Author Topic: 2003 KX 250 SF Conversion  (Read 161564 times)

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Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #180 on: November 15, 2015, 08:10:23 AM »
I got my shifter issue fixed by swapping out an OEM 2004 shaft and putting a new shifter on the bike.  It now shifts like a champ.  I went over to Danger4U2's track and did some laps, but the motor still just doesn't seem happy.  It doesn't rev cleanly under load, and I'm pretty sure that the jetting is very lean.  It's a shame, because the rest of the bike works so well.  I posted in the jetting section, but if anyone has any suggestions on where to start with the jets and needle position I would love the help.  Thank you!
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline alexander-vmann

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Re: 2003 KX 250 SF Conversion
« Reply #181 on: November 16, 2015, 05:05:05 AM »
sounds sweet, yo got any riding video coming up soon?
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my bike: 1993 kx500

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #182 on: November 16, 2015, 05:12:07 AM »
Thank you!  I'm still having some issues with the carb.  As soon as I get that cleared up I will post a ride video so you guys can make fun of my riding.   :-D
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline alexander-vmann

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Re: 2003 KX 250 SF Conversion
« Reply #183 on: November 16, 2015, 05:17:49 AM »
Thank you!  I'm still having some issues with the carb.  As soon as I get that cleared up I will post a ride video so you guys can make fun of my riding.   :-D
im just curious to se what that engine can do, mine is a 87 engine wich is almost the same, having some jetting/kips problom with mine to  :|
KX 500 newbie

my bike: 1993 kx500

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #184 on: December 06, 2015, 07:57:28 AM »
So I got all the stock jets in for my carb and got them installed, but now I am dealing with another issue that is familiar.  When I was riding at Danger's place, the bike died as I was finishing up my test ride.  I couldn't get it to start again, and it felt like it didn't have spark.  I pulled the bike apart (one of the joys of the SF conversion is no room to do anything  :-D) and did a process of elimination.  The compression check came back in the 180 psi range, and there are no unusual noises or vibrations.  The carb is flowing fuel, and the plug is new.  So I checked for spark at the plug, and of course nothing.  The OHM test revealed no flow through the plug wire, and the main wire was out of range.  This is the second coil I have had on the bike, and the second fried one.  I noticed that my mount was a little crooked and it is letting the end where the plug wire comes out touch the head a little bit.  Do you guys think that this is causing the fried coils, or should I just replace everything and start over?  I worried that something upstream is frying the coils and I am just putting a band aid on the problem.

Thank you again for the advice!
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #185 on: December 06, 2015, 02:53:17 PM »
I talked with zz3gmc about his 2004 250/500 bike, and I think I am going to relocate the coil to the side of the frame like he did, away from the engine behind the radiator shrouds.  I think the heat and vibration is just cooking them.
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline alexander-vmann

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Re: 2003 KX 250 SF Conversion
« Reply #186 on: December 06, 2015, 09:29:54 PM »
So I got all the stock jets in for my carb and got them installed, but now I am dealing with another issue that is familiar.  When I was riding at Danger's place, the bike died as I was finishing up my test ride.  I couldn't get it to start again, and it felt like it didn't have spark.  I pulled the bike apart (one of the joys of the SF conversion is no room to do anything  :-D) and did a process of elimination.  The compression check came back in the 180 psi range, and there are no unusual noises or vibrations.  The carb is flowing fuel, and the plug is new.  So I checked for spark at the plug, and of course nothing.  The OHM test revealed no flow through the plug wire, and the main wire was out of range.  This is the second coil I have had on the bike, and the second fried one.  I noticed that my mount was a little crooked and it is letting the end where the plug wire comes out touch the head a little bit.  Do you guys think that this is causing the fried coils, or should I just replace everything and start over?  I worried that something upstream is frying the coils and I am just putting a band aid on the problem.

Thank you again for the advice!
i think with electronics the wires transfers any heat FAST so relocating is definatly a good idea by you
KX 500 newbie

my bike: 1993 kx500

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #187 on: December 25, 2015, 08:58:09 AM »
I got my coil relocated and replaced with another one from Sandblaster.  I got her fired up and took her for a quick ride at my parent's house.  Here's a quick video of a section of the ride:

https://www.youtube.com/watch?v=mNJZiJI2We8

Here I am returning from the ride.  Man it was wet in the old cow pasture:

« Last Edit: January 05, 2018, 02:42:37 PM by umberto »
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline alexander-vmann

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Re: 2003 KX 250 SF Conversion
« Reply #188 on: December 25, 2015, 01:43:19 PM »
« Last Edit: January 05, 2018, 02:42:52 PM by umberto »
KX 500 newbie

my bike: 1993 kx500

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #189 on: December 25, 2015, 04:39:01 PM »
Thank you Alexander-vmann. It was really nice to have it running better, although I still need to fine tune the jetting a bit. My Dad did the video, and he said I was hitting them with dirt for quite a while after I passed them, so I guess it's doing pretty well as is.   :-D
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #190 on: December 28, 2015, 09:37:39 AM »
Here is a picture of the bracket I did for the coil.  It keeps it away from the engine and doesn't rub anything.

« Last Edit: January 05, 2018, 02:43:05 PM by umberto »
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline skunkworks

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Re: 2003 KX 250 SF Conversion
« Reply #191 on: December 29, 2015, 04:52:05 AM »
awesome build mate !

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #192 on: December 29, 2015, 10:07:58 AM »
Thank you skunkworks!  I've had a blast building it.
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline umberto

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Re: 2003 KX 250 SF Conversion
« Reply #193 on: January 03, 2016, 06:05:39 AM »
Happy New Year everyone!  For New Years I decided to try out bronchitis to see if I like it.  I think I agree with Sweet Brown:



Since I'm stuck inside anyway, why not annoy the wife and go out to the garage instead of resting.   :evil:  After my last ride I decided that the front brake needed an upgrade.  Thankfully I had some bonus bucks and a couple of gift cards to Rocky Mountain, so I picked up this dude:


https://www.rockymountainatvmc.com/p/765/35148/Tusk-Oversized-Floating-Typhoon-Brake-Rotor-Kit-Front?term=tusk+oversized+rotor

It is a substantial upgrade over the stock sized disk I had:



It does not list as compatible for an 03, but the caliper will bolt up without any brake line issues, and it will work with the Tusk wheels I have on the bike (2004 and up).  I stated in a previous post that I was able to use the wheels with two brake side spacers, but I forgot to add that I needed to adjust them down a bit to work.  The brake side is approximately 33.50 mm and the other side is approximately 32.50 mm.  I would start with them a little larger than those measurements and work your way down to the right size.  I started with the brake side to center the rotor in the caliper, and then adjusted the other side until the wheel fit.  It's not a ton of adjustment, but it does need to be done to use the wheels.  

Here is a final pic with the rotor fitted and ready to haul Goliath (my father's nickname for the bike) down from speed:



I've got a couple more fun mods to try out before I'm done with her.  Then it's time to blow her apart and address the unpainted welds and general appearance.  I think I really like the looks of this 250 Foxx posted.  What do you guys think?

« Last Edit: January 05, 2018, 02:43:47 PM by umberto »
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline sandblaster

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Re: 2003 KX 250 SF Conversion
« Reply #194 on: January 03, 2016, 09:08:40 AM »
I think your doing a great job.
Just keep doing what your doing  8-)
The four stroke engine: That's one stroke for producing power and three for wearing the engine out.