TM45, A1/A2 cams, K&N in airbox

Here is a chart showing first set of pulls average compared to to last set.
The page is labeled with jetting and needle settings - 1st pulls 160 main 2nd groove, last pulls 170 main 4th groove

Dyno chart comparisons

notice the air/fuel ratio chart on the bottom, humps match the power curves of 1st pull. wonderful tool!

 

this chart shows how being a little fat doesn't hurt near as bad as being lean - everything the same except 165 main vs. 170 main.

165 vs. 170

 

So I figure the AFR is best with the 170 main.......[img]i/expressions/face-icon-small-confused.gif[/img]

 

good info thanks hightower! your a stage 2.5 right?

 

best power with 165

stock bore, stock stroke, stock valves

 

GOOD info Hightower some of these guys need to study this!!!!!!!!!!

 

Chris, that looks like quite the dip in the midrange! Have you gotten a chance to go riding with the new jetting? I am wondering what kind of difference you felt.

My buddies and I found a dyno just over an hour away (its at a dealership we have passed tons of times going to my friends land up in WIS) and its 50 for 3 runs, then 50 per hour after that, which seems very reasonable.

One thing that worries me about getting the TM, is that I wont be anywhere near proper jetting, losing a lot of power. I know you are good at jetting, so if the tm dosnt respond with typical hesitation/bog etc seems like it might be a chore to get the jetting right on.

If I get the bsr 42 jetted for 800ft, can I leave the needle/air screw alone and then just change mains? I have the 45 pilot in now, so assume that would probably need to go back to stock @ 40, but want to be as close to perfect jetting as possible. (we are riding st. anthonies/ LS / Walden, and a place in colorado that is somthing like 5-7k feet) is + 5 on the jet for every +1500 feet of elevation a good adjusting point for the stock carb?

I am really excited about hitting the dyno to get my jetting straightened out, and to also compare numbers with my 3 yfz buddies. The one races mx, so has thousands into it, 450 kit- cams-full hmf-open intake- (-4) flywheel among other things, actually is only a few bike lengths ahead of my fat butt on the fat DS. my total weight is probably 550+220= 770 compared to his 350+150 + 500

What kind of numbers did Waynes yfz put out?

 

The 165 may have got him the highest in HP but the AFR is scary high at 17.5....

Personally I would have stayed with the 170 because there is less then 1/2 a HP difference and you are at a much safer AFR.

Some of us do know how to read the charts....

 

SCROUNDREL, I was referring to a stock bore, stroke and valves, where it builds HP for a rev limiter!!!

 

Have you tried moving the needle to make the midrange a bit fatter?

The best mixture for power is a 12:7:1. Looking at the run you start slightly rich, but it might be due to a full throttle opening when you start the run. Between 4500 and 6000 RPM the mixture is good, but then it goes leaner. This will rob some torque and HP. Getting 0.6 HP more with the 165 jet might be pure fluke. You will see if you do a multiple runs without touching the carb, none of the runs will delivery an exact match to the previous runs.

Luckily for you, your dyno that compares the 165 to the 170 jet, you can see the high end power difference the ratio around 12.7:1 has on the HP and torque.

For example, look at the power and torque difference of the blue line between 7600 RPM and 8200. Here the blue line is very close to the 12.7:1 ratio, where the red line is a bit leaner. The blue run makes a nice power difference of around 2HP more than the red line.

At 8200 RPM, the red line is at 12.7:1 and now from 8200 to 8900 it makes more power than the blue run, because the blue run is to rich and is loosing you some top end power. Again you gain about 2HP and some torque by running close to the 12.7:1 ratio.

I am sure you will pick up some more HP if you can get the 6000 to 8000 RPM range to be closer to the 12.7:1 air to fuel ratio.

I would take a rough stab at it, and think that the 165 will work fine, but you need to go down one or two clicks on the needle to make it run a little richer in the midrange. The needle should sort out the mixture between 4000 and 7500/8000 RPM.