Help setting up Gen 2 suspension for drag racing

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spooledup

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I am new to drag racing motorcycles and I need help understanding and setting up the suspension. I am planning on running it tomorrow and wanted to set up the suspension a little before I go. I want to have a general understanding of how changes affect it so I can start trying to figure it out.

My bike is a 2008 Hayabusa stock wheel base (measured about 59 inches) I have a lowering link on the middle setting. I am also going to be strapping the front end. I weight about 195-200 in gear and about 5' 8'' height. I am also at a high elevation (5600 feet with the DA usually in the 7000 feet range) so the bike is down 15-20% in power from sea level.

How much sag do I want to put into it? How does putting more or less sag affect how it reacts? Is sag and pre load the same thing?

How does changing the compression affect how it reacts? Where do I want to start?

How does changing the rebound affect how it reacts? Where do I want to start on this?

I wold also like to set up the front suspension for when I am riding and the bike when it is not strapped. I watched a few videos online about setting up the suspension so I have a really basic understanding of it.

Thanks for the help.

Cisco
 
Last edited:
:welcome:

Ideally, you want to have the bike squat on launch to get the best grip and stop the front from rising immediately. Dont set the rebound too hard as you dont want it to spring back too quick.

Also, you need to be aware that if your preload is too soft you may get the bike hitting the rear tyre. You will notice this from marks on the undertray etc. I dont know if this will happen on a stock length bike!

When I bought my 08 it had already been dragged and the previous owner had it all set on hard settings, it worked OK but you need to set it to suit yourself, I softened it all up a bit.

Important note: After the first set up, dont change two things at once before the next run. Keep a note of what you change, the times run and the affect that it had on the bike. If you change two things, which one worked?

I am no expert in suspension set ups as I'm still trying to get mine right. Ive got the new back light on order as Ive worn some of the lens away, mine is set at 63" with stock length bodywork. +4" Catalyst Street Tail in the paint shop as we speak, when that goes on I will fit the JRi shock.

Have you been to the track yet? what are the times? How did the bike feel?

Get this right and then get the 15-20% power back in there somehow, you are missing SO much fun! .....or move to the beach! :beerchug:
 
Thanks for the info. I took it last Friday. It was my first time taking a bike down the strip and I ran a best of 10.72 @ 131 with a 1.83 60' I have a lot to learn and still trying to get comfortable with it. I had a best trap of 133 but I think it has a 136 in it once I get my shifting down. It felt awesome and was a fun experience. I am going to try and get a lot more aggressive with my launch this weekend so I am hoping to at least get into the mid 1.7s (well depending on the difference strapping makes it maybe even faster) I would also like to see a 10.50 et. (baby steps) At our elevation some of the better riders are getting bikes similar to mine in the 10 teens. One of the guys is about 20 pounds lighter than me and a hell of a lot more experienced and I think he was in the 1.61 60" range.
 
spooledup said:
Thanks for the info. I took it last Friday. It was my first time taking a bike down the strip and I ran a best of 10.72 @ 131 with a 1.83 60' I have a lot to learn and still trying to get comfortable with it. I had a best trap of 133 but I think it has a 136 in it once I get my shifting down. It felt awesome and was a fun experience. I am going to try and get a lot more aggressive with my launch this weekend so I am hoping to at least get into the mid 1.7s (well depending on the difference strapping makes it maybe even faster) I would also like to see a 10.50 et. (baby steps) At our elevation some of the better riders are getting bikes similar to mine in the 10 teens. One of the guys is about 20 pounds lighter than me and a hell of a lot more experienced and I think he was in the 1.61 60" range.
Click to expand...

Take your time and take care, just get loads of seat time and practice, practice, practice. Once your confidence builds up, you will get better times. sounds like your doing OK to me.

How does the (altitude) power loss transfer in respect of times? for example, have any of your buddies run at altitude and then at sea level? I would be interested to see the difference in ET and mph.

Have fun and stay safe. :please:
 
chunk1340 said:
Take your time and take care, just get loads of seat time and practice, practice, practice. Once your confidence builds up, you will get better times. sounds like your doing OK to me.

How does the (altitude) power loss transfer in respect of times? for example, have any of your buddies run at altitude and then at sea level? I would be interested to see the difference in ET and mph.

Have fun and stay safe. :please:
Click to expand...


The altitude really kills our times. I have seen a few friends pick up close to a second on NA cars. My buddy ran the same time on N2O on his Camaro here as he did on motor in Houston which is sea level. My Supra is not affected as much but its turboed.

I got some new times tonight. The weather was really bad it was cold and windy as heck. I still have not messed with the suspension, I am waiting to get more info first. I did put the lowering strap and ran a best of 10.37 @ 134 my 60' was only a 1.74 on that pass. I did get a 1.67 60' but was having issues with my clutch slipping in the top of first gear. I hot lapped it and I think my clutch is already not to happy. Stock wheel base is very unpredictable, most runs the front stayed down but on one it came up what felt like 3 feet in the middle of first gear. It took a few runs after that to get aggressive again lol.
 
Sounds like your going the right way. 1.6's are ok for stock wheelbase. I run at 63". You'll get used to the wheelies.
 
Still yet to mess with the suspension but improved on my times. 10.18 @ 137 with a 1.695 60' I had a best 60' of 1.627 but it stars spinning in the top of first. I need an ultra soft tire.
 
chunk1340 thought you might be interested in what I'm up to.

I put the bike on the lowest link in the back, dropped it about an inch and a quarter on the tree and when I strap it, its hard to put a finger between the fender and nose. So ya its really low. I also put a shinko ultra soft tire. I learned a lot the last two days running it. I really think I'm around the max at this elevation on the stock gearing. I went 10.059 @ 138.057 with the DA at about 8100 feet. This run was with a 1.62 60'. I had a best 60' of 1.587, to get this I was leaving at about 8000 rpm and flashing the throttle as I start releasing the clutch. I was throwing away the clutch very fast to get it to 1.5 60' and it would bog a little around the 60' I think it needs cooler air for power or more gearing. I have been comparing times with local people and I have not seen anybody 60 this good on stock gearing and its about a 10th off of being the fastest stock wheel base bike here. Fastest is a 9.95 that tapped 142 to get there. I am putting in the work and looking for hundredths. I'm having a blast doing it, I love the challenge. Its been really hot here and the DA has been bad but Ive come a long way on my part and its showing. If it was towards the end of the year when it cools off I think it would go 9.90s with ease.

I'm trying all the little tricks now. Tonight I removed the secondary butterflys, the weights under the pegs and I'm thinking of removing the oil cooler. I am also going to try and lean up and hopefully I can get a consistent 9 second bike. I still need a tune and am going to gear it a little later on. After that I don't see consistent 9.8s being to hard to accomplish.

Friday night I ran about 12 10.2x passes and 2 10.1x passes at the end of the night when I got more aggressive. Saturday night I got even more aggressive and ran 4 10.0x passes. a couple 10.1 and 10.2 passes. Saturday night was about 10 degrees hotter also. Its crazy how consistent I am on this bike. Just thought you would like to hear a little update.
 
Try leaving low and rolling into the throttle as you feed it clutch. Work on having the clutch out and WOT by the 60' timer.

This works better for me than leaving at high RPMs
 
Ludicrous Speed said:
Try leaving low and rolling into the throttle as you feed it clutch. Work on having the clutch out and WOT by the 60' timer.

This works better for me than leaving at high RPMs
Click to expand...

Thats what Ive always done until Saturday. I usually leave at 4500-5000 rpm, whack the throttle and start letting the clutch out. I was stuck in the 1.62 60' and tried new things. First tried being slower with the clutch and it sucked. I went 1.70 60' then I tried throwing it out way sooner. The bike left a lot harder but started to bog around the 60. I had to start higher to keep it from bogging, but that is what it wanted to get into the 1.5s. I think the main problem is it needs gear or lower elevation, it just dogs out the way it is.
 
I killed the clutch today doing a little street racing. I knew it was on its last leg and Ive made a lot of passes on it. Before the clutch went I did launch it and spin the tire bad, it was a show lol. I walked out the black line and it was 168 regular steps so I'm guessing it was a little over 200ft. It was a fun ride.

What clutch mods does everybody recommend to get for drag racing. Ill probably put stock steels and fibers. Is the clutch cushion and clutch mod worth it? I was thinking of putting a little heavier springs as well.
 
spooledup said:
I killed the clutch today doing a little street racing. I knew it was on its last leg and Ive made a lot of passes on it. Before the clutch went I did launch it and spin the tire bad, it was a show lol. I walked out the black line and it was 168 regular steps so I'm guessing it was a little over 200ft. It was a fun ride.

What clutch mods does everybody recommend to get for drag racing. Ill probably put stock steels and fibers. Is the clutch cushion and clutch mod worth it? I was thinking of putting a little heavier springs as well.
Click to expand...

Brocks clutch mods for me when I ran the stock clutch, other mods are available. I always use the stock clutch pack too. Some guys here run the Blackbird fibers as they are the same but cheaper, I believe. ???
 
Thanks I ordered an OEM clutch and I am buying the brocks clutch mod from a friend. I ordered a few other goodies so hopefully my next outing will be in the 9s.
 
Little update. Put a -1 gear in the front and the bike came alive. First day out I got a 1.530 60' my best before on stock gearing was a 1.57 and it was hard to get that. I kept having trouble shifting into 2nd though and still have not got my 9. I had to take off the shifter and when I put it back it was higher than before so it was difficult to click it up. I re-adjusted it, ordered a tire and some leathers today. So I think the next outing should net some good times. Its been a blast. Ive been comparing my times to other locals and I have everybody beat on 60' on a stock wheelbase bike. And I am close on the ET, I got about a tenth to shave off to get the best stock wheel base time here. I am doing it with about 5 less mph, damn those light weights.
 
Today was a good day. The DA got down to 7100 feet and I got my first 9. Then I ran 5 more lol that first one was a *****.

Best of the night.

1.547 60 ft
6.413 @ 111.082 1/8th
9.963 @ 138.532 1/4
 
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