KX500. non sealing exhaust header pipe

[WRXBRUMBY]

hey guys first post for me, and new to the KX500 beast. will a non sealing exhaust header pipe cause the engine power to cough and splutter from mid to top rpm?

[KXcam22]

WXR,
I don't think so.  As I recall, pipe sealing improves low end power. I suggest that you check your jetting with the jetting chart as a starting point.  It sounds like it may be too rich. Also check for an 8 heat range plug.  What oil and ratio are you running?  All these things interrelate to a certain extent. Hope this helps. Cam.

[WRXBRUMBY]

cheers for your reply cam. 

i am running 1 jet size below standard, 30:1 fuel mixture (this too rich?)
just had motor rebuilt seals/main bearings, new conrod, new cylinder plating with piston and rings. hehehe for an exhaust pipe that is not sealing properly she has crazy amounts of bottom end and a good half a hit of mid range. it feels like it wants to explode into band but just breaks up from there on. The bike was on its first ride since rebuild, and really my first ride on it as well( hehehe im still a virgin when it comes to the fury of the kx500 power band )

i tried to do second gear burnout on the spot just to have a controlled load variable to test it with and it did it exceptionally well in the bottom end but when i opened her up it just died. spark breaking down you reckon?

is there a timing advance on these machines?(sorry if its a stupid question) cause i feel that the issue is to do with rpm and not throttle load.

p.s this joints awesome hehehehe my first forum

[KX500freak]

hey guys first post for me, and new to the KX500 beast. will a non sealing exhaust header pipe cause the engine power to cough and splutter from mid to top rpm?

welcome 

i,m with Cam about the diagnose,
mine is also been mixed 30 to 1 by accident and that gave for my bike issues like yours.
excessive smoking too .

by reading the topic ,what premix what ratio,you may learn a thing or two.
lots of guys are on 30to1
lots on 40to1 including myself.

and check for right spark offcourse

freak

[KXcam22]

WRX,
  By my opinion 30:1 is far too rich.  I never run any of my engines at less than 50:1.  Use a good synthetic oil such as Belray MC-1 (my favorite) H1-R or equivalent.  Post back with your exact jetting, plug and riding area conditions, temp elev etc. My feeling is that it is just too rich.  Lets fix that before we look and timing and other things.Cam.

[kaw rider]

what oil are you using
how many hours or minutes on rebuild.

[Hillclimb#42]

Silencer is probably loaded with oil. search for the jetting on chart using search at top. It should be jetted close to chart after rebuild. Hows th air filter? Checked the reeds while apart?

[WRXBRUMBY]

Cheers kx500 freak will read up on it.

KXcam22?..
Oil: I use Motul 100% synthese, Offroad 800 ester 2T(hehe that?s what it says on the bottle)

Plug: BR8ES (NKG)
Riding conditions: 0-500m (0-1640 feet)

Jetting: Jet is one below factory ( soz I need to read up on how to check jet sizes I don?t know how to remove them, and check sizes)

Open to all suggestions cam?.cheers

Kaw rider
Bout 3-4 hrs since rebuild

Hillclimb 42.
Yeah ive seen jetting chart and will try to understand it when I know how to fiddle with the jets thanks. Will check air filter next and reeds are new. Air filter looked ok from inspection holes(are these breathers?) might have to pull it apart and see. Heheh only couple hrs since rebuild. I assumed he gave it a clean for me(im doubting it now)

[Hillclimb#42]

 There's a nut on bottom of fuel bowl. First you'll have to loosen the carb clamps and turn bottom towards you. Loosen that nut, gas will come out. then the little nut you see inside carb is main jet. take it out and look through it to be sure its clear. Its small, but you should be able to see light through it. The size is on the end.
  Alot of times, as a bike wears, you are forced to fatten up mixture and jetting to keep it tuned, but after rebuild, you have to find your way back to leaner settings.
  I would leave timing alone for now, but you could always pull the ignition cover and see that the timing marks line-up. There's three lines right next to each other on stator, one on case. Middle line of stator should line-up with line on case as factory setting.

[KXcam22]

WXR,
  The offroad mixing ratio spec for that oil is 50:1.  Correct plug but the BR8EIX will give you better performance.  I prefer the BPR8ES.  If you are just learning the carb it might be best to take it off the bike and play with it on the bench.  Then it is easy to see all the jet numbers. Cam.

[barryadam]

And fix that leaky exhaust connection, will ya.
Remove and clean it really well, get some new o-rings and use plenty of high-temp silicone.

Come to think of it, I need to re-seal mine, too.  My LHS Boot is getting a bit of coverage.

 

[WRXBRUMBY]

-50:1 i will try that cam thanks (geeze i hope your right hehehe ) is that because its good oil or just the factory specs and where was this information for future reference? just in case I change oils.

Have never really had proper oil bought b4 as my last 2 stroke bike was back in the 90?s and it was an 86 KDX which I used lawnmower oil on hehehe what a tank. Since then I have sinned against all things 2 stroke and have had a husky 610 4 joke. this has made me a bit lazy I suppose. But I didn?t have to play with the jetting on the kdx, so all this is new to me.

Now guys im looking at the jetting chart. Please excuse my ignorance ive heard things like pilot, main, primary and slow jet, also I have heard of idle jets. Just getting a little confused at the moment

What are the only ones I need to worry about and does the names like main and primary mean the same? As do pilot jet and slowjet?

I know the air screw hehehe whoopeeeeee. Pretty sure the needle clip wont be to difficult(that?s on the slide?) just names of the jets. Once I have the understanding of what the names are and their locations I should be ok.(the jetting chart looks quite informative)

[KXcam22]

Look on sudco.com.  I think they have some elementary carb descriptions.  Basically there are only a few things to check.

1. float level. Set it and forget it.
2. Main Jet - size controls mixture  3/4 throttle to  wide open  - this is the first one that you set.
3. Pilot Jet - size controls mixture  zero to 1/4 throttle - controls starting, low speed running and plug fouling.
4. Needle clip location. - controls 1/4 to 3/4 throttle - all midrange stuff. (need to verify you have the stock needle just in case someone changed it)

5. air screw - set at 1.5 turns out and forget it.

See its easy. Cam.

[Danger4u2]

Here's some good sites,

http://justkdx.dirtrider.net/carbtuning.html

http://www.keihin-us.com/tune.htm

http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/index.asp?nav=31200&country=US

http://www.duncanracing.com/techfaq/Tech_keihin-carburetion-jetting.phtml

http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp?nav=31000&country=US

[WRXBRUMBY]

thanks for the sites danger4u2. very informative 

cheers cam thanks for your info that is exactly what i needed your a legend.

and you recommend 50:1 with that oil (or is that oil specs from oil manufacturer?)

also that jetting table, is that specific for his type of bike;
-reeds
-pipe
-oil
etc........
or is it just a guide for a ball park figure for temps and eleveations that can be used whatever parts you have on your bike?