ST2 Pistons & Barrels to 900SS

Slower than my shadow said:
Thanks for the welcome and all the info Rich :)

Sorry to hear the the loosening screw issue, it was probably down to the screw being a rolled item (they're always slightly undersized), if it was produced with dies the thread could have been produced to slightly interfere - and lock in place.

I was toying with the idea of using ST2 heads as well as barrels, but as most of the heat is produced in the heads, I might give this a miss for various reasons. 1, by doing that, I may as well just fit the complete ST2 mill. 2, with extra heat, more and big oil radiators would be needed - and the associated weight penalty. 3, oil only has about half the heat capacity of water, so heat will deff be an issue.

I'm not sure which engine oil you use, but I've done quite a bit of investigative work into Mobil 1, and it's just about indestructible. (I don't have any vested interest with the brand).

Before fitting the 748 rad, have a look for either a 999 or 1098 oil cooler, the 999/749 is narrower than 1098/848. I've fitted one towards the bottom of the fairing, just in front of lower exhaust. And plumbed it in series with the original.

Not sure if you've fitted the lighter flywheel, but it let's the engine spin-up very quickly, it was one of the most immediately obvious improvements I've had fitted.
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Be aware that the early 999 oil coolers were recalled and changed as they leaked. There may be some dodgy original ones on flee bay?
 
Some great info there Rich, top man.

Your machine probably runs hot for a couple of reasons, the main one being you've fitted hi comp pistons. The extra 20cc per cylinder doesn't really add that much in the grand scale of things. But upping the CR by say 1.5, is the equivalent to adding 150 cc or more to each cylinder, that extra charge will generate heat. Effectively you have an 1100 cc engine, now we know why the guys at Ducati redesigned the head on the 1000cc and 1100cc engines - to get rid of the extra heat quickly and effectively.

It might be worth wrapping the exhaust pipes, thus forcing the extra heat down (and out through) the exhaust.

I've been looking further at the oil delivery through the cylinder and to the head, along with the oil cooling of the cylinders.

The oil feed to the head only goes to the cam bearing block, then once the oil has made it's way past the bearings in roccker, cams, etc is allowed to drain back down the cam belt side of the cylinder, 2 drains on the vertical and 1 on the horizontal. By taking a feed from the high pressure side of the oil pump, (simple adapter block or Tee needed), I'm in process of getting a pair of cam bearing covers machined to accept oil via banjos. I've sourced an ST3 oil pipe that will plumb-in to to cam covers. To maximise the oil usage, it will be necessary to plug the oil feeds at the top of the cylinders. This will also help the flow rate through the cylinder jacket. The oil usage to cam block is low and doesn't cause any starvation elsewhere.

I have a pair of multistrada 1000 pistons, they're 94mm, so fit the ST2 barrels perfectly. the real sod is the compression height is a mm or so lower. Bugger. but if anyone stumbles accross a pair of hi-comp ones, buy them - as they'll still boost the compression, but more importantly they're at least an ounce lighter than the ST2 stock units

The vertical cylinder is quite easy to flood with oil as per "threads up topic", but the horizontal cylinder does potentially have the cope for air locking, I will be looking at this a bit more, unfortunately there's not a lot of metal on the jacket for a bleed.

The main problem I now have is the draining of oil from the cylinder jacket, my alternator cover is magnesium, there is one M12 X 1 threaded hole available, so it looks likely my local precision engineer will be busied again.

I'm a lot nearer to retirement than apprenticeship, but another tip when the engine's apart. Polish everything that sees the fuel mixture, so that's the pistons as well as the ports. The heat retained by specks of crap is unbelievable, keep everything shiney and nothing can stick to it and cause hot spots. That means everything you can access on the pistons. And if you can, open-up the holes under the oil scraper rings by (say) half a mm.
 
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Cheers Slowshadow,

I'll look into wrapping the exhaust. So far, running a bit hotter doesn't seem to have bothered it much at all. Also, I'm not convinced the temp gauge is that accurate as it seemed to run hot before any modifications.
I have two sets of ST2 pistons available, a pair with good rings and a pair with one set of rings if anyone needs them.
 
richc said:
Cheers Slowshadow,

I'll look into wrapping the exhaust. So far, running a bit hotter doesn't seem to have bothered it much at all. Also, I'm not convinced the temp gauge is that accurate as it seemed to run hot before any modifications.
I have two sets of ST2 pistons available, a pair with good rings and a pair with one set of rings if anyone needs them.
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yeah, I know what you mean about the temperature gauge richc . On ssie models the oil pressure switch can also a red herring, mine was always coming on when stuck in traffic. I fitted a gauge and it turned out that the switch would short internally when hot. Fitting one of the units from a Vauxhall Corsa solved the false light, I believe later bikes were fitted with the Vx unit as standard. Probably an exec decision made through a tenuous VAG GM link when Audi did some shopping and bought out the Pacific holdings.
 
Progress has been a bit slow this summer, just too many other higher priority tasks. However, not all has been lost. I acquired a couple of cam covers, a local engineer drilled and tapped holes all ready for external oil feeds.

I've fitted a 1098/848 oil cooler, this was a lot easier than I thought - I managed to source a ST2 radiator mount/rocker cover. Fleabags was source for the rad, it had both rubber bushes fitted and a top hat bush. I bought another top hat. And to my amazement they fitted. Just to be awkward I reversed the bushes, this did mean the rocker cover ' s faces needed a couple of mm shaved off, again a simple job for local engineer.

The rad came with feed pipes, one of which had oil pressure switch fitted, this will be used as the feed for the cam covers. It has been a relatively easy task to produce the oil feed lines.

The feed lines obviously came with pipe/rad adaptors. I removed the lower pipe and adaptor from rad. Then removed the upper oil cooler pipe from the engine block and replaced it with the one taken from the rad. So oil feed to lower rad all OK. The adapter taken from the engine block was screwed with new gasket into the lower union on new rad.

Now for the hardest bit, the oil redundant pipe removed from the bike was recycled. First the 15 degree fitting was carefully removed, without damaging the braided pipe. A third party 90 degree full flow elbow was fitted. So now the lower rad feeds the upper rad, then oil flows back down to sump.

I've routed the oil pipes that way, so the oil from the pump can support the oil from the lower rad, and the plumbing of the top rad prevents the oil draining back down to the engine when the engine's static.

I have a fuel injected model, so there was a little bit of fairing chopping, but not as much as first feared. I will take pics and try to show all.

Things are a bit tight around the front exhaust pipe, but wrapping the exhaust should help here.

The 999 oil cooler could also be fitted, the bracket would need slightly differing, and it would save on a bit of fairing cutting, but the rad is a bit smaller.
 
Well done, photos appreciated pls. I still have the same oil rad rolling around somewhere in my garage to be fitted to my 93 900ss. Some one on Ebay was making a full set of mounting brackets to make my job easier but he disappeared!

Cooler guards should be easy to come by at least for you.
 
I've taken a few pics as I was going along, I came to review them and found the files were all corrupt - thank you not Samsung S5. A brilliant bit of kit to start with, but as contract renewal approaches - pants, pants, pants, pants, pants, pants and more pants. Wish I could find my Nokia 8310

Currently tipping-down here, the bike's at the back of the garage, I will take some more with a camera when i can get to the back of the garage and it's dry(ish)

Yeah, 848/1098 cooler guard from Evotech, fits perfectly and looks very, very nice.


Edit to add more pants - I'm really disliking the s5.
 
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