Higher top speed

Hey guys, so I finally put a new clutch in the hog and all i can say is holyyy shiiit. I just fell in love with my bike all over again. I never realized it but the clutch was shot since the day I bought it. Now that shes gripping gears I can finally see what shes capable of. This is where I'm a little unsatisfied. I understand it's from 1982 but I bury the speedo in 4th gear and after 5th I always find myself looking for 6th but it's not there. My question, is there anyway to make the gears longer somehow or maybe a different final drive? The bike has more than enough power for another gear it really hurts my feelings when I'm in 5th gear at 10k rpm and I'm struggling to do like 120. I need a different speedometer anyways since this one only goes to 80. Does anyone know why they only designed the speedo to go to 80mph when they know damn well it can go much faster? What's the best option for a faster speedo. Will aftermarket be easy to install cause I've seen alot

 

You'd have to swap the final drive. I don't know if there's one you can swap to. Keep in mine that the higher ratio would put more strain on the drive line components. It will slow your acceleration. After all that, your might not gain top speed.

Some of the XJ/XS1100 bunch swap in the XS750 or XS850 FD to do just what you're asking about. The VMAX folks swap to European FD. I'm sorry I can't help with the XJ.

 

Almost all speedos were limited to 85mph in vehicles in the early 1980's. My 1980 Accord did the same thing. It is frustrating. It may have been federal legislation, but not sure. I believe the theory was that it would limit people seeing "how fast it will go" .... Stupid thinking.

Remember the national speed limit in USA was 55 mph at the time.

It was stupid. The speed limit here in SD freeways is now 80mph...

 

The federal speedometer thing was to encourage fuel savings. It was a psychological tool that mostly worked. Remember that we were in the middle of a huge recession, multiplt gas shortages, the very real risk of nuculear war. The 55MPH speed limit was part of trying to reduce the need for importing so much (very expensive at the time) oil from the middle-east and to some degree improve our national defense by avoiding the need to tap strategic fuel reserves.

As far as making the bike go faster.
You're going to need a full-fairing, more horsepower, or both. Changing the final drive won't help much. The 650 runs near her aerodynamic limit for the power the engine makes. The whole XJ line does for that matter. Heck, most motorcycles do.

 

So it sounds like it will be hard to find a longer gear final drive for the xj650..I doubt a little taller tire would help much but I guess it's something...its such a shame this bike is so limited with the 5 speed. I'd rather not make ever gear longer cause the low end on this bike isnt the best to begin with.

 

I have been looking at some fairings but it's hard to find something that would fit..I would love to fit on the fairings off of the turbo model but I feel like it's not a bolt on fitment

 

I won’t lie, more often than not, I wish for 6th gear to be there or to have longer FD ratio, but I also cruise on HWY 80-90mph.

However, I also noticed a lot of people on this board (especially newer members) make threads about higher top speed, making XJ faster, etc. IMHO you bought a wrong bike for your needs.
Treat it as cool (IMO) almost 40 yo bike with more than adequate performance for it’s age.

People keep snagging XJs because they are almost worthless value wise and then complaint that speed or performance isn’t as good as 90s sport bikes (which are also worthless).

Sell XJ and buy a sport bike.


P.S.

My XJ does 100 relatively effortlessly, have yet to try to make a top speed run but the way it felt at 120, it should be able to pick up another 5-10 mph if I hold it WOT long enough.

 

5th gear is pretty darned close to being direct-drive. Adding a 6th will lower engine speed for better fuel mileage, but it won't make the bike go any faster.

If you want a faster (top speed) XJ you need to be shopping for (in order of top speed gain) a 750/700, 900, or Maxim-X.

For a frame of refrence the XJ650 Maxim and XJ750 Maxim have the same gear ratios all the way through the driveline. The 750 makes a claimed 15 more horsepower than the 650. It goes around 5 MPH faster than the 650. Weight is a consideration, but it is a minor factor in this comparison.

The aerodynamics of motorcycles suck. More fast requires more power. A lot more.
The site I'm linking is meant for bicyclists, but the physics involved are exactly the same for motorcycles. Look at the curve. Power requirements to reach a higher speed increase at an increasing rate.
power_v_speed.html

Somewhere in this search is all the information you are looking for.
search

 

Thanks guys....I definitely cant complain she does perform really well for what it is...I'm not trying to drag race the bike or anything ..I'm just used to modifying everything I touch. The claimed top speed for the bike is 122...I bet it's closer to 130

 

Probably not.
The Seca 750 has a claimed top speed of 127MPH, and both my GPS and the radar trailer agree.

 

Have to settle into the high rev sound of our bikes. They purr even at high rpm's and vibration is minimal.

When I drive my bike in a relaxed way going 55-60 on country roads I usually get over 50mpg. Something to be said about the national 55 and gas savings.

I agree with Pavelk313 regarding speed. If your looking for a raging speed bike you can find plenty of sport bikes out there. However, you'll notice the high rev sound the sport bikes make just like ours and may look for more gears on them as well. XJ's are fast reliable bikes considering their age.