MPG On a 1981 Xj650

So I went on a ride the other day with some local fellas here in Tn, and Filled my tank before I left. My Trip meter reads 109 miles and I went to take it to the store this morning and ran out of gas it would appear about 500 ft from my house. Now I would think I should get better gas mileage than that. Anyone else wanna throw an opinion at me about that. Mind you my mileage isn't going to be super great I would imagine since I'm a larger fellow, round wise

 

109 is just around the time I have to switch the Petcock to RES.
Did you switch over to the reserve position or were you bone dry?


I was averaging low to mid 40 mpg.
Once I get my carbs finished (and re-check valve clearances) I am expecting a slight increase.

 

Yep. I had to flip mine to "RES" right at 100 miles. They need to be switched to reserve after burning about 2 3/4 gallons of fuel.

I got close to mid 40s on mine when I rode very conservatively. Too much pegging the fun meeter and it would drop closer to 35. :wink:

 

I was keepin the fun meter good and up that day as we have very mountainous terrain here and real curvy roads. And no, I never switched over to res and it was bone dry, just went and got a can of gas and threw some in her and she fired right up.

 

IF your petcock is working correctly you would have still had fuel in the tank when the engine quit with the petcock set to 'run'.

 

I could see a little reflectoin in the bottom of the tank, but i tried to change it to reserve and turned it over a couple of times and it wouldn't start so I just pushed it home.

 

I believe the Reserve is held along the sides of the tank, probably can't see it through the gas cap.

If it ran dry, when you switch to Reserve, before the bike will start you have to refill the carb bowls (PRI).

(Yeah - that 'power band ' range will hurt your mpg!)

 

I got 53.78 mpg last fill up... But that's with a 400 and driving her like I stole it haha... Much Better than my truck at 16mpg

 

My 82 XJ650 has the same size tank. @ 100 miles I stop at the next station, so your mileage (about 32 mpg, assuming the 3.4 gallon tank it was fun and then dry) was actually decent for aggressive terrain.

More of a concern is that you didn't "run out" sooner and have to go on RES. That's an important feature, and it may be smart to have your petcock looked at. Since you didn't switch to reserve, that may have all still been in the wings (it's about .6 gall I think), so you just ran out of the non-reserve gas. Worth looking at just so you can be sure. I keep an external emergency refill on the bike when I'm taking any trip where I expect to stop for gas, just to be safe.

 

My 82 XJ650 with 28K miles consistently delivered 47 mpg last year in mixed city / highway riding. I am pleased with that performance.

 

82 Seca 750 goes 160-170 miles before I have to switch to reserve. Its apx. 4 gallons from full fo reserve.

 

Okay guys, went on a ride today, about 220 miles over some pretty mountainous terrain, Filled up at mile 22, filled up at 86 and ran bone dry at 168, my reserve did not work it seems cause it was bone dry, About 120 of it was very mountainous. Would that affect it that bad? It was a day of places like this. I'm thinking I may need to at least go through my petcock??

 

I am thinking your petcock standpipe may be missing or dislodged from the valve assembly within the tank. Without it, it's just like having two reserve selections on your valve. Drain the tank, remove the valve assembly to inspect the security and integrity of the standpipe. If it is cracked/broken, it can have the same effect. And if you do this, make sure you get a new o-ring seal. Chances are it will be too old and crushed to reuse.

Oh, and for what it's worth... I get between 160-210 miles per tank in my 81. But then again I am running the larger 750 tank on my Maxim.

 

Bingo. If the standpipe "filter" is missing or broken, there is no main/reserve; you're always on reserve.

Petcock tech: http://xjbikes.com/Forums/viewtopic/t=25058.html

 

Yea somethings up, gonna have to tear into it again, Let it warm up the other day when it was 85 outside and rode to the store about 3 miles and went inside for about 15 minutes, then came out and it was very flooded. I did change the exhaust and haven"t re-synced the carbs but I don't think that should give me these problems, I did have a fellow riding behind me tell me he was catching a buzz off my exhaust the first time I took it out this year 8O