pore gas mileage

[kamkamdac]

ive been riding my newly acquired 1990 600 for a couple months now and every time i fill up and calculate my gas mileage its always around 38 mpg (35 was the lowest ive gotten and 39 was the highest). ive cleaned out the carbs, changed the oil and put in a new air filter and no change. i ride very conservatively usually shifting in the low 4ks. i use the bike for commuting and do most of my riding at steady speeds of 60 or 75 mph depending on the road im on (75mph=6.5krpm).

ive read that with conservitive riding your mpg can get as high as 50 and im nowhere near that. the bike has an aftermarket exhaust and a stage 1 dino-jet kit, could those mods be hurting my gas mileage that much?

[shift6]

yes, they can

[badwithcomputer]

Tone down the cruising speed RPMs, I too had a similar issue then one day I said screw it, I am going to keep it at around 5krpms which is about 60mph and was able to hit 45mpg. I also was in full stealth tuck mode!

You may also want to look at things like your float height and a/f screw position. Also, but I may be incorrect here, you may have adjustable needles? make sure those clips are in the proper position as well.

clean the soot off your tail pipe, how quickly does it turn black again? how is your idle? if you rev it up in neutral and let it drop is it a steady drop back to idle? or does it dip and come back up again?

[Kreylyn]

ive been riding my newly acquired 1990 600 for a couple months now and every time i fill up and calculate my gas mileage its always around 38 mpg (35 was the lowest ive gotten and 39 was the highest). ive cleaned out the carbs, changed the oil and put in a new air filter and no change. i ride very conservatively usually shifting in the low 4ks. i use the bike for commuting and do most of my riding at steady speeds of 60 or 75 mph depending on the road im on (75mph=6.5krpm).

ive read that with conservitive riding your mpg can get as high as 50 and im nowhere near that. the bike has an aftermarket exhaust and a stage 1 dino-jet kit, could those mods be hurting my gas mileage that much?

Step 1: Verify your speedo is correct or if it's off, what is the percentage (too fast or too slow).

Recalculate the mpg with any adjustments that are needed. I'm imperative that as a new rider you use a measuring device to confirm the speedo accuracy. If you use GPS, make sure it's multiple readings at a steady speed at several different speeds.

Step 2: If the speedo is verified right and or you have adjusted for the correct % off and you still feel it's low, then I would check the emulsion tube and jet needles for wear. That will cause a drop in mgp if worn.

A properly tuned set of carbs with a stage 1 jetkit will not decrease your mpg, but will simply smooth out the power for the full rpm range instead of you having lean spots.

Krey

[kamkamdac]

clean the soot off your tail pipe, how quickly does it turn black again? how is your idle? if you rev it up in neutral and let it drop is it a steady drop back to idle? or does it dip and come back up again?

when i clean the tail pipe how long should it take for the deposit to reaper? do i let it idle and wait or do i go for a ride? idle is smooth 95% of the time, every once and a wile while im at a red light the idle will sound uneven like one of the cylinders is stronger or weaker than the others, same problem happens if i set the idle to high (around 1500). probably a spark problem though. carbs are synced.

when i do a quick blip on the throttle on the way back down the rpms will dip about 200 then come back up to idle. a large blip where the rmps go above 5-6k wont cause the drop though

Step 1: Verify your speedo is correct or if it's off, what is the percentage (too fast or too slow).

im using an aftermarket speedometer with a magnetic pickup on the wheel. it is accurate within 1-2 mph at 75mph.

[badwithcomputer]

There's no set amount of time for how long it takes to reappear, if you clean it and it reappears black in a short amount of time, like a long ride perhaps you may want to consider a rich running condition. The quick blip and the drop tells me that it is running on the rich side as you say if you run it up to 6k it burns off all the fuel allowing it to fall normally. Rich running can cause a whole slew of issues, for me it caused a ticking which sounded like a bad timing chain. My carbs were rich in all aspects of the rpm range, so I had some fun.. not.

The way it was explained to me and maybe someone can elaborate is that different parts of the carbs control different parts of the rpm range. For example the needles may control the 6-8k range, if those aren't set right you'll run rich or lean in that part of the rpm band. in the idle to 3k range i believe is the pilot jet? anyway it goes on, I think I remember Krey explaining it in someone else's thread.

The answers are out there, it's just how hard you want to look for them. I am not an expert so wait for someone else to chime in, I am just throwing out scenarios of what I experienced.

[edromero]

Is it stock gearing? If there was a sprocket change, fuel mileage can suffer, and your speedo will be registering incorrect mileage

[pnut1236]

I dont know how your dynojet kit is set up but I just helped a buddy of mine replace his jet kit in his 88 kat 600. The bike had the dynojet stage 1 kit installed from the p.o. and he was only getting around 33mpg with it while taking it easy on the throttle, then we then switched to factory pro and he is now getting 45+mpg riding the same way. Also to mention that when we pulled the plugs with the dynojet kit installed they were soot black, I dont know if the p.o. followed the right directions when he installed it or that the kit was just that shitty.

[kamkamdac]

I dont know how your dynojet kit is set up but I just helped a buddy of mine replace his jet kit in his 88 kat 600. The bike had the dynojet stage 1 kit installed from the p.o. and he was only getting around 33mpg with it while taking it easy on the throttle, then we then switched to factory pro and he is now getting 45+mpg riding the same way. Also to mention that when we pulled the plugs with the dynojet kit installed they were soot black, I dont know if the p.o. followed the right directions when he installed it or that the kit was just that shitty.

i puled up the directions for the kit online and it says to run 110 mains for bikes with aftermarket exhausts and 106 for stock. the jets the P.O. put in the bike are the 106 ones even though its got an exhaust. so i dont think it should be running rich. pulled the old plugs and they were a bit on the dark side, but not by much.

im hearing that factory pro kits are the way to go, not to many people with dinojet kits. i mite take a gamble and pick one up just to see if it helps any, that extra 5mpg ads up real quick.

[hardlydangerous]

i puled up the directions for the kit online and it says to run 110 mains for bikes with aftermarket exhausts and 106 for stock. the jets the P.O. put in the bike are the 106 ones even though its got an exhaust. so i dont think it should be running rich. pulled the old plugs and they were a bit on the dark side, but not by much.

im hearing that factory pro kits are the way to go, not to many people with dinojet kits. i mite take a gamble and pick one up just to see if it helps any, that extra 5mpg ads up real quick.

main jets affect 3/4 throttle to WOT (wide open throttle)

if your cruising on the hwy and shifting at 4k your not even close to using the main circut.

first test the float valves. I usually bench test them. with the carbs off use a fuel bottle to supply gas to the carbs. if any overflow or leak the float valves are leaking.
Next check float level
set mixture screws
check the jet needles and clip positions. make sure all washers and spacers are used.
check slide lift holes for correct size

[indianboy7]

I had the same mileage with my dynojet kit. I would never really get better than about 35 mpg. Put a factory pro kit in, and now I rarely get less than 40 mpg.