dkgoodrich

Member
Sep 9, 2007
33
0
Mod Edit - Size limit for images is 800 pixels

Hi, I just traded a turbo kit for a RM 125 and a KTM 125

The KTM always seems like its bogging out, never really fells like the power band kicks in. Seems to smoke alot too. It almost fells like my yz when you just start it and hasnt warmed up. It also has a back brake problem and front wheel bearing problem but I can take care of that no problem.

The RM seems to be in good condition but it wont start, I think it needs new rings.. not sure If I should replace the piston as well. I checked spark, it shocked me.

My YZ I just had about 800 in engine work done to it, top to bottom, the rear shock is blown, and the water pump seal is leaking. I have a used shock and new seal kit and can take care of that.

I got the rm and ktm in hopes of getting something for my brother to ride and just want to get one running for him. The YZ is mine and I love it.. one weird thing, its bigger than the other to bikes, bigger wheels, bigger height, everything. Makes me wonder if the others are really 125s

I guess I want to try to get the KTM in decent running condition till parts come in for the RM.

How do I tell the years of these bikes? They are supposed to be a 00 and 01 and I know for sure my yz is a 00.

Please help I just need direction on were to start on the ktm for sure. I'm going to tear the KTM down tom and check the reeds, power valve and clean the carb.

Thanks for your time,
DK

Oh yea they all run that castro 997 and belray gear oil.
 
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AwfulSmokey

Member
Oct 15, 2007
55
0
Sounds like the KTM has jetting/carb issues. Try messing with the air screw. Turning the air screw out will help if it's running rich(this is what it sounds like to me). Turn it a 1/4 turn out and see how the bike performs. If it gets better, go another 1/4 turn out. repeat as necessary. If you end up more than 1.5 - 2 turns out, you need to get smaller jets.
 

dkgoodrich

Member
Sep 9, 2007
33
0
Thanks a bunch guys, This should get me started. I'll decode the vins so I know what year to order parts from and I will try to adj the carb. I can't see it being much different than adjusting my gas rc cars. I always wondering about how to adj the dirt bike carbs and when to change the jets, now I know. Thanks for your insight. I did always think that adjusting the screw out would richen and screwing them in would lean them out though. I guess I have it backwards?

Thanks for your time,
DK
 

dkgoodrich

Member
Sep 9, 2007
33
0
Did a compression check on the rm and ktm also a vin check
Turns out,
01 RM 125 - 70psi
00 KTM 125SX - 140psi

Tore down the rm and it looks like they ran it with no coolant or it burned it off because the middle O ring in the head, half of it was missing

I mic'd the piston to buy another one and its 55.86mm. and the pistons I found said std bore for a 01 is 54mm.. hum..

On the ktm I tried backing the black thumb screw [only screw I could find on the carb] out and it seems the idle droped a bit and may have helped a little power wise but really not much. I have been reading up on the power valve and how to maintain it and replace wore parts. I am also going to start reading up on jetting and carb settings, of which I have never delt with.

Any thoughts?
Thanks for your time.
DK
 

Matt Fisher

Member
Apr 17, 2002
136
0
If all three bikes don't have 21" front and 19" rear wheels, then you have something smaller than a 125. Buying a piston for a 125 if you own a 85 or 105 might not be such a good idea....
 

snb73

Member
Nov 30, 2003
770
0
DK,

Sounds like you adjusted the idle screw. Here are a few sites to get you going, but you know you should get some manuals. Clymer and Haynes aren't the best, they are cheap and have great info.

All should have 21" fronts and 19" rears like Matt said, if they are 125's. Post what tires are on the bikes and pics if you can. YZ's are the tallest of the 125's though.

Good luck, Steve.

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

http://www.keihin-us.com/am/tuning/

http://www.all-offroad.com/DirtBikes/Beginners/BGNov98.html

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

Look at the schematics here;

http://www.bikebandit.com/oem-parts

Go here and create an account. Add the bikes to your favorites. They list bike specs like tires size ect...

http://www.rockymountainatv.com
 

rmc_olderthandirt

~SPONSOR~
Apr 18, 2006
1,533
8
Matt Fisher said:
If all three bikes don't have 21" front and 19" rear wheels, then you have something smaller than a 125.


There are a lot of bikes that have an 18 inch rear wheel.

My '86 YZ-125 has an 18 inch rear
My '97 WR250 has an 18 inch rear.

I know that the 2008 KTM, 450 XC-F and 450 EXC-R both come standard with 18 inch rear wheels.


The best thing to do is to decode the VIN number to be sure of what you have.

Rod
 

atkkid250

Uhhh...
Mar 18, 2008
177
0
correct me if im wrong but...

the ktms are like my atk, they have a powervalve on the front of the cylinder? i was having similar issues with my atk 250, not quite as dramatic but similar, so i looked it up and it said for mine i have 2 full turns in and out from flush to play around with. I turned it 1 and a half out i believe? amybe it was in and it solved it up right dandy. but then agian i might be shooting a blank becasue it might not have a powervalve.
 

Blink-182

Member
Feb 2, 2008
127
0
where is the power missing on the ktm?

id check your powervalves and clean them, most people never clean them and they dont open or close all the way, and after that id check your reeds
 

dkgoodrich

Member
Sep 9, 2007
33
0
I replaced the water pump seals and rear shock on my YZ, I now have 13.5hr on my meter for that bike. I'm kinda curious if I am getting close to needing to re ring it. My original intentions were to re ring it at 15hr but my buddie says goto 25hr

I am still having problems out of the ktm 125 and did do a vin check and it is a 125 and I think its a 125sx

I am pretty sure the power valve isn't even opening. On bottom end it runs fine but on top its a turd. It starts first kick every time and compression was 140psi. I checked the reeds and they are carbon fiber, no cracks. I tore down the carb and it looked perfect inside and I shot some carb cleaner in every orifice.

Any body have any info on the power valve system of the 125 sx?

I'm trying to read up more about the valve, when I take off the little cover on the left hand side towards the front of the cylinder it and rev it, it does not move.

here is a picture of the cover removed and the placement of the marks, I believe the placement of the marks is wrong

ktm001.jpg
 

dkgoodrich

Member
Sep 9, 2007
33
0
We are going to order a piston and rings for it, I just was hesitant to re build it considering how it always fires right up first kick. My two strokes in the past seemed to be hard to start when they needed re built.

Carb cleaner should work cleaning it all up right?

Thanks for your time
I guess the only thing to really do it open it all up and see whats going on. ;)

dk
 

SpeedyManiac

Member
Aug 8, 2000
2,378
0
I bet the KTM is way too rich on the main jet and probably the needle too. What clip is the needle in? What size main jet? What colour is the plug?

Check the easy things first.
 

dkgoodrich

Member
Sep 9, 2007
33
0
I'm not sure about the size of the main jet, or what clip the needle is in. I really don't know a whole lot about carb tuning. It does blow a bunch of smoke but I figured it was because its dumping added fuel for when the power valve opens, but its not opening what so ever.
 
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