My XJ650 struggles to reach 90mph..

Hi gang,
Not that I am a boy racer but I find when on the M50 motorway that I can cruise away at 75mph but she seems to struggle to go past 90. The wind can also play a factor. She only has 26000 miles clocked on her..
I generally don't tend to go past 90 at my age but every once in a while its nice to have that xtra umph when overtaking.
Can anyone tell me whats the norm.. Is she capable of doing more.?
And if so..why isnt she.
I'm just wondering that's all.
Thanks,
Morg.

 

While I don't have a 650, members have claimed 120 MPH.

After re-assembling my carbs on the 750, I had a diaphragm that wasn't seated in it's groove, thus that slider wasn't helping out under power, yet it would idle perfect. To check this, on the bike, retract your intake boots into the airbox, seal the "kidney" vent with your thumb and cycle the slider piston. They will fall slower with the vent sealed than without. If one falls fast- there's your problem.

 

Thanks TimetoRide.
Will give it a go..
Just wondering also.. One of my plugs is a lovely tan brown but the other three are more of a chocolate tinge.
If the carbs aren't in synch would this also cause a struggle.?
Cheers,
Morg.

 

Something's definitely not right.

An XJ650 should go 90 no problem at all.

 

yea... you should be able to hit 90 in like 4th gear....

not that any of us have ever experienced it

 

You may want to close the Pilot some to match the "tan" plug color.
An eigth of a turn is considered a lot. This is going to turn up the heat and horsepower.

A bad sync is not an issue once the throttle blades are cracked open beyond "cruising speed"
How's your valve clearances, BTW ?? Hope you're not burning an exhaust valve. 8O

 

I am thinking the plug with the different color is the cyl. with the diaphragm issue.

Jeff

 

Power and High Performance depend on sufficient "Quantity" and "Precise Delivery" of Main Jet supplied Fuel.

Emulsion Tubes must be perfectly clean. Every orifice.
Diaphragm Pistons must be able to rise and fall without the least bit of drag.
(After scrubbing with ScotchBrite, ... I Polish the Bores with #5 & #6 Jewelers Rouge)
Fuel Lines routed correctly.
Fuel Gallery and Beenie-screens immaculately clean.
Verify porosity of any Inline Filter.
Float Levels within specs. (Confirmed via "Clear-Tube Method").

All other Mechanical Adjustments related to Peak Performance and Fine Tuning completed.

Coils, Wires and Plug Caps performing to specs.

Petcock Tower Filter clean.

Any malfunction-generating obstacle hindering the Carb Linkage from achieving W-O-T.