How fast have you gone on you're xj?

I recently replaced my stock 85 mph speedo with one off of a Honda 350 and it more accurate. It goes up to 100 mph now. Atleast I know I can go that fast.

 

The only way i was able to acheve that speed was a 20 mile plot of road straight and flat (west texas, there everywhere) not to mention the 5-10mph wind gust at my back and i gaught a REALLY good draft off the harley in front of me.

Thats brings up a good question. What is the margin of error for a motorcycle spedo at 145mph?

 

145mph? no way no how! I once owned a RZ500 that had 75hp at the wheel(two differnent dynos) and it was clocked at 138mph(unfortunatly by the police,big fine and I got to walk for awhile).I also owned a FJ600 and it was only good for an indicated 125mph but I think that it was closer to 115/120mph.
I dont care if you had a 50mph tail wind which dosent matter anyway after 50mph that isnt going to happen and running the bike at max rpm for 20miles would likly end with bad results.These are tough engines but that would be extreem torture for one.In fact when they test a new bike for top speed they only test it for a mile or two at the most becuase it is so hard on the engine.
These are the facts.

 

Ok I just hit 112 according to my tom tom and I almost shit a brick. not because of bike acting weird or fear of death or anything like that, but because I was just screwing around on a back road (strong wind at my back) and I looked down and saw it and was surprised because (due to the wind I think) it didn't feel like it and the bike was still pulling hard with plenty of power to go! I Love this thing!

 

100, I'm supposed to be able to do 130 when 5th redlines, but I get scared

on my xj700

 

ok with all due respect, the RZ500 and FJ600 were different gearing. the seca's were meant to race. that meant, having a sixth gear, slightly higher red line, top end gears, and being chain driven. ill have a video posted soon of a high speed run on you tube. also as far as the wind thing, you're right. i realized a 5-10mph wind at your back going 145mph doesn't really help your speed. Only that there is less resistance when moving. The wind would have to blowing 145mph+ to have any actual difference in top end. Thats not the kind of weather any one would want to ride in.

I do think a stage three jet kit, K&N air filter and Open pipes do factor into top speed.

I do not want to argue about this ill pm you when i post the video. thank you for your comment
thank all of you for keeping this post going.

 

I've gone 135 in a 77 monte carlo, (not stock) and boy did that feel like a boat ready to flip at any second.

On my XJ750RJ Seca (mind you I've only been riding bikes for two months and less than 500 mile overall riding) I've taken it up to 87 ish MPH. I only take it up there and then back off. When I get to the point where I feel confident in going past 100 then I will change my speedo Gauge. I love my bike.

 

On the 900, 104 MPH recorded with the Garmin. It was indicating 115. Recently I indicated 120, so about 110 actual speed. There sure is alot of wind out there !

I do think a 20 MPH tail wind would translate to about 20 MPH more speed, until you near red-line and run into the limits of the motor.

 

Josh,
I say this totally respectfully, and with no desire to impugn your integrity, but there is simply no way a Seca 550 was doing 145 mph.
Not even if you through it off a cliff.
Not under it's own relatively stock power.
I don't care what your WILDLY optimistic speedometer told you.
You did NOT travel at 145mph on a Seca 550.

I had a ZRX 1100, putting down 112.3 hp at the rear wheel (dyno verified) and she struggled to get above 150mph on the GPS.

My ZX-9R Ninja used to just touch 160mph, but she was laying down just under 125 hp and had a full aerodynamic fairing i could tuck under.

To stick to your guns, you'd have to convince us that your 550 found a magical additional 35 mph on top of a Seca 900, struggling to hit 110. (see post directly above mine). Not happening.

I still love you as a motorcycling brother, Josh, but your Seca has never gone 145 actual mph. Your gauges have deceived you.

Peace,
Christopher.

 

That was the top speed for ME, not the 900, which had plenty of pull left.
900 's have a taller middle-gear set. Florida has this law that 41 MPH over the limit is JAIL !! Separate cells for the bike and rider.

 

Thanks for the clarification Time.
I stand by my prior assertion on the Seca 550 and 145 actual mph.

I had an '86 Interceptor 500 that topped out at 129 mph. It had the highest hp to weight ratio of any bike to that date. they claimed 73 hp with a 12,500 rpm redline and just a hair over 400lbs, with a quarter fairing top and bottom. They also claimed a 135 mph top speed, but i never saw that and i used to pin that bike a LOT! I don't think many members are going to come in here and claim a Seca 550 is 15-20 mph faster than a Honda 500 Interceptor, are they?

My ZRX wasn't stock either. I use it as example here, because it is a prime example of a modern high-performance iteration of the standard UJM, similar in make up to our beloved XJs. It had a full Muzzy stainless system, K&N filter, jetted and shimmed to match, down one tooth on the countershaft sprocket and a Ted's 4 degree timing advancer. And i'm telling you it was a struggle to top 150 on my GPS on that bike. Is anyone in here still telling me a 25 + year old Seca 550 is hitting 145? Really? :lol:

I've just seen WAY too much anecdotal evidence first hand and read far too much other supporting information to believe that figure.

It is fun to dream though and i admire the adventurous spirit being displayed.

this country wasn't built by men in fear of speed limits.

 

That's it. After reading this thread, I'm strapping my GPS onto my handlebars somehow. My !@#!@% brand-new speedo cable snapped yesterday because the speedo support/input bearing is worn and sloppy and the odo gear would grab and bind up. Oh sure, all the teeth on the odo gear are now stripped so it shouldn't happen again, but I want an accurate reading at least once.

I thought the Seca 750's were rated for 137 mph top speed? I realize that I probably will fall short of that 27 years later but was that true or not?

 

I've broken 130 on my 81 seca 750. But we cut ~20 lbs of stuff off the bike, and i'm a skinny skinny man, for that pull.

 

Its been a while since I owned those bikes but Im sure that they both had six gears and were meant for "racing" more so than your seca.In fact the fj600is a bigger version of the 550 engine but in a sportier chassis.
As far as taller gearing goes,If that rz500 had had the power to use the stock gearing I think it may have topped out around 160mph but it didnt have that kind of power.That thing was geared so high that in sixth gear at60mph the engine was only turning 2500rpm,Im betting your seca is alot higher rpm then that at 60mph.Oh yea the redline was 10000rpm.
Think about it your seca probably put about 45hp to the ground if you are lucky and it is shaped like brick so I would say that 145mph is out of the question.
Oh one more thing,the new 600cc sport bikes put out about 95-110hp at the wheel and they can only manage around 150-160mph and I bet thats on a highly tuned one at that.

 

Hasn't this been done 3, 4 + times?

The TON... 100 mph (more like 170kmh)... Clocked by an R6, which shortly after passed me doing around 240-250 kmh.

 

My indication on the Maxim said 85, I'm sticking to that!
The ZZR will not go faster than the 152 I had indicated (with me @ 235 pounds on it).
I have only gone 1mph in the garage on the TL since I haven't ridden it yet (bought it in December).

 

I've had my 550 Seca up to 180! KPH! That's about 113 MPH. It will not pull to red line in 6th gear, no way, no how. It was starting to speed wobble at that speed so I've limited myself to 80 or 90 MPH max since. Last time I checked I couldn't find a legal speed limit over 75MPH in North America so unless I take up road racing my 550 is still plenty fast enough for me.

 

Really? My '81 pulls to redline in 6th (takes a little longer than in 5th) but then again I chucked the fairing. I've only had the '83 up to 90mph but I KNEW HOW FAST I WAS GOING! (Lovin' the speedo conversion.)

 

Cant hit 145 mph with my xj1100

 

http://www.xjbikes.com/Forums/viewtopic ... tml#117128

How about 148 MPH verified with an official timing devise??
Too bad this guy doesn't come around anymore.

On my first Seca 900, in 1985, when I was lighter, a guy had a prepped GSXR 750. Basically, he ran away from me. I indicated 135. He was GONE ! I also drag raced it, to a best of 12.8 @ 107 MPH. I weighed 220 LBS and the bike was never professionally "tuned".