Help taming the 300's power delivery

TexKDX

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Aug 8, 1999
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Hey 300E owners -

Many of you know I have a '99 300E. For two years I've been messing with the thing. The recent bout of throttle sticking (solved BTW) had me riding my '99 XR280 all the time. This really opened my eyes as to hpw fast I could ride by being smooth and keeping my entry speed up.

Now that the 300 is up and going again, with the most recent changes to it I find its power delivery to be too sudden and the reason why I can'r ride whoops on it. I geared it 13/52, down from 14/52. Makes 3rd more usable but accentuates the abrupt power delivery. Also ground the slide to a #7 and re-jetted to a 42 pilot/175 main (actually 45/180 for the cool weather now). The bike as an FMF M-20 (no stock pipe) and the TCII siliencer/SA. I do have the stock silencer in the garage. I run 93 octane Shell unleaded and 48:1 Yamalube 2R BTW, no race gas.

This past weekend I not only had it jetted too lean but also knocked the pipe seal loose at the engine. Totally unridable! Jetting richer and fixing the pipe seal helped a bunch, but the XR is still way easier to go fast and smooth on in the Piney Woods of LA.

Questions - What else can I do to make the thing run as though is has a steady throttle opening, instead of revving all the time? Mess with the power valve? If so, what changes would you make to it? Also, what about going back to the stock silencer?

A 13/50 might be a good idea, or maybe a 14/53? Just to take the edge off a little this way? The 14/52 just needed too much slipping in the tighter stuff.

Any other tricks I missed? Thanks guys!!!
 

Douglas

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Nov 29, 2000
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Tex,

I hesitate to give this reply because it may entail a new pipe! I recently started riding an '01 300 EXC, and I've been riding 4 strokes almost exclusively for the past 5 years. The first day (4 rides ago) we went to one of our most challenging test areas, that requires both tractability and major horsepower, to set up the 300. My gearing is 13/50. I took the stock pipe, a Fatty, and an SST. I rode and jetted with all three.........finally deciding on the SST, mostly for the reasons you are asking about. The SST gives a very linear delivery, and smooths out the abrupt delivery of the stock set up but will still lug down and pull, with a lot more mid, and way more top. Over the past few rides, I have been experimenting with the power valve setting...........I like the power valve screw backed off (Counter clockwise) to open sooner, with this set up. My jetting @ 4,000 ft. is 45p, 172m, #7 slide, NOZH #3, 1.5 A/S. We went riding yesterday, and my buddies with 2002 CR 250's and YZ 250's were way impressed with the 300 motor, actually expressing preference for it's linear power band, and saying it is totally different from our other (2) buddies 300's, and way better! Actually one of the 300 riders has bought the SST even though he had just purchased a "Gnarly", he liked the SST power way better. This is not intended to be an ad for the SST, it just works like you have said you want it to.
 
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KTMSMITH

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Jan 9, 2002
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I have an 01 300 exc. I have owned 4, 300exc's since 1991. You probably won't agree with my opinion, but I believe you are way too low on your gearing. I either run stock 14/52 or 14/50. Thats right, I gear up. I race Dist 11 enduros,..southern ohio, very tight. The 14/50 will smooth power delivery quite a bit. I also turn my power valve adjustent all the way in. This will make a noticable difference. I find the smoother power delivery allows me to ride faster and with less energy. I try to maintain mometumn and avoid shifting, usually staying in 2nd or 3rd in the tight stuff, using the clutch to maintain a smooth controllable delivery. Just my 2 cents worth.
 

Vic

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May 5, 2000
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The simplest solutions are often the best. I would try retarding the timing a bit.
 

TexKDX

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Aug 8, 1999
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KTMSMITH,

I hear ya on the gearing. Now that I have the jetting squared away the 14 may work better. I rode at Camp Clayborne over the weekend - Piney woods but more open and smooth trails. I short shifted to 4th quite often and found it helped corner-to-corner smooth things out. having just corrected a sticking throttle I was reluctant to spend too much time in 4th though!!!!!! Lots more top end when things go wrong in that gear.

I'll try the PV next. Any opinion on the stock silencer BTW? Thanks!
 

TexKDX

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Aug 8, 1999
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CLW, I was going to do a long post on that when I had a moment to do so.

Basically I did a hybrid solution of the various fixes I have heard about. The options are: the 2000 and later routing, 2000 and later routing with CR cable, 99 routing with CR cable, or CR cable with routing between the fork legs and down the left side of the frame.

I did the last thing - keep the throttle housing with the pulley horizontal not vertical, then route the CR cable down behind the light assembly, then back thru the fork tubes, down the left side of the frame. I moved one of the plastic cable guides (mine had 2 on the right; I moved the big one to the left side and kept the small one on the right for the kill wire and the front light wire routing) and put it in the upper hole above the radiator.

I need to go look a the bike again and give the EXACT routing relative to the clutch line. I moved the cable relative to the clutch line to get as little change in cable tension with the bars at full left lock. The RPMs will still rise a little bit at full left lock (not removing all the slack, rather holding a small amount of throttle opening then sweeping the bars full right to full left). That is as good as I could do.

Now you see why I need to do a long post - nothing is ever short from me! It's just that I did a bunch of research and every tidbit I found was helpful but not quite complete. I'd like to do as complete of a summary as I can of my findings as well as EXACTLY what I did on my bike.

The new KTM stock routing did not work for me with the stock length cable because I run my Scotts upside down and the Scotts enduro computer case above it. The CR cable would have worked with with the current KTM routing, but I did not like the big loop of cable nor the vertical pulley.

One other problem (self imposed) was I had the pulley in upside down in the housing. Not sure if I ever rode it that way or not, but the last time I took it apart Saturday AM that is the way I tried to put it back together based on how I thought I took it apart.

OK, back to taming the beast!!!!
 

fatherandson

Mi. Trail Riders
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Feb 3, 2001
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I inherited a 10 ounce (I think) Steahly flywheel on my '99. I feel it contributes to the "tractor" power of my EXC. $ .02
 

fishhead

die you sycophant !
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May 22, 2000
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Tex
Those are all good ideas. A lot of guys have gone to a single taper needle, CEK-3 or 4, cut the slide to a 7, and packed more gearing, 14-50, to tone down the power delivery of the 300 and clean up the low end. When jetted correctly the 300 will pull like a tractor. I had an opportunity to ride one that was very kdx like but stronger on the bottom and ripped on top.

On my 01 250 I found the single taper needle to be the best for woods riding. I run a 45p ddk-3 and 175 main at 50f and near sea level. On the 300 with the #7 slide I would start with the 45p cek or cej-4 and 178-185 main (conservative) corrected to your temp and altitude.

The CEK or CEJ will give you a smoother power delivery across the throttle opening compared to the NO_ _ series of needles. If you want more yank then you might try the DDK or DDJ needles. The DD_ needles will be richer in the mid throttle opening area than the CE_ needles.The KTM needles go from lean to rich to lean ( stall,sputter,hit, ouch!) which gives great throttle response if you can be on the gas a lot but can be a handful in tight stuff.

The only other thing I can think of would be the reeds, if they are getting a little ratty it could affect the response down low.

Needles are availble through sudco or carb parts warehouse for about 5-8 bucks ea. Its easy to test different ones during a ride it takes about 5 mins or less to change a needle.

I hope that helps. Others may have more specific reccomendations for your bike and riding area.
 
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TexKDX

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Aug 8, 1999
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Thanks Fishhead. I went to the 13 to try to cut down on the clutch slipping in 3rd and hopefully get it up more on the pipe. I'll order up the needles and give that a try. Also will do the power valve adjustment described above. Gonna try to keep the 13 but suspect the cleaned up jetting will make the 14 a whole bunch better than before.

Still no comments on the stock vs. FMF SA?

Considering I ride trials, the flywheel weight is worthy of consideration too...
 

KTMSMITH

Member
Jan 9, 2002
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Stock Silencer

If you want to maintain smoothness, I would not change the stock silencer. I have found the stock silencer to soften the power slightly compared to aftermarket. I don't run the stock silencer unless I have to because of spark arrester requirements. They are great silencers, but heavy and create extra spooge beacause of the "bullet style SA". Jetting recomendations are tricky for the three honey. They have to be the most catankerous bikes to jet out there. Every one I have owned has been different. Even guys running the same year bike have different results. One needle I have found to almost be universally correct is the 1366n.
 

fishhead

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May 22, 2000
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That is interesting! The 1368eka-2 is similar to the cek-4 but has a slight transition taper for about 4-5 mm. 1366n is practically the same as a CGG. I would interested in knowing your impressions of that needle if you give it a try.
 

sharp

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Sep 30, 2001
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I owned a '96 300 exc after being off bikes for 20 years. It was used and came with a procircuit pipe, the stock silencer, and an FMF turbin core w/o SA. I rode the bike for several months with the FMF silencer.

I installed the stock silencer and it seemed like it put the brakes on with respect to power delivery. I re-installed the FMF because I was play riding only and enjoyed the hit.

I did experiment with gearing. I was running 14/50 and dropped to a 13 cs. I didn't like it. It seemed like the rear tire would brake loose alot, and top out too quick albiet a slower speed.

If you've got both why don't you try and see for yourself? :)
 

TexKDX

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Aug 8, 1999
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Originally posted by sharp

If you've got both why don't you try and see for yourself? :)

Just looking for feedback on possibilities first. Always like to try to benefit from the "been there/done that" of others.
 

Strick

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Nov 8, 1999
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Tex,

I had dinner with a guy the other night that swore by turning the power valve in 1 1/2 turns. I have never addressed the power valve.

Making a 300, a 3-stroke: FMF Gnarly, w/FMF TCII, Delta II on low setting, 50t rear sprocket, at my altitude--> #7 slide, 1367N needle (CGH), 42p, 178m, 50/50 race/pump gas. My throttle was a rheostat!!
 

Bill Hibbs

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Aug 25, 1999
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I'd have to agree with KTMSMITH, I think you're big problem is you're gearing the wrong way. I run the 14/52 and start out in 2nd gear constantly. I too ride District 11. I was just at the local MX track and hadn't ridden in a while and was coming off the jumps Very Nose high, I then shifted into third and solved the problem. You just can run a 300 "on the pipe" in tight woods. It's a low end torque monster and I try to exploit that in my bike set up (Burley pipe, etc.) I've got my power valve screwed in as well.

I REALLY hope my throttle never sticks. :scream:
 

Buddy

Member
Aug 14, 2001
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CEK Needle EXC300

TexKDX
I have to agree with Fishhead on the CEK needle. My 01 EXC300 was rippen my arms out -Just about sold the bike. Friend told me the needle was the culprit. Boy was he ever right.
Just got back from 3 days at Moon Rocks Reno Nevada- 5000-6000ft
Dropped the CEK to last stop(per Stricks intructions)- It was perfect! Linear like pull with mild hit and plenty of power. 45P and 180M to go with that setup.Talk abouta cheap fix!
The SST pipe sounds interesting too.Where do I find out more about it?
Just my 2 cents!
Buddy
Keep your wheels round!:mad: :mad: :D
 

Strick

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Nov 8, 1999
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Buddy does offer the simplest/cheapest solution. Single taper needle, and larger pilot. Takes 5 minutes, and you don't even have to remove the carb.

Let's all try to remember one important item: the slide you are running. Putting a CEK in conjunction with a #6.5, which I do like (at lower altitudes- that is why Buddy has to go to the #1 position with his clip), is a good setup. With a #6 slide - CGK or maybe CGM ???. With a #7 slide, my favorite (many experiments ran) is the CGH (at 4500'-7500').

Needles and main jets are pretty cheap you can buy 3 or 4 of each and still spend less than $35.

Good LucK!
 

TexKDX

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Aug 8, 1999
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Thanks guys, this was exactly what I was looking for. I would have never guessed that jetting made such a difference in the ridability until it went from poor to almost unridable when I broke the pipe/engine seal! That told me that the lean condition was the culprit.

I'll order up a few needles and go at it. Also will screw in the power valve adjustment. Once these are done I'll give it a whirl with the 13. The 14 will probably go back on before all is said and done.
 

RoadRunner

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Oct 17, 1999
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After I got my jetting sorted, I actually went up one tooth on the front sprocket because my low-end response was so much better. The off-idle burble was gone. Now I run a 15/52. My exhaust pipe is stock and I have a pro-circuit s/a. While that gearing is probably way high for what you do, the fact that a simple jetting tweak could make that much difference says that you're heading the right direction.

Plus, always try the cheapest fix first:D
 

Tennessee Thumper

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Jan 23, 2000
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Going to a single taper really made my 300 much more linear.I found the CEJ(4) to work best.The CEK with the 7.0 slide was just a little to lean for me.
 

fishhead

die you sycophant !
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May 22, 2000
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Tex
As you can see by the various responses, jetting is as individual as a haircut. The optimum jetting package will depend on what type of riding you do and personal preference. There is not a one size fits all solution as some guys ride woods enduro's and some ride hare and hounds and some ride dezhurt. Each application has specific challenges that can be addressed with jetting for the application. Where you spend most of the time throttle-wise, 1/8-1/2 or 1/4 to open will also affect your perception of the jetting package. There are responses here for jetting from sea level to 7000 ft. To sort it out I found the Jetting Guide for Pro's By James Deanjdjetting.com to be a great help. With a little work you should be able to get a package together that works from top to bottom that is ideal for your application.

Suggested needles to start would be cek, cej,ddk, ddj, dek,dej.

Have fun:)
 

Strick

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Nov 8, 1999
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Fishhead - Kudos!!! Great post.

One thing I will add and reiterate ---> The slide you run has a major impact. Also, do you feel that cc's have an impact on jetting, and a one size (needle) fits all bikes approach may be a little nearsighted? I could not run the same needle in my 300 and 380 with the same success, and the 200 - forget it!

You mentioned throttle position (riding style), as I have in the past. That is why I live by seat of the pants -- Trial and Error, when jetting. The chart james dean has authored is useful, and so is DRN's Canadian Dave's discertation. Canadian Dave gets more into idle circuit, and air screw positioning.
 

fishhead

die you sycophant !
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May 22, 2000
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Strick,

Absolutly.

The slide cut-away interacts with the straight section dia. and pilot circuit to a lesser degree. On my kdx I found this interaction to be roughly one whole number designation on the cut-away = one letter desination on the straight section diameter. I repeat ROUGHLY as there are interactions with the clip positions and pilot circuit so this won't hold perfectly true but results will be clustered in this area. There are some advantages to be had running a 7 slide and richer needles in many applications. It might be ineresting to try a 5 slide and a larger straight section needle with a longer taper to obtain the desired results. Taming the 300 down.

All guides and advice are just that and are subject to field verification hence the need for seat of the pants testing. Most small bore bikes 125's and 200's prefer the d taper some 250' prefer the d taper and others prefer the c taper and a lot of guys prefer the g length needle on the 380's. 300's seem to fall in between with some liking g length and most preferring e length needles.

The subject of pilot jets is another story. Some can use fat pilots as a way to cool the combustion chamber down after a hard run. In the woods this can equal fouled plugs even when the straight section diameter appers to be balanced. Others accomplish similar results by using a very rich straight section and a fairly lean pilot if they spend little time below 1/4 throttle. It appers to me that most jetting packages that stray a good distance away from median or standard baselines are trying to address a specific problem which is very important to the application and perhaps unusual. An example would be a 400 aircooled Maico roadracing in Open GP trailbike.:eek:
 
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