Honda-SOHC

My experience is that moving from motorcycle oil to car oil isn't really that much of a problem.  Moving from mineral to synthetic, however, is more problematic.

Having said that, the problem isn't lubrication; K2's right - it's all about clutch slip potential.  As far as I can tell, the best way to care for the engine is to decide early on in the life of the bike what type of oil you're going to use - car, bike, mineral, semi-synth and so on.  Once you've decided, stick with the same type, remembering the frequency of oil changes will be infinitely more important than which particular type oil you chose.  Like K2, I tend to use car oil on the older bikes but for financial reasons; I change the oil far more regularly in my old bikes than I do in the modern ones (every 1,000-1,500 miles or so as opposed to every 3,000 odd) and if I was keeping to that sort of schedule exclusively with bike oil, I'd be bankrupt by now.  I don't race, and don't put the bikes under any unusual loads, so that suits me fine.
 
If you decide to switch between oils, I've found the best way to reduce/minimise/eliminate clutch problems is to strip out the clutch when you switch and either replace the fibre plates (not cheap) and/or clean all the plates with thinners and let them dry.  In both cases, soak the plates in the new style oil before putting them back into the pack.  At least that way you've got more of a chance of them responding properly when you flush the engine with new oil.

The fun thing about oil is that you'll find pages and pages of stuff of the interweb, either in articles or across forums, and as many different opinions as there are drivers . . .

If you decide you want to start digging around inside the engine (and save yourself a few quid), you could do worse than the primary chain tensioner mod about halfway down this thread.  I doubt you'll be able to do it without splitting the cases.

I did it when I put new chains in mine, and the engine now seems quieter than before, but then I also changed all of the bearings in the engine, so I'd bloody well hope it was quiet . . .  

As for oil, the shop manual for the 750K series said 10w40 should be used in the forks - that should tell you all you need to know.  Just bear in mind that when these engines were made, oil was oil - it didn't come cut with detergents and all sorts of additives - and those that were looked after have lasted pretty well.

2 hours - that's how long it's taken me to get the engine down to the crankcases and tidy the garage.  Not bad, huh?

Looking at the areas where the leak was emanating from, it seems to be attributable to one of a couple of things - the favourites are a poor seal around the thin strip of gasket covering the case near the front of the cam chain guide, or something due south of the up oilways (round the rear cylinder studs) from the crankcase.  The surfaces are completely flat, so it's not warp or scarring, but I can't remember if I used new o-rings around the oilway studs.  Having said that, if they weren't sealing, I would have thought any leakage would have taken the much shorter route to air - i.e. go out from the cylinders backwards and onto the top of the crankcases.  There was also nothing particularly unusual about the o-rings around the cylinder bases.  Whatever, it shouldn't be a particularly tricky fix.

I'll let the faces a while to dry out, and run them over with thinners before putting everything back.  I'll also pull the valves, check the guides, clean up the seats, gently re-lap the faces and put on new seals.  I already kinda live by Brian's earlier maxim of never throwing anything away, and numerous engine gasket kits have provided me with more than enough spares.  'll also clean the cylinder bases and reseat the larger o-rings before reassembly.

Suffice it to say I've got the bit between my teeth.  The problems I've got are ones that I understand and can fix, so it's just a matter of getting on and doing it.  I find it's easier to be motivated by this kind of situation than be down about it, 'cos I'm pretty sure it just needs a bit more twiddling to get it perfect.  And by perfect I mean oil tight and running without smoke.  Talking of which, pistons 1 and 2 had some carbon deposits on the tops, but 3 and 4 (remember 4 was smoking a bit) were pretty much clean as a whistle.  Dunno what - if anything - that means.

Tired now.  Busy day.

Hmmm.  I spoke a little too soon.

There's good news - jetwashed the engine and it turns out the stuff on the upper fins was just residual oil from the headwork that had dried and then solidified when it heated up.  There's no leaks from the top end.

However, the not-so-good news is that the joint where the barrels meet the crankcase at the front of the engine (i.e. around the base gasket) leaks.  Quite a lot.  I'm sure I had this happen before when a shop put the engine back together.  That time one of the rubber rings that goes round the base of the individual cylinders had been poked up too high into its recess, causing the leak and the oil pressure warning light came on.  This could be the same deal (without the oil pressure light) - or it's the areas where the surplus oil drains back into the crankcase from up in the head.  Either way, it's all got to come apart again (take head and barrels off).  Arse it.  Oh well, I'm getting used to it now.

There's also white exhaust coming out of 3 and 4.  They're the same end where the camshaft lunched itself, but I have a feeling they're exhaust leaks (the joints from the headers to the head aren't exactly wonderful).  It also wouldn't surprise me if the valve seals had hardened with overheating and now leak a bit.  Guess I'll have a look see while I'm in there - again.  

Thanks chaps - and special tip o' the hat to KC for the 2-stroke oil warning notes.

Having had a sit-down-and-keep-it-together session, I set to pulling the top end apart to try to trace the blockage.  Much to my surprise, it wasn't the jet - that turned out to be fine.  With the head off, I cranked the kickstart to pump oil through the oil passageways and found that there was nothing coming up the RHS cylinder stud that feeds the head.  Barrels off too - and they're fine in case you were wondering - and stud out, and the blockage turned out to be something (I'm still not entirely sure what) in the crankcase jet that feeds into the RHS stud gap.  
 
Spiked that hole with a long, thin pokey stick and something gave - I'm damn sure I did that to both sides before I started reassembly, but obviously not hard enough - and cranking the kickstart pushed equal amounts of oil through both L and R feed holes.  I pumped some cc's though just to make sure it wasn't going to jam up again, and then took the RHS oil gallery cap off so I could have a look along the length of the engine.  Nothing obviously amiss there, but just to be sure I made a cleaning out stick from of a long piece of thin threaded rod with a nut on the end, and covered the nut with a small piece of cloth (I needed something that was just wide enough to feed in without touching the sides and pull out again whilst resting on one side to pick up any junk).  

Again, nothing too sinister there, so I'm kinda concluding the blockage was a couple of beads of vapour blast media that had stuck together and wouldn't shift; the sharp poke broke the surface tension between them and they fell apart.  The gallery was shiny and empty after the rod cleaning, so once the new head turns up, I'll clean and modify the towers, and mount them without any other cam train parts.  I'll then use the kickstart again to make sure the oil flow is fine.  The only other things I needed for reassembly were a new base gasket, some of the round rubber pucks that go under the cam towers and the teeny-tiny o-rings that go round the jets and blanking holes at each end of the towers.  Having rebuilt the engine three times now (don't ask), I had spares knocking about.

Rockers and rocker arms have been polished and I now can't really tell the difference between the ones that were on the RHS and the ones on the LHS - thank God for hardened faces/rods. Looks like the only real damage was to the cam shaft journal and the RHS tower, probably 'cos I ran it for such a short time.  Yeah - it could have been much worse (Pete - the same self-removing cam sprocket bolt trouble as yours caused this most recent rebuild; mine cut into the rocker cover and sent metal bits all through the engine . . .).

And I cannot begin to explain just how much time, effort and pain the removable frame section has saved.  The ability to remove the top end with the engine in the frame meant that I could pull off some bits, diagnose the trouble, put most of the bits back on, all without having to disassemble half the bike (or scratch the frame in the process.  Equally, I can test the oil feed with the kickstart, pump and tank in place; that'd've been a hell of a job out of the frame.  Right now, the bike is 95% complete - I only need to add the head components and rocker cover and we're off again.  Without any fear of contradiction, that frame mod kit has already more than paid for itself.

Not bad, huh?  Didn't exactly turn out nice again, but this time it's much easier than I thought it would be . . .

Ah - OK.  Don't want to fry the generator, so I'll work out what to do with the wiring later.

I'm pleased to say the neutral switch turned out to be a simple fix - I'd put the little locating plate in upside down.  Turned it over, did up the bolt and it pushed the switch further into the mount - which meant that when the drum turned, the ball bearing was depressed far enough to switch the neutral light off.

I'm less pleased to say that whilst trying to get the engine set up yesterday - carb balancing and so on to try and cut the clutch rattle down - it got very hot and started squeaking.  Couldn't locate the source of the squeak, and pulled the plugs to make sure it hadn't overheated and/or reduce the danger of it seizing.  The engine's undergone a rebore, new gaskets and seals and heavy duty studs, new bearings throughout (plain and ball), new chains, camshaft, valves and all sorts.  I also had some 2 stroke oil in the petrol to give the pistons an easy-ish time.  And I know from using the kickstart it's got great compression.

So anyways, I had too much oil in the engine - following Hondaman's guidance, I'd filled the oil pump before fitting it and that (in part) threw off my filling calculations.  I'm hoping the squeak - and the quick heating up - was caused by oil overfill increasing the crankcase pressures and maybe oil squeaking up past one of the pistons.  One of the spark plugs looked more oil-fouled than the others, and since the valve guides and seals were all replaced, that could explain what was going on there.  I don't s'pose it helps that I was working on the bike in a sheltered (read warm-ish) garage with little airflow, which wouldn't aid cooling at all.  But at least I know oil was getting up into the head - taking two valve caps off it was spitting out.

After draining some oil off, I've run the bike briefly this morning, and it seems to be OK.  It's not MOT'd yet, so I can't take it out and ride it around, but I'm hoping to get that rectified later this week.  I'm just praying the squeak isn't something more serious - I've just had to overhaul the top end of my 450 because a shop I'd asked to set it up moved 2 of the rocker adjusters too far and the shafts have been running eccentrically in their journal holders.  The really worrying thing for me is that the giveaway was that it was squeaking, too . . .

Hoping for some good news.

Guys

I'm putting the finishing touches to my K2 rebuild and I'm at the point of fitting the headlight, but I've run into a few snags with the wiring - mainly that I've got more spare unconnected wires than there seems to be space/need for.  I'm getting my head round it slowly, but was wondering if anyone else has added one of the left hand mount plastic high beam switches to a K2, and if so, what changes needed to be made to the connections?

Coming out of the RHS switchgear, I've now got the following connectors:

Red/yellow - connect to starter circuit
Black - connect to cut out circuit
Black/white - connects to cut out circuit
Black - connects to lighting circuit
Brown/white - connects to instrument light circuit
Blue - high beam circuit
White - main beam circuit

Yellow?
White/Yellow?

All the diagrams I've seen say there should be 7/8 wires out of the RHS - can't quite understand why I've got 9.

From the high beam switch:

Brown with blue stripe
Black

I have a feeling I may need to undo a few of the existing connections and reroute them, but like I say, I'm struggling a bit.  Any advice as to what needs to go where would be great.  Oh BTW - I've tested all the other circuits and they work fine (brake lights, tail light, indicators, horn, neutral switch, oil pressure switch).  I 'spose that's what's referred to as a good start . . .

And something else that has just occurred to me - the bike is a European spec K2, which means it has a sidelight (for want of a better word). The lights should, therefore, have four positions - off, sidelight, headlight and high beam.  Unfortunately, I don't think this is going to be an easy job - with the K2 switchgear, there doesn't seem to be any way to have the main beam and full beam on at the same time - it's one or the other.  Guess that's why occasionally everything used to go dark when switching between the two.

Storage - yes.  Moving about - no.

I use the centre stand for the rear end and like Matt, I've got one of these for the front end.  The pin fits into the headstock allowing you to build the front end and fit the wheel (assuming the yokes are in place).  Took me all of five minutes to get my 750 K2 frame off the floor and onto those two.

If you haven't got (or got room for) a hydraulic table, get a trolley and drop the bike onto it when you need to move.