I have my squirt adjusted to the smallest (shortest time duration) squirt available via the screw adjustment but need more (less). Even at the minimum squirt duration it's too long. Question is.....can I shorten the pump rod in like 3mm increments to shorten the squirt duration? I have been reading in the ktmtalk.com forums that folks in the thumper forum with accel. pumps are bending their rods to shorten the squirt duration to like one second. Just wondering if there would be any negative consequesce to doing this?

 

Try getting the smallest nozzle. Instead of shortning the duration lessen the volume of each squirt. I put the smallest nozzle on mine and have no problems. I believe Hightower also did the same thing.

 

The smallest available is a 50. Do that and you're done.

 

Well, I had been using the 50 the whole time trying to lean out that squirt. My needle was also the leanest (97) in the top clip (leanest) with a 145 main. Activating the pump pertty much threw of my entire jetting because of too long of a squirt. I just came back from my garage where I took about 4mm off the pump rod and WOW....PERFECT!!![img]i/expressions/face-icon-small-happy.gif[/img] It was simply squirting fuel for too long of a duration whereas it was still squirting where the neelde & needle position was coming into play. Like I said, I have been reading a LOT about this mod on ktmtalk.com with the 520/525 bikes & they are reducing their factory 2.5 second squirt down to 1 second with awesome results. Just too much damn fuel introduced all at once seemed to be my problem, it was blowing a big poof of smoke in the driveway when I gunned it off idle. Absolutely perfect now, I highly recomend this mod to all those frustrated with setting up their accel. pumps! Enjoy.....[img]i/expressions/face-icon-small-wink.gif[/img]

 

You do know that there are 2 screws for the rod? 1 for start and 1 for stop?

 

I use thumb throttle, I prefer it, but to use it with pumper I had to modify the light return to be a little stiffer, and the pumper spring to be a little weeker. This weeker pumper spring allows for a little bit softer squirt, thereby lessening the amount of fuel delivery, but still strong enough to atomize against the needle well. this softer squirt is just a coincidence, not planned, but may actually be a plus. I use #50 pump nozzle.

One mistake I've seen alot is people using too big a pilot - usually a 40 pilot is used when not using the pumper, but if guys are gonna use the pumper the pilot needs properly tuned by standard method (carb manual gives procedure), and for my bike its a #35 pilot, some need 30, and others as low as 25 depending on altitude. Too big a pilot will have a guy fighting hardcore with the pumper settings.

Oh, and along with what mudstud is saying - I have the travel limit screw (the tiny long one on the carb top) adjusted to allow for a very short squirt - I just turned it down one turn at a time until the sputtering disappeared that too long a squirt duration was causing at point of needle. And the preload screw (the one on the linkage arm with the spring around it) adjusted to start squirting just off idle. it basicallt squirts right off idle and stops just before 1/4 throttle.

 

17.5 pilot works well with a 50 pump nozzil on the TM45 and 48 carbs

 

17.5? That sure seems to be a big jump from the 40 that came in it, doesn't it? No problems with this lean of a pilot?[img]i/expressions/face-icon-small-confused.gif[/img]

 

Mikuni which is right up the street from me told me to run a 29.5 to a 32.5 if you are running the pump. They said the Harley's seem to like this setup.

 

where can you get a 17.5 pilot?