Topic: Oh Oh !!!!!!!!!!!!

[HondaMan]

So with brew and tools in hand,not at the same time mind you,I started pulling the head off my K2.
Everything a piece of cake until I started pushing the rocker arm shafts out....both shafts on the right side(kick side) are broken right at the waist...what the hell...fade to long sip of nectar and scratching of head...how can both shafts be broken?
Made a mental note to go to SOHC forum and cry, and continued to dis-assemble the head,all bolts are out and am letting it sit before pulling it off..I'm afraid of what I'll find.Has anyone else found their rocker shafts broken ?

Mr. B;

This is caused by someone overrevving and floating the valves enough that the pistons hit them. The shock often snaps the rocker shafts at the wasp-waist point.

Those rockers on that side may be bent: one clue is to see if the adjusters are extended further than the ones on the other half of the engine to get the required valve clearances. If so, replace those rockers.

Check the holes where the rocker shafts pass thru the housings; make sure the holes are round and no cracks are there. These units are really quite stout and can take some serious beatings without further damage.

If you're looking for HP, DON't sub in Honda's later-model shafts: these have little bolt holes midway between the rockers (and the K4-later units have little bolts to hold them still). These later shafts do not spin, and this costs about 1/2 HP in the top end, from friction. If you're not so concerned about losing the power, go ahead and put in some newer units (the K0-K2 parts are not available today) and you will find they quiet the top end a bit (which is how this change came to be...).

[mattcb350f]

Oh oh, the old renovation project in the way again.. Good to here the pistons are coming out though. I wondered about that add, it was up for about three weeks and it said something like " frame and forks, best offer. engine.".  I was hoping maybe the order was mixed up and he actually had an engine. 

Oh well, winters a comin' ...snow in kapuskasing already, better get er' in the basement

 Matt.

[beelsamin]

Thanks Hondaman,these kinds of advice are really handy when working on an engine that you aren't familiar with,I joined this site after a friend said how much help and assistance he received here.With what I've heard so far it looks to me that I'll be pulling the motor completely apart. It'll take me awhile,but I'm sure it will be worth it.

[Terry in Australia]

If you're looking for HP, DON't sub in Honda's later-model shafts: these have little bolt holes midway between the rockers (and the K4-later units have little bolts to hold them still). These later shafts do not spin, and this costs about 1/2 HP in the top end, from friction. If you're not so concerned about losing the power, go ahead and put in some newer units (the K0-K2 parts are not available today) and you will find they quiet the top end a bit (which is how this change came to be...).

G'Day Mark, seeing how the later shafts have those two 5mm threaded holes to locate them in the cam towers, but there's still a 6mm bolt in the centre to stop them coming out of the cam towers, can you just not install the two 5mm screws if you've got later shafts? Cheers, Terry.  

[HondaMan]

Thanks Hondaman,these kinds of advice are really handy when working on an engine that you aren't familiar with,I joined this site after a friend said how much help and assistance he received here.With what I've heard so far it looks to me that I'll be pulling the motor completely apart. It'll take me awhile,but I'm sure it will be worth it.

I've always thought so...got a soft spot for the K2, myself.   

If you're looking for HP, DON't sub in Honda's later-model shafts: these have little bolt holes midway between the rockers (and the K4-later units have little bolts to hold them still). These later shafts do not spin, and this costs about 1/2 HP in the top end, from friction. If you're not so concerned about losing the power, go ahead and put in some newer units (the K0-K2 parts are not available today) and you will find they quiet the top end a bit (which is how this change came to be...).

G'Day Mark, seeing how the later shafts have those two 5mm threaded holes to locate them in the cam towers, but there's still a 6mm bolt in the centre to stop them coming out of the cam towers, can you just not install the two 5mm screws if you've got later shafts? Cheers, Terry.  

Sort of like that...I think the earlier shafts were considerably harder, though. They would polish the aluminum bores after they spun awhile, you can see that difference if you have the two types side-by side. The later shafts will fit like you say, but I would bevel the edges of the little threaded holes first, so they don't spin up some free aluminum shavings, just in case. In any case, the free-spinning ones last much. much longer: mine show only .001" clearance after 120k+ miles, while the two K4 engine parts I have, with less than 27K on either, show .004" one-sided wear on the exhaust side shafts and almost that much on the intake sides. I should probably take the 2 different shafts down to a Rockwell tester to see how hardened (or not) they are...