, although I recognize that I won't be total original with the powdercoating vs chrome. I'm also hunting down an aux tank from a member here.

Comments and advice from those who have been down the road appreciated.

When completed, this will be the first CT-90 I will have ever ridden. Funny story on the trip home from Ohio, first gas station, guy comes up to me and launches into how he used to ride these all the time, can climb anything etc. I can't wait to join the scooter mafia. After owning expensive and powerful European V Twins, this bike has me more excited than any of them.

Also my first restoration so take it easy
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Old 08-24-2010, 05:55 PM   #2
sailah OP
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spooge tank hooked up for rust removal

sailah screwed with this post 08-24-2010 at 08:05 PM
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Old 08-25-2010, 12:29 AM   #3
wanna bECO
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.. nice work! Can't wait to see the finished product . I want one of those so bad!
Just cuz my bike is shiny, doesn't mean that I'm a hiny

current stable

'94 Harley .... a blue one
'82 Honda passport
'87 Honda spacy 250
And an E Bike
85 spacy 250
81 passport (in pieces, many parts for sale)
The hit's just keep coming.. bought another 81 passport (11-28-09)
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Old 08-25-2010, 07:42 AM   #4
Joined: Jan 2010
Location: Cin City, OH
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Great pics, nice the way it's coming along. Looks great, and you picked the nicest color in my not so humble opinion.

Waiting for the engine rebuild story.
Oh I used to be disgusted, but now I try to be amused-E.Costello
'01 Kawasaki W650, '05 Yamaha XT225

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Old 08-25-2010, 09:28 PM   #5
Let me take this duck off
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Joined: Apr 2009
Location: BC
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nice if you clear coat the metal your save your self some trouble of reploshing it.
Life's journey is not to arrive at the grave safely in a well preserved body,but rather to skid in sideways totally worn out shouting WHAT A RUSH, WHAT A RIDE.
"Life is a tragedy when seen in close-up, but a comedy in long-shot." Charlie Chaplin
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Old 08-26-2010, 05:36 AM   #6
sailah OP
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The engine covers were powdercoated. The polishing looked good for about 5 minutes.

No story on the engine rebuild other then the frozen piston. One thing led to another and I had every component taken apart.

I'm going to Vegas this weekend and will get the bike finished next week.
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Old 08-26-2010, 12:13 PM   #7
Not Cheap,Thrifty
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Joined: Mar 2009
Location: True North, GA
Oddometer: 299
Great job so far! I done one of these last winter and when I finished I turned around and sold it and have kicked myself ever since for it.
These things are awesome little bikes. Ok that's it now I have seen yours I want another one now The search begins!

Keep us updated
" The only difference between crazy people and sane people are crazy people talk about the thoughts going on in their head "
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Old 08-26-2010, 12:24 PM   #8
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Enjoying your build, is that KTM orange??
Get fit. Stay safe. Enjoy life. Learn something to help someone in need.
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Old 08-26-2010, 05:20 PM   #9
sailah OP
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Thanks for the comments. It's been fun tearing it apart,now the wait begins for parts. The cylinder is at the machine shop and once I get the new bearings, I'll put that together. I think I have everything to get a roller once that happens.

Bunch of little stuff I'll wait to the end to order from DrATV.

The color is just "orange" at the powdercoaters. I thought about trying to get it matched, but said what the hell. All the chrome has been done chrome/silver powder so it'll never be original. I just want it to look sweet.

I have another one I might make into a frankenbike. Throw some XR forks on it, rattle can the colored parts and use that for a beater. It gets pretty expensive when you have to buy the hard to get parts like an exhaust, frame cover, airbox etc. I'm guessing I'll have 1200-1500 into the project when all is said and done.
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Old 09-19-2010, 07:50 PM   #10
sailah OP
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Well it's been longer than I thought to get this hoss back together. I keep having the battle to go all out and replace things like bolts or just shine stuff up on the buffer. I think if I was to do it again, I wouldn't have spent the money on powdercoating. Yeah it looks great, but a decent job with a rattlecan can pretty much get almost the same result esp if you bake the paint and harden it.

Anyways, I'm pretty much in the home stretch. It was a fun project and lessons learned for my next rebuild. That's right, on the lookout for the new project. Not sure what I'll do with the trail 90. Most likely get it registered in Maine and ride it.

Frame, swing arm, and shocks assembled.

Motor which took forever to rebuild mostly out of laziness. I trashed all the seals taking it apart then forgot to order new ones so that delayed the entire project. I put all new bearings in except the crank bearings. It's hard to tell but I painted the case halved with duplicolor aluminum wheel paint which looks almost identical to the powdercoat. For the money, I'll def paint them myself next time. The covers are powdercoated. Piston and cylinder are fresh from the machinist along with new rings.

The unobtanium sub tank. Basically a canteen for spare gas. I bought a ton of parts from a guy in VA including a spare set of rims, drive hub, air box and the sub tank for $100. They usually sell for that just for the tank. I don't know why I really wanted it, but whatever, it looks cool. I painted the air box and the sub tank with rustoleum charcoal grey. For some reason I was getting runs, so I'll wait a week, sand the runs out and reshoot.

As it sits today. I need to redo the forks, should be easy I hope I don't need seals. I'm getting sick of ordering shit for this thing!! The engine needs a countershaft seal for the low range box. I also need a speedo cable, headlight and probably a few odds and ends. I want to assemble as much as humanely possible before I put the next order in to get everything at once

The guy I bought the parts from threw in a complete wiring harness so along with mine and the schematic I should be able to get it running.
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Old 09-19-2010, 07:57 PM   #11
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Sweat, toil, and no stitches, either. Da-yum, Dude!
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Old 09-20-2010, 07:38 PM   #12
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your restore

nicework I restored a k5 ct90 couple year ago lots of fun to ride. Where in Ohio are you
Bob in Cincinnati
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Old 09-22-2010, 05:15 AM   #13
sailah OP
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Old 03-04-2011, 03:38 AM   #14
MT Don
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nice you have a budget you are working to and/or, how much do you think you will have into this project when completed?

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Old 03-04-2011, 06:57 AM   #15
Zwei Kolben
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Location: Mike's Sky Rancho
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I would go with IRC TR 1 tires.....They look really similar to the original Yokohamas.

Here is my unrestored 100% original 72, it has 870 miles on it.

I assume you know about this place
This is SPARTA!
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