Yoshimura ST 1 ST2

[ZeePopo]

Does anyone have data on these two cams after a tune? All I found are direct swaps with no tune. Been wondering how good they can be after a tune on HP and torque curves.

 

[Busa Quick]

I have them on my Gen 2 with 1441 and Woosner 13.5 CR pistons. I put them in using the specification provided by yoshimura. I really enjoy the performance for street riding, and ripping around. I recommend you get a tune once they are installed. And if I were to guess, you will probably gain around 10 horsepower if you don't do any other modifications. Even if you don't change the cams at all, you'll want to check the valve lash. I had to change about six of the 16 valves. They weren't off by much but you will need a shim kit. Also I had to time the cams a little bit as they were not perfect. I don't think I would blame Yoshimura, I think it depends on how tight your chain and sprockets are. If your timing chain is worn, your chain will make the cams time a little different. My bike was very low miles when I did this mod.

I feel like the cams are very nice their packaged well and they look like something you would buy from the factory as far as cleanliness.
I also ran some stage one yoshimura cams on my Gen 1 Hayabusa for around 27,000 miles. On that bike, I found that lost just a little bit of bottom end but gained mid and top end.

I know I said a lot, I hope it helps

 

[Bumblebee]

I had a set of Yosh cams in my oil burner GSXR years ago..they made a huge difference in that bike...and it lost a bit on the low end but made big gains in the mid to top end....

I imagine the ones for the Hayabusa are similar profiles to the ones for the old oil burners...

 

[ZeePopo]

I have them on my Gen 2 with 1441 and Woosner 13.5 CR pistons. I put them in using the specification provided by yoshimura. I really enjoy the performance for street riding, and ripping around. I recommend you get a tune once they are installed. And if I were to guess, you will probably gain around 10 horsepower if you don't do any other modifications. Even if you don't change the cams at all, you'll want to check the valve lash. I had to change about six of the 16 valves. They weren't off by much but you will need a shim kit. Also I had to time the cams a little bit as they were not perfect. I don't think I would blame Yoshimura, I think it depends on how tight your chain and sprockets are. If your timing chain is worn, your chain will make the cams time a little different. My bike was very low miles when I did this mod.

I feel like the cams are very nice their packaged well and they look like something you would buy from the factory as far as cleanliness.
I also ran some stage one yoshimura cams on my Gen 1 Hayabusa for around 27,000 miles. On that bike, I found that lost just a little bit of bottom end but gained mid and top end.

I know I said a lot, I hope it helps

Do you a copy of your dyno? Love to see the curve on 13.5 pistons.

 

[Busa Quick]

I have not made it to the dyno yet. I've done all my own tuning using ECU flash and data logging. I can say I was surprised how much fuel I had to add almost everywhere to get the air fuel ratio right. I hope to get the bike to the dyno this year, I have a place picked out I just need to find some free time.

My seat of the pants dyno says that I improve the power everywhere especially the bottom end. I still think a turbo bike would be a bigger improvement for outright power, but I feel like I have usable power all the time. I kept the stock oil cooler and run a yoshimura alpha race exhaust with no extra silencer. I know there are faster bikes out there but I am super happy! I have no cooling problems, and the original lead acid battery the bike came with. I think the startup RPM is slightly lower but it never hesitates to start.