LC4 640 starter clutch fix

[meat popsicle]

Originally Posted by warewolf

...

In other words, to go for a hoon means to take it for a thrash, preferably to bring it back with the discs blue & smoking, no rubber on the rear tyre and scrapes on the footpegs, stands, exhaust and fairing lowers. Say to the owner who's been hearing the exhaust wail echo off the surrounding countryside amid valve-bounce that "Yeah, goes orright mate, but a bit gutless in the top end."

...

Its got a good sound to it. I'll have to introduce the western US to it.

[jonz]

Originally Posted by dustjunkie

rapiti,

I just used a standard flywheel puller.



I had to get some really long 6mm bolts, in fact I got 6 really long 6mm bolts, cut the head off of three of them, and spliced them to the other three with a coupler nut, but in the end it worked great.

I talked with Dustjunkie and got the 6mm threaded rods from Ace Hardware. Those were too soft. I broke one off , bent some others, and pulled the threads off another. I finally gave up. Luckily, I live right and talked with a former KTM mechanic now working at the Honda dealer. He had the puller (in fact, a whole set) and loaned them to me.
I must be living right as it will only cost me a six'er of the new beer Miller Chill (said he wants to try it). Mechanical stuff sure is easier when you have the right tools.

BTW, the spring around the starter clutch was fubar'ed. I'd already bought a new starter clutch so that is in now. With a little welding on the fairing subframe, I may have a running 640 ADV by next week.

[warewolf]

Originally Posted by goatherder

SKF Seal # 19993.

Originally Posted by clintnz

I got the NZ$9 SKF seal as above

Arse. The local SKF shop didn't understand the above part number, fortunately I had the dimensions and he came up with a 50x72x10 in-stock so I grabbed it. He could get a x8 but reckoned the x7 wasn't listed. However he says the spring will be the same for all thicknesses.

Where are you at with yours, Clint?

[losiu]

Hey guys,

I just noticed a link to this thread on a different thread (thanks) and together with a PM I got a couple of weeks ago, where I was asked about the durability of the fix, I've decided to post a few words about it here.

Well... I keep hearing different things about the durability of the fix. I posted this thread right after I did mine. The bike has been starting like new ever since. No problems at all. I also used a weird O-ring seal, as it was the only one I could find locally. Knowing the right SKF seal number, I could easily get that one but... oh well... mine turned out to be totally great too.

Pawel, who also posted lots of pics on this thread had less luck but the metal blocks in his sprague clutch were supposedly much more worn out than mine. He ended up replacing the whole unit.

I say it's a good idea to do the fix when waiting for the original part is not an option. Also, when you have access to all the tools or the price of the whole unit seems high, this is a really cheap alternative.

As i said, it totally worked for me.
Any feedback from the ones who have done it as well ???

Losiu

[rapiti]

Hey, Losiu!

I cannot comment on the fix, as I bought a new assembly, but I kept my old sprague clutch and plan to retain it as backup once I source the seal. I do thank you for the thread, as it helped me diagnose the problem I had been living with.

I trust Summer riding season has put a smile on your face. Best to H.

Paolo

[Primo]

Hi!

I gave it a try.Unfortunatley due my own stupidity it didn't work as i assembled the starter clutch wrongly - i put the new spring in (which i took btw from my LC4's old fork seal as i've changed them to new ones) and it fit just perfect.
Then i tried to install the metal _??stopper ring??_ and i think, i did it wrong.
After putting all the things back together in the engine i gave it a spin.
Oh the horrible voices and inhumanity.
Worst thing was, i had to go to Germany the next day on that bike and it was evening already.
So i opened up the engine again and discovered not so good news.
The metal stopper ring came off and spring was cut in pieces and the little knuckles ing the s-clutch were all over the place.Fortunaltey none of them did not fall deeper into the engine.Then the cleaning began.After that, when i got all the pieces out, i re-assembled the s-clutch but it was ruined by the starter mechanism and starter sprockets.

"Ones misfortune is another's happiness" as they say - I remembered, that there's a guy i know, who had blown his 620 LC4 Duke engine block.Here the distances are small, and he was about 60 miles away and he had that s-clutch he was willing to give away.After 3 hours or so we were back at the garage with decent part.Quick install, quick test - all good - then quick oil change to wash away the rest of the blown spring and other metal pieces from the block.

So, i think if i had assembled all of the pieces correctly, it would work.
Old spring was quite a snake already if to be honest.

But still, thanks a lot, Losiu

[K2ride]

Did the job last week based on this thread.

The garter spring was in 3 parts, some of the excentric bearings were scorned with a few of them having bits broken off & stuck on the magnetised flywheel as well as part of one of the stator's ceramic caps broken off but the rest of the stuff in there was Ok.

I hand filed/sanded the excentric bearings back into reasonable shape, installed an SKF 19993 oil seal garter spring, lightly sanded the starter gear's contact point with the sprag clutch & sealed the stator's broken ceramic cap with a dab of epoxy.

Put the whole thing back together, crossed my fingers & went for the button &...... Bingo, the stator now works like a charm for $9 instead of $100!


About the damaged excentric bearings,

Some where badly scorned on the sides preventing free movement in the assembly & some where pinching the garter spring in their slots; a couple of hours of carefull hand work brought them back to a useful life ...to my surprise, I must say!

This ''restrictive movement'' of the assembly might be the cause of some of the unsuccessfull attempts at this repair & the garter spring certainly won't last for long if it's being pinch by some of the excentric bearings; carefull inspection & correction of each & every parts of the sprag clutch assembly should be done while replacing the garter spring & putting the whole thing back in the bike.

Also,
When installing the sprag clutch back into the flywheel, you need to push it in deep enough that it will kind of snap into place (Magnectic click, I think); it may look to be in deep enough but it might not be the case & could move out of the flywheel to do some major damage.


Btw,
I have access to my dealer's 640's flywheel flywheel puller &, with this tool, the garter spring replacement will be done as regular preventive maintenance from now on ...even if I, now, have my kicking technique down to an art form!

It's an easy fix & takes no more than 30 minutes to do so if the excentric bearings are intact!


You the Man, Losiu!
&
Thanks to all whom have added to this thread; do keep it up guys!

[clintnz]

Originally Posted by Primo

Oh the horrible voices and inhumanity.
Worst thing was, i had to go to Germany the next day on that bike and it was evening already.
So i opened up the engine again and discovered not so good news.
The metal stopper ring came off and spring was cut in pieces and the little knuckles ing the s-clutch were all over the place.

I think I made a similar mistake when I did mine, the circlip that holds the s-clutch in place in the hub on the flywheel can easily go in the wrong way - there are actually tiny slots in the tabs on the top of the s-clutch that the tabs on the circlip are supposed to go through. However the circlip also fits in the wrong way quite nicely with it's tabs going between the tabs on the s-clutch.

When I took mine off again the circlip had come out but luckily nothing had strayed far.

Cheers
Clint

[drtwiggy]

Originally Posted by gunnerbuck

Great post, but a word of caution: On LC-4 engines with the Kokusan 4K-2 ignition it is recomended to use a flywheel holding device rather than the crank locking screw to tighten the flywheel nut. The 120 LBS torque required could damage the crank web. It's ok to use on the LC4s that only require 44lbs torque on the flywheels.

I just ordered a 19993 seal from Rocket Seals and I am searching for a place to buy the fly wheel puller. Any suggestions?

How do I tell if I have the Kokusan or SEM ignotion? Seams like I could do some damage if I have the Kokusan. Mine is a 1997 lc4 egs-e.

Finally is it a good idea to get a replacemt gasket/o-ring (which is it?) for the fly wheel cover?

ciao.

[warewolf]

Originally Posted by gunnerbuck

On LC-4 engines with the Kokusan 4K-2 ignition it is recomended to use a flywheel holding device rather than the crank locking screw to tighten the flywheel nut. The 120 LBS torque required could damage the crank web. It's ok to use on the LC4s that only require 44lbs torque on the flywheels.

Alright, I attempted this job and got stumped: couldn't undo the flywheel nut.

My bike is an '05 EU/AU model. The book says 150Nm for the flywheel nut = 110 lb.ft. The crankshaft locking screw is listed with a torque value, but it only has a normal thickness washer. I tried using another 5mm longer M8 bolt, but it didn't engage with anything even when fully screwed in. The crank would still turn freely.

How do I know which variant of Kokusan ignition is fitted? The specs in my books don't say.

So, how the heck do I stop the crank from rotating? I tried putting the bike in gear and standing on the rear brake pedal, but it would slip with a fair pressure applied... I suspect that's the clutch slipping? Do I need a clutch holding tool? What's this flywheel holding you speak of, gb?

Toys <------------------> Cot

[jonz]

Originally Posted by warewolf

Alright, I attempted this job and got stumped: couldn't undo the flywheel nut.

My bike is an '05 EU/AU model. The book says 150Nm for the flywheel nut = 110 lb.ft. The crankshaft locking screw is listed with a torque value, but it only has a normal thickness washer. I tried using another 5mm longer M8 bolt, but it didn't engage with anything even when fully screwed in. The crank would still turn freely.

How do I know which variant of Kokusan ignition is fitted? The specs in my books don't say.

So, how the heck do I stop the crank from rotating? I tried putting the bike in gear and standing on the rear brake pedal, but it would slip with a fair pressure applied... I suspect that's the clutch slipping? Do I need a clutch holding tool? What's this flywheel holding you speak of, gb?

Toys <------------------> Cot

I used an impact gun and it came right off.

[losiu]

Hey everyone,

I'm about to answer my own question about the durability of the fix.
Today, my bike unexpectedly didn't start at the touch of the button. Instead, it made a series of sounds and noises described in the first post.

I'm sure the spring broke.
I'm debating whether to get a whole sprague clutch or do the cheap fix again.
Right now, I'm into doing the cheap fix as I'm not planning on taking the bike far away from where I live anytime soon. If I were to do that, I'd consider replacing the whole unit this time.

On the other hand, the spring from the O-ring seal lasted good 10.000kms with no problems at all.

Hmmmmm....

Losiu

[Seikkailu_R]

I choose different way.

And now both old and new starter clutch are waiting what to do.
(not enought time to find proper spring for old one and now waiting for magneto puller...)

After just a few days of practicing LC4 is quite easy to kickstart
Two months, driving daily, and no problems.

Bike feels so light now
Is there more heavy parts that i dont need?

[pkrasko]

Hey does anyone know the part number for the flywheel extractor?

I think this one should do the trick. It's by MAC Tools and cost 1/3 of the price as the one from KTM.

http://www.mactools.com/Mac/Mac+Prod...ther/MN08-0293

[dancolin]

the puller i used didnt look anything like that.. was the big kind so not sure if that would work..

anyone have a US part number or source for the seal? would it be something a Napa or simular auto parts store would carry?