I installed a new EGT today on my 350L and I can't believe the results. First of all let me give some details.
I live at about 3500' and the temp today was about 40* F
The 350L came from the factory with a stock 200 jet, but because of the elevation here I ran a 180 main jet. That was before any mods.
I have since added a HSP xplorer 400 pipe, UFO on the stock 34 mm, V-force delta 2 reeds with spacer, and removed the airbox and added a K&N filtercharger.
HSP recommended a 2 size increase for the pipe alone. I figured between the UFO, the new reeds, the filter, and the colder weather I would go another 2 sizes. This would give a 4 size increase total.
I dropped the pilot jet from a 30 to a 15 per the instructions with the UFO, and I dropped the needle clip one position to the #4 position; also per the UFO instructions.
I then installed a 220 main jet and proceeded to test the EGT.
I started at about 1/8-1/4 throttle and the EGT showed about 800* F.
I then gave it about 1/2 throttle and the gauge jumped to about 1000- 1100*F.
At about 3/4 throttle temp was about 1200-1250*F
At full throttle it showed about 1400-1450*F
I could'nt believe it was that hot. I installed the probe per the instructions with the probe about 7" from the exhaust flange.
The pamphlet that came with the gauge showed the following
1/8 throttle 800-1000
1/4 throttle 1000-1100
1/2 throttle 1100-1200 *F
3/4 throttle 1200-1250
full throttle 1250-1350

I think I am a little rich on the bottom end but I am definetally lean on top end. So I then installed a 250 main and full throttle showed 1350-1400*F, still too lean. So tomorrow I must go and get some bigger jets, like a 260,270,280.
Does this sound about right?
Will the temperature really drop when I hit the sweet spot or will it just gradually drop with each subsequent jet increase.
I think I will move the needle clip back up one position to the #3 position to lean out the 1/4 - 5/8 range.
Anyone ever have any problems with an EGT not reading accuratally?
If I could get some input from anyone running a EGT or any of the mods I have I would greatly appreciate it.

Thanks

Doug

 

Usually the EGT will just slowly go down as the mixture richens, not suddenly hit the right zone. You are headed in the right direction, it usually works better for me to start rich & work my way down, not that it is easier to jet as much as protecting your enging from extreme internal heat.
Usually, there is a 'lean spot' somewhere between 1/4 and 1/3 throttle that you have to watch for on 2 cycle engines. I have been told that the UFO will help to eliminate it, but I have no personal experience with them to be able to say for sure if it does or not.
Also, be sure to do your testing with some load on the engine, it will give better 'real life' readings that way, and if the guage ever gets to 1500*, ease off, and ease off NOW, that is just TOO HOT, you will be nearing the melting point of your aluminum piston.
Also, an EGT will have a slight delay in the reading (it takes a little bit for the probe to heat up & give an accurate reading). Hold a throttle position as best you can until the reading stabalizes.
Good luck.

 

I am also running an EGT guage and you can see from my signature at the bottom what mods I've done to my bike so far.I have a 34mm carb on my bike now instead of the 30mm stock one.I also have a UFO on it too.But my bike is an aircooled piston port motor and I don't have the pipe on it yet. My jetting is as follows: 20 pilot 2.0 cutaway on UFO 3rd clip on needle and a 230 main jet.When you drop the needle it will lean out the midrange and bottom end too because of the UFO.My temp is nice and stable right from about 1/8 to WOT. It will idle at about 800 deg. and rise to
1150 right at 1/8 throttle and rise to 1250 at WOT.When I get the pipe(if it ever shows up.....)I will probably be running a 260 to get it right.I think one of your problems might be that you have no airbox on your bike.If you have one you should try putting it back on and seeing how it runs then.I have tried jetting different bikes without airboxes on them and it was a nightmare to say the least!!!If I were you I would reinstall the airbox, try a 20 pilot and drop the needle 1 clip to the center clip and try a 260 main. Jetting with a UFO is a real pain in the butt but its worth it when your'e done.By the way I wouldnt let the temp get any higher the 1300 cause any higher than this and your piston will expand enough to score it causing the rings to seize.It will happen long before you burn a hole in it.Be careful.

 

Thank you Farmr123 and Sparkys for the great information.
Sparkys, I think I will take your advice and reinstall the airbox again and see what happens to my temps.
I installed a 280 main this evening and took it for a spin, temperatures stayed in the 1250-1300 range at WOT.
Tomorrow I will reinstall the airbox and move the needle clip back to the #3 (middle) position.
I will try the 260 and see what the temps do.

Thanks Again

Doug