Let's get this CT70 K0 back together!
- Thread starter kawahonda
- Start date
kawahonda
Active Member
Looking back on page 4, it appears that the longer tube is coming from the main portion of the tank, with the shorter one being the reserve (deeper) portion.
So longer tube = "O" port?
Shorter tube = "R" port?
Also, does anyone have any pics of all of the nylon/plastic wire bands that go on the handlebar and where exactly they go and hold?
So longer tube = "O" port?
Shorter tube = "R" port?
Also, does anyone have any pics of all of the nylon/plastic wire bands that go on the handlebar and where exactly they go and hold?
kawahonda
Active Member
Fired it up! Next time, I should try starting it with choke OFF. Fired right away after many, many attempts once I moved it off!
Would have been interesting to have tried to start ignoring the choke next time....
I'll proceed with the general break-in procedure I outlined.
Big shout out to you guys and my dad for the rebuild. I hope it shifts and drives well.
Would have been interesting to have tried to start ignoring the choke next time....
I'll proceed with the general break-in procedure I outlined.
Big shout out to you guys and my dad for the rebuild. I hope it shifts and drives well.
kawahonda
Active Member
@racerx
@fatcaaat
@cjpayne
@kirrbby
I am taking wagers at indicated top speed with stock intake/carb with the best tuning I can throw at it at a 1/2-3/4 mile top stretch. Winner receives $5 via Paypal.
Taking bets now. Closest gets $5.
I'll reveal winner in 30-45 days once the break-in is done.
@fatcaaat
@cjpayne
@kirrbby
I am taking wagers at indicated top speed with stock intake/carb with the best tuning I can throw at it at a 1/2-3/4 mile top stretch. Winner receives $5 via Paypal.
Taking bets now. Closest gets $5.
I'll reveal winner in 30-45 days once the break-in is done.
Last edited:
cjpayne
Well-Known Member
46mph is my 1st guess before break in, in ideal conditions, points @.016, and 30psi in the tires on pavement.
Btw, I have found that if I just slightly crack the throttle open and hold, they start easier. If they are flooded(and the plug isnt gas soaked), I hold the throttle wide open, then try.
Btw, I have found that if I just slightly crack the throttle open and hold, they start easier. If they are flooded(and the plug isnt gas soaked), I hold the throttle wide open, then try.
The motor sounds tight, healthy and in need of some carb adjustment + break-in miles. Full break-in requires 4-digit mileage, though most of it should be done by the 500-600 mile mark. You can reasonably expect the bike to pick up a little on the top end until there's ~1K miles on the clock. Actual top speed, as indicated on the speedometer, involves enough variables to make your estimating competition interesting. Typically, I expect 47mph from an 88cc + "fast road" cam combo, running a 16t cog on the countershaft...everything else stock.
Do yourself a HUGE favor....learn proper starting technique. If you keep slap-kicking the motor, we'll have to start another competition: who can guess when you'll be going back inside the motor to replace the broken kickstart pinion gear. If you really need extra crank rotation to get a motor started, have someone push the bike and either have the tranny in second, or third, gear while you hold the shifter...releasing it once the bike is up to (pushing) speed. Seriously, I'd hate for you to needlessly break something after all the time, money and effort you've invested.
Do yourself a HUGE favor....learn proper starting technique. If you keep slap-kicking the motor, we'll have to start another competition: who can guess when you'll be going back inside the motor to replace the broken kickstart pinion gear. If you really need extra crank rotation to get a motor started, have someone push the bike and either have the tranny in second, or third, gear while you hold the shifter...releasing it once the bike is up to (pushing) speed. Seriously, I'd hate for you to needlessly break something after all the time, money and effort you've invested.
cjpayne
Well-Known Member
After reading this info, I've changed my mind to 55. Fully tucked in should give you 2-3mph more. I'm really hoping you get 60!!!
At these increased speeds, I'm kinda thinking your going to want to upgrade the forks if you do alot of street ridding or fast offroading.
Coastal Redneck
120cc
I'll second that opinion, you want bulletproof forks on your bike, especially for fast offroading & trail riding... nothing worse than broken forks sending ya to the hospital (or morgue, LOL).
kawahonda
Active Member
Wow, these are some good guesses guys. I will definitely keep you all updated. I'm going to definitely give it time....it's going to take some time to put some miles on a CT70 since I live in residential-land. If I was out in the countryside I could accumulate miles more quickly. I will do my best. I'm hoping that at 500 honest miles I could do a top-speed run. So I apologize in advance if it takes more more than 2 months...I will honor my bet to the winner, and yes, I will be tucked in when I do it!
Honestly, I thought I may pick up 5 more MPH with what I've done over stock, but it sounds like more. I'm quite shocked that most of you think I should have about a 50MPh machine. That's most excellent and exciting!
Honestly, I thought I may pick up 5 more MPH with what I've done over stock, but it sounds like more. I'm quite shocked that most of you think I should have about a 50MPh machine. That's most excellent and exciting!
kawahonda
Active Member
SOmething ain't quite right with the carb. I put in a new needle seat. I have 1 larger needle and 1 smaller needle...and the stock needle. I may need to swap needles--I'm running the larger "Keystar" one (and I hate this company....but these are made in Japan which is nice).
Playing with the idle stop (and lifting up on the throttle to set) doesn't seem to do anything.
The air-fuel mix screw does, and so far that's the only way I can set my idle. Any types on how to set that? I think I have it 1.5 turns from "IN" right now.
Perhaps there's a throttle cable adjustment that I'm not aware of....
Playing with the idle stop (and lifting up on the throttle to set) doesn't seem to do anything.
The air-fuel mix screw does, and so far that's the only way I can set my idle. Any types on how to set that? I think I have it 1.5 turns from "IN" right now.
Perhaps there's a throttle cable adjustment that I'm not aware of....
Sounds to me like correctable problems...as in "problems, plural".
Keyster carb rebuild kits are good product. Frankly, however, I prefer the Dratv version, it has everything, including new main & pilot jets.
Best guesses...
A small vacuum leak, although the simple fact that the pilot airbleed screw has a noticeable effect might mean otherwise. Partial blockage of the emulsion tube wall orifices; those are smaller than the pilot jet orifice and can be a MoFo to clean completely, even with a thin wire. Might have low fuel level inside the float bowl; the pilot & main jets sit at slightly different heights above the bowl floor. That the curb idle (throttle stop) screw isn't doing anything is a red flag; i.e. something is assembled incorrectly. But, that should be an easy thing to identify & correct.
When rebuilding a carburetor, I like to set the initial curb idle adjustment by eye, while the carb is "on the bench". Look inside the venturi and turn the screw clockwise until you just the throttle slide just move a little above the completely seated position. That will at least show you where the adjustment range begins/ends. If the idle is too slow, which it should be, you'll know that a slight bit of clockwise rotation will (should) be all that's needed to get positive adjustment. I have the sense that you don't really know if the screw is moving the slide, or not, at this early stage.
FYI, main jets rarely clog up, unlike pilot jets. And I cannot recall seeing a vintage original jet needle that was worn, or oxidized (brass is remarkably stable metal) so you can reinstall those original pieces and if they work right, just leave `em.
Keyster carb rebuild kits are good product. Frankly, however, I prefer the Dratv version, it has everything, including new main & pilot jets.
Best guesses...
A small vacuum leak, although the simple fact that the pilot airbleed screw has a noticeable effect might mean otherwise. Partial blockage of the emulsion tube wall orifices; those are smaller than the pilot jet orifice and can be a MoFo to clean completely, even with a thin wire. Might have low fuel level inside the float bowl; the pilot & main jets sit at slightly different heights above the bowl floor. That the curb idle (throttle stop) screw isn't doing anything is a red flag; i.e. something is assembled incorrectly. But, that should be an easy thing to identify & correct.
When rebuilding a carburetor, I like to set the initial curb idle adjustment by eye, while the carb is "on the bench". Look inside the venturi and turn the screw clockwise until you just the throttle slide just move a little above the completely seated position. That will at least show you where the adjustment range begins/ends. If the idle is too slow, which it should be, you'll know that a slight bit of clockwise rotation will (should) be all that's needed to get positive adjustment. I have the sense that you don't really know if the screw is moving the slide, or not, at this early stage.
FYI, main jets rarely clog up, unlike pilot jets. And I cannot recall seeing a vintage original jet needle that was worn, or oxidized (brass is remarkably stable metal) so you can reinstall those original pieces and if they work right, just leave `em.
kawahonda
Active Member
I believe emulsion tube and all jets (accept for main) are brand new. I even installed a new seat...
I took apart everything I could from the outside and it all checked out. I was missing the little thin gasket on the top cap, but that's it! No effect.
Yep, the pilot is the only way I can control the idle.
I guess it's going to have to come out. I hate taking CT70 carbs off! But whatever.
LIke you said, I may just reinstall some of the original stuff. Time to bench check everything again!
I took apart everything I could from the outside and it all checked out. I was missing the little thin gasket on the top cap, but that's it! No effect.
Yep, the pilot is the only way I can control the idle.
I guess it's going to have to come out. I hate taking CT70 carbs off! But whatever.
LIke you said, I may just reinstall some of the original stuff. Time to bench check everything again!
