Thread: Tranny Question - 4 speed to 3 speed

Hello everyone, My name is Kim and I am a newbie here looking to ask a few questions.

I recently purchased a 1971 KO - upon further inspection when we got it home we determined that it was maybe just a little bit bigger of a project than we wanted. Yesterday I happened across a 1970 HKO in pretty good shape for a price I couldn't pass up. We figured we would rob some parts from the KO and then re-sell it.

My husband wants to know, is it possible to switch out the trannies - he would like to switch out the 4 speed manual for the 3 speed semi auto to make it easier for me to ride. How hard would this be if it is possible?

Thanks in advance - I will post some pictures of my new toy soon!
Kim

It can be done. There are a number of differences between the 3-speed and 4-speed, tho'. Probably the biggest difference is that the 4-speeds are harder to find, so they're worth more. That alone might make it worth keeping the HK0 all together.

To use the 4-speed with the auto clutch you'll have to split the cases on both engines, pull the transmissions and reinstall the 4-speed in place of the 3 speed. Be sure to keep the four speed kickstarter assembly with the 4-speed transmission.

In my opinion, it's a lot of work for very little return. The extra gear won't buy you much, because the 4-speed has closer ratios than the 3-speed. Mostly, you just have to shift more. If I was in your position I'd fix them both and go riding together. (Make him ride the H-model.)

-kevin

If both engines run then just swap the entire engines. As far as replacing just the three speed transmission with the four speed transmission I am not sure. I do not know if they are interchangable. If they are that means splitting the engine cases and alot more work involved.

Don't touch the 4 speed. Keep it whole and put it on a shelf. Do what you need to the 3 speed to make it run well and be reliable. It won't take long on this webboard to realize how important it is to all of us to keep the matching H engine and bike. You might consider keeping the 3 spd whole and sell it to buy a new Chinese automatic.
Just ask and you'll get the info you need.
They aren't too expensive.
I agree w/ you on the ease of the auto trans. It's nice when you're just putz'n round town. I'd never get rid of my H though. What color is the H?

Thank you for the replies - we talked about the fact that we didn't really want to switch it out because the H is harder to find. I told him I can learn to use the clutch because I would rather have it in as close to original condition or as much as money will allow right now!

The color is candy topaz orange - I will try to post some pictures tonight. We started tearing it apart last night to clean and I made my first order of probably many orders from dratv.

Kim

We got another one.HOOK,LINE and SINKER !You are now totally addicted.
Good luck,
Dennis

Now you're talkin' yfz! Taught my daughter how to clutch & shift while sitting on the front when she was 9. If you want to ride it, you'll learn quick enough.

Another possibility would be to source another used 3-speed semi-automatic engine. They do pop up on ebay and sell for next to nothing. Any 6V example, meaning `69K0 - 1982 should be dead simple to install as your training engine. It's pretty unusual to get a 3-speed with a bad transmission and maybe one in 10-15 examples will need to have the connecting rod replaced. With a little care & just a tiny bit of luck, you can rebuild a 3-speed motor for around $400. That's done right and includes the shipped cost of the base motor and your choice of boring the existing cylinder or fitting an 88cc kit, which is a new cylinder & piston kit.

I'll throw in with the 'don't tear into the 4 speed!!!' crowd. That's one nice thing about these little bikes is they are great to learn on! If someday you want to get a bigger bike you will already know how to use the clutch. 1 day max and you'll have it figured out. That said nothing wrong with a auto either. They certainly have their advantages. Here's one on eBay. Good luck.
RK
eBay Motors: Honda Trail 70 CT70 70cc Engine w/3-Speed Transmission (item 140257719076 end time Aug-15-08 1700 PDT)

We have decided to leave it stock - we want to someday completely restore it and think it would be better if left alone.

Thanks again for the replies!

Here is a pic - I posted an intro thread over in General but did promise pics . . .