Re: Reviving a '91 GSXR750
Kind of embarrassed, but I'm not suspecting the CDI anymore. A little background first.
I bought the bike in non-running condition with the carburetors removed. I got it from a local shop that was selling it for the previous owner. They had started working on it, but it got too expensive, so the guy just wanted to get rid of it. The mechanic said the main issue they had found was ovaled emulsion tubes (among several other minor things, most of which I've been able to address). The PO had converted to dual K&N pods and the carb had presumably been jetted for that setup. I'm not sure about the needles and emulsion tubes, but the main jets are 150s and the pilots appear to be stock (37.5). I replaced the needles and tubes with new stock units when I rebuilt the carbs. Spark plugs are also new and gapped correctly. Also, I currently have the tank off, and I'm using a remote fuel bottle (Motion Pro?) to supply gas. Pretty sure I'm getting plenty of fuel.
The problem with revving occurred with open carbs (no filters installed). Over the weekend after I shimmed the needles (mentioned above) I went out to start it and check a few other things. I forgot to pull the shop towels out of the carb inlets before I started it. Guess what? It zinged up 7 or 8k just like it should when I wacked the throttle. Then I realized what I had done. So I installed the filters, and it's back to normal (won't rev). I wrapped cardboard around ~3/4 of the filter circumference, and it's better but still not what I'd call ridable. So, I'm back to jetting or more restriction on the intake, etc. I'm assuming the PO had it running at an acceptable level, but I don't know that for sure. Any input you can give me on carb setup with the K&Ns and an unknown aftermarket exhaust would be appreciated. Thanks.
1991 GSX-R750, 2006 Ducati ST3s
2000 Yamaha WR400, 2003 Honda TRX300ex
Last edited by twerth; 07-29-2019 at 01:20 PM.