07' 525 runs lean, hot and dies...

Hello fellow thumpers, I am new to your site, so i thank you in advance for your advise and opinions.

I am an advanced enduro/offroad rider switching from a yz426f to a 07' 525 exc( 50 state street legal) and loved it for the first 20 hours. I broke it in on the street for the first 3 hours, and did the required maintainace for that first service.The next weekend I rode 400 miles in the dirt, (single track to atv trails) at mostly higher speeds(35-80mph) with no problems, just some poping in the upper rpm's on decel because of how lean they had to jet it to pass CA green sticker.

I trail ride (90%) and ride on road when neccesary to work or ect... When the hour meter got to about 25-28 hours Inoticed on a hard trail ride that the bike would die in corners and was hard to start again. Still ran good once it started again, but would die at slower speeds.

After the few problems I faced, I decided to still race my first enduro.

-first 15 miles= good

-@ mile 28 =ktm was boiling over because of VERY SLOW single track corse.

what do I need To be enduro ready?

John,

Have you actually raced a bone stock unmolestered 525 EXC? Your bike will not run properly until you do several things.

#1. Its way to lean stock and must be rejetted to run correctly. The JD kit is $100.00 buy it!

#2. Your silencer has a restrictor that causes havoc with carburation,heat and robs the bike of its ability to exhale and make power. It must be removed.Have you been riding that bike and trying to race it with the restrictor still in the pipe?

#3. For an immediate fix to whatever is going on now it sounds as if the overflow canister needs to be drained if you havent already removed it. You should look into removing the plumbing and excess "Stuff" that was added to these bikes to get them street legal and pass EPA.

Go to KTMTalk.com and search De-Emission and cannisterectomy. There is a thread with phoptos and step by step instruction on getting the 07's performing as they were designed.

Hello fellow thumpers, I am new to your site, so i thank you in advance for your advise and opinions.

I am an advanced enduro/offroad rider switching from a yz426f to a 07' 525 exc( 50 state street legal) and loved it for the first 20 hours. I broke it in on the street for the first 3 hours, and did the required maintainace for that first service.The next weekend I rode 400 miles in the dirt, (single track to atv trails) at mostly higher speeds(35-80mph) with no problems, just some poping in the upper rpm's on decel because of how lean they had to jet it to pass CA green sticker.

I trail ride (90%) and ride on road when neccesary to work or ect... When the hour meter got to about 25-28 hours Inoticed on a hard trail ride that the bike would die in corners and was hard to start again. Still ran good once it started again, but would die at slower speeds.

After the few problems I faced, I decided to still race my first enduro.

-first 15 miles= good

-@ mile 28 =ktm was boiling over because of VERY SLOW single track corse.

what do I need To be enduro ready?

2 things come to mind.

1. have you rejetted? The JD jet kit is a great way to painlessly dial in your jetting. Thumpertalk sell them as well as well as WWW.roughhousecycle.com both great guys to work with

2. With 20 + hours on the motor since the last valve job have you checked the valves.

the number 1 thing that will have an immediate effect is to drill out the rivets and remove the ridiculous tiny baffel in the esilencer. The stock silencer will not allow the hot exhaust gases to escape and cause them to build up in the motor. If you dont want to modify the stock silencer, go to KTMTalk.com and look in their parts classifieds and get a silencer from an 04 or 05 EXC, that will acheive the same results. And I also heartily endorse getting A JD jetting kit and rejetting your bike. KTM has the bikes running very lean from the factory and for them to run correctly you must rejet.

the jd jetting kit is a waste of money when you can raise your needle and buy a bigger pilot jet. possibly turn up your accelerator pump. I take those kits out of bikes all of the time and throw them in the trash can. the jd kits make your bike lean.

I agree with all of the above ecept for the last. The stock emissions control needle has nearly zero taper. Thus raising it does almost nothing. Furthermore the area of the needle jet less the area of jet needle is less than the area of the main jet. thus changing the main jet does nothing. This is the reason the JD kit was created and why is is so popular, there are other combos that work for the technically inclined but the JD works as well as any and with much less fooling around.

Your current running/quiting condition is most likly from the fuel tank vent not functioning! For fuel to flow out air must flow in, the factory system can only work if the bike is ridden very gently from the box past the government testors and put away. Once you ride thru some bumps gas sloshes into the vent hose, runs to the canister box at the back of the engine and once that box is full the tank can no longer vent, bike can only run intermittently. Two options here:

A: A complete canster ectomy. In that case modify the tank vent exactly like the XC-W and other off road models, get rid of the canister, plug the hose to the intake port and you will be good to go.

B: If your in Cal and or worried about big brother checking you, you can just remove a drain plug from the bottom of the canister.

Also you need to remove the blockage plate from the muffler.

You need to rejet, JD is the no brainer way, if you want to go the more complex route sall Sudco, order OCEMN and OCEMP needles and main jets in the 155 to 165 area. As that does not sound logical, remember what I said about needle jet, jet needle area, with the OCEM_ needles the taper will be steeper and they will not block the main so a smaller main is in order.

Also, do not try to jet the bike by decelleration poping. Sorry to berade your new piece but the exhaust pipe to manifold juncktion is horible! It allows freash air into the pipe under the high vacuum of deceleration, that oxygen mixes with hot exhaust/hydrocarbons that are only partially burnt causing the mini explosions. You can mitigate it by sealing the head pipe with hi temp silicone.

the jd jetting kit is a waste of money when you can raise your needle and buy a bigger pilot jet. possibly turn up your accelerator pump. I take those kits out of bikes all of the time and throw them in the trash can. the jd kits make your bike lean.

In the trash? Really? I'll take every one you throw away and I'll even pay the shipping. PM me next time you take a JD kit out :)

Ok I pulled the cannister and re-routed the crank breather from the carb. It now runs correctly and idles good, thanks for the input.

DJH, Travis, Penguin and Chaz have it nailed. DJH and Travis have lots of experience and always provide good advice...listen to them they are the premier aftermarket service guys. The advice they offer here and on KTMTalk.com is without err.

At 25 hours you should have checked the valves already. The JD Jetting kit is worth every penny and you can buy it directly from JD for $75.95 http://www.jdjetting.com My 525 has never hiccuped, bogged or puked coolant and I ride tight, tight , tight singletrack at 8-12,000 feet in Colorado.

p.s. listen to Travis and DJH...

possibly turn up your accelerator pump.

Just the opposite of most advice. Stock, the AP squirts too long. Change over to the Honda diaphram to shorten the squirt.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now