I started to mess with the shock preload by giving the rear a few turns to add more tension to the spring. It seems preloading make the shock stiffer and sits a bit lower as it is preloading. My son is jumping the shiite of his JM150 and gaining lots of poundage so I am afraid he is going to bottom out the bike and put bad stress on the frame and other parts. Do I need to get a stiffer shock or will preloading take care of this problem?

 

Sorry dont know much about preloading the shocks. All I really know is they absorb the shock.

 

windtrader the preload will stiffen the shocks up stiffen the fronts up alot but keep the rear a bit softer so he can preload (so to speak) off a jump

 

<div class="FTQUOTE"><begin quote>Originally posted by: jetmotoracer

windtrader the preload will stiffen the shocks up stiffen the fronts up alot but keep the rear a bit softer so he can preload (so to speak) off a jump</end quote></div>

The kid is a jumper for sure. Loves the ATV track at the state OHVC parks, lots of air to be had. That is why I am concerned about setting up the suspension as best I can given the limits of a cheapo Chinese design and parts. Just figured I should do what I can to minimize / eliminate bottoming out as that has got to be bad for the bike. Just not sure if preloading reduces bottoming out. It seems like preloading reduces roll and makes the ride stiffer by reducing the range but does not really add more resistance to the shock when under the most compression.

Have you messed with adding air to the shocks? The '07 JM150 has air values to increase the hardness. I have no idea how much air is required, I think a lot, more than a bike pump can pressurize. This type of shock seems like you can reduce bottoming out by adding air.

 

is he casing the landings? and it seems to me when you a-just the preload it puts more upward pressure on the shock or putting more resistance in the suspention

 

<div class="FTQUOTE"><begin quote>Originally posted by: jetmotoracer

is he casing the landings? and it seems to me when you a-just the preload it puts more upward pressure on the shock or putting more resistance in the suspention</end quote></div>

Not sure what casing the landing means. If you mean he is hitting so hard the frame hits the ground, then no but it does not mean that he is not landing hard enough to compress the shocks all the way.

I thought preload meant you turn the large nut on the shock so that the spring gets more tension, thus the term pre "load". I think we are saying the same thing. If so, then the question still remains, does preloading make the shock absorb a higher downward load? I don't think it does. It just seems to make the suspension stiffer and keeps it flatter and rides a bit lower.

 

casing a landing is not completely clearing back tires completely onto the landing. if he isnt clearing it then this will cause him to land hard. and yes adjusting the preload will stiffen up the shock to an extent but if a 200 pound guy was riding it then you would need new shocks made to handle the weight but you said your son was young so i assume he is under 200 pounds. my 250 sits so low i take half the jump with me and if i wouldn't hit a whoop section just right it would bottom out the shocks and scrape the front end theirs no paint on the bottom any more. any way its a matter of style and shock. if its to stiff it will hurt. to stiff and it will ride like crap. by the way how old is your son im 13?

 

OK. He always clears landings since most big air jumps are on nicely designed and maintained ATV courses. I am just concerned that I don't want for him to cause damage to the bike from hard landings.

I think I won't preload it too much to keep the ride fairly smooth. Too stiff and rides too hard and puts more stress on bike since it is jolting more than softly absorbing the trail.

btw - He is 13 too but I'm not telling him you are on a 250. :-) He weighs 100.

 

alright sounds like a plan

 

Hey Jetmotoracer is your shift lever in its original postition or have you moved it to make it eaiser to shift?