track day fun on a Gen1 750 - Suzuki GSX-R Motorcycle Forums Gixxer.com
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post #1 of 35 (permalink) Old 09-23-2016, 11:55 PM Thread Starter
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track day fun on a Gen1 750

I wanted to share my recent experiences tracking my 1986 GSX-R750.

Back in April, I was able to do the first track day on my GSX-R. It was an interesting experience of discovery. Years ago, I built and rode on the street a 1986 GSX-R1100. It was slightly modified in the usual ways and made about 20 Hp more than stock (112 Dynojet HP). So, I had some idea of the Gen1 Gixxer experience.

Of course my 750 version was a different animal with no street bike compromises (the lights are decals). It was fast and light and while I had no trouble riding it, I was no where close to the limit; a combination of my meager skills and caution. At ACS (Fontana), I could circulate at a 1:55 lap time. Some would say that isn't bad for a 30 year old 750 on 18" street tires (BT-016s).

Recently, I was invited by the guys at Motorcyclist magazine to take the GSX-R back out to ACS so they could ride it and take photos for an article. At the track, I did the first session to be sure everything was ok and then turned it over to Zack Courts and Ari Henning for testing.

After the next session, Ari asked me to reduce the front preload (I'm heavier then either of them) and add some rear compression and rebound which I did. The report after the next session was positive so we left the settings there. Ari said it was "perfect".

Both riders were already running in the 1:46 lap time range which I thought was pretty racey. Ari went out one more time to see if he could do better. When we checked the times, he had posted the top time of our group (intermediate) with a 1:41.9 time. That, folks, is cooking! The fastest full race liter bikes were only about 10 seconds a lap quicker and they were on race tires.

Here is a link to the article and the on-bike video of Ari riding the GSX-R750.
Video: Classic 1986 Suzuki GSX-r750 on the Track | Motorcyclist
Attached Images
File Type: jpg 20160916_113533.jpg (71.3 KB, 30 views)
File Type: jpg Level 2 Turn 3 (Session 5) ACS_8106_Sep1616_by_Keegan-CaliPhoto.jpg (48.9 KB, 29 views)
File Type: jpg Level 2 Turn 4 (Session 4) ACS_6994b_Sep1616_by_Keegan-CaliPhoto.jpg (56.0 KB, 25 views)
File Type: jpg 20160916_103414.jpg (89.9 KB, 27 views)
File Type: jpg z_Pits-Etc AC2_9270_Sep1616a.jpg (49.1 KB, 27 views)
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post #2 of 35 (permalink) Old 09-24-2016, 02:46 AM
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Re: track day fun on a Gen1 750

Thanks for sharing. Sounds and looks like you did a great job on restoring the bike. I'm a long time subscriber of that magazine and read a lot of Ari's articles. He seems like a genuine guy and in recent years it seems like his riding ability has skyrocketed! He does a lot of club races for the moto mag for those that don't know. I'm thinking he could have gone even faster on your bike had he not been worried about bringing it back to you in one piece.
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post #3 of 35 (permalink) Old 09-24-2016, 08:03 AM
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Re: track day fun on a Gen1 750

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Originally Posted by Carnage View Post
Thanks for sharing. Sounds and looks like you did a great job on restoring the bike. I'm a long time subscriber of that magazine and read a lot of Ari's articles. He seems like a genuine guy and in recent years it seems like his riding ability has skyrocketed! He does a lot of club races for the moto mag for those that don't know. I'm thinking he could have gone even faster on your bike had he not been worried about bringing it back to you in one piece.
+1


Nice job on the build Tate!
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post #4 of 35 (permalink) Old 09-24-2016, 08:49 PM
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Re: track day fun on a Gen1 750

Bike is looking good Casey. Someone just sent me an updated pre registered for the AHRMA Barber Vintage Festival and it looks like it will be fun. Ari is signed up and it says he is riding a Kawasaki, Carry Andrew is signed up and trying to finish his GSXR. Billy Hammell is riding a Suzuki. All together there are currently 13 registered, I think its 6 Suzuki's, 4 Kawasaki's and 3 Ducati's.
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post #5 of 35 (permalink) Old 09-24-2016, 09:05 PM
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Re: track day fun on a Gen1 750

Awesome!! Also a subscriber, do you know if this will be in print?
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post #6 of 35 (permalink) Old 09-25-2016, 02:46 AM Thread Starter
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Re: track day fun on a Gen1 750

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Originally Posted by Tekime View Post
Awesome!! Also a subscriber, do you know if this will be in print?
Ari said it would be (fingers crossed).
Maybe in the next issue.

Here is a link to an extended video.

Also, thanks for the positive comments on the bike.

I will do a more comprehensive story explaining the restoration/mods on my personal website (Moto Rosso Motorcycles).
Its not up yet, but will be in the next few weeks.
When it is ready, I'll post back here with the link.

Tate
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post #7 of 35 (permalink) Old 09-25-2016, 02:49 AM Thread Starter
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Re: track day fun on a Gen1 750

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Originally Posted by Outsider V6,V7 View Post
Bike is looking good Casey. Someone just sent me an updated pre registered for the AHRMA Barber Vintage Festival and it looks like it will be fun. Ari is signed up and it says he is riding a Kawasaki, Carry Andrew is signed up and trying to finish his GSXR. Billy Hammell is riding a Suzuki. All together there are currently 13 registered, I think its 6 Suzuki's, 4 Kawasaki's and 3 Ducati's.
Yes, I was there last year.
Unfortunately, Ari had to cancel.
I talked to him today and he had to bail due to increased work at the magazine.
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post #8 of 35 (permalink) Old 09-25-2016, 02:54 AM Thread Starter
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Re: track day fun on a Gen1 750

Quote:
Originally Posted by Carnage View Post
Thanks for sharing. Sounds and looks like you did a great job on restoring the bike. I'm a long time subscriber of that magazine and read a lot of Ari's articles. He seems like a genuine guy and in recent years it seems like his riding ability has skyrocketed! He does a lot of club races for the moto mag for those that don't know. I'm thinking he could have gone even faster on your bike had he not been worried about bringing it back to you in one piece.
Ari is an excellent rider.

Remember, he only had a previous short session on the bike before this video (about three laps) so to go this fast on an unknown bike is phenomenal.
He asked for two small suspension adjustments and then cranked out some quick laps.
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post #9 of 35 (permalink) Old 09-25-2016, 04:24 AM
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Re: track day fun on a Gen1 750

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Ari is an excellent rider.

Remember, he only had a previous short session on the bike before this video (about three laps) so to go this fast on an unknown bike is phenomenal.
He asked for two small suspension adjustments and then cranked out some quick laps.
That's what so much free track time can do for a person.
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post #10 of 35 (permalink) Old 09-25-2016, 08:34 AM
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Re: track day fun on a Gen1 750

nice build!

i recall you mentioning building track-bike, but never remember seeing any fotos. are you are running the stock 36mm CV carbs, along with the short stroke engine? what type of rear shock?

where did you get the headlight sticker? i like it.

thanks for posting.
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post #11 of 35 (permalink) Old 09-26-2016, 12:53 AM Thread Starter
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Re: track day fun on a Gen1 750

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Originally Posted by 86gixxxer View Post
nice build!

i recall you mentioning building track-bike, but never remember seeing any fotos. are you are running the stock 36mm CV carbs, along with the short stroke engine? what type of rear shock?

where did you get the headlight sticker? i like it.

thanks for posting.
Ok, now you have the photos

The Slingshot engine was a good solution to the problem of wanting a cable clutch like an LTD and reproducing the shift-side cover to also replicate the LTD look.
So yes, the carbs are open stack 36mm CV carbs that have been extensively tuned by Mickey Cohen on his dyno.

For a rear shock, I used a 2005 R-1 unit that had been modified by Race Tech for this application along with a custom spring.

The decal was supplied by the painter so I don't have a source for it.
He designed it specially for me.
There is also a tail light decal.

The idea was keep the appearance as close to stock as possible, but to include some of the Yoshimura fairing bits.

I purposely chose the 18" wheels for the same reason.
For those who insist on 17" wheels, this case proves you don't have to have them along with the ground clearance/geometry problems to go fast.
Attached Images
File Type: jpg Apr-22-2016-Fastrack Riders - Level 2 - Turn 4 (2pm) - ACS_5167_Apr2216_by_KW-CaliPhoto.jpg (49.5 KB, 14 views)
File Type: jpg 20160118_144720.jpg (74.2 KB, 14 views)
File Type: jpg 20160324_170243.jpg (33.9 KB, 13 views)
File Type: jpg 20160324_170532.jpg (49.1 KB, 15 views)


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post #12 of 35 (permalink) Old 09-28-2016, 01:08 PM Thread Starter
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rear shock details

The rear shock did require some modification to the battery box to clear the top of the shock/reservoir. This actually was fine because I used a smaller Lithium battery.
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File Type: jpg battery box mod 1.jpg (46.7 KB, 14 views)
File Type: jpg shock installed final 5.jpg (68.2 KB, 15 views)
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post #13 of 35 (permalink) Old 09-30-2016, 01:23 AM
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Re: track day fun on a Gen1 750

thanks for the information and posting additional fotos.

112rwhp is impressive for a 750 oil-cooled engine, especially with the stock 36mm CV carbs. your engine tuner does good work.

hope you continue to enjoy more track-days.

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post #14 of 35 (permalink) Old 09-30-2016, 02:20 AM Thread Starter
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Re: track day fun on a Gen1 750

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Originally Posted by 86gixxxer View Post
thanks for the information and posting additional fotos.

112rwhp is impressive for a 750 oil-cooled engine, especially with the stock 36mm CV carbs. your engine tuner does good work.

hope you continue to enjoy more track-days.

Thanks for that.
I built the engine and Mickey Cohen tuned the carbs on the dyno.
Here is the dyno graph.
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post #15 of 35 (permalink) Old 09-30-2016, 03:22 AM
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Re: track day fun on a Gen1 750

Great looking bike and great thread. Well done mate!
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post #16 of 35 (permalink) Old 09-30-2016, 09:44 PM Thread Starter
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Re: track day fun on a Gen1 750

Quote:
Originally Posted by 86gixxxer View Post
thanks for the information and posting additional fotos.

112rwhp is impressive for a 750 oil-cooled engine, especially with the stock 36mm CV carbs. your engine tuner does good work.

hope you continue to enjoy more track-days.

Just a point of clarification; the 112 HP reference was about my 1100.
The 750 made slightly more (see dyno graph).
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post #17 of 35 (permalink) Old 10-02-2016, 11:58 AM
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Re: track day fun on a Gen1 750

yes, i noticed that the 750 made more than 112rwhp...even more impressive.

for comparison's sake: my mostly stock 86 750 track-engine, with a 90 head, and 36mm flat slides, made 99.6rwhp, with about 51lbs of torque. dyno's have variances, but regardless, you built a healthy 750 engine. i wonder if it is mostly due to the short stroke engine design, or if my engine needs a proper 90-91 bottom-end, for higher revs.

my other 86 750 engine, which is completely internally stock, with 36mm flat slides, makes about 95rwhp, and about 48lbs of torque, but it is a more peaky power band, like a typical first gen 750 engine.

please share some of your engine build details. thanks
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post #18 of 35 (permalink) Old 10-02-2016, 06:26 PM
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Re: track day fun on a Gen1 750

Wow! Gorgeous bike and some awesome ride footage!

Thank you for this, sir! Bravo!


-crisp
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post #19 of 35 (permalink) Old 10-20-2016, 10:17 PM Thread Starter
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Re: track day fun on a Gen1 750

Quote:
Originally Posted by 86gixxxer View Post
yes, i noticed that the 750 made more than 112rwhp...even more impressive.

for comparison's sake: my mostly stock 86 750 track-engine, with a 90 head, and 36mm flat slides, made 99.6rwhp, with about 51lbs of torque. dyno's have variances, but regardless, you built a healthy 750 engine. i wonder if it is mostly due to the short stroke engine design, or if my engine needs a proper 90-91 bottom-end, for higher revs.

my other 86 750 engine, which is completely internally stock, with 36mm flat slides, makes about 95rwhp, and about 48lbs of torque, but it is a more peaky power band, like a typical first gen 750 engine.

please share some of your engine build details. thanks
Thanks for the feedback on your engine combos; can you share the dyno sheets?
I will be posting a link to the entire build story very soon (I just need to incorporate the photos into the story).

My opinion is, that for a lightly modified engine, the short stroke (1988-'89) engine is the better choice. My engine has 76mm (+3mm, 811cc) forged pistons and Carrillo rods. The key is the DOT head and Slingshot cams; my head had some minor porting done. As is usual, putting a good combination together with all the details looked after was the key. Things like header size, cam timing, port matching, etc. are all parts of the puzzle.

The dyno tuning at the end of the project is very important for optimizing all of the mods. Here is a better dyno graph showing HP and torque on the same page.

Some would say that the extra displacement makes a difference, but I think it only affects the slightly greater torque number compared to what you are seeing with 750cc. It was a chance happenstance anyway as the engine came to me with +2mm over cylinders and one cylinder was scored. I would have built it as a 750 if I had started with a good standard sized cylinder block.

The extra torque just makes the bike easier to ride at the track and it still has a good top-end hit. Hitting the rev-limiter is easy with this engine as it pulls hard.

The CV carbs needed extra tuning on the dyno, but they are very ride-able.
Attached Images
File Type: jpg Final dyno run GSX-R750-1.jpg (65.0 KB, 17 views)
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Last edited by T8KC; 10-20-2016 at 11:35 PM. Reason: Clarity.
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post #20 of 35 (permalink) Old 10-26-2016, 12:49 AM Thread Starter
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1986 GSX-R750 build article link

Ok, the build article has been posted on my website. Most of the photos should be up in the next couple of hours so if you don't see them all they will be up soon.

https://www.motorosso.net/1986-suzuki-gsxr750/

Any comments, corrections or helpful advice is appreciated.
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