XS400 top speed??

Vloukole

XS400 Enthusiast
Messages
57
Reaction score
0
Points
6
Location
Parys
Hi guys

What kind of speeds do you guys get at what rpm? My xs will go 120km/h (+-72mph) at +-8500rpm. I read that some people claim that their xs top speed is around 100mph. Are they able to reach such speeds and is mine therefore not tuned correctly? I cant see my xs reaching 100mph.
 
If you have sohc engine about 95mph is probably be about it.I don't know how many rpm you`ll be at though.You could probably get more top end by tuning and rejetting the carbs along with a 2 N 1 exhaust system.
 
Will I be able to use one of my mufflers and just fab a 2 into 1 header? The exhaust is not stock. Pipe is atleast 1.5".
 
I have a stock 80. 95mph was what it topped out at i believe it was around 9000rmp. I could have gotten 100 but id rather not push the bike a those rpms for long. Not to mention 100mph on such a small bike is sketchy.
 
I would say it is a transmission thing. What sprockets do you have?

Another suspect of course is the speedometer. Most of them are not very exact.

With 16 / 39 sprockets you should have 100 km/h at 6000 rpm (6. gear, XS400 SOHC).
 
Yeah I forgot to mention that yesterday regearing your sprockets will get you more top end speed as well.
For more top speed you would want to decrease the number of teeth on the rear, or replace the rear with the same and put one with a tooth or 2 more on the front.. vice versa for more torque/acceleration witjh a little less top speed. Its all preference which to do but ive read on this forum that the front is easier to change and swap out if you dont like the result
 
The fastest i can get "cranky" to is about 85mph in full tuck and Wide Open Throttle (and even at that you could time how long it took to get there with a calendar). I have stock sprockets and dual exhaust. I am fat and old so i think going faster on this bike will require my fat butt loosing weight... but that's why i have my SV1000
 
RM, weight only effects the rate of acceleration, it has no effect on top speed. I'd suggest looking at your carbs and jetting. You should be able to do better than 85mph. I have no problem doing 85mph with a large windshield and fully upright riding position. And I know that my jetting isn't dialed in perfectly...
 
... My xs will go 120km/h (+-72mph) at +-8500rpmv ... I cant see my xs reaching 100mph.
If your bike is geared to go 72 @ 8,500 rpm it will need to rev @ 11,800 to reach 100 - but if your redline is 10k, your top speed has to stay under 85 mph.
 
Fastest My bike has gone is probably 110mph, friend went out after I first got it and opened her up. Needed to blow out the cobwebs. :) He said when he looked down at the speedo it said around 110 and there was still some throttle left. Plenty fast for me!

78 XS4002E
 
110mph what did you do to it?[/QUOTE

The bike is all stock, stock gearing, it may have taller tires than other bikes or the speedo is off at higher speeds, I know at low speeds my speedo is off by one or two MPH. Plus at 110mph it was pushing 9000RPM, pretty close to death for the SOHC.
 
Back
Top