Just installed the pumper today. there is a noticable flat bog when shifting and accelerating on the street at just off idle. I don't think it will be a problem in the trails but on the street it is noticable. i am talking about a roll on of the throttle while smoth shifting at low rpm. Not talking about blasting to redline and power shifting. If i decel, and throttle up it doesn't bog.
it is just when i let off, clutch, shift, then roll on again. any ideas? I did not adjust the spray as some folks have suggested, but i didn't check it either to see if it is spraying on the needle. I guess i should do that first huh? how do you adjust the pump to spray less at 1/4 throttle? can you move the spray function with the allen screws? is the a manual for this carb in .pdf somewhere? Is the fuel/air screw adjustment on this carb an AIR screw or a FUEL screw? i know some are air and i think 2 stroke carbs are fuel.
i remember something like if the screw is in front of the slide it is air, and if it is at or behind the slide, it is fuel.

 

Too many questions at once. Accelerator pump is adjustable with a Phillips screw for the start of the squirt. You really need to make sure its hitting the needle first.

Mixture screw regulates the amount of air AND fuel pre mixed into the engine after the slide. The ratio of premixed air and fuel are determined by the size of the pilot jet and pilot air jet.

Carb is pretty rich for our bikes in stock form.

Look for black soot out of your tail pipe.

David

 

First of all, congrats on your new carb. The Mikuni Tuning manual can be found here: http://www.mikuni.com/pdf/hs40_manual.pdf The HS40 is the same design as a TM36-68, so it will work fine. The manual describes how to adjust the accelerator pump.

You really should make sure the AP squirter is aimed directly at the needle. If it isn't, you will get a bog on acceleration that can't be jetted around. But that isn't the bog you're describing.

The bog you've got on roll-off/roll-on is caused by the shape of the needle. I experienced it too, and the fix was using a 9EBY1-50 needle, along with a P-4 needle jet. A lot of guys fail to change the needle jet because you have to pull the carb apart to get to it, but it really makes a difference. When you change the needle, you will need to go up on the pilot jet too - around a 15 or 17.5.

The mixture screw on the front of the carb is for FUEL, and really it's setting isn't all that critical on a TM36. These carbs like to run rich. By turning the mixture screw in, I can get the bike to lean out, but I can't get it to flutter rich by turning the screw out. I picked a setting that allowed the bike to idle without blowing black smoke.

You didn't mention your elevation, whether you're running an aftermarket air filter or not, what exhaust you have, or if you're running the lid on or off the airbox. For a base setting though, I can give you my jetting at 2400' ASL:

Main Jet: 130
Pilot Jet: 17.5
Needle Jet: P-4
Needle: 9EBY1-50
Needle Clip: 3rd slot from top (middle position)
Fuel/Air Screw: 2 turns out
A/P Pump Timing: Starts at 1/8 throttle and stops at 3/4 throttle
A/P Squirter: Pointed directly at the needle (fuel should splash off of the needle)
K&N Air Filter with lid off
Full Exhaust

 

Thanks Mustang, I did change the main and pilot for baseline purposes but left the needle and needle jet stock although i DID order them. I will give it a go and adjust the jet to splash off the needle while i have it off.
BTW i am just above sea level here in NJ and have a FMF slip on Q4, lid off, stock air filter.

 

I've posted pretty detailed log of my TM36 "tuning" in another thread but for close to sea-level I'd say the correct needle & jet combination is either Needle Jet: P-6 + Needle: 9EBY1-50 OR Jet: P-8 + Needle: 9EBY1-51

For higher elevations it's good idea to go one setting leaner (like Mustang) to either P-4 + Needle: 9EBY1-50 OR Jet: P-6 + Needle: 9EBY1-51.

Pilot jet either 15 or 17.5.

Main jet size will depend totally on your air box configuration, 115 or there about for stock snorkel, 130 to 135 with no lid. Somewhere in between for the KDX snorkel.

Those settings really are the cookbook recipe for properly jetted TM36-68 for the KLX. Anyone can just get the parts, drop them in and the bike will run great. From there on it takes just little fine tuning with pilot screw, AP setting and needle height to find perfection.

--
Mikko

 

I had the idle mixture screw adjusted improperly as well as the Accelerator Pump.
I adjusted the idle mixture screw to the middle of the range which was exactly 2 1/2 turns out, it got better but still a little stumble so i started playing with the AP and got it pretty good. it will suffice for the rest of the year as i have 2 more events and then i am done for the year. Over the winter i will take it off and check the spray to ensure it is hitting the needle and i will swap out the needle and needle jet to one size smaller. i Have the stock needle and needle jet currently. It seems pretty good but i am sure i can fine tune it a bit more.