MPG and modifications poll

[Ryan Stanley]

I recently swapped out the stock intake with those cheap $7 pods and some homemade velocity stacks using parts from the old intake. I have yet to rejet the carbs or adjust them in any way.

I just recently went on about a 7-hour roundtrip ride with this configuration, averaging about 65 mph, I'd say, though I had to keep slowing down for 25 mph areas. It took me less than two tanks of gas to make the trip, and I got an average of about 38.2 mpg.

Is this good mileage for an XS11H?

I will be getting the carbs rejetted and such tomorrow, and will be interested to see what effect that has on the mpg's. I also want to try the acetone thing. Will let you know how that works out.

[dbeardslee]

Ryan - That sounds pretty good to me. The best I ever got was 37.5, and that was all highway. I usually average 32.5, but that's with some pretty aggresive throttle twisting.

[xschop]

another test run

In my 1995 Honda civic, last summer, I replaced the blown head gasket because she started overheating. While I had the head off, I polished the chambers/valve faces and lightly ported the intake runners to give them that "brushed" look ......I was getting 35 mpg's before the head job and K&N filter, then 37 afterwards.....I was very happy since it was almost 200K on the clock after the rebuild......This last week or so, I ran a complete tank (13 gal) of Shell gas with 3oz of Acetone to see what would happen......41 mpg's avg!.......with an engine of 208K miles.....Anyone up in the high altitudes trying this yet?

[Korr]

My 78E only gets about 27mpg average i think...i usually have to pump at 110 miles if i don't switch to reserve. Only mods are a kerker exhaust and octopus removal that was there two owners ago. No idea if it's been rejetted or not. I could probly get 30-35mpg if i stick with a constant 65mph speed. I'm always changing speeds. In the city i'm only going 40-45 mph tops(speed limit is 35-40). As soon as i am on the freeway i'll get her to 70, 75, 80mph. It will always go back and fourth between those 3 speeds. That's probly why my gas milage sucks so much compared to everybody here. So how fast do you guys go on the freeway/highway?

[dbeardslee]

Korr - Could have something to do with SF and all those hills you guys have to deal with. I wouldn't want to be the guy who had to buy brake pads in that town .

[xschop]

SF Gas

Do they still add MTBE to your gas there? What's your ethanol % also.....

[snowdog51]

ace

tried it like it bike runs much better with
car does to.
bill



thanks to chop

[Korr]

I actually live in union city. My commute to work is pretty straight forward, no hills or anything, just lots and lots of cars and even more cars. I take the 880 south to work. Maybe it's cause i'm thirty and lost my patience or something cause i can only stand going 65mph for so long hahahaha The last four bikes that i had before the xs one was the 250 rebel i could only go about 70 tops, the one after was a 1994 honda magna 750 which is just as fast as the xs, but ate up a TON of gas on the freeway, next was a 1992 FZR600 which made me know for sure that i end up hurting all over after a 30 minute ride on a sport bike, next was a 1982 920 virago that i was not happy with the power and mainly small fuel tank. All those bikes i didn't mind going 65-70, but the XS will not let me go at those speeds for longer than 3-4 minutes...weird!! It really likes to go at 75mph minimum

oh btw, all of a sudden this week the bike is being more fuel effecient. i'm at 130 miles and could probly do a little more before reserve now woohooo!

[xschop]

lil' Acetone experiment

After soaking some old float valves in a mix of 50% Acetone and 50% crap gas from lawn mower (has ethanol) for a week, I don't see any deterioration on the little black rubber (I think these were from an old set of Yammy carbs). I also soaked an old gas petcock gasket (XS1100) and some stock fuel line for the last few days.....no problems even at a 50/50 mix.

[db_chambers]

Dave C

I have a 79 xs eleven special, 8200 miles, all stock w/ K&N air filter, and I only get 25-27 no matter how soft or heavy I throttle it. Kinda sucks for my 45-mile commute each way! Have to fill-up sometimes twice a day. What can cause such poor fuel mileage? I am new to this bike, my dad's/garaged and rarely ridden since 1983. Carbs gone over by bike mechanic. Please help! Thx

[dbeardslee]

Dave - This thread has some info on stuff that affects mileage - http://www.xs11.com/forum/showthread.php?t=746.

Have you checked your compression? If it's been sitting for a long time, chances are the valve seating surfaces are pitted. I got a pretty good improvement in mileage after redoing my head. Lapping the valves, cleaning the valves and ports, replacing the stem seals, and setting the valve clearance paid off. Made it idle nice and smooth too.

I think the head is one of the more neglected items when it comes to maintenance due to perceived difficulty (valve clearances are supposed to be checked every 6k). The carbs certainly have to be setup, adjusted, and synched correctly but the lift, duration, and condition of the valves controls how much of the fuel/air mixture actually makes it into the cylinder and has a big bearing on how efficiently it is converted into energy. If you're a decent mechanic, it's a pretty straight forward operation and a good project for those cold winter months. Something to think about.

[db_chambers]

Cylinder 1 has about 140 psi and the other three around 180ish, so I know it has that problem. Just dumped $1300 into getting it running. The mechanic mentioned something about sticky valves. I am not at all a good mechanic. How much should I expect to pay to have the head done? Shop rate is $68/hr. 27 mpg is better than the 16 I get with my diesel truck. Just thought it should get closer to 4o or so.

[dbeardslee]

Dave - You might check with Prometheus578 - He's in Olympia, and is affiliated with a motorcycle shop. He knows the 11's inside and out. I'd be careful about who I let work on a thirty year old motorcycle. $68 and hour seems reasonable, but not if your paying for someone's learning curve. Might be some other members in your area too.

The trickiest part of doing the head is messing with the cam chain (need a chain breaker/riveter). The rest of it is pretty straight forward. There's plenty of good info on this site to get you through it if you decide to try. The great thing about winter is, with no one riding, you'll get really fast replies to your posts

My advice is to do what you can yourself. Not just from the financial perspective, but because thirty year old bikes can be pretty cantankerous. It pays to know how to work on 'em, as you never know when some little thing will give you trouble on the road. I like to carry my mechanic with me.

[xschop]

bad gas

I see you live in Oregon. What is your altitude there. Also Oregon may have the same laws as Cantafordya for fuel additives. But your culprit just may be the coils. Go thru the steps to test them from the book specs. You would be surprised what a new set of aftermarket HP coild will do for these old bikes.....JAT

[Yahman]

db_chambers, Nice to see a new member in this part of the country, welcome to the community.

You're getting about the same mileage that I am. My XJ runs great, but the mileage could be better. I just got it running this summer and will have to live with it that way until the winter of 2009. That's when I plan on doing a complete frame up restoration.

Larry