One step from being a runner, but a no go!

D

Digginrebel

Member
This is my ugly, first CT70 project that I nicknamed the Teacher because it has been a learning experience! I choose this 92 model as my first project for several reasons. First, it was cheap at $100, had a straight frame that needed a patch welded in under the seat and un bent forks and had original engine, though locked up. If it could be taken off and put back on backwards by a teenager - it was! There was nothing correct really at all, thus without fear of damaging an earlier model with my inexperience, it was perfect. My plan is to make a good runner, then tear back down and apply some paint to learn that as well, then use it around the farm. Everything is done and seems done correctly, EXCEPT THE CARBURETOR! I rebuilt original twice and no good. Broke down and got an aftermarket carb and now idles, but no throttle response. The carburetor Gods are frowning on me bigtime! I have yet to successfully work on any of my carbs on any of my projects. Not giving up, but darn frustrating!
20190725_060339.jpg
 
6

69ST

Well-Known Member
For that money, you did well...much better than you may realize, at this time. The only things the `90s (a.k.a. 12v) era bikes lack are aesthetics, and the classic engine guard, which may be useful for your strictly offroad application. IMHO, this looks like a great base to build into any form you like. The 12v bikes are functionally the best of the breed: 12v engine - the only one with a lighting coil, improved seating, upgraded suspension, 6" headlight, conventional sweeper-style fork, etc. 1991-94 bikes seem to fall into maybe 4 basic categories: ultra-low mileage & nearly perfect, midrange, meaning vary shades of decent condition, usually not too many miles & mostly complete; fair-to-poor some missing parts; left-for-dead which can mean anything ranging from a bit better than your was, as-found, good for parts. It's that first category, plus the unobtainium parts unique to these models, that makes purist-restoration difficult from multiple angles.

Once your goal becomes a solid, nice-looking rider, the balance swings toward your favor. There's almost no chrome on these models which automatically means avoiding a big expense. It also means sourcing whatever parts you feel are the best bang-for-the bucks. To that end, I'd source a new K0-K1 style reproduction carburetor; the parts are readily available and they're much more tuner-friendly than the late round-bowl/emission-compliant Keihins. Going by what you've posted & appearances, this bike sat long enough that the carb body casting could be oxidized, internally. (I wouldn't toss the original carb but I wouldn't bet money on it, either.)

You didn't really say much of anything about the engine rebuild. In fact, that was implied, not stated. What was done and have you checked the compression? The odds that a valve job was needed are high so, if that wasn't done, it may be bleeding-off too much compression to run properly.
 
D

Digginrebel

Member
Digginrebel said:
This is my ugly, first CT70 project that I nicknamed the Teacher because it has been a learning experience! I choose this 92 model as my first project for several reasons. First, it was cheap at $100, had a straight frame that needed a patch welded in under the seat and un bent forks and had original engine, though locked up. If it could be taken off and put back on backwards by a teenager - it was! There was nothing correct really at all, thus without fear of damaging an earlier model with my inexperience, it was perfect. My plan is to make a good runner, then tear back down and apply some paint to learn that as well, then use it around the farm. Everything is done and seems done correctly, EXCEPT THE CARBURETOR! I rebuilt original twice and no good. Broke down and got an aftermarket carb and now idles, but no throttle response. The carburetor Gods are frowning on me bigtime! I have yet to successfully work on any of my carbs on any of my projects. Not giving up, but darn frustrating!View attachment 62593
Click to expand...
Yep, replaced the top end. Fought with that as well, but think It is good now. I can get it to idle, but no throttle response at all. Like cable is ineffective. Pretty sure is original cable.
 
D

Digginrebel

Member
racerx said:
For that money, you did well...much better than you may realize, at this time. The only things the `90s (a.k.a. 12v) era bikes lack are aesthetics, and the classic engine guard, which may be useful for your strictly offroad application. IMHO, this looks like a great base to build into any form you like. The 12v bikes are functionally the best of the breed: 12v engine - the only one with a lighting coil, improved seating, upgraded suspension, 6" headlight, conventional sweeper-style fork, etc. 1991-94 bikes seem to fall into maybe 4 basic categories: ultra-low mileage & nearly perfect, midrange, meaning vary shades of decent condition, usually not too many miles & mostly complete; fair-to-poor some missing parts; left-for-dead which can mean anything ranging from a bit better than your was, as-found, good for parts. It's that first category, plus the unobtainium parts unique to these models, that makes purist-restoration difficult from multiple angles.

Once your goal becomes a solid, nice-looking rider, the balance swings toward your favor. There's almost no chrome on these models which automatically means avoiding a big expense. It also means sourcing whatever parts you feel are the best bang-for-the bucks. To that end, I'd source a new K0-K1 style reproduction carburetor; the parts are readily available and they're much more tuner-friendly than the late round-bowl/emission-compliant Keihins. Going by what you've posted & appearances, this bike sat long enough that the carb body casting could be oxidized, internally. (I wouldn't toss the original carb but I wouldn't bet money on it, either.)

You didn't really say much of anything about the engine rebuild. In fact, that was implied, not stated. What was done and have you checked the compression? The odds that a valve job was needed are high so, if that wasn't done, it may be bleeding-off too much compression to run properly.
Click to expand...
Any recommendations on a decent brand aftermarket carb? I am not having any luck picking anything.
 
D

Digginrebel

Member
racerx said:
For that money, you did well...much better than you may realize, at this time. The only things the `90s (a.k.a. 12v) era bikes lack are aesthetics, and the classic engine guard, which may be useful for your strictly offroad application. IMHO, this looks like a great base to build into any form you like. The 12v bikes are functionally the best of the breed: 12v engine - the only one with a lighting coil, improved seating, upgraded suspension, 6" headlight, conventional sweeper-style fork, etc. 1991-94 bikes seem to fall into maybe 4 basic categories: ultra-low mileage & nearly perfect, midrange, meaning vary shades of decent condition, usually not too many miles & mostly complete; fair-to-poor some missing parts; left-for-dead which can mean anything ranging from a bit better than your was, as-found, good for parts. It's that first category, plus the unobtainium parts unique to these models, that makes purist-restoration difficult from multiple angles.

Once your goal becomes a solid, nice-looking rider, the balance swings toward your favor. There's almost no chrome on these models which automatically means avoiding a big expense. It also means sourcing whatever parts you feel are the best bang-for-the bucks. To that end, I'd source a new K0-K1 style reproduction carburetor; the parts are readily available and they're much more tuner-friendly than the late round-bowl/emission-compliant Keihins. Going by what you've posted & appearances, this bike sat long enough that the carb body casting could be oxidized, internally. (I wouldn't toss the original carb but I wouldn't bet money on it, either.)

You didn't really say much of anything about the engine rebuild. In fact, that was implied, not stated. What was done and have you checked the compression? The odds that a valve job was needed are high so, if that wasn't done, it may be bleeding-off too much compression to run properly.
Click to expand...
She is now all GO! Rebuilt the carb yet again and now smooth as it can be. Now to learn to redo the front shocks for a better ride. Many thx!
 
6

69ST

Well-Known Member
Digginrebel said:
She is now all GO! Rebuilt the carb yet again and now smooth as it can be. Now to learn to redo the front shocks for a better ride. Many thx!
Click to expand...
A fork rebuild is straightforward...mostly cleaning, tidying-up/refinishing.

Carburetor rebuilds, OTOH, can be anything but straightforward. Meticulous attention to detail counts...as does patience/persistence. They are fairly simple devices, with few moving/wearing parts. That said, what is (virtually) always overlooked is the fact that it contains some of the most precise tolerances (the jets, jet needle, air bleeds and...especially the emulsion tube orifices) found on the entire bike. Seriously, nine times out of ten (if not more) stubborn carburetion problems are a result of stubbornly tough deposits obstructing some passage(s), throwing the fuel delivery off balance.
 
kirrbby

kirrbby

Well-Known Member
When you clean a carb, and you think you're done, AND as you start to reassemble it...
Use the straw on a can of carb cleaner to spray into EVERY single hole that you can find on the carb. EVERY hole, big or small, leads to somewhere. Spray into a hole and watch for the fluid to come out of another hole. If it doesn't come back out...there is a blockage, that need to be cleared.

Be very careful when you do this. Wear some safety glasses or face shield, rubber gloves etc.
And never, ever do it while standing in wifey's flower garden :--)
 
kirrbby

kirrbby

Well-Known Member
...or, while smokin a doobie...when your kitten is climbing your leg...while warming your butt by a campfire...while nekked...while standing next to your vintage Z28...with your mouth open...while making soup...while standing next to your neighbors vintage Harley...while wearing your blue suede shoes...
 
D

Digginrebel

Member
kirrbby said:
...or, while smokin a doobie...when your kitten is climbing your leg...while warming your butt by a campfire...while nekked...while standing next to your vintage Z28...with your mouth open...while making soup...while standing next to your neighbors vintage Harley...while wearing your blue suede shoes...
Click to expand...
Too funny, but true. I am still fighting getting the petcock flush, but discovered one thread hole is stripped! Great. Other carb on the 92 has an unrebuildable petcock, but diagram shows no part number for it. Works in reserve position without leaking for now
 
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