Hi all I was casually reading some old posts here when I realised I might have an issue to address. I have a '94 M900 (38,000km's on the clock) and was looking up info about cylinder studs snapping and I kept seeing mentions of checking the oil gallery plug, then I found mentions of fingernail like bits of aluminium in the oil screen. Well I did an oil change the other week (the first under my ownership) and guess what I found on the screen? I don't have pics of it as I cleaned it all up and put it back together then tried to forget about it but it was definitely aluminium. It didn't quite look like the pictures I have seen but was a little sliver of ally, is there anywhere else it could have come from? On the plus(negative) side I also have 7/8 of the original cylinder studs which I was going to leave until they needed doing but I'm guessing might be good to do all of it now?
Hi I also had slivers of ally on the filter strainer on some but not all oil changes, on my 93 900ss, so a couple of years ago i decided to remove the engine and investigate. With the vertical head and barrel removed the gallery plug can be inspected to see if it’s backing out, it’s rubbing against the crankcase on the alternator side if it’s on its way out and mine was loose enough for it to be rotated without any resistance. So it was a full strip down to replace it, which is fairly straightforward, ( the primary gear was the only difficult part to remove ) With the plug removed it was apparent that the threads were extremely loose/worn having been vibrating about in the crank for too long I had been running my bike for about 10 years and 30k miles in my ownership prior to stripping it, but after seeing the plug damage I’d advise against doing the same
Awesome, thanks for the pics! Yeah looks like I'll need to pull it apart, better start ordering bits and pieces. I was hoping to get a bit more riding in before anything major, oh well at least I'll know it's sorted. Anything else I should look at while I'm in there? I have cylinder studs on my list, I'll need to check end float on a couple things (especially if I ditch the case gasket that might be there as it's an early model).
I fitted a replacement gasket from I think it was Athena, this allowed me to retain the original end float on the crank and gear trains, also they are renowned for burning oil if the piston oil control rings or valve guides are worn so it’s wise to inspect these carefully I found it a reasonably straightforward strip and rebuild with no problems with worn parts, but I did find that it had had some high compression pistons fitted prior to my ownership so I was surprised that the gallery plug hadn’t been done. It did allow me to do a decent job of repainting the engine cases though !!
I've just found out that mine has been machining itself into oblivion. Threads inspected, locktite & centre punched. Luckily, mine is completely stripped & getting another gearbox again
M, Not sure if you have stripped similar engines before (but you seem pretty handy) I found "Andys Motorcycle Obsessions" a great help, also "turbobike" "Brad the bike boy" & "Desmo werx" I was similar to you, a broken cylinder head stud turned into a total strip down. There really wasn't anything I needed that wasn't answered by the fine people on this site. Prepare yourself for the primary gear when it finally let's go. Cheers Gaz
Thanks Gaz, I have done a few engines but always happy for any advice others can offer, I have actually been watching those channels looking for the little nuggets of info that make things a lot easier. Removing the primary gear will probably be something I pay someone to do if I get to it, my pullers are a bit too light going by other people's accounts
As you are having to go so deep into the engine, why not check out the availability of st2 barrels & cams, believe me they transform the engine completely, Andy's Motorcycle Obsessions did the barrels & not the cams, unfortunately he couldn't tell the difference an extra 44cc made with just the barrels. But together ❤️
I had the opportunity to buy cyls, pistons and cams recently, asking price was more than I had at the time and the cylinders have since sold. The cams are still available though are they worth it on their own?
I'm unable to give you a definite yes, I did the barrels & cams & had the ports modified all at the same time. The end result are on the dyno sheets. That is as long as I've posted the correct pictures ?
You'll struggle with a regular puller because it won't fit in the available space but with the correct puller it will come off easily and not fly across the room when it does as it's contained in the body of the tool. I got this; From GB motorcyle products, I got mine on ebay some years back and have used it many a time with no bother, if you were local I'd happily lend it to you but I think the distance would make that tricky! Once in there, definitely check the valve guides. My M900 exhaust valve guides were well worn (but intakes were fine) after not so many miles of having new guides so it's definitely a thing. Plus, I would check the condition of your gears, especially the 6th gear cogs - mine broke 4 teeth off one side and I've seen a few where the 6th (only the 6th?) gears look a bit battered, including a spare gearbox that I've got sitting on the shelf. Needles to say check all the bearings for wear, I had a gearshaft bearing fail on my M900, the parts are cheap enough but it's a big job to revisit it later. As for gaskets, I did away with the centre gasket and used 3 bond but you'll need to redo the preload/endfloat on the mains and gearbox.
Thanks! Good point about the guides and gears, the engine is almost at 40,000k so needs a good health check. That puller looks hefty! If thats designed for the job I can see how the skinny multi leg pullers would easily fail.
Mine had a complete engine rebuild (including new valve guides) and then the 6th gear broke around 17k miles later. When I stripped it down I was shocked at how loose the exhaust valves were in the guides - by that measure I'd expect yours to be at least a little loose. As for the puller, it works great and you don't really need to tighten it that much either, just nip it up and then hit it with a (big) hammer and the impact releases the gear off the taper with no drama, I have heard of people using conventional pullers (if you can find one that fits in the space available) and reporting dramatic releases when it finally lets go.
