97 300 EXC Jetting Advice Needed

[KTM Mike]

I have 97 300 exc bought used last spring. Did not ride much last year, but do need to work on jetting. I ride at 800 to 1000 feet in elevation (Northern Lower Michigan) - lots of low speed/rpm riding as most of it is a family affair with wife and kids (thats what happens when they all love the sport!) But i do get out for an occasional hard ride to blow my cobwebs out! Bike tends to load up and run rich just off idle and a bit higher in rpm - fouls plugs occasionally. At upper mid range and higher rpm seems fine, maybe slightly rich but not bad. On decel (say trailing throttle down hill for example) engine will surge.

Stock exhaust and silencer etc 32 to 1 premix. Currently carb is jetted as follows: 175 main, 42 pilot, n85c needle, clip in second groove from top.

Anybody with specific suggestions/experience with jetting this bike? From other web sites i see comments about modifying the slide to address a similar sounding issue. Is this really needed?

As I am new to this bike and KTM's - any other suggestions? I just tore down top end - major carbon build up - all clean and polished now! Power valve is now spotless - did seem a bit "stiff" - perhaps this impacted jetting? Any ideas on adjusting powervalve given my generally low rpm riding?

TIA

Mike

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[DanS]

Try a search for jetting 300's. You will find some very good advice for cleaning up the bottom end. Going to a #6.5 or #7 slide is what most people do as well as going to a straight taper needle like a 1367N. I'm sure the jetting experts will help you out. Good luck.

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Now thats a BIG piston!!
Go big or go home!!
CR500,XR600,KTM300exc

 

[BP]

I ride in Ohio & PA, 300-1400 ft. elevation.
I run 172 main, 42 pilot, N85D needle 2nd from the top, 1 1/2 out on the air screw,
also might want to try 2 turns out on the air
screw. Good Luck & Happy Trails !!!

Brian

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'96 Harley Sportster 1200 s

 

[BP]

Oh, by the way, the manual says to run a 40:1 to 50:1 fuel ratio with a good quality oil. I personally run BP 93 octane unleaded
mixed at 40:1 with Champion Racing Lubricant's WP2 .

Brian

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'96 Harley Sportster 1200 s

 

[KTM Mike]

Dan S and BP thanks for the responses. BP off hand your set up seems to make sense - a bit leaner on the main - though to be honest i dont have clue as to the difference your use of the N85D needle vs my using a N85C. Can anyone explain the difference between these needles?

Also - Dan S mention the 6.5 or 7 slides - what effect/difference are between these slides vs mine (a 6)?

On the topic of oil ratio etc - per the prior owner they always ran Golden Spectro. Last summer i ran a hodge podge of various - not particularily good oils, but more of it was Golden Spectro - little did i know then that Golden Spectro is known to carbon up the power valves etc - this is the first bike i have owned with a power valve! I plan on running Maxima Super M this year (my kids Polini supposedly does best with it as well) but was leaning toward a bit more lubrication at 32 to 1. Perhaps I should reconsider?

Thanks again

Mike

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[BP]

Mike,
The "D" needle is one step leaner than the "C" needle. This jetting set up was recommended by my local KTM dealer's mechanic.
The 6.5 and 7 slides are leaner than the stock 6. If you use a leaner slide, then you will have to use a tad richer jetting as in the main and pilot.

Brian

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'96 Harley Sportster 1200 s

 

[BP]

Mike,
Try www.holeshotktm.com , they have a forum just for KTM jetting. There is one post on there with over 75 responses with peoples jetting from all over the country and world.

Brian

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'96 Harley Sportster 1200 s

 

[KTM Mike]

Brian

Thanks for the tip on the holeshot site - you're right - tons of jetting info. Between that, comments here and a keihin jetting chart i came across - its all now starting to make sense - this is really my first every serious effort at jetting - learning lots!

It looks like it really boils down to: 1) I will try the d needle along with varying clip position, then if that dont do it... looks like the slide. Its actually going to be while before i can really mess with it... but I will post results here when i do. Thanks again to all who responded.

Mike

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