which gas?

[barberad]

I always wondered about this. I have found out through this site and others that the gas was a differant blend when our bikes were new. As far as the cost goes, in a five gallon tank the differance in price is like the cost of a candy bar, which I don't really need anyways. When I was in Japan, alot of gas stations had what they called "Super Hyaku" or super 100, I really don't think it was 100, more like super unleaded w/ techron. It would really make the bike move though, at least at $1.40 a litre (4 years ago) I would tell myself it did. So most of my buddies and I would run the base service station gas (87) and every couple of tanks put some japanese high test in. Here in UT they have 85, but I don't think I want to try it. Either way, I generally fill up before I get to reserve. So unless you put a tank on from a "Concours" you only going to get about 125- 150 miles from a tank.

[madmax-im]

Well with my '82XJ with rejetted carbs and 4 into 1 exhaust and 4 k+n pod filters I am getting 160 miles before hitting reserve so all told I could come close to 200 miles per tank.Before I did any mods this bike did get 50 mpg..now its abt 45mpg.All that on Regular unleaded 87octane.I've never had any problems with it knocking or loss of power.Never had premium in it...will run seafoam thru nowadays.

[barberad]

Hey Max, I read " My XJs' in the Hosp. ", So technically your gas milage is either really good or really bad right now. I guess it just depends on your perspective
Hope she's back up to full power again, soon. I'll give 87 a try.
Dan

[Ivan]

Originally posted by Crazcnuk
There was an issue with '80-'81 XS11's 'knocking' at between 3500 and 4000rpm. They said this type of detonation does not harm the engine. However, they made a replacement Vacuum advance unit to get rid of it. 3H5-81683-09-00 Is the replacement part number, but I doubt any are available any more.

Sumnabeech!

Was wondering why mine knocks like that. Didn't sound like a true knock from a bearing or the crank thrust bearing. If you don't mind, what did the updated advance do? just retard the timing a bit at that RPM?

Also, if the selection of fuel within 4 octane causes a ping, it may be time to consder putting in the next step cooler sparkplug. Just an idea.

[randy]

I had that issue with my '81 SH. I raised the slide needles with washers and the ping disappeared.

[madmax-im]

Originally posted by barberad
Hey Max, I read " My XJs' in the Hosp. ", So technically your gas milage is either really good or really bad right now. I guess it just depends on your perspective
Hope she's back up to full power again, soon. I'll give 87 a try.
Dan

LMAooo yeah it kinda sucks...I just installed a Jardine 4 to 1 and when out test riding ...the bike just bogs worse than it did before with the MAC exhaust...so into the shop he went...I should have him back next week.In the meantime my '81 XS1100SH keeps me preoccupied...not to mention my Honda ST1100 but I still cant wait to get him back...its been a long time since he has run right so we will see....BNE

[Crazcnuk]

Ivan, I am not sure whether it retards the timing, or just changes how/when it comes on/off.

There is a bulletin about it on the Yamaha parts site. It's the very last tech bulletin in the list for 1980 G models.

Randy, so you made it richer to get rid of the 'knock"??

[Ivan]

You wouldn't have a link to the site? Every time I try to find the Yamaha factory stuff, all I see is golf carts and Star motorcycles.

[Luxury]

I run 91 because it's the only stuff around here that doesn't have ethanol. I was under the impression that the materials used in older fuel systems (seals, hoses, etc.) don't like ethanol. Maybe that's an urban legend.....

[Ivan]

Older stuff used to have trouble with alchol in the fuel. Mostly float needles. Alcohol would deteriorate them and then the bowl would overflow. When alcohol in fuel became more commonplace, they started making the needle tip from Viton, IIRC, and it doesn't deteriorate.

[Crazcnuk]

Alcohol could deteriorate some of the older rubber (synthetic?) materials over time.

They (the powers that be) determined there was a 'safe' level of alcohol that would not harm anything in any vehicles, and that is what you see in most 'alcohol blend' pumps.

It's something like 10% alcohol max, or whatever.

I run a tank of the Mohawk alcohol blend gas through the car every once in a while, just to keep the tank free of water.

[barberad]

Ivan, I think this is the site you want
http://www.yamahaaccy.com/parts.aspx, one of the Kind people from here at XS11 turned me on to it. Put your type/year/model in and on the change assembly drop down box scroll all the way to the bottom. That's where the tech. bulletins are.

[randy]

Randy, so you made it richer to get rid of the 'knock"??

That's exactly right. It was quicker than re-jetting and it worked, so I left it that way. ran fine after that for 5-6 yrs 'till i sold it. Consistent 33 MPG, wasn't too bad for a Special running 90% of the time in NYC traffic!

[xs11lover]

My 78's and 79. Need the good stuff or they ping when really getting on it. the 80 and 81 specials I had liked cheep gas & I think it lasted longer than Hi Test. I wonder if it has anything to do with the carb change?

[xs11lover]

Oh yeh, I've been getting 93, the highest I can buy, and adding octain boost. I seems to work nicely.