1980 500w newbie project part 2 - the engine

[park3164]

Hi all.
Finally some limited trades are available again for the "red rust heap" project. The engine parts and cases have been cleaned, and I have ordered some parts. I'm waiting on oversize pistons, and new exhaust valves as the old ones once cleaned were obviously toast. I'm finding browsing this forum invaluable, when going through past posts on valve train parts etc. And the advice from members such as Harry Muffin and EVguru has been most helpful re engine bearing replacements. By chance, there is an odd size bearing supplier only a few suburbs away with the 30mm QJ 306 MA bearing, which I will get via the workshop at trade prices if needed
I noticed the comments about the two versions of Morini valves, and am getting valve seats, new springs and new type collets/valve caps along with the newer version exhaust valves. I'm in this far so thought may as well get new intake valves, which seem harder to find. Herdan in the US have them on their website, but whether they will get to OZ may be the question. I guess rocker arm bushes should be renewed, and valve guides. Would people suggest any other top end valve gear parts I should think of?
With regard to the barrels, it looks unlikely I'll find someone here who can bore a tapered cylinder bore. How much of an issue might it be if there is a standard bore without taper ?
Stand by for more newbie questions re the crank, which is currently being checked, measured and sludge traps cleaned out.
Thank you again for patience with my questions,
Fiona
Sydney Australia

[park3164]

An update for the 5 speed 500's engine. Rebore has been done, and the crank inspected. Some crankpin wear and the big end bearings not in good shape. Fortunately there were big end undersize shells available for purchase from Mdina. The crank should be back soon after machining the pin for the new shells.
I thought it may be of interest to folk to see rare pics of Morini and Ducati Pantah 500 crankcases and conrods side by side in the shop for comparison.1st photo is the Morini crank showing the wear and the Pantah crank in the background. Still a bit to do before the engine will finally be back together in the frame and the red bike start looking like a bike again.
Fiona

[Vitesse]

Any obvious conclusions from having the pair of them to inspect and compare?

[park3164]

Hi Vitesse. The engineers and other people on the forum are better qualified than I to comment on the differences. Going by what the engineer working on my engine said, I can comment as follows:
He was quite impressed by how similar the size and layout of the cases were, even wondering if Morini had copied Ducati. I did mention that the Morini cases evolved over 10 years before the Pantah (dont know how bevel cases would compare though).The top case is the Pantah's left half, with the 90 degree V compared to the Morini 72 degrees.
Overall the Ducati cases were a bit thicker in structure but had a similar reinforcing rib pattern especially round the opening for the front cylinder. Cylinder bore was a bit wider for the Pantah, and there is an extra hole in the upper rear region of the Pantah cases where the swing arm goes through and supports the engine. Camshafts are in between the V for both bikes. The right side Pantah case had a roller bearing for the crank, instead of the Morini plain bearing.
Conrods differed several mm in length ( I will look again re which is shorter), and the Pantah conrods had a bit more thickened edges including round the eyes for the small and big end bearings. Though the Morini revs a couple of thousand lower, he said the conrod was still a high performance rod for a street bike.
The Pantah's crankshaft pin was thicker (42mm I think? versus the 35mm plus a wee bit for Morini), and the vertical plates ("cheeks"?) supporting the crankpin were of higher quality/more expensive forged steel, compared to the Morini cast cheeks. You can see the different finish of the dark cheek metal in the photo. When tapped with something metallic the Pantah cheeks rang clearly like a bell and the Morini cheeks sounded duller. Interestingly, the Morini cheeks had 2 round balancing weights embedded in them but the Ducati did not.
I wish my bikes crank pin had been in the good condition the Pantah's was (but the Morini's gearbox was in much better shape
Cheers,
Fiona

[stradella]

park3164: you are making good progress with your Morini.

The Morini 500 has a bore and stroke of mm 69 x 64; the Pantah 500 is mm 78 x 58, more over square than the Morini (over square meaning that the bore is greater than the stroke). The Pantah would rev higher, which helps to make more power and a faster bike.

Another similarity between the two is the use of a belt to drive the camshaft (one for the Morini and two for the Pantah). Morini must have been an early adopter in the use of belt-driven camshafts. The Morini 350 was praised for its advanced design features. It is a pity that the Morinis don't have more effective oil filtration but some Morinis seem to rack up big miles without need for a rebuild.

I don't think Morini copied much from Ducati; a tighter angle between the two cylinders resulting in a more compact engine, push rod operated overhead valves v. overhead cams, the belt-driven camshaft.

[72degrees]

At least your conrod eyes hadn't gone oval

A belated comment on the re-bore. When I had my 350 cylinders done I took them a photocopy of the appropriate page from the 'blue book'. I don't know what they did and the rebuilt (with the last two new rods NLM had) engine hasn't done enough miles to comment on longevity, but it goes well.

What are the gearbox internals like - particularly bushes?

[park3164]

Thank you 72degrees for the head's up about the rebore and gearbox bushes. And thank you stradella for the encouraging words.I have to hope for the best with a conventional rebore, as there was no one locally who could bore a taper.
The only defect he found on initially checking the gearbox was the sprocket shaft RHS bearing in the crankcase. The gear box bushes will be checked closer in the next few weeks once the crank is finished.
I will in due course appreciate any advice folks have for setting up the breather system for an original airbox. The bike had K and Ns and no template for hose sizes and lengths apart from what is in the parts manual.

[simonnorthroad]

Morini 500 engine has a THIRD fewer parts than a 500 Pantah motor, no faffy shim-valve clearances to set (good luck getting at that rear head) and only loses out about 5mph on top end

[3potjohn]

Hope you can avoid the weather. Not looking too clever further north. Folk near our river tend to jack the bikes up when it comes over the top.
Last time I had my 350 apart I replaced every bearing I could get. Unusually lucky for me a new pair of pistons and a full gasket set turned up at about half price that very week. I just gave the bores a light hone.
John

[park3164]

Thanks John. I actually got stuck up in the north for 4 days till roads south opened. At least my K2 didnt get it's feet wet this year, but last year the garage filled to 1cm below the crankcase vents overnight - a narrow escape for the stator and flywheel from any inflooding. I hope to have more engine progress to report soon for the 500.
Cheers,
Fiona