the kinetic tfr project

A while ago, I installed a Malossi 70cc kit on a tfr. This is not the TFR that I ride on the street or the one that I have insurance for. It is for off road use only.

Anyway, It was a while ago. About 100 miles and 6 weeks ago that is. It is a great kit. I had ordered it from 50cc.nl (part number 14103). It cost 101 Euros ($139) plus a million dollars for shipping and handling. I kid - it was $68 for shipping. This is what was included in the kit:

Cylinder, Head, piston, 2 rings, 2 gaskets, wrist pin (bushing), and 2 c-clips
You can see photos of it when it arrived here >>
If you do get one, make sure you are very careful to unpack it gently. I have read about several people who break the rings when they take it out of the package (the piston ships in the cylinder).

When I went to install the kit, it came at an opportune time because the engine on that kinetic had stopped working. I didn’t know what was wrong with it, but I came to discover that the head nuts had come loose and I was losing compression out of the head gasket. It had opened up so wide that it blew part of the old gasket out to the side and ripped it. Even the aluminum one was wrecked. So it was great that Malossi included new ones in this kit.

Here is what I did to install the kit in instructional format. Remember, kids, I may or may not know what I am doing.

1. Remove your engine.
This is not absolutely necessary. You can install the kit by removing the rear shocks, folding the subframe so the engine is far enough away from the frame that you can unscrew the metal plate that protects your cables from melting on the head. Once you get that off, you can remove the head and cylinder when it is still on the bike. Some people like to work this way. I don’t. I would prefer to work on a table.

When I removed my stock engine, it looked like this:


2. Remove the old head, piston, and cylinder.
There are three nuts that hold the whole thing together at the top of the head.

Depending on your exhaust setup (since some exhaust mounts use the bolts) there may be some extra nuts down there. Unscrew them all and take the spark plug out if you got a new head with your kit.

Remove the decompression valve by pulling out the cotter pin (if you need to - depending on your setup, you may not need to do this. Avoid if unnecessary). Make sure you don’t let the spring on the valve shoot off - remember that it’s spring loaded. Here is a diagram that I made from another post of the decompression valve:

You can remove the valve spring now, or you can wait until you take the head off. if you remove it now, you will have to be careful not to let the actual valve slide through into the chamber. It can go all the way in and get lost down there.
With everyghing (except the valve) removed from the head, it looks like this:

Slide the head up and off of the connecting bolts.

Slowly and carefully slide the cylinder off of the connecting rods. watch the gasket closely. it is made out of a crumbly paper and will break and tear. A piece of mine chipped off and fell into the crankcase and I had a hard time fishing it out with some tweezers.

3. Remove the piston
There are 2 c-clips that hold the wrist pin in. It is a bushing and you have to remove the clips and push it out one side. I had no idea how i was going to do this. I ended up taking a small socket and using it as a punch to get the pin out. I took an adjustable wrench and just pushed the thing out. In the photo I am just holding it to show how it was done. When I actually did it, i used a rag so i wouldn’t damage the piston with the wrench.

My piston had some carbon on it already:

Here is the inside of the case:

4. Put the new piston on
I just reversed the directions on the removal. I put the pin on the same way that I took it off. Wrench and socket. It went on pretty easy. I also used the stock c-clips even though the kit came with some new ones. The older ones looked like they covered more area and I figured that the turned in ends on the clips would hold the pin in better (see photo).

5. Put the sleeve back on
Slide the paper gasket on to the crank case. This is a little tricky and should be done with some care. There are threads that can catch on the paper gasket and tear it.

Slide the sleeve over the pistons and bolts. The trick here is to get the rings on the piston to slide into the sleeve. First, smear the inside of the sleeve with 2-stroke oil. This is pretty important. You will need to align the breaks in the piston rings with the tiny, corresponding notches that stick out of the piston. Again this is VERY IMPORTANT. You can find the notches by spinning the rings and watching what is going on on the piston in the gap. I was able to easily slide one ring in at a time because the sleeve has a bit of a taper that makes it slide in and compress the rings correctly at the same time. So, I squeezed the piston ring to compress it with my fingers as mush as I could and slid the sleve down on it slowly. I think the second one took a little doing, but went inside after a few tries.

Make sure the piston slides in and out without catching on anything.

6. Re-assemble the head
Put the head back together and back on. Getting the decompression valve right is the trickiest part here. I suggest You get the valve on (with spring and lever) before you put the head on. If not it is possible to drop the valve stem into the chamber (and possibly through a valve and into the crankcase). You will have to take everything appart to pull it out again if this happens. You will need to be handy with a pair of needle nose pliers to get all the parts of the valve back in if you took it apart. One has to hold the spring while the other puts the cotter key back in. Test to make sure that it is opening and closing properly.

7. Re-jet your carb
That’s pretty much it. You will need to rejet your carb to get your mix right. Here is what I recommend for the mix with a dellorto 13.13 carb and a proma circuit exhaust: I broke this kit in on a 62 jet and it seized up on me (overheated) when I opened it up after keeping it under 30 for the first 100 miles. So I would recommend breaking it in with a 64 or 65 jet.

Also, this kit eats a LOT more gas than the stock setup, so don’t forget to fuel up. I ran out of gas and couldn’t figure out what was going on. It took me a second to realize (to my disbelief) that had already burned through a full tank of gas.

8. Break in your kit
This is the only downer with getting a kit. You will have to exude some self control and put about 100 miles on it before you should see what it can do. I highly recommend referring to Smitty’s (from smc custom mopeds) break-in procedure. He is a professional and has done this a lot.