Fastest 1100

[XJ Rob]

I was having a discussion with my Father about which XS or XJ was the fastest built. I told him if anyone would know it would be this group.
Before he started riding 1300 Ventures he owned 2 XS 1100's One was a 79 but we can't be sure of the model. The other was a 81 1100 midnight. I myself have an 82 XJ. I haven't yet had the pleasure of twisting the throttle that far. Only took a short ride to make sure the gears were ok.
I'm just wondering which one had the most H/P or which one was actually the fastest built.
Thanks
Rob

[CatatonicBug]

I remember a thread a while back that mentioned that the '78 XS was the fastest. It had something to do with the gear ratios, IIRC. After that year, the government required some changes that killed the speed a bit.

[DGXSER]

Everything I have read indicates the 78 like Catatonic stated. IIRC all of these bikes had the same gears, but the 78 had different cams and a valves than the later models. Others here know the exact details much better than I do. The 78 of course was a standard (no special available that model year) and the standard has a larger rear wheel at 17" diam. so more distance per rev than the special models.

Honestly, I doubt there are many around who will feel the difference or push one enough to see the difference. JMHO (Yes Tod, I know there are exceptions to that )

[81xsproject]

Close, the 78 and 79 standards had the same cams. The only difference between the 78 and 79 was timing and the size of the starter jet in the float bowls.

[crazy steve]

The '78 is the 'quickest' winner, hands down. It was the first mass-produced bike capable of turning sub-12 second quartermile times (a fact Yamaha used in their advertising; '...the XS11 will do 11's...'), managing a 11.79 in 'Cycle World's road test, although they did smoke the clutch by the time they were done at the strip. The quickest any of the later models could manage was very low 12s. I was told by a Yamaha dealer at the time that besides the tune, the '78 had a slightly better exhaust system (larger I.D. and a larger crossover). Whether that is true or not, I can't say.

Fastest? Well, I saw 140 indicated on mine (just once!) and it still wasn't done pulling, but I was running out of road..... and nerve.

'78E original owner

[tw1980]

Mine used to hit a wall at about 130.After I added a few mods it keeps climbing.My tires are only rated to 130.So I get a little nervous.I also made a promise to my tw(trophy wife)that I won't splat.Seems she still wants me around.Poor misguided girl.I don't know top speed but it hits 140 fast and is still climbing.Also Oregon puts you in jail if you get clocked at over 100 mph.Seeders beware! Terry

[81xsproject]

Yamaha parts catalog shows all the same numbers for 78 and 79 exhaust. The carbs are jetted the same (off the choke), same heads, same pistons, same cams, same gear ratio, same size tire, etc, etc. The only difference that I can think of between 78 and 79 is the timing advance. Speaking of, if anyone is interested, I have a '78 advance I am planning on selling soon.

[Montreux_Blue]

So does the 17" wheel make any difference as far as acceleration over the 16"?

[tw1980]

Hey 81xs

You interest me with your 78 advance.I assume you are referring to ignition timing.Why can't I just advance the timing on my 80.Why do I need a 1978 unit?Sorry if this is a rookie question. Terry

[The Lorax]

I think I read somewhere that the '79 F would do the 1/4 in 12.12, and the SF would do it in 11.95 the difference in rear wheel size as I understand it gives the special a quicker take off, but limits it on top end. I'm sure somebody will know the specs for certain, I'm basing my postulations on faded memory, I should go to the spec pages and see if it's there. have a nice day and ride safe

[Crazcnuk]

"So does the 17" wheel make any difference as far as acceleration over the 16"

Yes, the taller wheel will slow acceleration a bit, but increase top end slightly, if you have enough power to pull it there.

[The Lorax]

went back and re read one of the cycle world articles here on the website, said that the E ran an 11.82 @115 mph, the F was 12.06, and the SF was 11.93. not really a significant difference between the 16" and the 17", about a tenth of a second, but the special was also 15 lbs lighter, so draw your own conclusions, is it the smaller rear wheel, or the 15 lbs, likely both, but the E I do believe is the speediest of the bunch. have a nice day and ride safe

[Crazcnuk]

The wheel size difference is pure math.

As for the weight difference: Same rider? Same amount of gas? etc etc.

You can't go strictly by dry weight.

[DiverRay]

The E model had a different advance curve, as Jesse stated. I was running an "E" advance on my '79, and it DID make a little bit of a difference. Hard to tell, but I was riding the same roads every day to work. The bike seemed to change just slightly, and I had a little more grunt on one or two hills.

[Steptoe]

here,s something

I had a bearing dieing in my centre gear box,
have a spare in the shed,thru it in and now 100klm is 3500rpm whereas before 100 was 4000 so there must be variables in there to. not sure what model the new gears were out of though