Hi all - I'm new at modding sleds, thus I have a lot of newbie questions. I'm asphalt racing (1/4 mile) my 97 Ultra SPX. It has a stock motor and clutch. I put PSi pipes on it today, and it's not going any faster than it was with stock pipes - possibly even slower. With the stock pipes it was revving to 8000 rpms pretty quick, dropping to 7800 and then quickly getting back up to 8000.

The PSI pipes are supposed to run at 8600rpms. I made a few passes today - it revs to 7500 at a medium pace, and then very slowly climbs to 8100 by the stripe. I stayed in it a little past the stripe and it climbed a little more before I shut it down.

On the jackstand it pulls to 8800

Being new to mods, I'm not sure where to start. Lighter weights in the primary? If so, how radical of a change should I make? Stock is a 10-54, which I assume is 54 grams. My dealer has some 49s on the shelf - is this too radical of a change?

I also think I want to increase the engagement to get it out of the hole faster - it seems more sluggish with the pipes - I think this makes sense - I assume the pipes move the powerband up, so I'll want a higher engagement. Is my thinking right? It's engaging at 4800rpm right now.

Any thoughts or suggestions?

Thanks!

Yes you will want to lower the weight, it is hard to say how much because ecah sled will react different to changes so you will have to experiment to get what you need. Pipes do not always need a bigger engagement to work better and it will be more important to you with what you have for traction. That motor makes good torque so I would not look for more RPm's down low but increase your top end RPM for sure. Try and see what you are running at the stripe and you might have to run a little lighter weight to get your desired result. You might have to try some different springs also to get you where you want to be. Don't judge by RPM on the stand it will be much different under load. As you get more power you will then start to see traction issues come about because of increased power so keep thinking about that as you make changes. write them all down and compare results, data is huge so you don't keep doing the same things over and see progress in your changes. Remember jetting also, if it is to rich it will not allow the motor to run the RPM it is capable of. You will want to have a selection of jets and weights and get used to changing them as you will with the weather changes. If you have more questions you can PM me also and I will try and help you anyway I can.

Good luck

Thanks! The plan I have come up with after talking to a lot of people (unfortunately PSI seems to be closed for the day) is the replace the 9000 mile old driven spring and make a pass and see how it does. I'll check the piston wash and see if I need to do anything there - we have all the jets we need. If that pass didn't get the rpms up, I'll throw the 49s in for the second qulifying run and see what happens. Maybe we'll change some other stuff before eliminations - it's always smart to change things before eliminations

The 49 gram weights and new secondary spring in the 4th hole(second tightest) worked great. 8500 - 8550 rpms. I made it to my first final round in 11 years of racing! I lost in the final by .0113. Had I hit the brakes I would have won - we were on a double breakout pass.