Engine knocking only in 6th at m id- high revs?

[Afriblast]

Hi guys, my blaster has a knock in the engine when in 6th gear and at mid- high revs. This is somewhat strange to me as the engine is "quiet" in all the other gears. The blaster is stock except for a Twin Air filter and the airbox lid is removed, any help would be appreciated!I:I

 

[Valhalla]

if the knocking is happening just before you hit the power band, then it is completely normal. your exhaust timing is off a little just before the power band and is causing the knock because the sound waves reflecting the fuel back into the chamber are off sync with the piston.

 

[Afriblast]

Thanks Valhalla, the only thing bothering me a bit is that it start when the powerband is just kicking in and then the engine start to lose power! It doesn't really sound like a mechanical knock to me, could it have something to do with the air/fuel mixture as it started when I put the Twin Air in and removed the airbox lid?

 

[Valhalla]

dont sweat it. perfectly normal. mine knocks as well and im running a K&n with no lid.

its easily fixed by going down a gear or 2 and bumping the RPM up a tad

 

[Afriblast]

Thanks for the help man!

 

[pittboss45]

What is the jetting? With the filter and no lid you can be running a bit lean at those RPM's

 

[Afriblast]

That was the thing I originally thought could be the culprit as I'm still running the stock jet, do you believe it could be it?

 

[cirame1]

definalty without the lid u may be runnign lean i would bump it up 1 or 2 sizes and see how she runs wats the plug look like?

 

[Afriblast]

Thanks, will get one or two bigger jets this weekend and will let you know how it goes!

 

[Valhalla]

i've went up 2 sizes to compensate for the increase in air and it still does it for me.

 

[quam]

well, you should check the jetting before running off and rejet the carb.
check the plug in that part of the throttle band.

 

[wrench man]

Mine did that too, I jetted it up until it stopped.

 

[Afriblast]

Ok so I will order 250&260 jets and take it from there, thanks you guys!

 

[Johnny Blaze]

I put a K&N in my blaster and a pipe and i had to jump to a 440 main. everyone thinks thats crazy but the plug color is good and she rocks socks. Jetting is EVERYTHING!

 

[blasterboy91]

dam i didnt even no they made jets that big...

 

[quam]

hey blaze, when you check the plug, you're checking at full throttle right? if you just idle the bike then check the plug, you're only reading the pilot circuit.