Thread: Some SL650 fuji triple questions
03-16-2014, 12:34 AM #1
Some SL650 fuji triple questions
So I ended up with a basketcase '92 SL650. It actually looks pretty decent but had been sucking in water and broke a couple piston skirts and wiped out a thrust washer. So after sourcing another one for parts I'm now in the process of re-assembling the engine. First question....What's with the huge caverness recess in the heads? This thing is gonna have like .150" squish! I'm used to seeing a lot less than this. I also found some port info and noticed the 780 porting is a little lower. So that got me thinking......why don't I just put all the cylinders back on with 1211 only and no base gaskets like I do on various other mod builds. This isn't really getting modded but surely it would have to help with a slight bump up in the compression right? Also do I need to update/reroute cooling lines or leave them as stock? If I were keeping this thing I would surely break out the carbides and attack the upper case, I don't even know how the fuel mix finds it's way up into the cylinders, I see so much room for improvement.
03-16-2014, 05:58 PM #2
Well, I went ahead and re-assembled today with NO BASE GASKETS. 1211 sealant only. Still have about .130 squish. Leakdown test went just fine so I hooked up a battery and cranked her over. Fresh hone with freshly scuffed ring edges on used rings netted 120# cranking compression. It has been my experience after a bit of run-in it will come up. I'm expecting it to be 125-130psi. I know this would be just fine for a Yamaha or Kawi triple but how about this little Fuji?
Pic of all the worst parts, and the assembled engine.
03-17-2014, 06:27 AM #3
120 is good for the Fuji. Don't be surprised if it doesn't come up.....
03-17-2014, 07:09 AM #4
- Join Date
- Jun 2010
- Milwaukee WI
No base gasket may affect port timing. It may run with less power. Could possibly be a little better on the bottom end but possibly lose some up top I would think.
03-17-2014, 07:39 AM #5
Which would be just fine for this little 650 I'm sure. It's not exactly a rocket out of the hole.
04-24-2014, 03:47 PM #6
Test rode last weekend. It feels very powerful from a start to midrange. Does not feel at all like a little 650. And the top speed feels real good too.I'll do another compression check and see if it came up any. This thing has power trim that still works too! Here's a pic.
10-06-2014, 09:34 AM #7
Ended up keeping this instead of selling. My son really likes it. Compression after some break in time is at 127/125/125. GPS readings are 43-43.4 consistently. Low to midrange is VERY good for a 650. Just cut the center bars out of the grate and the plugs show rich so maybe we can get 45 out of it?? Flame arrestor is stock with a K&N on the end of the housing. Maybe I should try taking the k&n off to lean it out a bit.
10-06-2014, 09:44 AM #8
- Join Date
- Aug 2014
- Richardson, Tx
Easiest and most reliable way to build more power in that Fuji engine would be just make it bigger. 750 cylinders, pistons and heads will drop right on that engine, could be run with existing ignition and carbs (rejetted of course), will make a lot more power and could be found probably basically free. You could also explore a better pump setup, if you are still running the original '92 pump.
10-06-2014, 09:59 AM #9
10-06-2014, 11:29 AM #10
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