Legotoy

http://oldskoolsuzuki.info/forums/index.php?/topic/3013-will-a-b12-engine-go-in-a-1100-w-frame/ Have a read of that thread, should give you an idea.

What brand gasket set did you use? Just interested, maybe tolerances in that brand had something to do with it - thinner head or base gaskets for example?

147.5 main jets at the moment (what I sent him). Glad it's running better now!!

Hopefully Jpich85 doesn't mind me posting this, but we're here to share knowledge so I thought people might like an update. We spoke, and the last time the bike was on the road it had an airbox and standard jets (112.5's). It now has pod filters (no airbox) but still the 112.5's. I've sent him some bigger jets to try. Fingers crossed.

Keep at it - the 900 hybrid is a lovely thing to ride once sorted. Smooth and torquey. I have gone for 14/43 gearing too which makes it even more responsive. If the inlets are hard, try hot air on them and a little silicone grease to ease the carbs on. If they are so hard they have cracked and have air leaks then that's bad of course. Good luck.

Re: jets – I bought a Factory Pro jet set from the USA (e*ay), which also comes with full instructions which is where I got my info from. I can lend you the 147.5 jets to try if you like? I say “lend” because they were expensive and I’d like them back ;-) The kit comes with needles too, but if you have nothing but stock stuff installed now then just the jets would be a good place to start. The carbs are no problem to get on/off. Maybe your carb rubbers have hardened? It is tight to the top frame rail but not really had issues myself. Vent tubes don’t need filters, article link here: http://oldskoolsuzuki.info/archives/531 Search “Journey to the center of Mikuni’s BST38SS carbs” in the OSS Vault

Hi mate, I've just been through a lot of similar pain with my GSXR/RF conversion, so I hope some of my experience is relevant. In my experience a month is plenty long enough for modern fuels to "go-off" and lose octane rating as well as partially block the jets. Since the pilot jet affects running up to quarter throttle it could be that a partially blocked pilot jet is causing it to run lean overall? I had mine sat for a month, and then it only ran on 3. A carb clean and fresh fuel sorted it. I have also just removed the airbox, although it did run the 900 motor on stock airbox and jets for a short period. (112.5 / 115 / 115 / 112.5) Current settings are as follows: 4x single "V&H" type oval filters Main Jet: 145 in all four carbs Pilot Screws: 2.5 turns out Needle on 4th clip from top, although I may lower it as rich running is causing the idle to hang up a bit. Float Height: 15mm on all four carbs Oh and I run my cam breather tube to an old beer can zip tied to the frame rail for now. A new baby means I am poor as you like, so have to save up for a fancy breather bottle ;-) Finally don't forget to use sufficiently long vent tubes for the diaphragm and float bowl vents. Otherwise cross winds could hurt how your bike runs. There's a good article here on OSS about those two.

I have sent you a PM, but what sump are you using?

Thanks guys for the replies, that is really useful. Shame that it confirms what I thought - rebore time! And I only just got the thing on the road too. I suppose that's what I get for using used parts. thanks again.

Thanks for the reply Skelly. I didn't count the strokes, but did hold the starter for the same amount of time, did two tests and took the average. Test was cold since the carbs are off - but no problem with throttle being closed! So the results will be under-reading anyway, and less than perfect, but sounds like there is a problem requiring a strip and measure at least. Bum. It is interesting to me that the comp shot up so much with a little oil in the bores...

When I put my GSXR/RF motor hybrid together I suspected at the time that the cylinder bores were past it, or the rings gone, or both. I figured at the time I would run it - better to check it worked before throwing loads of money at it. Today I got round to doing a compression test: #1 was 95psi #2 was 115psi #3 was 90psi #4 was also 90psi So the cylinder pressures (cold) are between 17% and 21% variance of each other. When I dropped a touch of oil down the bores and re-tested the reading shot up to over 190psi. That alone would indicate the bores are shot, as opposed to valves for example. How bad is 90psi? Rebore straight away or rag it til she blows? The motor runs but feels a bit limp... It doesn't smoke or use oil strangely though.

The pic is tiny because I didn't have a decent camera phone back in 2007!

I have done this B12 into 750w conversion myself, back in the early 2000's. The bike was a beast and well worth doing the conversion in my opinion. There are a few compromises you have to make though so beware. The water cooled motors are more compact, and the cylinder block is more upright. The oil cooled motor also has a wider cylinder head, so those two factors combined means the B12 engine was slightly canted backward in the frame (sump was not completely level). You can't really tell by eye, but trust me. This is so the cylinder head clears the frame downtubes. A proper conversion would mean re-engineering at least the front frame loop. To make mine work I accepted the slightly canted back attitude of the motor, and used the lower rear mount as the starting point. It bolts up pretty well. Every other mounting point in the 750w frame had to be re-made to fit the B12 though. The sump on the B12 (or 1100 oil cooled, same engine) has bolts in the oil galleries that will foul the lower frame rails, and so had to be ground a little to clear it. Again I accepted the compromises of a slightly thinner wall to the frame tube where needed. It is a long story of how to fit it, but it can be done without major welding.