Losing power beyond half throttle

[Stinger02]

I just got my kat on the road last weekend at its running well except that if i twist the throttle beyond half way, the bike starts to choke and kill. What would cause this? Carbs? Air filter? Fuel? Thanks for any and all help, havent had a chance to track it down yet, weather has been rainny here the past few days.

[arsenic]

[Kfreak]

When you say loss of power..... meaning engine bogs down then picks up at a certain throttle position? Or does the motor just die... shut off? What's the bike? 600? 750? fuel injected? Carb?

[arsenic]

has a "kat" ever been FI?

[Kfreak]

Well..... with all the crap people do to their bikes, you never can tell anymore.

[Trackerrrr]

Float levels could be set way low. Main jets or emulsion tubes might be clogged also.

[Stinger02]

oh im sorry i forgot to add that tid bit, its a 2001 750, its carb. It bogs bad and doesnt recover. It doesnt flat out kill the motor because if you back down off the throttle the engine recovers just fine and continues to run, but if you turn the throttle again beyond half way, it bogs, and if you hold it there im guessing it would bog down till the point that it would stall.

it does smell a little rich, ive never touched the carb, not saying that someone else hasnt, but i had to cut the choke cable off because it was frozen and replace it, so im thinking no one has messed with the carbs due to lack of maintance. As far as I can tell the exhaust is stock.

[Robgsxf750]

Make sure it doesn't have a K&N filter in it. I had one and this sounds exactly the same problem I had.

Arsenic - in your picture, what's the difference between the 'needle jet' and the 'jet needle'?

[arsenic]

ones the needle itself, one is the "emulsion tube"
jet needle = needle
needle jet = emulsion tube

[IndyGunner]

Cut the choke cable off???

[Robgsxf750]

Gone over 2 months Ed not smoking. Good for you!

[The CyberPoet]

oh im sorry i forgot to add that tid bit, its a 2001 750, its carb. It bogs bad and doesnt recover. It doesnt flat out kill the motor because if you back down off the throttle the engine recovers just fine and continues to run, but if you turn the throttle again beyond half way, it bogs, and if you hold it there im guessing it would bog down till the point that it would stall.

My guess is that there's a combination of things going on -- plugs starting to foul AND the mix going way too rich.
I'll also guess that at some point someone put in a DynoJet jetkit and didn't tune it well, PLUS they used the DynoJet jetkit springs (rather than keeping the stock springs), so the diaphragm slides aren't opening at the rates they should be under normal use.

Step 1: Remove the needle, examine it. If it has more than one slot in the top of the needle, that will tell us what kind of needle it is. Count the number of slots, and examine the tip (blunt vs. sharp) and report back... Note DynoJet and K&N brand needles are the same thing (K&N sold DynoJet brand with their own packaging for a while). All will have the plastic & metal washer that you see on the OEM needle in the picture...


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Meanwhile, Arsenic, that's a great graphic you posted in the second post of this thread -- mind if I swipe a copy (and ask where you got it?)

Cheers,
=-= The CyberPoet

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[IndyGunner]

Gone over 2 months Ed not smoking. Good for you!

thanks

[arsenic]

I got it at gixxer.com, go for it CP Pre 98 Katana, the DJ kit's don't have the different springs, that's only 98+.

[Stinger02]

wow lots of good info guys, gonna have to get with a buddy or someone that knows how to take all of this stuff apart, never messed with carbs before. How do you get to that needle?