Doctor Funk, or, the strangest CT90 you've ever seen

adventurco

Nick Ol' Eye
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Doctor Funk, or, the strangest CT90 you've ever seen

Ok so update on this thing. I threw a Shinko Golden Boy and new tube on the rear, got the carb to stop leaking fuel and slowed the leak on the petcock enough to where a rag will handle it until new rubber comes in for the petcock.

All set to take it for a shakedown this AM. This bike definitely has a manual clutch installed from one of the other models (S90, etc) as the CT90 came only with an automatic clutch.

I can shift into gear as normal, but the clutch is acting funky. It takes a lot of gas to get it moving, and even when I'm going 10-15 mph (in first) it will stall out when I fully release the clutch lever. Looks like I'll be pulling that side cover off later and investigating.

Edit: I got it to drop into gear and was able to release the clutch. The gearing is funky on this thing, I thought I was in first but I had to really play the clutch and go about 20 mph until it would go and not stall.

Maybe this thing has the dual range transmission installed?


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adventurco

Nick Ol' Eye
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Ok, that makes sense. Dual range FTW!!

54d198584426b6e4cca823ec266a27cf.jpg
 

Hurco550

Keep er' Between the Ditches
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irk miller said:
I hope you're wearing sunscreen.
How would you get a tan if you wear sun screen?

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Hurco550

Keep er' Between the Ditches
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That ain't me lol I was actually the camera man

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irk miller

You've been mostly-dead all day.
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HURCO550 said:
That ain't me lol I was actually the camera man

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What's going on with the circular saw blade mounted on a side grinder?
 

Hurco550

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irk miller said:
What's going on with the circular saw blade mounted on a side grinder?
The entire picture is a "what not to do". We were trolling a fb welding page when we took that picture.

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adventurco

Nick Ol' Eye
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Guys can I has my thread back?

https://youtu.be/RQpKAfe1w9M


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XS750AU

Coast to Coast
HURCO550 said:
The entire picture is a "what not to do". We were trolling a fb welding page when we took that picture.

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Lets hope he does not start playing with it while sitting on that!
 

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cbrianroll

Coast to Coast
Love the saw grinder..... we modified a skilsaw once to run an 8 in blade instead of 7, bad idea.....really close to getting stiches, other than that it worked great.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Doctor Funk, or, the strangest CT90 you've ever seen

I pulled the head yesterday out of curiosity. It does indeed have a big bore kit on it. Bore measures approx 54mm up from the stock bore of 50mm. According to a rough calculation this should put the actual displacement close to 104cc. Cool. Cam is stock. I put it back together (twice) since I broke off an intake stud and had to drill and tap it.

I picked up a stock 4-screw carb at Mid-O for cheap, cleaned it up and threw it together with some new gaskets. The throttle cable is too short so I'll need to make a new one before I can run it.

The carb that was on there was the #1 carb from a cb200 (i believe) which had a #38 pilot and #95 main. The stock carb for the CT90 that I put on has a #38 pilot and a #75 main. I am going to order a few jets since the plug actually looked pretty black I may be able to get away with running it a bit leaner.

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vwrabbit

Been Around the Block
I love these little 90s. My uncle had one me and my brother tried resurrecting back in the 90s when we were teens. I believe we got it running, but that's about it.
 

pacomotorstuff

Coast to Coast
I think I can shed a little light on the extended oil filler / dipstick.
It is probably an aftermarket breather (though might have been a CYB part) to help relieve internal pressure. At high rpm's, the single little breather of the stock engine can't handle the pumping pressure and starts to puke oil and can even blow a seal, so the additional breather helps get rid of the pressure.
The stacked plates in the extension act like a series of baffles to knock down any flying oil droplets, so it gets returned to the crankcase.
The first one I ever saw was in the mid-sixties on the CB450 that Jim Odom raced at Daytona, though I believe various racing Honda factory racers and conversions used them.
It's such a cool piece, I may try to coerce my machinist into building one for my 175 twin over the winter.
I know it seems odd in the day of 600cc "beginner bikes", but the Honda 90 slopers were road raced back in the day and a huge amount of performance equipment could be had - you've got the big bore kit and if you had the stroker crank from Powroll, it would go out to 133cc.
And yes, it is the strangest CT90 I've ever seen.
A great ride.
Pat
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Thanks Pat! Very cool info on the breather. Some of the mods that have been done are nicely done, others not so much but once I clean up the mess I think this will be a fun little scooter.
 

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