To make sure the slide in the same position each time I test without me having to mark the twist grip and keep an eye on that mark and the road at the same time.

It's just so easy to hold it to the stop

 

Inconclusive!

Cranking open the throttle in 3rd gear to the 1/2 throttle stop at 30km/h and having the CT Speedometer Systems Pro app on a Smart phone record the elapsed time between 40-70km/h on the slight uphill grade...

The elapsed time for the 9EBY1-50 needle (richer) set at the 4th clip groove from the top came in at 2.6 and 2.8 seconds.

While the elapsed time for the 9EBY1-51 (leaner) needle at bottom full rich clip groove came in at 2.7 and 2.8 seconds



There is .01mm diameter difference between the needles.

So for now the nod goes to the "50" needle for its average elapsed time of 2.7 sec vs 2.75 seconds average for the "51". Plus the richer "50" needle at the 4th groove seemed to feel stronger gassing it along the dirt shoulder on the way to where I U-turn and do the timed run back, and though it seemed to respond a hair slower or was it just duller sounding.. when I cranked it open at 30km/h it evidently made it up because the E.T. was good.

Anyway it was GREAT just using 1 gear to test instead of 4 or 5 thanks to that Google app. and the throttle stop eliminated the variable of whether the throttle was in the same position each time. Almost as good as an a/f gauge and O2 sensor because it was so easy.


I may put the leaner needle back in at full rich and ride bike seeing how it cold starts and roto-tills the shoulder of the road etc before I put the richer needle back in at the 4th groove from the top

- Actually I am going to use the leaner needle at full rich as it pulled the front wheel up nicely at the pegged to half throttle 1-2 shift-which I see the richer needle does not after one last test ride and the richer needle sounds a little 'woolly' at lower rpms ..

 

Richard, are you still getting the A/F monitor in the near future? You mention that there's only .01mm difference between the needles, and I remember you mentioning that the difference between the needle jets is small. True, but in a carb these small differences usually make big tuning differences. I see what you're trying to accomplish with the throttle position stop, but I'm not sure this will really yield the precise result that you're looking for. At least as important as the mixture performance at specific throttle positions is the transition performance as the throttle moves through the entire range...actually probably more important.

Richard, we've had several of these TM36 threads now, so I can't recall without trying to go back and find all of them. Did you run the P4 needle jet and 9EBY01-50 setup in your carb?

 

It'll be 3 mos before my a/f meter and exhaust bungs etc get here.

I started off with the P6 needle jet as I think I'd found in posts from others near sea level (you have to pick a combo and start somewhere) The 50/51 needles and needle jets are sized in increments of .01mm.

Transition jetting is important, but there's still plenty of info online about marking your throttle grip in 1/4, 1/2, and 3/4 increments as a tuning procedure. So the throttle stop was a start, didn't cost anything but a little time, and allowed me to eliminate an important variable. If I'd just used markings on the grip and had the throttle even in a slightly different position, timing the 40-70km/h bursts wouldn't have been valid testing. It'd probably be easier to find a long steeper uphill section of road to test max km/h in a particular gear at 1/2 throttle on even if I have to ride a few km to get there.

It was interesting to feel how much power was there at 1/2 throttle max because we're accustomed to thinking of the main jet and WOT as all-important.

Isolating the needle to 1/2 throttle also let me identify a needle richness at the setting it was at before I started testing that wasn't readily apparent using varied throttle openings just riding around

I'm sure the P4 would be too lean because I'm already richer than that with the P6. There's always the question of using a different pilot jet in conjunction with a different idle mixture screw setting and even using a leaner slide to clear up some of the low rpm richness of the richer needle setting, but that would take forever and would really need an a/f meter to do efficiently.

The bike's running better and tuning was fun for a change

 

Now that I know the gas I was using might have been questionable-or at least the gas station, I thought I'd play with jetting a bit

I tried shimming the leaner 51 needle a hair richer with a couple of the special washers I have for doing just that. I used two washers-one under the needle and one under the little needle hold down thingy bolt to even things out and not bend the thingy so it no longer maintained proper pressure once I removed the shim from the needle..

The engine didn't like being half a groove past full rich any more than it'd that at full rich. Still too lean

So I tried using the richer 50 needle but this time with the clip in the middle groove, since it was sounding a little fat with the clip in the 4th groove. That was much more crisper and more powerful I'd say as I got to my usual shutoff point at a surprisingly faster km/h than usual.



I'd tried that middle needle position before but felt it wasn't rich enough for some reason..maybe the change of gas stations has something to do with it or the even warmer weather nowadays.

I think I am done with jetting until my larger main jets arrive from the US sometime in the next 30 days, but the 135mj felt great a few minutes ago.
'

I still have that Webcam to put in my XR200 if I get antsy. If I didn't have to take the engine out of it to put the cam in, I'd have done it already..

 

Interesting that as far as I can see no one has ever bothered to port the intake manifold out to match the TM36. Which means there's probably also there hasn't been anyone enlarging the head's port opening -not even rounding off the edges to facilitate the TM36s or ported intake's larger opening.

I'll have to see what it looks from the engine side view by holding the carb/intake manifold up next time I have the carby off.


I did take the time to measure things up a few months ago:

The KLX rubber intake had an opening of 35mm w x 31mm tall where it fits up against the head

Max size possible after porting the intake appeared to be 40mm w x 36mm tall - IF grinding out the inner rubber doesn't make the entire thing kind of fall apart etc

The engine port was 35mm wide x 33mm tall (I don't remember if that was factory size or the most I felt it could be opened up to)


At any rate, a too-small intake or head port opening could be a big factor any performance gain to be had from a 36mm or larger carby

 

Richard, you may be over thinking some of this, at least as it pertains to the KLX. Done as a fun pursuit where any work, time, or money spent by the individual isn't required to be "under the spotlight" of money-well-spent, it can be an interesting project. Goodness knows I've done plenty of projects over the years that wouldn't have passed the smell test of logic and bang-for-the buck, but one can still do them if you have the time, money, and experience to do so without making the vehicle unpleasant to use or very fragile. Heck, I've already poured in a good amount of time and money on my KLX in terms of suspension, exhaust, intake, fuel capacity, etc., so I understand the desire. Still, at a certain point it really may make more sense to just get another bike. At this point, I might have actually pursued getting a clean, used, not-too-molested KTM250 EXC for my type of riding instead of going the route I'm on. And NO...I'm not crying in my beer about spending some time and money on my KLX, as I've been having a ton of fun of this bike. In a couple of weeks I'll be having some more fun doing a nearly 3-week trip in southern Utah on this bike, and it has worked excellently for these types of trips for 5 years now.

 

I never thought of port matching to be expensive nor considered to be over thinking a mod. If you can pull the head off to change a cylinder or even take the carb and intake off, you can do some port matching while it's apart to match a bigger carb?

I might get a bigger bike if they were available here but they are few and far between and over-priced when you do find them

Otherwise I am missing your point. If you just want to follow the pack, be my guest

 

pump as much time and money as you want into this Richard.

It just means that all the bases will be covered and others can see if the return on investment pays off for them. Most likely with port matching though, it's not worth it haha!

 

Yeah, that's me...a pack follower...LOL!