pete roper

This is the second or third time I’ve heard of camchain/tensioner related failures on an MGX 21. First one I heard about belonged to the bloke who runs Wildguzzi. It I believe actually snapped a camchain somehow trashing one side of the motor. It was rebuilt and from memory did something very similar again shortly after. The story really frustrated me because ALL of the second generation Hi-Cam motors are essentiallt identical as far as the bits that spin and go up and down are concerned. The cooling system is plumbed very differently in the small port 1400 motors but the lubrication system, which includes both the cam chain tensioner feeds, the under piston cooling sprays and the cam, tappet and cam bearing feeds is all identical to the 1200’s and the MGS is the same, identical, to the other 1400’s which are all much of a muchness. Once the flat tappet fiasco was sorted out the motor was pretty much bulletproof. I’ve seen a few dropped valves but that is usually due to the valve timing being incorrect after rollerisation or lack of oil changes but other than that most problems are oil leaks and oil pressure and phase sensor failures. What made these MGX’s fail really frustrates me because nobody seemed willing to dig into it! Shops just seemed to shrug and either replace the motor or just push the bike into a corner and forget about it. Something like that would have driven me batty! Fixing it is the least of the problem if you don’t know why it failed in the first place! There is no point in just rebuilding something after it has blown up like that unless you work out why because, oddly enough, if you don’t, the chances are it will just do it again! I’d have had at it like a dog at a bone but alas I never had the chance. My best guess, and it really is a guess, is that there is some fault in the machining of the oil galleries in the crankcase in the rear wall of the timing chest. Unlike earlier motors the front main is a pressed in steel sleeve with a tri metal coating, it’s not designed to be replaced. I’m sure this system was adopted for cheapness of manufacture but the upshot is that oil delivery around that bearing to supply both it and the under piston sprays, the cam chain tensioner feeds and the front cam bearings and rocker/cambox feeds is done through a fairly complex system of drillings and machinings in the crankcase itself. The ‘Guess’ I’m making is that somehow or by something that main delivery gallery is somehow blocked or partially occluded preventing the tensioner plunger from priming properly and maybe starving the front cam bearing of oil and causing a potential cam seizure in the cambox. Sadly I’ll never get the chance to follow up on this hypothesis and nobody else is likely to want to so it will, no doubt, remain as one of those eternal mysteries that blacken the company’s name from time to time. As it is I was never a fan of the ‘Small Port’ motor anyway. Too smooth and it seemed to have moved away from the bare bones ‘Engineering Purity’ I see in the Big Port 1200’s. That’s just my own bias though. That and the fact I think the 1400’s are huge, under suspended, overweight, tubs of shite of course!

I’m a big fan of the Centy, but I’m me……..

It helps if we know left or right?

On the bottom end there is always the risk of oil pick-up exposure on the ‘Broad Sump’ engines but it really simply depends on whether you’re willing to risk there being damage. If you grab the rods from underneath and try and move them on the journal, as long as they don’t noticeably move or make squelchy noises they are probably OK. If you want to make sure simply drop the rod caps off, push the pistons and rods up the bore enough to see the top shell and make sure. Now ‘Best Practice’ is to never re-use rod bolts unless they are ones designed to be torqued to stretch. The reality though is that many, many Guzzi owners regularly and repeatedly re-use rod bolts with no issues so if it were my engine? That’s what I would do. It’s not a race engine. It doesn’t need to be treated like one. If the shells show signs of wear? Flick a new set into it. You can give the crankpin a ‘Poor man’s linnish’ with some wet and dry as well if you think it needs it. If it is scored or pitted though it’ll need regrinding and the rods closing and grinding.

Sorry, I haven’t been following this topic. I’ll have a scan through.

No worries. You’re welcome.

OK, so here are pics of my vast tool! Well, actually three tools. I’ll endeavour to get the pics up and then if anyone needs further explanation I can add some. The largest one is for the clutch boss nut, the intermediate one is I think the driven shaft nut and the two smaller, three gear shafts use the smallest one. The dimensions are nut OD and tooth size for the peg slots. Many thanks to Rolf for making them for me and sending me a set. They’ve served me very well over the last probably quarter of a century!

On that, who should I meet outside the Bungendore pie shop on Monday but Bart! After raving about the Beetlemap Michael had just installed in his Greenie he went on the rant about having found the company that now owns the jigs for the S’toons. I think he said they were in Tassie? Anyway he’s sending his, (Terribly lightly damaged, like tiny surface dings, but this is Bart!) pipes off and they’re going to re-tube them for him. I think the sum of $800 for the pair was mentioned but I’m not certain. I’ll see if I can get more details…….

Yup. None for the ‘Old’ six speed shaft nuts though. Sorry, Michael’s workshop is still a horror show from the crane installation. I wasn’t able to get near the ‘Special Tools’ box today. Hopefully I’ll be able to in the next few days and I’ll get dimensions and take some pics.

Unless similar nuts are used in some of the later bikes, (And apart from the pinion nut in the CARC bevelbox I can’t think of any.) I would be very surprised if the factory still has them available. Certainly the CARC six speed boxes don’t use them and I’d be surprised if any of the smallblock, three shaft, six speeds do either. The V100 I know next to nothing about but from reading the manual I can’t remember seeing or having reference to any similar fasteners.

I can probably measure mine in the next few days. They’re at Michael’s workshop though and his new crane is being installed at the moment so the place is a shitfight but I’ll see if I can dig ‘em out and measure them. Having a socket is infinitely better than buggering about with alternatives, believe me.

Nice to hear from you again Dave. Nah. The two machines have little in common but, at least for me, they compliment each other perfectly. My sig is actually accurate but both Grisos are goers, although the red one is up for sale, but only my white Mana is currently working. The black GT has a blown motor and my red 2008 is ‘Hors de Combat’ at the moment with a buggered starter motor and/or solenoid that I haven’t got around to fixing. Did you ever get your Griso back on the road after ‘The Hammer’ buggered it up?

You’ll get no argument from me……

Bart! Look at the date of the ad! It’s seventeen years ago! And what are you doing chucking it on its side you dork!? Words will be spoken next time we meet!