'92 140,000Km rebuild.

[racerrad8]

So I think I may have found a "potential" cause for the issues that made me pull the motor..  


If it had a mate sitting there next to it, I bet when I pulled the sparkplug and put the next one in, at least one of those stones might have fallen in. The miss and oil leak started after I had pulled the carbs and I naturally initially thought I'd done something wrong in the carbs.

I wonder if when I get the head off I'll see damage from a stone bouncing around in there.

I use compressed air to blow out all of the debris before pulling the plugs, heck I do it before pull the valve cover as well. Just for the reason, rocks, dirt & bugs are down in the head after removing the side scoops.

Randy - RPM

[tmkaos]

I never even thought that that much debris would get up there but on closer inspection there was all kinds of crap in the fins, 3 ciggy butts, a small nut and washer, stones, a etemologists (bug lover? spelling?) wet dreams with all the various NZ flying insects, some dried grass and feathers. I guess those scoops do an admirable job of delivering air, and whatever maybe floating in it, to the heads. I do distinctly remember occasions where when lane-feeding, drivers or passengers would flick their butts out the windows just as I passed, and a couple of times I've thought "That one's got me"..

[andyb]

And once it's clean and the plugs are out, you cover the damned holes by whatever means before do much as blinking rapidly above.

That's how you avoid learning that the screws for the throttle linkage fit down those plug holes, and subsequently how to r/r the head to remove a screw from the chamber.

(In fairness, I had to retime the cams and found some power, as the slotted sprockets were either set improperly or there had been some camchain stretch in under 10k miles.)

[Pat Conlon]

  Wise advice Andy. Gary Mastro (Gazza) had that same accident. A screw from his throttle cable splitter dropped down into his engine via a open spark plug hole. He tried everything to get that little bastard out, ended up having to pull the head.

[racerman_27410]

  Wise advice Andy. Gary Mastro (Gazza) had that same accident. A screw from his throttle cable splitter dropped down into his engine via a open spark plug hole. He tried everything to get that little bastard out, ended up having to pull the head.

Speaking of Gary have you heard from him lately Pat?   My contact email for him is no longer working.


KOokaloo!


Frank

[Pat Conlon]

Pm sent

[Harvy]

  Wise advice Andy. Gary Mastro (Gazza) had that same accident. A screw from his throttle cable splitter dropped down into his engine via a open spark plug hole. He tried everything to get that little bastard out, ended up having to pull the head.

Speaking of Gary have you heard from him lately Pat?   My contact email for him is no longer working.


KOokaloo!


Frank

Frank..... I just google talked Gary that you are looking to say hi.

Harvy

[tmkaos]

So some more progress.. One step forward and one back though I think..

Started on removing the head in earnest, checked the valve clearances, removed the cam tensioner, tip wasn't too badly worn so I reckon it'll be ok to go back in. Removed the cams, and I was a little gutted to notice that 3 of the cam bearing journals are quite badly scored. You can see the 2 lines here just on the oil hole and to the left of it. Sorry for the shit cell phone picture.


This is the worst one, I reckon that the scores are about .1 or .2 deep, both in the head and the caps and the cam bearing surface. There's no money for new cams let alone whatever needs doing to the heads to repair them if they are repairable, I'd imagine welding and re-boring the holes is a nightmare. So I will engage my best toolmaking skills and smooth off the burrs raised on the edge of the scores on both the cams and the recess in the head and bearing caps. We'll call them extra oil grooves. 

I pulled out the shims, and I reckon they are factory, they are nearly all the same, mainly 2.800's with a smattering of 2.750's and 2.700's. Clearances weren't too bad but some of them are out.
                Intake       Exhaust
Cylinder 1  .13 .16       .19 .20
Cylinder 2  .13 .11       .18 .18
Cylinder 3  .15 .13       .16 .19
Cylinder 4  .13 .15       .16 .16

The shim calculator spreadsheet is pretty cool, as found in the files section so cheers FJMonkey for that.

So tomorrow at work I'll clean up the cams and check them over for warpage. Wonder if I can slot the cam gears myself - AndyB you might be the one to ask about this.. What do you reckon? I can work out the PCD of the bolt holes easily enough, and do a program on my CNC to slot them. Hmmm.. Got to squeeze some more of those factory horses back in there somehow.


James

[ribbert]

So some more progress.. One step forward and one back though I think..

. Removed the cams, and I was a little gutted to notice that 3 of the cam bearing journals are quite badly scored. You can see the 2 lines here just on the oil hole and to the left of it. Sorry for the shit cell phone picture.

From the shit cell phone photo, I wouldn't be too fussed about the scoring.

I fitted slotted cam sprockets at 90k because I couldn't line up the timing marks properly and was surprised at the difference it made.  Well worth doing.

Noel

[racerrad8]

So I will engage my best toolmaking skills and smooth off the burrs raised on the edge of the scores on both the cams and the recess in the head and bearing caps. We'll call them extra oil grooves.  

James

James, as you have already mentioned...polish the journal & cam and let it run. That is minor compared to a lot of the stuff I have seen.

Randy - RPM

[tmkaos]

So I got the head off this morning before work..  Holy cow it was stuck on there good.. There is a plastic surround around some of the studs holding the head on, this had all cracked and perished and was jammed inside the head, holding it tightly onto the barrels. I had to lever the head off using the wooden handle of my ball-pein hammer the whole length of the studs. The 2 studs around #3 were the worst, they are also quite badly corroded.

So some good news.. on initial brief inspection the bore on #3 looks ok, it might still be an oil control ring that has gone on me but if it was a compression ring I'd expect to see damage.

The combustion chambers and piston tops are in quite badly covered with carbon build up.

I found something interesting on the underside of the head, someone has ground a number and letter combo into the head using a dremel or engraving tool. It reads "1 J 90"


Does this mean anything to anyone? looks like maybe the block has the same number hand-written into too, I'll confirm that this avo.. Maybe a workshop job number?

[tmkaos]

God I love Autosol..  If only the rest of the bike was this easy to fix!! 

[FeralJuggernaut]

I'm not sure...  but I recall reading someplace that they put numbers/codes on the case that relates to the bearings on the crank.   I thought it was on the next level down from your photo, but it may not be a hard and fast rule.   again, just a guess... 

[tmkaos]

I'm not sure...  but I recall reading someplace that they put numbers/codes on the case that relates to the bearings on the crank.   I thought it was on the next level down from your photo, but it may not be a hard and fast rule.   again, just a guess... 

I was reading up that last night, thanks to Pat Conlon I believe in the files section, and they did but the numbers I've got don't refer to that. Strange. i reckon it's just a workshop job number so they could keep track of which bit went together. It's handwritten, not stamped like the factory would do.

Anyway, leaps and bounds tonight.


Started from this, pulled the rear cam chain tensioner guide out, very little wear so that's good. Removed the engine mount collars, one was free, one was seized so hopefullly it'l be a bit smoother afterwards. They look pretty nasty.. should clean up ok. I've been dropping the steel parts into the ultrasonic cleaner and they've been coming up mint.


I had a closer look down the bores.. and bugger it, #3 is scored very slightly. I think I can get away with a re-hone, and new rings. I'll take the barrels into the guy who used to build our race motors, it's been a few years but hopefully he'll give me mates rates.


So the motor is pretty filthy, lots of corrosion and crap everywhere, but cleanish on the inside, which is what you really want I guess.


There's so much shit gone into the sump I'll have to take it off and clean the whole thing out from that side too. I was trying at the beginning to keep it all out but it was unavoidable and I just gave up once I realised that the barrels had to come off.

A couple of the dowels that hold the head and barrels on are rusted right out. One of them is seized into the head and I'm going to have to machine it out.

The studs are pretty far gone with rust and like I said, the plastic coating on them has just shattered and gone everywhere, I think these studs might need replacing - what do you guys reckon?

The pistons look ok, there is a tiny amount of scoring on the top 3-4mm of 3 out of 4 of them, but I reckon I can clean this up, and with new rings I think they'll be ok.

Barrel is going into work to check bore sizes and tolerances.

Started cleaning up the head today at work, I'll check it for flatness and de-carbon the combustion chamber before I pull out the valves and check all the guides. Had trouble finding a set of V-blocks small enough to set the cams up on to check run-out. I did manage to clean up the bearing surfaces though on the cams, haven't done the heads or bearing caps yet.

Fingers crossed everything else is ok..

James

[fj11.5]

God I love Autosol..  If only the rest of the bike was this easy to fix!! 

, looks great, is it still original coated or cleaned bare alloy,, I've had good luck using cleaners with a cloth wound around my dremel saves a lot of work