250-500cc Retard your timing?

try advancing it then

I'm scared.

is it hard to pull the flywheel - special tool needed ?

No/yes.

no. buy a flywheel puller. or you can make one out of a piece of plate steel.

Martin thanks for the picture. Looks real easy to do, just take cover off and two bolts.

So I took cover off and turned ring clockwise or in oppsite direction than motor turns. I only moved it the width of line marked on case. When I started the lines where lined up. How much can a person advance the ring with out doing engine damage or will it just start to run crappy first. I did not have chance to try out bike yet but next time at track I was planning just keep advancing it a little at a time since it so easy to do. I just do not want to go to far and hurt bike. I would like to improve throttle response off bottom it not bogging just slow to react to throttle input, its like I give it throttle and nothing happens for about the time it takes to slip clutch. But if I just wait it will just take off hard on it own with no clutch needed. Did anybody else notice that the ignition cover on the bottom flair out in a small spot so it does not seal completely like it meant to drain. I could see a problem if a person stopped in deep water crossing with bottom part off motor submerged. Thanks for any help.

More timing means more heat on the piston which means more wear. How ever, I sure you can go a little and bring the bike up to where it is supposed to run. Sometimes it is nessasary to richen it up a little to go along with the increased timing.
this is all stuff I learned racing boats, bikes may be different.
GP

Do you think the slow throttle response of idle could be cause by timing. I had bigger pilot and main jets in carb from factory and bike got alot more crisp after lowering both one size. Motor rips hard from bottom to top it just that 1/4 sec wait off idle or low rpm on bottom to get going that bugs me, there is no bog or burbble like it to rich or lean. My son 2010 yz 125 has no hestation off idle at all with same carb and make me think I could get my bike better also the yz just sound alot more crisp everywhere like Martin said his bike did after he advance his timing in a earlier post . I have got use to it and in corners open the throttle a little sooner at 1/4 way around corners instead of 1/2 way around knowing it will be a delayed response till it kicks in. Thanks for any help.

I've been lurking along with this thread, not saying much. But from what I see, there's a lot of guessing going on. Timing is just ONE tuning element. As I said before, easy to try, easy to return to original if it doesn't work out.

Pedec, so far, I'm not sure we know for certain that your throttle response issue is because the motor needs different timing. Maybe, maybe not. But how do you know? And I don't mean to be a trouble-maker. I just prefer knowing to guessing.

Has anybody looked into the squish distance these bikes are being delivered with? A TON of current production bikes from KTM, GasGas, and Husky are being sent out with really large squish distances and this just kills low rpm performance. Makes them idle poorly, run sluggishly off the bottom, hard to jet, spooge out the back, and so on. Correcting hard engine specs like squish probably should be done before messing with things like timing and jetting. You just can not jet out a bike with bad squish. Improve it, yes. Get it right... no. I went through fits getting my KTM 380 right until I figured this out. Worth looking into.

letitsnow, an old trick is to add mass/weight. In this modern age of making everything lighter, some weight might help. Running a steel sprocket, o-ring chain and heavy duty tube adds weight for the engine to turn. The usual effect is more traction, but also more control and less tire spin. Side effect: better braking feel because things don't lockup. I have done this for those nasty, greasy root and rock infested races, it works.

If your bike is running well, don't mess with the motor, there are other options.

Thanks for the ideas. My 2008 cr 125 has 160 psi compression cold with about 15-20 hours on it. The plug looks great light tan and motor starts first or second kick cold and first kick hot and idles great. Just a little spool at silencer after 1 practice and 2 races I only ride motocross in c class with it. If temp is 5-15 c I need to turn air screw in 1/2 - 3/4 turn in to richen off idle hestation it gets a lot worse if I don t. But at 15-30 c air screw is at 1 1/2 to 1 3/4 turns so pilot must be close. Bike goes from bottom to top very fast and smooth once it start to get going. I still have stock gearing and weigh about 195 pounds which might be why it has hard time to get going but when I am on my boys yz 125 it has no hestation at all as soon as you move throttle it starts to move and gets into the powerband fast. I did put walleybean yellow and green powervalve spring in which help get into powerband sooner and last a little longer but did not help off idle hestation. I did not move nut on powervalve linkage and might move it up and see if it helps sound like it helps on wr model. Thanks again for help or ideas

Thanks for the ideas. For right now I am working on finding a better belt to keep my skirt out of the spokes...

lmao