KX Riders

Maintenance & Technical => KX500 Original => Topic started by: WRXBRUMBY on May 31, 2008, 09:19:31 PM

Title: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on May 31, 2008, 09:19:31 PM
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?
Title: Re: KX500. non sealing exhaust header pipe
Post by: KXcam22 on June 01, 2008, 04:01:20 PM
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.
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 01, 2008, 07:05:09 PM
cheers for your reply cam.  :wink:

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 :oops:)

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
Title: Re: KX500. non sealing exhaust header pipe
Post by: KX500freak on June 01, 2008, 08:21:38 PM
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 :-D

freak
Title: Re: KX500. non sealing exhaust header pipe
Post by: KXcam22 on June 02, 2008, 06:38:01 AM
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.
Title: Re: KX500. non sealing exhaust header pipe
Post by: kaw rider on June 02, 2008, 08:50:40 AM
what oil are you using
how many hours or minutes on rebuild.
Title: Re: KX500. non sealing exhaust header pipe
Post by: Hillclimb#42 on June 02, 2008, 09:59:53 AM
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?
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 03, 2008, 12:06:06 AM
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)


Title: Re: KX500. non sealing exhaust header pipe
Post by: Hillclimb#42 on June 03, 2008, 02:11:46 AM
 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.
Title: Re: KX500. non sealing exhaust header pipe
Post by: KXcam22 on June 03, 2008, 06:05:48 AM
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.
Title: Re: KX500. non sealing exhaust header pipe
Post by: barryadam on June 03, 2008, 07:24:08 AM
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.

 
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 03, 2008, 08:04:13 PM
-50:1 i will try that cam thanks (geeze i hope your right hehehe :lol:) 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)
Title: Re: KX500. non sealing exhaust header pipe
Post by: KXcam22 on June 04, 2008, 03:25:10 AM
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.
Title: Re: KX500. non sealing exhaust header pipe
Post by: Danger4u2 on June 04, 2008, 09:32:51 AM
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

Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 04, 2008, 03:17:05 PM
thanks for the sites danger4u2. very informative  :wink:

cheers cam thanks for your info that is exactly what i needed your a legend. 8-)

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?

Title: Re: KX500. non sealing exhaust header pipe
Post by: KXcam22 on June 04, 2008, 05:23:48 PM
WRX,
  The jetting guide is exact.  I spent 5 years fine tuning my jetting only to arrive at the exact guide settings. Treat it as the gospel for stock to almost any combination of BOLT ON performance stuff.  I had the gnarly/reed spacer/reeds/mild porting setup and it was still perfect.  The 50:1 is off the manufactureres web site.  Remember that oil burns much hotter than gas so the idea is to run the least amount of oil that still gives good lubrication.  IMO the 16:1 and 32:1 days are gone (with my dads 1950 outboard motor).  A good synthetic allows leaner mixtures for less heat with better lubrication qualities.  My outboard specifies yamalube at 100:1.  If you are concerned about the oil I can vouch for Belray MC-1 at 50:1 for a nice long engine life.  Hope this helps. Cam.
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 05, 2008, 08:56:02 PM
thanks cam, and the rest of you guys. You have given me confidence to have a crack. i will be doing carb this weeked i hope if time permits.

cheers for the help with the carb and jetting. im pretty good from the reeds onwards with the mechanicals and the like, its just the tuning and performance part of it that i lack. this might give me the missing piece of the jigsaw ive been waiting for thanks.  :wink:

i will let you know how i get on.

heheh soz more questions............

better to set the jetting to the colder temps or the higher range temps we have here in Aus. cause we range from 0 all the way to 40 degrees celcius (depending where you ride)

is jetting kit worth buying?

what should the plug gap be? (soz havnt got manual yet. and by the looks of it you guys have more info neways)

thanks
Title: Re: KX500. non sealing exhaust header pipe
Post by: Hillclimb#42 on June 05, 2008, 11:38:55 PM
Its just important to know where you are. If you set up for warmer temps, then you'll be lean when it cools off. It will idle higher, run better off of idle and may have pinging on top-end. If you go by your cooler temps, ( much better for engine) it may run fat during peak of the day. (Less throttle response, choppy or bogging traits will be a little worse.) Usually you can find a happy middle and adjust mixture screw to compensate for temp changes. Worse case scenario, you will be to change main jet out in the brush. If you are pinging while pinned, (leaning out) or bogging and never cleaning out while mashing it(rich) you can change the main jet pretty easy, by method I wrote about earlier.
  I only change my main for winter riding in extereme cold, so you probably won't have to mess with it much. Learn all you can about reading the colors on spark plugs. You'll be an expert in no time. By the way you really need that Owner's Manual. Guys on here are true KX experts, but that manual gives you confidence when wrenching on the parts of the bike you haven't been in before. It also lays it out in an order that makes the most sense for disassembly and reassembly. It has many lists of factory spec.s that vary from year to year.
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 06, 2008, 12:26:38 AM
thanks for your post hillclimber. this is all gold information. cheers. :wink:

Title: Re: KX500. non sealing exhaust header pipe
Post by: KXT500 on June 07, 2008, 03:20:13 PM
so where is this jetting chart?
Title: Re: KX500. non sealing exhaust header pipe
Post by: GDubb on June 07, 2008, 04:50:05 PM
(http://www.kxriders.com/coppermine/albums/userpics/10482/kx500jetting.png)
Title: Re: KX500. non sealing exhaust header pipe
Post by: barryadam on June 08, 2008, 04:40:23 PM
I found the jetting guide to be "right on".  It gets you to the right carb settings immediately, which combined with the "how to start your 500" sticky somewhere around here, will make having that 500 a whole new experience.
I now have flawless carburation and guaranteed 1-kick cold starts thanks to these two tools.

Barry
Title: Re: KX500. non sealing exhaust header pipe
Post by: WRXBRUMBY on June 08, 2008, 05:19:25 PM
AAAAAAAAAAAAAAAAAAAAAAWSOME!!!!!!!!!!!!!!!!!!!

Hey guys I had a play today and your looking at one very happy and prob soon to be one very scared little man here.

I followed all the tuition that you fellas gave me, to the money and it was spot on.

I pulled apart the carb, and to my surprise the ?Main jet? (thanks cam hehe, I wouldn?t be able to use the lingo if it weren?t for your post) had fallen out.
So I endeavored to put this back in. (cause I assumed running just off the needle jet would have made it a tad rich hehehe)

Main Jet was 165 (spot on)
Didn?t check the ?pilot jet? cause my bottom end is awesome (thanks cam again for the lingo hehe)

I then took the liberty of changing the needle clip to the third position. (needle code said R1368N, is this standard? :?)??????.

Does everyone have a little trouble with the spring or was it just me hehe.(nothing that 2 zip ties couldn?t fix  :wink:)

Now I took the old girl out after putting her back together, then she fired up first kick. (from my experience finding TDC then giving it a boot full works most every time) and it already sounded crisper.

after she was warm, I then tried a ?controlled load? acceleration (a burnout on the cement)

all I can say is OMG :-o. I have a feeling I am in for a bit of trouble. It just sounded so strong, it was like unleashing a dragon :evil: :evil:.

If you were in Aus id buy you all a beer cheers for all your help, cant wait to test ride it for real.
And fellas its been a great welcoming from all of you, I appreciate and thank you all very much for your advice Kxcam, and Danger for you 2???.