The 96mm head and base gaskets eventually arrived for the 851, you bewdy! I could finally tidy up the scattered collection of parts I kept shuffling around the shed depending on where I needed some elbow room. I tell ya, it's not easy being a messy lil' grot-monster.
It's pretty underwhelming really, within a morning the engine is back together looking exactly as it did before: putting a little more air between the pistons/heads/valves is not the most spectacular looking thing in the world...unless you don't have enough of it.
Now, this is where my brain starts doing those lil' arcy sparky electrical fault type noises as I try and figure out what raising the cylinder head in relation to the timing layshaft will accomplish cam timing-wise..."ZZZHHSSTT!....ZZZHCCTT!" Don't take this as gospel, but I think..."ZZHHSSZZTT!"...the inlet will be advanced, and therefore exhaust retarded....but by how much I have absolutely no idea.
I always planned on going through the cam timing malarkey again but I'm kinda curious to measure the difference it makes on the dyno, and I had some alternative cam timing figures recommended to me, so I decided to just assemble as is and use that as a baseline to measure changes against.
NB: On a slight but connected tangent, there was the possibility of increased access to a dyno on the horizon which influenced my thinking, "standby to standby" for an update...
So the donk was back together but I wanted to tidy up some items that had been bugging me a lot more than the dust-bunnies scampering around the corners of the shed, starting with that bloody exhaust.
This was top of the pops when I pulled the thing apart. I was so shat off after discovering the squish issue that any thoughts of forking out even more cash for something I still wasn't happy with had my eye twitching. Finding out a 6m length of 45mm stainless tube was only $70 was all the encouragement I needed, and besides, I badly needed to be cutting, grinding, hitting something and $70 was cheap therapy even if it all went in the bin.
Actually bending the tube was the fly in my soup: how? Waaaaay back at the start of this blog I mentioned a tired old orchard workers cottage on our property. Somewhere back in the mists of time someone had obviously had a little too much lunchtime grappa and backed into one of the 50mm steel verandah posts, putting a slight bend in it. So, with two projects in mind, I picked up one of these:
Yup, it did the trick on the verandah post, but as you might be thinking this is a pipe bender...not a tube bender. Things tend to get a bit "kinky" trying to bend tube with this sort of rig, but I had an old school plan: fill the tube chock-a-block with sand and apply heat when bending....
....and it worked...sorta. Albeit mainly because I'd realised that very little actual bending was required. Eh? Yeah, I mean have a look at Falappa's '92 888 Corsa exhaust, it's not that far off dead straight:
This is the exact photo I'd given the exhaust guy so I'm buggered if I know how he arrived at the exaggerated bends he built....but best I don't think about that sorry saga. (cue yelling into a rubbish bin again).
Sorry, I didn't take any pics, but it was an absolute bastard trying to keep enough of the sand-filled tube up to cherry red temperature with my butane torch as I was simultaneously trying to do the bending. Even with the minimal bending required the tube was just on the verge of kinking/rippling so I chose to err on the side of caution and call it quits before I had to start again. Basically I needed (a lot) more heat, as the sand wicked away the heat from the tube. Then I had the unbridled joy of cutting the lower mandrel bends off the previous cock-up and consigning the remains to the scrap metal bin.
Stick welding (I don't have tig or mig) these onto my new tubes wasn't ideal but some 1.6mm stainless electrodes were just workable with minimal current as I carefully stitched my way around the tube to avoid overheating and blowing holes in it. As per usual I spent about 2 hours welding and another 8 hours grinding/sanding/polishing making it look half decent. Add some spring hooks and here you have it:
Yes, it's a little too straight, which is accentuated by the shorter mufflers, the continuous run without the usual joint in view to break things up, and 45mm tube vs 50mm on the Corsa system:
It's not quite right, but it's getting closer. I'd leave it at that....for the moment
Next up was tidying up the cooling system. The thermostat/hose arrangement on these ol' girls is just an abomination, hanging way out in the breeze like a complete afterthought:
"Hey, Giuseppe! I collecta smoko, nonna's arancini issa warmer than your motocicletta, she issa still cold!"
"Vafancullo! Scusi Luigi, from race to road issa too rapido, I forget the thermostat!"
As you can see above the water pump inlet is vertical(-ish) and requires a pretty funky OEM hose arrangement incorporating a heavy/ugly spider-like hose manifold that I was keen to get rid of. Later models had a horizontal water pump inlet that made for a much simpler setup.
So I'd ordered a later water pump cover and the appropriate impeller which is a slightly different shape....only to find the later impeller is also a tad different around the mechanical seal and wouldn't suit my early side cover:
Luckily a few minutes on the lathe replicated the shape of the new 'un (you could easily do the same in a drill):
Swapping out the right angled earlier thermostat for the later straight unit and replacing the coolant fitting on the horizontal cylinder head for one that incorporates the temperature sensor were the final pieces of the puzzle:
So that's the big and not so big ticket items for 851 Version 2.0 pretty much complete...but what have we achieved?
Picking up some bathroom scales was more convenient, and I suspect more accurate, than weighing something this light on the vehicle scales at the track. Bottom line? Ready to race, with no fuel = 166.6kg, so all the dickin' around had saved somewhere between 5 - 6kg.
And the exhaust? You've seen what it looks like (the jury is still deliberating) but what does it sound like? The sound quality is utter shite but this gives you some idea (turn it up!):
