How much does tire size matter?

[Michelle]

Hello! I'm looking at running slicks on my 2016 fz07 next season since I'm going to take a dabble into the racing world. Some slicks are hard to find a 180/55 rear. I know MotoD sells SC1 rears in that size. I was wondering what difference it makes to run bigger tire sizes like a 180/60 180/65 or 190/60. What are the pros and cons? Do people run different front sizes too? Or stick with the 120/70. 

[M, Hausknecht]

The only viable front is 120/70 or the new 125 front from Pirelli (but it isn't optimal). Rear tires are more involved. With stock chassis geometry, you really want to use 180/55 rears. However, 180/60 rears are more readily available and most racers use them or even 190/65 rears. The problem with the bigger rears is that they are much larger in diameter than the stock size rears and, therefore, you really want after-market triples with 26-28mm offset to achieve reasonable trail. With the stock triples and a larger rear tire you're going to have relatively little trail, leading to much reduced straight-line stability and a bike that won't want to finish corners without additional steering input. I also use after-market shock linkage but that isn't so much a geometry issue as it is a way to get a more linear load on the shock (damping is more effective with a more linear load). Unfortunately, the rear wheel is too wide for  a 160 rear but that is all the bike needs from a horsepower perspective. The 180/55 Pirelli slicks are also about a pound lighter than the 180/60 tire, which is a good thing.     

[klx678]

Your next to last sentence...  has anyone fitted MT-03 wheels?  It is a shame that companies cater to the "I like fat tires" crowd, what's next, vintage Firestone repops ala Bike Exif?   I'd love to have a 140 or 160 rear tire, knowing the 180 is just plain more costly overkill.   If it wasn't overly expensive I'd have my rear rim narrowed.  

Edited October 12, 2023 by klx678

[cornerslider]

When I switched to the Pirelli SC1 on my 2016 FZ-07, the rep suggested that I switch to the 180/60..... He said the profile of that size increases the contact patch while cornering, and offers more grip/traction. I liked the SC1 in the 180/60 size, but found with the higher profile, I needed to modify my gearing slightly. I race @ BIR, where I'm WOT through T1 & T2. I found bike developed a slight "bog" at high speed with the extra circumference of the 180/60. My motor is stock (internally), and I think maybe it just lacks the HP to rotate the slightly larger tires at WOT. I have since gone back to the OEM 180/55 tire size, and back to OEM gearing. I'm happy with that choice. I'm glad I tried a different size, but I was happier on the 180/55. Hope that helps-

[Michelle]

@cornerslider You talked about a gearing change. My 2016 FZ07 really struggles on the straightaways. For my home tracks I'm mostly in 3rd-6th, 4th-6th there is little top-end pull after about 8-10k rpms. Would a gearing change help solve this issue and give my bike a bit more top-end pull? I have an M4 exhaust and tune from Vcyclenut with just a K&N performance air filter. So I guess I'm wondering if a gearing change would help or maybe a tune with a better air filter? 

[cornerslider]

It sounds like you are running the stock air box....  It tends to be very restrictive. I heard it was an emissions thing? My bike used to fall on its face after about 8K RPM. Once I got the Hordpower intake, all that went away. I would check your rulebook of whatever org you're racing with. Once I removed the OEM airbox it brought my bike from "supersport" class, up to "superbike". That is a big jump!  As far as gearing goes, it's a balancing act. I can't answer that without knowing what track you are racing, AND for every action, there is a reaction somewhere else when it comes to gearing. My best advise- ask around the paddock to what other FZ-07 racers use at that track. Hope that helps. Don't forget to have fun -

[M, Hausknecht]

1 hour ago, Michelle said:

@cornerslider You talked about a gearing change. My 2016 FZ07 really struggles on the straightaways. For my home tracks I'm mostly in 3rd-6th, 4th-6th there is little top-end pull after about 8-10k rpms. Would a gearing change help solve this issue and give my bike a bit more top-end pull? I have an M4 exhaust and tune from Vcyclenut with just a K&N performance air filter. So I guess I'm wondering if a gearing change would help or maybe a tune with a better air filter? 

Maximum power with a stock motor is at roughly 8800rpm, and it falls off quickly above about 9000rpm. If you can reach 8800rpm in 6th, that is as fast as your bike can go without other changes. If your gearing only allows you to reach 8000rpm in 6th on the longest straight, for example, shorter gearing will help you go a little faster. To get a few more HP at higher revs, you need a shorter intake tract; the Hordpower and Yoshimura intake systems are the best examples. I prefer Hord's unit because the filter, a K&N, doesn't require cleaning as often as the Yosh foam filter medium.

I race on the east coast and typically run 15:45 to 15:42, but my motor develops maximum power at 10100-10200. With a 180/60 rear tire and 15:43 gearing, the bike can exceed 135mph (GPS). Where do you race and with which org?

Edited October 14, 2023 by M, Hausknecht

[Michelle]

On 10/14/2023 at 11:33 AM, M, Hausknecht said:

Maximum power with a stock motor is at roughly 8800rpm, and it falls off quickly above about 9000rpm. If you can reach 8800rpm in 6th, that is as fast as your bike can go without other changes. If your gearing only allows you to reach 8000rpm in 6th on the longest straight, for example, shorter gearing will help you go a little faster. To get a few more HP at higher revs, you need a shorter intake tract; the Hordpower and Yoshimura intake systems are the best examples. I prefer Hord's unit because the filter, a K&N, doesn't require cleaning as often as the Yosh foam filter medium.

I race on the east coast and typically run 15:45 to 15:42, but my motor develops maximum power at 10100-10200. With a 180/60 rear tire and 15:43 gearing, the bike can exceed 135mph (GPS). Where do you race and with which org?

I'm also on the East Coast! The main tracks I run are PIRC and Summit Point. Sometimes I'll make the hike up to NJMP and I do want to eventually try NCBike. My FZ definitely struggles on the straightaways of these tracks in high RPMs. The overall top end just really dies off as you said after about 8k which I don't like. I'd like to aquire pull throughout the entire powerband especially the top end since this bike is banging through gears more than a 600 per say. With these smaller engines, I feel like the use of the rev range is really important to carry as much speed as possible where you can. That being said based on you're experience you think it would be more worthwhile for the Hord filter and a gearing change such as the 15:42? I know each track is different but maybe that would be the best starting point? 

What have you felt is the main difference between the 15:45 and the 15:42 gearing?

Also, can you run the Hord exposed filter in the wet? And I take it I'd need my ECU reflashed too? 

Thanks! 

[M, Hausknecht]

The Hordpower intake uses a K&N air filter and its location seems to be such that it doesn't see much water. I have no concerns using it on a wet track. You will need a reflash; putting aside friction-reduction strategies, there is no way to get more power without more fuel.  JD's website indicates he has the intake in stock currently (doesn't always because of periodic parts shortages), so you can get one now. From the dyno graphs on his website, you'll see that with his intake and a decent pipe, a stock motor has useful power to 10,000rpm. With that in mind, you should run a 15 tooth driver for all the tracks you list.  Summit Point has the fastest straight of the tracks you list; I use a 43t rear sprocket there with a 180/60 rear tire and don't run out of revs, even with slightly over 90rwhp. With less horsepower, you could probably get away with a 44 at Summit. Pitt and NJMP don't have any long straights; I don't think I use 6th gear at either. At NC Bike I've used both a 43 and a 44. Be aware that the Hordpower intake is not Superstock legal because it eliminates the stock airbox.

I'm aware of two strategies for selecting final gearing. The traditional strategy is to run the shortest gearing you can that doesn't result in running out of revs in 6th gear. The idea is that you'll accelerate quicker with the lowest gearing you can get away with. The second strategy is to select final gearing that allows for optimal acceleration out of the most important turns (like Summit exiting T1, T9 going up the hill, and T10 headed down the front straight; like Pitt exiting the first and last corners), and that avoids any need for a quick upshift and then a downshift immediately thereafter, or an upshift while fully leaned over. I tend to follow the second strategy most often. For the difference in top speeds with gearing and tire circumference changes:   https://www.gearingcommander.com/. 

 

[Michelle]

6 hours ago, M, Hausknecht said:

The Hordpower intake uses a K&N air filter and its location seems to be such that it doesn't see much water. I have no concerns using it on a wet track. You will need a reflash; putting aside friction-reduction strategies, there is no way to get more power without more fuel.  JD's website indicates he has the intake in stock currently (doesn't always because of periodic parts shortages), so you can get one now. From the dyno graphs on his website, you'll see that with his intake and a decent pipe, a stock motor has useful power to 10,000rpm. With that in mind, you should run a 15 tooth driver for all the tracks you list.  Summit Point has the fastest straight of the tracks you list; I use a 43t rear sprocket there with a 180/60 rear tire and don't run out of revs, even with slightly over 90rwhp. With less horsepower, you could probably get away with a 44 at Summit. Pitt and NJMP don't have any long straights; I don't think I use 6th gear at either. At NC Bike I've used both a 43 and a 44. Be aware that the Hordpower intake is not Superstock legal because it eliminates the stock airbox.

I'm aware of two strategies for selecting final gearing. The traditional strategy is to run the shortest gearing you can that doesn't result in running out of revs in 6th gear. The idea is that you'll accelerate quicker with the lowest gearing you can get away with. The second strategy is to select final gearing that allows for optimal acceleration out of the most important turns (like Summit exiting T1, T9 going up the hill, and T10 headed down the front straight; like Pitt exiting the first and last corners), and that avoids any need for a quick upshift and then a downshift immediately thereafter, or an upshift while fully leaned over. I tend to follow the second strategy most often. For the difference in top speeds with gearing and tire circumference changes:   https://www.gearingcommander.com/. 

 

Thank you so much this was super helpful! I think for now I'm going to start with the gearing changes since summer 2024 will be my first time racing. After seeing how I place and hold up with the competition I'll probably make more power mods like the Hord intake. I might run an MWR filter in the meantime since it's much cheaper than the Hord. Any more suggestions for a new racer?  

Edited October 17, 2023 by Michelle

[M, Hausknecht]

If you're going to stick with the stock airbox, just remove the snorkle; the filter and another top for the airbox don't seem to matter to air flow. I know my buddies at TST sell the MWR air filter, but it just doesn't matter. The primary reason the power drops off after 8800rpm on the stock motor is because of the length of the intake tract, not any inherent restrictions in the airbox or the filter. The Hordpower and Yosh intake systems shorten the intake tract, bumping the torque curve up a bit in the rev range, resulting in more peak horsepower.  

The stock suspension isn't great. You want a decent shock with adjustable damping, proper springs for your weight and pace (faster riders put a greater load on the suspension and, therefore, prefer stiffer springs), and a cartridge kit for the forks or, at least, a Race Tech Gold Valve and heavier fork oil (cheap, effective, but a bit of a PITA to adjust). Steel-braided brake lines and an R6 remote reservoir master cylinder, even with the stock pads, will allow two finger stoppies and very good front brake feel. The stock chassis geometry is ok with a 180/55 rear tire. If you want to run a 180/60 rear, the bike will handle much better with adjustable triples. Buy these and start with 26mm fork offset:    

  Then what you want is a lot of track time in a racing environment. Track day riding is ok for developing decent riding skills but, IMO, it doesn't allow you to learn how to race and how to pass another rider who may be your speed or only slightly slower. So, when you start to race, enter as many races as you can and, if possible, run endurance races.  Good luck!

[cornerslider]

I've been following this thread for a few days.. As much as I'd like to contribute @M, Hausknecht has a way of articulating things MUCH better than I can, and has more experience than I have with racing. I have experienced the points he communicates. I would however, strongly encourage you to consider the Hord intake for next year. I have over $13K into my 07.... The Hord intake was the BEST $300 I ever spent -

[Michelle]

17 hours ago, M, Hausknecht said:

If you're going to stick with the stock airbox, just remove the snorkle; the filter and another top for the airbox don't seem to matter to air flow. I know my buddies at TST sell the MWR air filter, but it just doesn't matter. The primary reason the power drops off after 8800rpm on the stock motor is because of the length of the intake tract, not any inherent restrictions in the airbox or the filter. The Hordpower and Yosh intake systems shorten the intake tract, bumping the torque curve up a bit in the rev range, resulting in more peak horsepower.  

The stock suspension isn't great. You want a decent shock with adjustable damping, proper springs for your weight and pace (faster riders put a greater load on the suspension and, therefore, prefer stiffer springs), and a cartridge kit for the forks or, at least, a Race Tech Gold Valve and heavier fork oil (cheap, effective, but a bit of a PITA to adjust). Steel-braided brake lines and an R6 remote reservoir master cylinder, even with the stock pads, will allow two finger stoppies and very good front brake feel. The stock chassis geometry is ok with a 180/55 rear tire. If you want to run a 180/60 rear, the bike will handle much better with adjustable triples. Buy these and start with 26mm fork offset:    

  Then what you want is a lot of track time in a racing environment. Track day riding is ok for developing decent riding skills but, IMO, it doesn't allow you to learn how to race and how to pass another rider who may be your speed or only slightly slower. So, when you start to race, enter as many races as you can and, if possible, run endurance races.  Good luck!

Thank you again for all of your help! My FZ currently has Andreani cartridges and a K-Tech Razor lite shock. Everything is sprung for my weight and was dialed in by a suspension specialist at one of the track days I went to. I have a Brembo RCS 17 master with Spiegler steel lines. Driven TT rear sets with an exhaust, basic ECU flash from Vcyclenut, and K&N filter (snorkel is removed). I'm going to run the 180/55 rear for my first racing season since I'm on more of a budget than most so I can't go as all out as I want to on fancy mods. If I have room in the budget I'll definitely upgrade to the Hord it sounds very worth it. 

 

I guess my last question is where can I purchase the Hord intake because it seems to be out of stock pretty much everywhere?

[M, Hausknecht]

The only way to buy a new Hordpower intake is from J.D. Hord:  https://www.hordpower.com/index.php?main_page=index&cPath=65_69&zenid=feg0mhha26qvjdv8pg5gjgk4h4 . Since he relies on Yamaha for some of the parts, the system is periodically unavailable but he has them now.

Good, you're set for suspension and brakes.

 

[Michelle]

1 hour ago, M, Hausknecht said:

The only way to buy a new Hordpower intake is from J.D. Hord:  https://www.hordpower.com/index.php?main_page=index&cPath=65_69&zenid=feg0mhha26qvjdv8pg5gjgk4h4 . Since he relies on Yamaha for some of the parts, the system is periodically unavailable but he has them now.

Good, you're set for suspension and brakes.

 

The website still says "sold out" but I can add the item to cart and it displays the price and all. Did he just not update the website? 

[tomlichu]

On 10/17/2023 at 4:30 AM, Michelle said:

Also, can you run the Hord exposed filter in the wet?

Yes, you can run it wet. I live in Seattle and commute in the rain with Hordpower (only been a month). No issues when it rains. I would keep an eye on the filter and just clean and oil it more frequently. The road grime really kicks up into the rear spring and airbox when it rains. The tiny bits of water getting into the airbox is likely getting vaporized instantly once it goes into the engine, and the oil helps keep the filter hydrophobic.