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Old 04-17-2007, 01:03 PM   #1
losiu OP
wheelie addict
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Joined: Jan 2004
Location: POLAND
Oddometer: 577
LC4 640 starter clutch fix

First of all, I’d like to thank Beez who inspired me to do the work described below. Based on his description of the problem which he had posted on an e-starter thread, it sounded like the same problem I had been having:

Originally Posted by Beez
I had the starter clutch go on my '97 620. Kicked it for a couple of years before I finally got it fixed. I've heard this problem many times here and on KTMtalk so it seems to be a weak point on LC4s. If this is your problem the starter will turn fine but you will hear a loud, horrible KLaaccKK! KLaaccKK!
He also sent me an interesting PM in which he told me that, supposedly, the starter clutch could be fixed with the right sized spring from an O-ring seal.

Let’s get to work then !!

I am not a professional mechanic nor do I have the repair manual for LC4s. I did this based on my experience working on the LC4s I’ve had (and some luck).

The tools needed to do the work are very basic. There are two things that I can think of that are an absolute necessity to do the work right: beer and the flywheel puller.

The first one is probably readily available where you are. The puller might be a little harder to get. I was lucky because my buddy had one made for him when he was rebuilding his engine. He kindly lent it to me and I can tell you right now that if you don’t have this particular tool, it is probably impossible to do the work.

No.7 on the diagram below is the part you need to get to.

1.You have to unscrew the flywheel cover (with the stator inside) on the right.

It’s a good idea to find the TDC and then take out a bolt from the front of the engine to lock the crankshaft in place. In order to do that, you need to take off the thick washer that sits on this bolt, and screw the bolt back in. You might need to try a few times moving the crankshaft back and forth a little to hit the right spot. When the piston is in TDC, the bolt goes right in and locks the crankshaft in place.

2.You don’t have take anything else off at this point. I was doing it for the first time and to make sure I was doing the right thing, I took the e-starter out and basically, the whole right side of the engine (this is NOT necessary to do the repair). It’s at this stage that you’ll need the puller.

3.When the flywheel is off, you’ll notice another “wheel” attached to it with 6 screws. Again, I took it apart to take a closer look but it doesn’t need to be done to get to the faulty part.

If you turn the flywheel over, you’ll see this:

4.You need to use pliers to get the starter clutch out. It looks like a kind of bearing at first, but when it’s pulled out, it looks like this:

5. What you see above are irregular shaped metal blocks held in place within a metal ring by a spring. The spring was so loose that one of the metal blocks slid out of its place and looks like it's missing.
Put the whole thing flat on the table to take off the spring without losing the metal blocks. You also need to make sure that the blocks don’t turn in any way when you put the new spring back on.

6.You can see that this spring has seen better days.

7.This was the cause of the starter clutch “slipping”. The metal blocks couldn’t lock the crankshaft together with the free wheel which is spun by the starter engine. The slipping created the grating sound described earlier by Beez.

Here a problem occurred. Based on my information, the possibility of replacing the worn out spring with a spring taken from a large rubber O-ring seal was only a theory which proved to be a little trickier than expected.

8.All the springs pulled out of the rubber O-ring seals that were more or less the right size in diameter, were too thick to fit in the groove around the metal blocks. The spring has to kind of hide inside the groove and if it doesn’t, it won’t fit back in the engine. Basically it needs to be just the right size. I have no idea what diameter the original spring is when it’s new because mine was all stretched out. This element, the metal blocks and the spring, is sold as a whole unit and costs around $80. You can’t buy just the spring.

9.I got 3 rubber seals and measured the springs. The first one was clearly too thick.
Here's a pic of the one that was originally in the starter clutch:

This one turned out to be too thick:

10. I finally managed to get a seal made by a company called "ERIKS” whose measurements are 50 x 72 x 7.

The thickness was right but the diameter seemed a little small (50mm). I decided to put it in anyway because the old spring didn’t work at all and I really had nothing to lose by trying.

It worked fine and the starter works great with no weird grating or KLaaccKKing sounds.
From this point, everything is easy – put it all back together in reversed order and start your bike

Here's what my e-starter sounds like after the repair.
The engine was cold and I used no choke in order to let it work for a while.
Does it sound healthy or what ????

The total cost of the repair is probably around $15 ($2 for the rubber O-ring seal and $13 for the beer)

It's also worth mentioning that the work can probably be done within 2 hours if you have the right spring :)

Good luck :)

KTM 690 R - The new wheelie weapon
Husqvarna TE 250 - The little beast
Husqvarna 333R - The ...umm..... how do I put it....

losiu screwed with this post 04-18-2007 at 04:20 AM
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