no top end

[ddewey78]

I am running a pwk and it seems very flat on the top end, almost like a lack of fuel problem, but its not. I have no clue how to tune this carb, where should I start?

[DieHard2Smoke]

could you give an example of whats going on, is it pouring out blue exhaust, poor throttle response, any popping going on... etc

[ddewey78]

its wierd, it just acts like no power, no smoke, throttle is crisp down low. it almost acts like its loading up. I upshift and it takes a split second to clear out and it rips, right up till im about 3/4 wound out. crappy explination i know, but its the best i can do

[Gmbond]

Is this something new, or has it been like this since you got it?

I ask because while my 500s are fast, they don't feel like they rev out like my 250 or even the 125. It's just the motor makes the power earlier and lower.


If its a new issue, I'd check your silencer packing, and repack.

[DieHard2Smoke]

very true, 500s are much faster if you take advantage of short shifting and using the torque to run a higher gear. unlike my 250 that you ring out to make good power.

my 85 has massive midrange hit, but if you let it rev out to max rpm it feels very weak. just how large bore single cylinder engines work... unless you port them for the moon

[AlisoBob]

Fat = Flat

Lean = Mean

[2strokeforever]

post up your jetting, including what needle is in there
silencer packing
reeds, no gap is aceptable
compression
sealed exhaust

[Tharrell]

Fat = Flat

Lean = Mean

Exactly what I was thinking.
Actually, I was thinking, Bob will be here soon about rich jetting.
Funny how the basics can make or break your ride huh?

[ZETTNORCAL]

I have a kx 500 running the same way. But it also surges (let off the throttle and Ping, Ping, Ping, ping..........) then when I get back on the throttle it has to clean out a little before it runs smooth again. I feel like it gets up in the RPM's but does not make any power up ther just noise? This bike has ran this way since i got it. I have gone up and down with the main jet and in and out with the air screw but never fooled with the pilot. 160 main seems to be the best so far
Starts right up cold with choke on no throttle. Needs the choke to run when cold first 2 mins. Starts up easy when hot. no throttle. even idles

???

[hoofarted]

Sounds fat to me.

[2strokeforever]

I feel like it gets up in the RPM's but does not make any power up there just noise?

if it really lean it will rev out good, but be way down on torque, top end torque, as in it wont be able to hold 4th gear up a hill

[ddewey78]

very true, 500s are much faster if you take advantage of short shifting and using the torque to run a higher gear. unlike my 250 that you ring out to make good power.

my 85 has massive midrange hit, but if you let it rev out to max rpm it feels very weak. just how large bore single cylinder engines work... unless you port them for the moon

This does make some sense. I did really notice it after riding my 00 250. That bike is by far the best running 250 I have ever ridden. So maybe swapping between the two made it more noticably.