NC50 clutch spring upgrade

So after all of the upgrades I did to my '81 Express (carb, intake, reeds, exhaust), I couldn't get it to start moving for the life of me. I searched and searched, but couldn't find much helpful information on changing out the clutch springs on this particular engine.

I got some springs from Treatland (they're a bit short, but they work. Look for longer ones, probably 35mm):

https://www.treatland.tv/ProductDetails.asp?ProductCode=GY6-yellow-clutch-springs-1500

Here's everything I used:

Harmonic balance puller

8mm socket

10mm socket

12mm socket

14mm socket

14mm wrench

Vise grips

Flat blade screwdriver

Rubber mallet

Gasket maker

carb cleaner

New 10w40 oil

First and foremost, drain the oil out of the transfer case. My oil fill bolt was behind the kickstand area, no different looking than the rest. Removing the fill bolt at the front of the transmission speeds up the process, but there's only about a quart of oil. Also, make sure you put down newspaper under the entire length of the transfer case.

The next step is to loosen and remove all of the bolts along the transfer case. Don't take the kickstart arm off, that whole assembly comes off with the side cover and you'll have a pain reinstalling it if the spring pops off.

Find a place to start working your screwdriver in between the halves of the case and gently tap it in with the rubber mallet in several locations to separate the case evenly. A fair amount of oil will drain out that couldn't reach the drain plug. Peel off all of the old gasket, it'll never seal up right again. Spray out the inside of the case with carb cleaner next, it makes everything a lot cleaner to work with and you'll need an oil-free surface for the gasket maker to adhere well. Next is gasket maker time (unless you bought a new one). Just squeeze it on to the case half you removed and cleaned. Set it aside for a few hours so it develops a skin.

After you've finished up with your gasket, pull the exhaust off and insert a screwdriver above the piston to stop the engine from turning. Use your 14mm socket to remove the clutch nut and then attach the puller using the two small, threaded holes. The only bolts I had that were small enough were the case bolts, I believe they're m6. The clutch popped off easily with the puller and the clutch shoes were right on the back, kind of like a drum brake. I used my vise grips and some braided cable to pop the springs off, same method to put the new ones back on. The new ones were so stiff they gave me trouble stretching them, enough to make me fearful they would be too strong.

I reassembled it anyways, added new oil, and gave it a kick to start it. It revs until it hits its powerband, then it starts catching nicely. I went around to some hilly areas and was able to take off up steep hills and accelerate all the way to 30, something that would have never happened before. Now I'm not going to be so afraid to take it out on busier roads with the new acceleration. Forget drilling holes in your shoes, replaces those old, worn out springs.

Re: NC50 clutch spring upgrade

Good, look at Honda 125cc clutch springs. They are a fuzz longer. Same ratings, 1000, 1500, 2000

Re: NC50 clutch spring upgrade

I found a set of the 1500 125cc clutch springs to compare. DIO/Hobbit 1k on the left, stock hobbit on the right.

image.jpg

I haven't opened it up to see if they fit. It's going to be a minute before I get to

Re: NC50 clutch spring upgrade

Jack Rutherford /

Dredging because that harmonic balancer puller looks like it could pull all clutches from every year express.

Re: NC50 clutch spring upgrade

Why wouldn't you just try lightning the shoes?

Re: NC50 clutch spring upgrade

Jack Rutherford /

I just want an all purpose clutch puller.

Re: NC50 clutch spring upgrade

> Jack Rutherford Wrote:

> -------------------------------------------------------

> Dredging because that harmonic balancer puller looks like it could pull

> all clutches from every year express.

With the right bolts it would, or a steering wheel puller. You also might break the tool in all cases.

Re: NC50 clutch spring upgrade

Jason Majernik /

Reviving an old thread....

What springs would be an upgrade for a 1980 NC50? I’ve got mine apart and plan to lighten the shoes. Before I put it all back together, I’d appreciate any insight into the springs. I’d rather do this once, so I’d prefer to upgrade the the springs now if you all even think it’s necessary after lightening the shoes.

I’ve added a People’s pipe to a stock engine, cylinder and carb (this can be re-jetted) and Boysen reeds, but low end sucks. Would also like to add a 1 mm spacer with 2 gaskets at the cylinder base (have it, not installed yet), while milling off about 1.8 mm on the cylinder head, maybe more, depending on comp. Goal is higher top end with adequate or more low end on stock equipment sans exhaust. Air filter is also aftermarket.

Go with original or upgrade? If upgrade, what do you suggest?

Thanks!

Re: NC50 clutch spring upgrade

Jack Rutherford /
nc50.png

nc50 clutch spring length installed. gy6 clutch spring length is 32mm uninstalled. might be an option.

Re: NC50 clutch spring upgrade

Jack Rutherford /

Re: NC50 clutch spring upgrade

Jason Majernik /

Saw those on treats. I don’t understand what +1000, 1500 or 2000 means. I’m going to assume it’s a tension rating and +2000=least tension. Not exactly sure how to determine what would be best. Any ideas?

Re: NC50 clutch spring upgrade

Jason Majernik /

I’ll try those blue 35mm. Thanks, Jack!

Re: NC50 clutch spring upgrade

Jack Rutherford /

Numbers are the rpm where clutch engages with those springs.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account