Some questions concerning spooge

[Doc Brown]

I run my EC300/19 50:1 with Putoline MX9, which has a very low pour point and should produce less spooge than e.g. Motul 800 with an extremely high pour point.
But it in fact it produces quite a lot of spooge and so do my buddies bikes, three GP300's and my GP300/18.

All bikes are jetted slightly different, mine run on a JD red needle, Martin's is totallly stock and runs very nice and the two others use the NECW needle but different main jets. All bikes get 50:1 premix. And they all spooge.

On the GP300 with JD-red I reduced from 50:1 to 60:1 and finally to 80:1 to get rid of the spooge. After talking to James (Dean) and also a kTM technician who said KTM's TPI's run 30:1 at WOT but as low as 100:1 at very low throttle opnenings, I went back to 50:1 just to be on the safe side.

I had two 300 EXC's and both Katos survived far over 150 hrs with 80:1 using Amsoil Saber. The GP300 killed 7 spark plugs in less than 10 hours and was immediately cured by just using a different oil.

In a nutshell: how can I reduce the spooge? My bike is already jetted on the leaner side as I dont go WOT in high gears for more than just 7 seconds. I tried different oils (Putoline MX9, Motul 710, Motorex Crossp. 2T, Silkolene/Fuchs 100S, Castrol Power1) but there was no big difference.

Thx for any advice!

[ECRider]

I have a 2018 GP300 and running a TSP cut head and NECH needle 38PJ 175MJ #8slide. The head work with squish reduced to 1.35mm helped to reduce the spooge which used to dribble on to the brake caliper at 50:1 Castro tts synthetic oil. I now run 55:1and spooge has reduced to a minor dribble at the muffler after a days ride. I ride a mixture of fast and technical trails

[Doc Brown]

Many thanks, appreciate your help.

I had a slight fear that this might be a possible answer. Me too considered that it could be a problem with the head design, the squish seems to be very big for a strong twostroke. I have no clue why GG made it this big, maybe to just be able to accept bigger deviations from the desired value during production...

Did I say that my bike runs really nice? So nor problem here, its just a little flaw. But I always try to get things perfect

[ECRider]

TSP actually reduced the compression ratio after maching to reduce the squish but couldn't take it down as low as they wanted to due to insufficient material thickness in the head.
The bike use to have a real kick coming into the mid range & signed off early. The power now is smoother & strong throughout with longer rev range.

[Doc Brown]

Sounds good to me. Many thanks for sharing your experiences.

[Cox76y]

DOC,
i too am having the same problem with my 18 300 six days. Jetting seems fine n Im hesitant to go any leaner. I had a 2012 with a HOH exhaust n pipe n JD jetting kit. Squish was adjusted by TSP in Australia. In 5 yrs riding I never had a foul plug n cant ever recall having any spooge at all.
So far on my 18 I have gone through 5 plugs in less than 500kms of riding. Im hoping to get the squish set soon and I hope that will help reduce the problem. The only other thing I though of was that the vent hoses from the powervalve and cylinder were blocked and the crap from them was working its way back into the combustion chamber. Not sure if this is the case though n not sure if the GP model has them.
At the moment though I have to always take a spare plug with me on a ride cause there is a good chance I will be needing to swap it over. Never had to do this before.
Anyway, hope someone can work it out.
Josh

[taylor146]

Originally Posted by ECRider

TSP actually reduced the compression ratio after maching to reduce the squish but couldn't take it down as low as they wanted to due to insufficient material thickness in the head.
The bike use to have a real kick coming into the mid range & signed off early. The power now is smoother & strong throughout with longer rev range.

Hi ECRIDER
Do you know what the comp was to start with and what they reduced it too?

thanks

[ECRider]

Originally Posted by taylor146

Hi ECRIDER
Do you know what the comp was to start with and what they reduced it too?

thanks

Before head work compression was 155psi and afterwards 150 psi

[memphis2857]

Originally Posted by ECRider

Before head work compression was 155psi and afterwards 150 psi

That’s awfully low. Should be around 200.


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[Jakobi]

Originally Posted by memphis2857

That?s awfully low. Should be around 200.

Yes no yes. The number alone means sweet FA. Some 'quality' gauges use adapter fittings.. they can add a couple of cc's to the trapped volume which will in turn give a lower reading than the engine actually is. Even more so if the volume of the tubing is counted.

Comp readings mean verrry little unless a specific gauge is used to make comparisons.

My cheapo gauge always reads low, but my engines run strong and happy. I just work off percentages of compression loss along with piston blow by, coating wear, etc visible when peaking in the exhaust port... to help determine when a top end is due. Typically around 70hrs for me.