catastrophic news me thinks. I have had my alternator cover crack around the bearing. on stripping, i can feel quite a lot of end float on the crank, and worryingly some up and down movement. are my crank bearings knackered? What are the measurements for end float and giggleness?? or is some movement acceptable (not likely!!).
Had this happen on two bikes, a strong indication that the main bearing has gone. If you remove the alternator case and find any physical movement on the main bearing it is almost certain that the main bearing has gone. You should also check the crank big ends as well. My 748R engine with just 4,000 miles on it had both go and needed a complete rebuild. It's not the first I have seen with this trouble but don't be tempted to ignore it as it will only cost more money potentially.
A fairly sure sign that the mains have gone. The crank has a .15mm preload so no endfloat should be perceptible. Radial play should be negligible and you certainly shouldn't be able to feel any.
Thanks for your compassion. Yes, of course I suspected that it was knackered, but was not relishing the reality. As it stands I would appreciate an overview of the special tools that I might need to fix it. Can I make something up for the swingarm to frame, or does someone sell them? I have a micrometer and dti depth gauge and verniers. Not particularly looking forward to this, but at least the heads will be off to do the tappets!! Roughly how much are the big ends and mains and who's best to get them off. Also where can I get an engine stand from. Regards.
Ps got a cover. Engine has 20000mls and yes It vibrated, but that was after I changes my front tyre so I put it down to that. With hindsight, I did perceive a little more noise after I fitted the new water pimp impeller. At least it lasted Donnington.
OEM parts are pretty expensive as are the gaskets etc. My parts to repair my engine were £900 in total which included mains and big end bearings.
The swing arm to frame should be ok, it was on my 748 anyway a 1998 year, the bronze top hat bushes in the swing arm protrude through into the frame about 10mm holding it in place when the bolt is removed, i'm not completely sure whether this changed on newer models. Steve
All swing arm models in the 748 - 998 series are all the same. The hardest part is often removing the swing arm pivot bolt. If you are removing the engine yourself then you need to start putting penetrating oil on it long before you start to think about trying to remove it as they often rust in and some have found them impossible to remove and have resorted to various ways of cutting them out which is not ideal and may result in a new swinging arm pivot bolt or in some cases a new swinging arm. I have done several of these and the worst took a whole week of drenching in combinations of penetrating oil and WD40 and then constantly trying to drive it out. I got an engine stand from a member on here which was the stand itself plus a cradle to jack the engine into the frame. Very nicely made and it makes the job much easier, you don't actually need a stand but the engine tends to tip over a bit if you don't have one. Here's some photos of my SPS on the stand in question.
