the quest for better MPG

[vedgar]

road test of 80 SG

In the day road test showed and average mileage of 42.7. 22 is NOT GOOD

[crazy steve]

In the day road test showed an average mileage of 42.7. 22 is NOT GOOD

My bought-new '78 never managed to get over 40, and only hit 40 once, even after complaining to the dealer and having them attempt to increase mileage. Those original road tests claimed 47 mpg on the highway and the number of owners here who have reported even getting close to that number can be counted on the fingers of one hand. I'll agree, 22 is low, but high 20s in town on a properly-tuned bike isn't out of line. These bikes were built as performance machines, not economy kings.

If mileage is the main reason for owning a bike, buy a Harley; my '93 1200 Sportster routinely delivered 60 mpg when stock, dropped to 50 after souping it up with big cams and hipo heads....

And the link to the recommended coil replacement is here... http://www.xs11.com/forum/showthread.php?t=4868

[motoman]

When bought new, was told my Venturer was a 50mpg bike. I'm sure the double-nickel speed limits(+5mph) keep it close to that, two up, fully loaded down on LD rides, but I was really diisapointed back then getting only 45-47mpg. Fuel then also had more 'bang'. Combine that with the slower speed limits and mid to high 40's fuel mileage was the norm on these ole' scoots.

Fast forward to today, with higher speed limits and less 'bang' from the fuel, that same bike, two-up, same load runs in the 36-38mpg range with an occassional 41mpg.

[alaskey2]

I got my SS brake lines from here

http://www.technafitstore.com/category-s/39903.htm

[mack]

carbs

Where are your C clips set on your jet needles. My SF gets 38-43 mpg depending how I'm riding it or if I'm two up. Something is very wrong if your getting 22. Check the easy stuff first:

How's your air filter, you got a mouse nest in there?
Check jetting for sure. (including your air jets)
Check timing.
Spark plug gap, caps resistance, try new plugs
Do you have any brake drag?

[James England]

I would recommend using green 3ohm Dyna coils to replace the ignition coils and ditch the ballast resistor for good. I also always replace the plugs with iridium plug and remove the resistors from the HT caps and put a piece of copper wire in there. Also, I use graphite-cored, silicone HT leads.

I always do the above on every bike I have...including two XS11's, XJR1300, GL1000. I wrote a guide here on fitting Dynas onto the XS1100. It's dead easy.

I don't know what you pay for iridium plugs over there but I have a source here for them at 34 Canadian dollars.....

[James England]

Oops..I thought you were in Canada. But actually USA. No doubt iridium lugs are cheaper over there anyway...like everything else. I bet you're not paying $8.79 a gallon for gas....

[James England]

Where are your C clips set on your jet needles. My SF gets 38-43 mpg depending how I'm riding it or if I'm two up. Something is very wrong if your getting 22. Check the easy stuff first:

How's your air filter, you got a mouse nest in there?
Check jetting for sure. (including your air jets)
Check timing.
Spark plug gap, caps resistance, try new plugs
Do you have any brake drag?

+1 on that. Air filters can be very clogged and make a big difference. I'd replace it if dirty.

Iridium plugs have a built-in resistor so if he fits them, he can remove the resistors in the caps.

The OEM setup of cranking a 3ohms and dropping to 2.2 once the starter button is released isn't ideal, IMO. Especially when running at 3ohms is so easily achieved. If the ballast resistor stops working, so does the bike, so that's another reason to get rid.

On all of my XS11's I've found the OEM spark to be pretty weedy..straw coloured and weak and that's at 3ohms. On my brand-new one, the coils stopped working after 3 months. The Dynas are far better than the Mike's XS ones which have achieved a certain notoriety here.

Green Dynas, iridium plugs, no resistor in caps and silicone graphite HT leads result in a whopping blue spark. I doubt that this alone will cure the 22mpg but it will certainly help, along with check everything else. A fat, healthy spark must improve combustion.

I'm also wondering re float levels?

It's possible that someone has mucked about with the jets and needle position too. Checking the diaphragms would be a good idea too. Personally, I'd take the carbs off and clean them and check all the jets etc.....

[mack]

Coils and plugs

I don't want to steal this thread, but ask a question of James. When you started running the hotter coils and plugs, did you find that you had to tune the bike slightly richer than stock to compensate?

[kevxs]

my needle clips are in the middle position, jets are stock, I've replaced the air filter with a k&n, i'm sure giving it a cleaning won't hurt. i dont think my brakes are dragging, front spins freely, rear not as much. should a rear wheel spin more than 3/4 of a turn after spinning by hand and releasing?

[James England]

my needle clips are in the middle position, jets are stock, I've replaced the air filter with a k&n, i'm sure giving it a cleaning won't hurt. i dont think my brakes are dragging, front spins freely, rear not as much. should a rear wheel spin more than 3/4 of a turn after spinning by hand and releasing?

No, re the rear wheel, you're turning the wheel and rear gearbox in oil, drive shaft too. They all drag and it sounds fine.

[James England]

I don't want to steal this thread, but ask a question of James. When you started running the hotter coils and plugs, did you find that you had to tune the bike slightly richer than stock to compensate?

The iridium plugs are the equivalent of the BP6ES, so they aren't a hotter grade. The coils are producing a fatter spark but that shouldn't really affect heat.

No, I didn't do any other tuning on the XS1100 or GL1000. I noticed immediately better starting on both bikes and a mysterious 'cough' which would appear occasionally, and which I'd assumed was carburetion, disappeared entirely on the XS1100. The engine felt more responsive but of course, there's always the placebo effect to think of! Definitely better starting, no cough and no problems.

I've fitted them to my XJR along with iridium plugs etc, even though the OEM coils worked fine. Again, I didn't retune and it all was fine on the gas analyser of the Dyno.

With the Dyna coils and leads etc, you're basically getting a bigger, healthier and more powerful spark and that must be better for combusition. I suppose if someone has had poor combustion and then starts mucking about with the jets as a 'cure', then a retune might prove necessary after fitting Dynas. Easy enough done and probably best to check anyway...

[jetmechmarty]

I suppose if someone has had poor combustion and then starts mucking about with the jets as a 'cure', then a retune might prove necessary after fitting Dynas. Easy enough done and probably best to check anyway...

That is why it's always best to eliminate the electrics first.

[James England]

That is why it's always best to eliminate the electrics first.

A lot easier too.

With that 'cough', I could have torn into the carbs, messed about with jets, float levels etc etc....and really messed things up. Many POs will have done things like this, them offloaded the bike. Same goes for the starting...whilst it was never a problem, the engine had to crank over a few times to fire up. I could have spent time and money on the choke plungers and essentially wasted both. The Dynas cured both. After fitting them, the engine fired so fast that I hardly heard the starter motor turn the engine.

I fit these coils as a matter of course now. My XJR has the 2.2ohm grey ones. The XS1100 is effect for the green 3 ohm and trashing that ballast resistor. I don't like having hot things that close to the fuel tank anyway! A bit primitive too...wasting as heat current produced by the generator. Better that the current should power the coils and produce a nice zap.

I've said this before but I had a whack off green Dynas, through a gloved hand on the bars and wearing boots. I was checking the spark by grounding the plug on the head. The current earthed through the glove and my boot and I had a hell of a shock on both! My girlfriend was horrified...she's a nurse and told me that 8 people a year die in the UK from licking 9v batteries to see if they have any charge! It produces arrhythmia in the heart and stops it........

[jetmechmarty]

Note to self: STOP LICKING BATTERIES.