KLX 250 roller bearing head

[cloggy]

 All my UK KLX and KL heads have tacho drive. Even the one  that didn't have the driven worm had the worm drive on the end of the cam
 As for the whole lot coming out with a tug, none have so far. I've taken the seal off the centre; it seems just to be a fibre spacer for the cable outer to abutt against. Derail talks of replacing the worm drive with a blank plug. I had assumed that this was due to the worm drive sucking/pumping the oil in the opposite direction, not that ultimately it could go anywhere or fill up much of an empty space. I'm wondering if all this is a bit of a myth, that perhaps plugging an empty chamber somehow got confused in countries/models that had tacho drive with removing the tacho drive and replacing with a static plug. I've  rechecked my 1979 USA parts book and found the end plug; doh.
I've looked at parts fiches for the Z250 and the ally collar is quite complex as it is also a sleeve for the worm drive. I'll look at the running bike and try to see how far the threads go down, assuming I can get the plug out, but at present I'm not convinced there's much benefit replacing it.

[grouty]

Trust me ..... I took Derail's advice a couple of years ago and made a plug to fit the chamber. It works perfectly. The plug stops the oil filling the chamber and re-directs it to where it's needed. Down the cam ! The only issue I had was a tapping noise when the engine was started. This was down to the pulsing from the oil pump causing the plug to move slightly back and forth. I cured this with a couple of o-rings under the plug to push the plug against it's stop. I only ground enough off the teeth on the cam worm to clear the plug.
I have thrashed the daylights out of the motor since doing this, and found no wear on the (outer) large cam journal. A good move !

[cloggy]

 Yeh my other bike now has the plug but this has the tacho drive and  there's very little space in there for the oil to pool since the tacho drive gubbins fills up the space. Since one has to cut off the end of the cam to make the plug work I'm not at all sure the available empty volume is very much different. Might check my running bike tomorrow and take a look at the cam drive.
 I know that leaving the drive worm et all in there is not going to guarantee the safety of my journals as one of my heads is already knackered.
 A local had a KLX back in the day and he had two heads under warranty in the first six months. I talked to Amsoil when I got oil for my DRs and they said go thinner if you have oiling issues on plain heads. The 0-40 they sell isn't far off water cold, perhaps that's what 0 signifies, anyway the oil is sold to be used for  a lot of cold starts where normal oil gets too thick on morning start ups. They did say thicker oil has ultimately better antiseize characteristics but that's not much good if it doesn't get there in time.

[cloggy]

 I used a heat gun for nearly an hour on a knackered head
 It finally came out [been bonded in at the factory]
Looking at the design there is no earthly reason to replace it with the plug. There is a very small splash lubricated shaft that has a drain into the sump via a headbolt gallery but the amount of oil that can escape this way is infinitesimal. The amount of space taken up by the drive and driven components is greater than that with the aftermarket plug, combined with the cam worm drive removed of necessity. So I'm leaving it as is and concluding that the plug was originally intended to replace an empty chamber as my other bike. Unfortunately this means that I have no easy way to increase the oil capacity to the journals.
 

[cloggy]

 I've built up the roller head with a new cam The roller head cam sprocket has a single long shaft 14mm bolt and a composite washer  connecting it to the cam. Has anyone any idea what the torque setting is?
The head is common to the KLT three wheeler, the late KL, and the KZ road bike; and also  more recently the quad.

[grouty]

Out of interest, what does the composite washer do ?
Is the bolt 14mm A/F or 14mm dia thread. The general tightening torques given in the KLX manual would probably apply to the thread o.d. and pitch. Except if the composite washer is squeezed between !

[cloggy]

 It appears to be a composite washer with a very thin rubber sandwich. However as it's bolted up to about 20ft lbs I'm not going to disassemble to check. I would imagine it's there to isolate the bolt head slightly from shock forces, but I know nothing. It takes a 14mm socket, though I would say the shaft is a larger diameter than the head studs which take the same socket

[farmer58za]

Hi All
I'm really a two stroke fan but today, my mind's firing every 2nd revolution 

2 questions:

1] Is the cam journal bearing wear a weak point on the KLX?

2] Grouty, you mentioned a Megacycle roller bearing conversion. Are they worthwhile?

http://www.megacyclecams.com/catalog/Page41.pdf

Regards
David

Does it just have a roller bearing on the cam chain side, and a plain (in the alloy) one on t'other ?
If it does, then that will be the later C model if it is a KLX motor. Good old Kawasaki finally woke up the the shortcomings of the original set up.
As far as I am aware the cams are the same. Not sure if the head is from a KL or KLT.

If it has bearings both ends of the cam, it is possibly a Megacycle conversion.

Have you got your KLX up and running yet ?

[cloggy]

 YES!
A local guy got through three heads in one summer, but then I've had old engines that are fine.
I guess it's how they are warmed up on starting
 The oil goes in one end of the cam from the small journal and feeds two rocker pads and then the big load bearing plain journal on the cam chain side. The further it travels the less oil there seems to be.
 Even Kawasaki seemed to know there was a problem. If you read their oil change intervals, very very short for a converted roadster engine.

[grouty]

Cloggy is right !
The early heads were the worst for contact patch area on the cam chain side. They became bigger in 1980. This helped a little, but did not stop the mound of scrap heads piling up at the dealers.
Frequent oil changes as Cloggy said, plus the need to ensure there is plenty of oil in there to start with.
The head on mine went west in 1983. I had'nt done that many miles, but I guess maybe a low oil level and not warming it up properly did the trick.
The later genuine roller bearing heads from Kawasaki cured the problem. You can find these on the 82/83 KL250's and the "rare as hens teeth" KLX250 C1
The Megacycle cam is good. Has needle roller bearings both ends too.