XR70 bottom end with CT70H transmission problem
- Thread starter 916mestizo
- Start date
916mestizo
New Member
lol Interesting indeed...
So I am sure Racerx already knew this but the Dratv trans gears didn't work.
Despite the description they give that says the gears are all interchangeable, they are not! Basically the gears are close but not quite the same width as the Honda gears, also the shaft cuts where the cir-clips go are in different positions to go with their gear width's. I managed to get 2nd and 3rd onto the honda shafts, installed the drum and then attempted to put it into the case to see if maybe it would work, but no dice. If I use the whole set then it would be fine, but my dad wants the CT70H 1st and 4th gear ratio's not the ATC 70 ratio's the new trans comes with.
So we ordered NOS gears and put it back together this past weekend. It moves so much smoother now, but while shifting it on the bench it still seems to get hung up on 3rd and 4th sometimes. Not sure if the if that's because it's not running or maybe an issue with the shift arm that grabs the detents on the shift drum. Hopefully someone here can chime in on that.
Also when putting in the 6x1 bolt into the side of the shift drum on the stator side of the motor, is there a specific position/gear the trans should be in before I tighten down or does it not matter?
Also as an FYI Dratv would not take the trans back without a 25% restocking fee and us paying to ship it back... again despite their description not being correct about its interchangeability.
If you're running 100% NOS Honda parts...and everything is correctly assembled...the tranny ought to shift as expected. IOW, that satisfying snick between gears, up or down shifting. However, these trannies really need rotational movement to shift normally. They usually don't like to bench-shift. Spin the primary shaft and see how that affects bench shift quality. As for the drum fixing bolt, it's important that you use the original, with the original washer; it looks generic but it isn't. No specific clocking is needed for torquing it. Remember, it's only there to limit endplay...without binding the drum.
A secondary method for bench-shifting/testing: use the M10 drum bolt for one direction, the shift star fixing bolt (screw) for the other. That'll overcome normal recalcitrance of a non-spinning transmission.
Lastly, for now, these are new parts. They'll need a little break-in mileage.
A secondary method for bench-shifting/testing: use the M10 drum bolt for one direction, the shift star fixing bolt (screw) for the other. That'll overcome normal recalcitrance of a non-spinning transmission.
Lastly, for now, these are new parts. They'll need a little break-in mileage.
916mestizo
New Member
Ok thanks, just wanted to be sure that something else wasn't wrong before it goes back into the bike. Gonna be a little bit before we put it back in as my dad is now modifying the seat pan to take an airtech seat fairing.
916mestizo
New Member
So after reading a couple of other threads on here, I have another question about this swap.
The threads I was looking at showed that the newer 3 speed auto's have a kind of "mushroom" shaped pin on the drum that the shift arm engages... while the 4 speed auto's all seem to have a "flat" shift pin on the drum.
Should I be using a 4 speed auto clutch shift arm instead of the 3 speed auto clutch shift arm, or maybe go the other way and run mushroom pins on the CT70H drum?
I'm not sure if it will even be an issue, but I figured I would ask before we get everything back in the bike again.
The threads I was looking at showed that the newer 3 speed auto's have a kind of "mushroom" shaped pin on the drum that the shift arm engages... while the 4 speed auto's all seem to have a "flat" shift pin on the drum.
Should I be using a 4 speed auto clutch shift arm instead of the 3 speed auto clutch shift arm, or maybe go the other way and run mushroom pins on the CT70H drum?
I'm not sure if it will even be an issue, but I figured I would ask before we get everything back in the bike again.
916mestizo
New Member
I was thinking that the different size of the pins would possibly not engage as well and I would possibly need to get an ATC 70 shift shaft/arm since they use the flat style pins on the drum like the "H" did but were for an auto clutch 4 speed.
I guess we will just have to see if it works once it's back in the bike.
kirrbby
Well-Known Member
There have been many others who have done just what you are doing, 4speed auto, mixing the same parts as you, including me. My guess is that the shift drum compensates for the flat style pins.
One time I took a auto clutch shift shaft and cut it off to use in a CT70H engine. Worked like a charm.
One time I took a auto clutch shift shaft and cut it off to use in a CT70H engine. Worked like a charm.
Roy Chambers
Member
Hi, I just joined the forum after trying to find a part number for the First Gear Bushing in a CT70H Transmission!
I also have a Transmission like the one being discussed by 916mestizo! I bought this Transmission off of e-bay around 2007. It came complete with the shift Drum, Forks, all the Gears, Shift Shaft, and even the Kick Start assembly.
I do not know if it was from a K0 or a K1, and I don't even know if there is any difference between the two.
I got it out of the box last week and inspected it. I did notice the Smiley Faces, just starting to appear on one of the Shift Forks, but did not think of it too much until i read this post. My bigger concern was the amount of clearance the First gear had on the Shaft.
So, one of my questions is, is this Bushing replaceable? If so, what is the Part number? If not, then what is the part number for the First Gear?
My Transmission, does not look anything like the pictures of 916mestiz does!
Like i said, First gear has a lot of wobble and only one shift fork is just starting to SMILE, more like a 3 point contact.
I would also like to know if this Transmission was worthy in new condition? OR is the China one that Dr ATV sells better?
I kind of like the Honda Gear ratio better then the China one, it look's to have a closer ratio then the China one.
What is your opinion, racerx ?
I also have a Transmission like the one being discussed by 916mestizo! I bought this Transmission off of e-bay around 2007. It came complete with the shift Drum, Forks, all the Gears, Shift Shaft, and even the Kick Start assembly.
I do not know if it was from a K0 or a K1, and I don't even know if there is any difference between the two.
I got it out of the box last week and inspected it. I did notice the Smiley Faces, just starting to appear on one of the Shift Forks, but did not think of it too much until i read this post. My bigger concern was the amount of clearance the First gear had on the Shaft.
So, one of my questions is, is this Bushing replaceable? If so, what is the Part number? If not, then what is the part number for the First Gear?
My Transmission, does not look anything like the pictures of 916mestiz does!
Like i said, First gear has a lot of wobble and only one shift fork is just starting to SMILE, more like a 3 point contact.
I would also like to know if this Transmission was worthy in new condition? OR is the China one that Dr ATV sells better?
I kind of like the Honda Gear ratio better then the China one, it look's to have a closer ratio then the China one.
What is your opinion, racerx ?
kirrbby
Well-Known Member
Welcome to lilHonda Roy Chambers.
I'm not sure what part that you're referring to. Please tell us the name or number from the parts fiche.
Also, what looks different between your trans, and 916mestizo's? Maybe you can post some pictures..? CT70H transmissions are all the same.
https://www.partzilla.com/catalog/honda/motorcycle/models-with-no-year/ct70h-a/transmission
I'm not sure what part that you're referring to. Please tell us the name or number from the parts fiche.
Also, what looks different between your trans, and 916mestizo's? Maybe you can post some pictures..? CT70H transmissions are all the same.
https://www.partzilla.com/catalog/honda/motorcycle/models-with-no-year/ct70h-a/transmission
Roy Chambers
Member
Hi, Kerrbby, thanks for the reply.
Part number 3, Countershaft low gear. On your partzilla, 23421-065-010.
My gear has a Bushing in it, and it look's like Honda's work, and not some home made fix.
Thanks Roy.
Part number 3, Countershaft low gear. On your partzilla, 23421-065-010.
My gear has a Bushing in it, and it look's like Honda's work, and not some home made fix.
Thanks Roy.
fatcaaat
Well-Known Member
. And trx90 is waaaaay beefier
Roy Chambers
Member
Thanks Guys!
Maybe I was SHAFTED!
I am going to give the whole thing a good examination tomorrow.
It may not even be a CT70H Transmission that I bought off of e-bay!
It was around 2007 and I did not do anything more then open the box at the time.
I got it out of the box other day to look at it, cause I am going to build a new engine for my CT70K1!
I just bought the bike from my friend who moved away.
I tuned it up for him a long time ago. The bike is a K1 Auto, but it has a 6 digit K0 engine in it.
So, I am going to go over to the barn and see if I have a useable donor Crankcase.
I don't see any point in tearing this Engine down, it runs pretty good, starts on first kick, and does not smoke.
I also bought a USED CT70H Crankshaft around the same time!
I guess that I should take a good look at that too.
Thanks Roy.
Maybe I was SHAFTED!
I am going to give the whole thing a good examination tomorrow.
It may not even be a CT70H Transmission that I bought off of e-bay!
It was around 2007 and I did not do anything more then open the box at the time.
I got it out of the box other day to look at it, cause I am going to build a new engine for my CT70K1!
I just bought the bike from my friend who moved away.
I tuned it up for him a long time ago. The bike is a K1 Auto, but it has a 6 digit K0 engine in it.
So, I am going to go over to the barn and see if I have a useable donor Crankcase.
I don't see any point in tearing this Engine down, it runs pretty good, starts on first kick, and does not smoke.
I also bought a USED CT70H Crankshaft around the same time!
I guess that I should take a good look at that too.
Thanks Roy.
wanrep
Active Member
Good to know. Filed for future use.
kirrbby
Well-Known Member
Looks like all, or at least a lot, of the 12v engines use this same 1st gear setup.
My partial ATC trans does not have those parts with it...sorry.
https://www.partzilla.com/product/honda/23422-041-000?ref=21619a64461d7c5e1f85e3a6f4166e5366f01229
fatcaaat
Well-Known Member
I'm fairly certain that all XL70, SL70, CL70, and S65 transmissions are fully swappable. However, the tooth counts vary between the gear sets. The good news is that you can swap out gear sets across the board...so you can take two seconds from a SL70 and put them on an H and so on. It might actually be cheaper and faster to purchase one of the AHP/TB parts 4 speed trannys and use the H drum to get the right pattern and swap the gear from a 3 speed on the kicker. I did more than 5k on a 124+r engine with one of these transmissions and it never skipped a beat.