Back from the Track - Problem

[Goes9s]

I went to the track today and encountered a problem I never experienced before. Normally I run a shinko Ultra Soft 200 tire, a number of engine and suspension mods with a cycle tek air shifter and a 2 step launch master. I never had a problem with this set up before - running 9.6 at a density altitude of 4500 - 5400. Today I decided to run a MCR2 tire to try and get me to the 9.5's at this altitude. The MCR2 tire hooked like no other. It shifted so hard from 1st to 2nd that the bike literally jumped. I thought the front wheel came up a little but when a few spectors came by to look at my bike they said that bike JUMPED when it when into 2nd. The problem is that when the bike shifted from 1st to 2nd it popped into nuetral for a second then back into 2nd. Has anyone experienced this before? Why did it do this today when it never did it before and is it because of the hard jerk into 2nd? How would I fix it, go back to the shinko or maybe change the delay of the air shifter? Is there a fix that I can do and still run my MCR2? Thanks for your help!

 

[Mr Bogus]

transmission is undercut already?

 

[Goes9s]

Transmission is stock and has had no issues so far. The only thing I've changed from today and last week is the tire.

 

[Goes9s]

Forgot to mention; foot shifting I have no issues in any gear at any RPM.

 

[Mr Bogus]

I was speaking with Paul Gast (Fast by Gast) and he was quick to inform me that for drag racing, the Busa trans needs undercut in first and second gear minimum.. I would bet you have the transmission popping out of and then back into gear with that new found traction.. It is not supposed to be all that uncommon for the things to pop out of first gear.. NIGHTFLIGHT was with me when the guys from Orient Express said the same thing..

 

[Goes9s]

Thanks for your input; so you think it boils down to the new MCR2 traction, no spin in 2nd any more, causing additional strain on the transmission? Do you know who is a good POC to fix this and approximately how much?

 

[Goes9s]

What is the transmission relationship to foot shifting? Why don't I have a problem from 1st to 2nd when a foot shift? Is it because there is enough delay to take the strain off the tranny?

 

[Mr Bogus]

What is the transmission relationship to foot shifting? Why don't I have a problem from 1st to 2nd when a foot shift? Is it because there is enough delay to take the strain off the tranny?

I think you are probably right, foot shifting is allowing the dogs to fully engage (I have no drag racing experience with the busa myself like this) There are a good number of guys here with extensive drag race time on the busa that should chime in I was quoted $300 for a full upshift undercut and it seems to be a pretty standard fee..

I would suggest you contact Daniel (Cloud 9 motorsports) and get his input.. "GoldenChild"

 

[djsin]

undercut is the way to go...

 

[Professor]

Those MCR2 will bite hard!

Make sure the shift ram is adjusted with enough length to go past the point needed to place it fully in 2nd gear. (throw is a bit longer in second) If that is OK, you might add just a tad bit of delay to the box. Is you valve mounted to the radiator overflow tank? Shorter tubing will make a difference.

You may have been on the edge of having an issue before and the MCR2 is making it worse. Otherwise as said above, it may be time for an undercut.

 

[Goes9s]

Those MCR2 will bite hard!

Make sure the shift ram is adjusted with enough length to go past the point needed to place it fully in 2nd gear. (throw is a bit longer in second) If that is OK, you might add just a tad bit of delay to the box. Is you valve mounted to the radiator overflow tank? Shorter tubing will make a difference.

You may have been on the edge of having an issue before and the MCR2 is making it worse. Otherwise as said above, it may be time for an undercut.

Thanks Professor! Can you elaborate a little more in detail on the shift ram adjustment? Not quite following what I need to adjust? Thanks.

 

[GoldenChild]

You want to allow more throw on the ram to allow it to fully push the lever from 1st to second as that gear is the furtheres throw of all the gears....Depending how you got ram mounted u want to mark where nut is now on shift rod,take aloose from shifter arm,loosen nut,turn u clevis in/out some then reset nut and hook back up to rod...

 

[Goes9s]

You want to allow more throw on the ram to allow it to fully push the lever from 1st to second as that gear is the furtheres throw of all the gears....Depending how you got ram mounted u want to mark where nut is now on shift rod,take aloose from shifter arm,loosen nut,turn u clevis in/out some then reset nut and hook back up to rod...

Aaah, gotch ya! That makes sense. I'll double check that as well. Thanks again for your help. Any other ideas out there?

 

[aaronxs400]

when i was still racing harleys, whenver we had this issue we added more kill time to the air shifter. buddy of mine won 4 championships without a backcut tranny. many people spend the money to do it but if your not seeking that absolute hundreth of second saved from having a short kill time that you pry dont need it.

 

[dadofthree]

 

[Goes9s]

All posts seem to be good sound advice. I'll start with the most simplistic approach and work my way through the checklist. Thanks again.

 

[boofoo]

I got a kinda related question.
1-2 upshift fine. Top of 1, 3, 4, 5 fine BUT top of 2nd cuts out / stumbles. After some research seems most people are saying that's a sign of 2nd gear on the way out and needs to be torn down and cut. Is that right or is there something I'm missing.

 

[JimmyTNT]

one thing nobody mentioned was chain slap!!! My dirtbike wont shift for crap if the chain is too loose. some of my older drag bikes would too! If you're stretched, thats just all the more extra chain to whip around if its not tensioned enough!

 

[BIG GUY]

I don't have a lot of experience with drag racing, but I do have a couple questions. It does sound like it is time to have the tranny undercut, but could he have had a problem with the air shifter not having enough air to get it all the way into 2nd gear? I do a lot of street riding with some occasional trips to the track and have been thinking about getting the tranny undercut. What level should I take the work to the tranny to? Should I do all the gears or just first and second? Who should I have do the work?