That's an interesting project. Where did you get all the information about the steps to do? Can you post some pictures? Be interesting to look at and to follow along.

Hi everyone,

I am doing an oil cooler conversion on my GS500E using complete GS500F OEM parts (oil pan, lines, radiator). My bike is a 2016 model.

I have plugged the upper hole behind the oil filter with an NPT plug and drilled a small 3.1mm bypass hole in the lower crankcase port.

With a permanent oil gauge, I am getting 3.5 bar when cold, but it drops to 0.4 bar at hot idle (100°C) and only goes up to 1.5 bar when accelerating.

I know the original GS500F uses an internal restrictor bolt (the one removed with an 8mm allen key). Does anyone know the exact inner millimeter diameter of the hole inside that factory restrictor?

I want to know if I should drill my NPT plug to match it, and if I need to widen my lower 3.1mm hole to prevent backpressure.

Thanks for the help!

Agree, unless you know what you're doing...return back to stock to get a baseline. I purchased my 2002 Suzuki GS500 and it had a lean misfire...then I realized the previous owner put in an air filter from the pre GS500E models...2002 year OE filter has a restrictor ring at the top, which solved my issue.

Aftermarket exhausts always make things tricky to tune. I would start by putting back the stock exhaust and seeing what happens.

I chased my tail for a year and a half on a misfire and it turned out to be a pattern air filter. That did it. Went back to the factory air filter specific to my year and everything rocked and rolled.

Hey!

Thanks for the reply. I wan't sure if anyone was here.

An update, I increased the piloit jet from 17.5 to 20, and main from 130 to 132.5

That didnt change anything. I tested the ignition coils and timing gap and resistance of the pickup coil. All are in spec.

One interesting discovery is that the missfire doe not happen when the airfilter is removed. It has stock airfilter and aftermarket exhaust but I dont see how this could cause a missfire still.

I didn't even consider the valve gap could be the issue....they would have to be too tight for this to make sense. Compression is within spec though.
Worth a check though ,this will be a fun fix.

 

Ahhh, the old Canadian snow season , how I don't miss it 🤣🤣🤣🤣

I must make a plan to get Josh's page saved somewhere in case he ever takes it down

The Josh Karnes carb link is GOLD! thanks.

Ahhhh, man! Sorry for the late response. After a couple of weeks of no responses, I kinda figured this was a dead corner of the forum world and forgot to check back. Thanks for the response and the info. Yes, I'm in Canada. I tracked down an actual shop manual that I can hold in my hand, and that has been a great thing to have. I've not really messed with anything too much...bad form, I know...but I just want to ride it! Put new tires on her a few days ago. I invented many new cuss words but managed to get it done. (as luck would have it, they balanced perfectly with the existing weights, so I was able to not fight that battle) Winter snow is just a few short weeks away here, so I'll have plenty of time to pull things apart and make a dog's breakfast of it!

I'll check those links. Thanks!

If you cant find th epinout You will have to get the wiring diagram from the katana and the gs500 to compare and identify which goes where in old versus new.

Quote from: herennow on August 19, 2026, 01:44:26 AMyou mean you are looking for the wiring diagram or for the connector?

the pin positions on ecu connector