2003 KX125 Blowing up

[wildcard]

I have 2003 KX125 that has had two brrels and heads under warranty in two months because it keeps blowing the top off the plug and wrecking the barrel .Jetting is stock and the plug is a good light brown colour. If we go up on the jetting or lift the needle the bike just fouls up. Fuel is standard 95 Ron plus Silkolene Comp2 SX at a 40:1 mix. Ignition timing is central and the air filter brand new. Kawasaki don't know what to suggest!....Any suggestions would be most welcome.

 

[steve125]

Have you been hearing some ping or knock under heavy load, full throttle conditions? Is the bike all stock?

 

[marcusgunby]

The std KX is prone to detonation in std setup-you should be running 98 octane super unleaded and preferably with 3% silkolene pro boost.Also back of the timing a bit-make it about 1mm retarded.Lastly change the plug every 6 rides to be safe.

 

[bclapham]

Originally posted by marcusgunby
and preferably with 3% silkolene pro boost.

maybe i can start my own Cult with these sort of conversion rates?

sorry to hijack this thread, but i just had to say the kx is a fine motorcycle! :thumb:

back on topic, i am suprised we havent heard of this happening here (especially in socal) since the pump gas here is way inferior to the stuff back home, but that said, bikes dont necescaerily ping here, but just run bad on the pump gas. what is the differnce between the stock and US jetting on this bike?

 

[marcusgunby]

Bruce it seems the jetting is the same-steve correct me if im wrong.

 

[steve125]

Marcus "seems" can get us in trouble quick! :) Here's the USA spec. Main 420 needle 6CHJ11-82 3rd clip  pilot40   2.5 out air screw  throttle valve 5.75. Let us know the euro spec Marcus. :worship:

 

[marcusgunby]

Seems about the same :p im not going into the garage in my dressing gown for anybody.

 

[steve125]

LOL! :)

 

[marcusgunby]

Couldnt resist-i went and found the manual-its the exact same spec.

 

[holeshot]

Are you saying that the electrode on the spark plug is breaking off? It comes with a "thin" electrode plug, which I've heard can break off from vibration (on other bikes as well). I was thinking of changing to an equivalent "normal" plug.

Either that, or I'll have to borrow Bruce's Little Brown Jug of MTBE.

 

[steve125]

Wildcard run at least a 50/50 mix of pump and race fuel and your detonation problem will be solved. You posted over in the suspension forum like this is some big mystery, well it's not, detonation is the cause your engine failures and the fix is race fuel.

 

[Eddy V]

Originally posted by wildcard
I have 2003 KX125 that has had two brrels and heads under warranty in two months because it keeps blowing the top off the plug and wrecking the barrel .Jetting is stock and the plug is a good light brown colour. If we go up on the jetting or lift the needle the bike just fouls up. Fuel is standard 95 Ron plus Silkolene Comp2 SX at a 40:1 mix. Ignition timing is central and the air filter brand new. Kawasaki don't know what to suggest!....Any suggestions would be most welcome.

Wildcard,is your problem solved yet?

 

[eibellk]

One problem I see is that you are breaking in the motor with Synthetic Oil. You should break in your motor with vegitable based oils and race gas. This may not be the source of your problem, but I am sure it is a contributor. Run about 1/2 a tank thru it and then you can switch to your preferred synthetic (I use Amsoil but Silkolene is an excellent oil too).

Additionally, if your plug is breaking off, that can't be a good thing! I use NGK V type plugs (B9EV should be a good starting point).

40:1 is fine, but you might want to richen it up during breaking.

Kurt.

 

[luvtolean]

Originally posted by steve125
Wildcard run at least a 50/50 mix of pump and race fuel and your detonation problem will be solved. You posted over in the suspension forum like this is some big mystery, well it's not, detonation is the cause your engine failures and the fix is race fuel.

Don't forget, in the UK he can get 98 octane at the pump. Their pump is better than ours.

Have you considered trying the pricey RM125 plug? I don't know the number off hand, but NGK say it was designed for high vibration. Maybe this is what you need.

3% is about 33.3333:1. ;)

 

[marcusgunby]

Im wondering if the rm plug is a thing to try.It makes sence-as long as detonation isnt the cause.

 

[01RM125]

The 2001 stock plug is the expensive R6918B-8,
I run the BR8EV with not problems for the 4 months I have had the bike. With all I have read I have been thinking of spening the extra 20$ and changing it less often, but I've yet to fork over the extra 20$.

 

[marcusgunby]

Right ive heard of a few more reports of this problem using the std plug -most owners seem to run a BR8EG/V or BR9EG/V plug with no failures.I even remember riders having the same problem with this plug back in 1992.Never heard of it on a BR.EG/V.

KX owners look at your plugs.

 

[Fark]

Originally posted by eibellk

40:1 is fine, but you might want to richen it up during breaking.

Kurt.

 

Can you be more specific in this statement?  If there is more oil in the fuel, the bike will run even more lean.  If you really wanted to get nuts you should give the airscrew a turn.

And I wouldn't believe the synthetic oil myth.  That's just me though.

 

[luvtolean]

The "synthetic oil myth" came from old 4 stroke cage motors that weren't machined to today's standards, and wouldn't break the rings in properly. Some new cars come with synthetic oil from the factory.

It means nothing to a 2 stroke...

 

[marcusgunby]

Bringing this back up for good reason-dont use the BR EG series of plugs-mine broke the ground strap and mashed the piston/head.It had no detonation that might normally cause this.Also the loug was only 2 rides old.
Ive been told by the kwak dealer to only run the BR9EVX
Im going to run the expensive plug that the RM125 uses to ensure it doesnt happen again.Also a few reports of cdi,s /coils and stators going bad:(

 

[Rich Rohrich]

Originally posted by luvtolean


Don't forget, in the UK he can get 98 octane at the pump. Their pump is better than ours.

The UK 98 octane is an RON rating. Given the fairly common 10 point sensitivety of current pump fuels it looks like this :

98 (RON) + 88 (MON) / 2 = 93 pump octane

In other words their fuel isn't much different than ours in terms of absolute octane ;)

 

[bclapham]

if the spark plug is acting as a tuning fork, then why not lower the frequency? BR9ES? or what about adding an extra washer under the plug?

the problem is, this sounds quite bogus and there seems to be no way of knowing if the prob really is fixed, ie. can the lack of a negative result be concluded to be a positive result. whatever happens your gonna be livin on the edge man.:(

 

[marcusgunby]

Thats the problem bruce-i dont want to prove what the problem was-i only want never to see it again.I do believe the plug was acting like a tuning fork-it was a very fast track and the engine was under a load more than on most of our tracks.If the answer for suzuki was to use a special plug then i will do the same, until i know i can use a different plug.This is bad as my previous KXs have served me well generally:(

 

[marcusgunby]

Heres the photo of the damage

 

[holeshot]

:scream:

So are you going to use the R6918B-8?