Low-end blubber

[91kx]

Can someone please tell me how to get rid of the blubbery low-end throttle response on their bikes?I have a newly rebuilt top-end and crank with a PC pipe and silencer,stock reeds in good condition and switched the pilot from the stock 60 to a 55.I ride about 500-2500ft above sea level.I know it's not just mine 'cause the 98[with FMF pipe] I rode a year or so had the same problem.Any help would be appreciated!

[woodsy]

A couple of thoughts.  Make sure that your float isnt set to high, check the float needle (letting to much gas into the bowl), check your air screw adjustment (out is leaner), and drop the slide needle 1 click (move the snap ring up one groove).
Hows your air filter?
Woodsy

[91kx]

My clip is at the top groove of the needle,filter is clean.All appears clean inside.Is the kx 500 particularly sensitive to float height?I never adjusted or felt that I needed to on my previous bikes since they never had throttle response issues.How do you adjust and or measure?Thanks!

[John]

I have had the same problem with my bike. I re-jetted it and tweaked the float level so that the problem changed. The problem now, is when I have revved the engine and let go of the gas (engine brake or what you could call it on a two stroker) the bike gives me a couple of nasty pushes when the engine fires, not too god when on a motard in tight turns on tarmac. My solution is to not let go of the gas   or use the clutch. There is no idle on the bike but it still fires spontaneously when I "engine brakes". Could these problems be related? Any idea - anyone? This problem gets worse when the engine gets really warm.

The top-end is rebuilt, new reed cage, new spark plug, PC expansion chamber, no leaks etc.

Yes, the bike does not blubber in the low end but I seem to have moved the problem?

[woodsy]

John:
Your bike sounds closer to "normal" then 91kxes does.  That "run on" feeling is something that mine has had since new.  I found that getting the air screw set properly REALLY helps this issue!  I have recently found out that a flywheel weight REALLY improves on the 5's tendency to do this!
91KX:
 Sounds to me like some one has been doing alot of tweaking.  You may have to go back and untweak it once you fiqure out where all the fuel is comeing from, your WAY lean.  YES, the float level setting is crucial for low end performance!
I set my floats by "eye", take the bottom off the carb, lift the float up until it just starts to compress the plunger in the needle, make sure that the horizonal line on the side of the float is angleing upward away from the top edge of the carb (this will give you slightly less fuel in the bowl then the factory 15 - 17mm height).  I have heard that those little screws in hose connectors (the onesthat fit in the high speed jet plug hole) really make a nice adjusting tool!  
If you have never rode a K5 that perform's cleanly off the bottom YOU ARE IN FOR A TREAT!!!  THERE IS NOTHING THAT COMPARES!!
Woodsy

[mikesmith]

I found the best was to run the lean side on the pilot,and as woodsy says the floats set a little high( less fuel in the float bowl).Try one thing at a time and write down the results for a referance.

[Rick]

Once your jetting is set, purchase a moose spacer and a flywheel.  You will not believe the improvements...

Rick

[Paul]

The ONLY place I differ with Rick on the jetting and flywheel comment is at the track. I love the extra flywheel everywhere BUT the track, there I love the instantaneous, neck breaking, shoulder seperating snap of a badazz 500cc 2 stroker

[DrMojo]

Where is a good source for the Moose spacer?  Have a part number?

Al

[DrMojo]

I just purchased a Moose spacer from Monkey Butt.   Any tips on how to install it?  Let me known.

Al

[ShanMan]

I just purchased a Moose spacer from Monkey Butt.   Any tips on how to install it?  Let me known.

Al

Seeing as how I just did this, I thought I might tell you how it went for me....which is to say easy as pie!

First, just to clear the area, I removed the subframe so the airbox and all the other clutter is gonzo.

Then I pulled the carb from the boot and swung it out of the way. I recommend draining the fuel from the floats intentionally so that you avoid the mess of it draining itself later.

I unbolted the carb boot and reed cage from the back of the jug (cylinder).

In my case, I figured because I would be in there, I may as well install a new set of reeds. If you are just adding the spacer, simply place it between the jug and the reed cage. Be sure to use the fresh gaskets that come with the spacer. No sealer required.

Slap the carb boot back over the reed cage and bolt it all back up to the jug. Reinstall the carb into the boot.

At this point, kick the bike over to make sure everything is good mechanically. If it is, reinstall the subframe and you are done.

Side note: because of the reed spacer, the mouth of the carb will be closer to the frame tube than before, but there is sufficient space to get the airbox boot back in place.

Hope this helps.  

[DrMojo]

ShanMan,

Thanks for the info.
 
Al

[91kx]

Shanman let me know how you liked the spacer.

[DrMojo]

91kx,

I will let you know how the spacer works out.

Al