its got the SHAKES!

[synergycycle]

So my ktm 250 sxf has a little problem and I was hopeing some of you could help me out. when I go fast (4th gear) through some bumpy sections on my bike I get this uncontrolable speed shake! its kinda scary and I wish it didnt happen. what causes that?

 

[sumx54]

Sounds like you need to adjust your rebound on your shocks. Your tires are maybe not getting to the ground quick enough and the timing is throwing the bike off a bit.

 

[ghglenn]

Two factors. If the rear suspension's spring is too tight (preload), not enough sag, it can cause head shake to show up at high speed. The shock needs to be "in the stroke" to work well, not at the top.

Or, rider position/fatigue....Usually, this is main cause. The elbows need to be up and rider needs to be on balls of feet (attack position) otherwise, the bike will begin to get "feedback" from tired rider and start to "headshake".
Very common in desert racing, high speed over long distance....That is why most run steering dampeners like "Scotts"...


Hope that helps.

 

[TheLonelyIsland]

Two factors. If the rear suspension's spring is too tight (preload), not enough sag, it can cause head shake to show up at high speed. The shock needs to be "in the stroke" to work well, not at the top.

Or, rider position/fatigue....Usually, this is main cause. The elbows need to be up and rider needs to be on balls of feet (attack position) otherwise, the bike will begin to get "feedback" from tired rider and start to "headshake".
Very common in desert racing, high speed over long distance....That is why most run steering dampeners like "Scotts"...


Hope that helps.

thats alot of info! you ride moto-x?

 

[synergycycle]

Two factors. If the rear suspension's spring is too tight (preload), not enough sag, it can cause head shake to show up at high speed. The shock needs to be "in the stroke" to work well, not at the top.

Or, rider position/fatigue....Usually, this is main cause. The elbows need to be up and rider needs to be on balls of feet (attack position) otherwise, the bike will begin to get "feedback" from tired rider and start to "headshake".
Very common in desert racing, high speed over long distance....That is why most run steering dampeners like "Scotts"...


Hope that helps.

Im thinking its suspention, I messed with it a bit , THANKS!

 

[GasCan]

Head shake can also be caused by the front forks being too low in the triple tree's and many will raise them a bit. I have mine up about 1/4" above the top clamp. If adjusting these, re-torque the top bolts at 20nm and the lowers at 15nm.

 

[ghglenn]

thats alot of info! you ride moto-x?

Yeah, been around MX most of my life.

Also agree on checking the fork position in the triples, the bike's geometry is just as important.