Had some dyno time on sat and wanted to know if the Air fuel ratio should be about the same as cars go anywhere from 12 to 14:1? It was running real lean at ldle and couldn't get it better than 19:1 but as soon as you hit the gas it went right to 13:1. For some reason at 4500 RPM it dipped and got rich with a dip in tourqe on the dyno graph. What would cause that dip. I have a 720 with the high compression TVI piston, alba full exhaust and extreme head porting with big values and MrHP grind cams. I still have the TM45 on race gas. How lean can you run the DS motor? Any help would be great. I will try to post dyno results. they are big files.

 

It may want more fuel, When my ds idles I can see the exauhst comming out of the pipe and w/ a few cracks of the throttle it blows out a 3 ft flame sometimes. I wouldnt go too lean if you have a steel or cast iron sleeve, It may want to move @ around 200-210 degrees.


What is your pilot size?


What main jet?


Needle placement?


Wheres your air fuel mix screw at?


Are you running the snorkle w/ K&N?

I Dont like to run lean @ Idle. JMO

 

squatcher,

ITS THE ALBA PIPE!!!!!
I went thru this not to long ago on the dyno. The Alba head pipes are way to big for modded motors. I dynoed at Eric and Randalls, and they had to give up on trying to jet that thing right. They bolted up the drag pipe, and shazzzaammm, everything was fixed. Not to mention, the Alba pipe would NOT rev over 8500 rpm. I had thought I was floating valves before I took it to them. Not the case, the pipe is a pile of garbage, and that is where it belongs in my opinion. Just as an example of the difference in dyno curves between the Alba and drag pipes. At 8500 rpm ( this is not peak hp.) the Alba pipe was at 32 hp, and the drag pipe was at 60 hp. Peak Hp, the Alba was at about 59 and the drag at 65.57. The peak was held for only about a 1000 rpm with the Alba, and the drag held from about 6500 - 8000. Mind you that after the peak with the Alba, it dropped faster than Monica Lewinski in the oval office.

The Alba curve had that very same problem your talking about, rich, lean, rich, lean, rich, lean. Horrible.
Anyway, just my 2 cents.

Gary

 

Air to fuel ration for best power is 12.7:1. Its not always possible to get it spot on across the RPM range with a carb, but anything form 12.1 to 13.5 is good.

If you are lean at idle, then you are running to small a Pilot jet. If the air screw is turned out more than 3.5 turn and its still lean upgrade the pilot. At 19:1 ration you might have to install a 48 to 50 Pilot jet to get the idle mixture right.

Also, the Pilot and air screw plays a big part in throttle position from idle to about 1/4 open. Then from about 1/4 to nearly full throttle the needle and main jet combination plays the biggest role. At full throttle the main jet is the main part to worry about. You have to move things in combination to get the best ratio. If the bike is not performing well between 1/4 to nearly half throttle change the needle position or change to a different needle taper. At full throttle play around with the main jet till you get it right.

The best way is to get the idle circuit fixed 1st, then sort out the full throttle main jet and lastly play with the needle to get the mid section sorted out.

If the needle is not working get yourself a jet kit and start again. The stock needle might not work for your combination.

 

Is there an accelarator pump on your TM45 (some use them and some don't.)

You may want it a bit lean on the bottom if you have the pump activated. This will prevent flooding when the pump is activated.

What Freez said sounds good except. Don't waste money on a "jet kit" You can get different needles and jets as needed but, a "kit" is a waste of money.

 

Intake leak?

 

I will check for an air leak today, I am running with the pump active with a 70 nossile ( I am ordering a new one 50) I think that might take care of the richness at 4500 rpm. Settings are as follows 145 main (bigger dropped HP) 40 pilot, stock needle bottom clip position, air screw is only 1 1/2 turns out. If I went out more turns I was way lean 27:1 Direct mount K&N filter. What else should I order and try. Dstroyer I am running into the same stuff. Peak HP was only about 1000 rpm range and monica was in the house. Before I put the bigger values in I had a real good curve. What other pipes would anyone suggest for this motor? thanks for the feedback guys

 

Squatcher,

Im not sure if you had Eric or Randall dyno this on Saturday, but it seems as if we have very similar motors. If it was Eric, you could ask him about the Alba pipe I used. He could confirm these problems. Because the drag pipe is extremely loud and not spark arrested, I will be buying the Ron Woods pipe just for those times its needed.

Gary

 

I had it dynoed here in Phoenix. My friend has the only hydraulic dyno in the state. (that I know of) the dyno hooks up to the wheel hubs. I can hold the bike at what ever RPM and get measurements. I had pictures but my dig. camera took a crap before I could get the pictures out. What do you think of the trinity exhaust or the LTE duals?

 

I believe the Trinity pipe is identical to the Alba pipe. Ive never seen, the LTE duals yet. It would be interesting to see what kind of performance it has with the highly modded motors. Now this would be a shootout worth seeing. A pipe shootout on higher horsepower motors.

Gary