| Author |
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Zerba
| | Posted on Thursday, December 04, 2008 - 07:04 pm: | 
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Hi guys so here is the deal i am planning to track day my new 2009 xb12r and am worried that my stock tranny will top out on the main straight. I have done a lot of research into it and from what i have come up with is that the revlimiter is holding me back by topping out at at 140 mph (tested 4 times by me). My friend was telling me i can get a bigger rear sprocket and that will lengthen my whole gear ratio. So that means that all my gears would lengthen. are they available and if so has anyone used one with good results? |
Buelltuner
| | Posted on Thursday, December 04, 2008 - 10:10 pm: |
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you would actually have to go down teeth in the rear to gain MPH. more teeth (larger sprocket) would yield more acceleration at the cost of top end speed. the best thing would be to invest in a chain conversion so you could adjust for rpm range and speed that your bike is capable of. depending on the track, the stock motor (assuming no motor mods) may not even have the power to reach rev-limit in top gear. and yes, when chains are used for gear changing, they are very effective. |
Bombardier
| | Posted on Saturday, December 06, 2008 - 05:13 pm: |
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petebueller has developed a larger engine sprocket which should suit your needs.
He is on this board as a sponsor Buellerparts. |
Xoptimizedrsx
| | Posted on Sunday, January 11, 2009 - 11:02 pm: |
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you need gearing even then to get the gears moving sustained speed requires HP. no way around it.
HP/rpm+gearing= speed you can tweak a little more out on a xb12 with a 2.30 ratio below that you must add hp.
mike |
Petebueller
| | Posted on Monday, January 12, 2009 - 09:40 am: |
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I've always found the XB12R gearing too low, both in first and top.
We have tram tracks here and some intersections are more metal than tarmac. In the wet you want to keep the revs down to avoid wheel-spin, and also avoid an up-change mid intersection, and then in top I was always lifting the toe in 5th gear. That is why I came up with a higher custom gear for my bike.
The secondary ratio (belt) seems impossible to change without a chain conversion. I like the belt and a secondary change also means recalibrating the speedo.
I did a bit of prototyping on primary gearing with a few different sizes and settled for a custom 42 tooth primary crank pulley instead of the standard 38 tooth.
The only top speed test we did was with a 41 tooth crank pulley on a 2007 XB12R with a Micron and an American Sport Bike map. The bike hit the rev limiter at 240kph (150mph). The speed was verified by a GPS. I am claiming this as the highest speed for a belt driven XB.
I have a 42 tooth on mine, and the theoretical top speed at the rev limiter is 250kph (155mph). I had a few people say that 150 mph was not possible without engine mods, and I have proven to myself that this is not true.
I had to take my Micron off because of the EPA. When I can, I will put it back on and see just what the bike will do.
I had a Laverda Jota 120 that could do 250kph, and I can't see why I can't get my Firebolt to do about the same.
Anyway Zerba, I can get a stock 2007 XB12R to the rev limiter. This means that higher gearing will give me higher top speed to the limit that my bike can pull.
Even if you build your engine up, you need to get a fair benefit to beat the extra 10 or 12 HP of a Micron. With the Micron and the cog you can increase your top speed by 10 to 15 mph. If you do engine work, you can get the 15mph. (More if you can get more revs.)
A serious attempt would be a Micron, a good map and the primary cog and chain that I have developed. I am a paid up sponsor here so I can tout my wares. I am wrapping up my business, so the ones I have for sale are the last. I have only have 7 left. This is a pulley and a chain. You can get one made in future, 42 tooth pulley plus a chain that is increased by 2 links. As a one off this will be expensive.
I am selling mine to BadWeb members at AU$425 + postage. The AU$ has dived so this is now US$290 + postage.
Everyone who has bought one thinks it is feels like the perfect gearing for the bike. Around town it makes no difference to fuel consumption, but one the highway I am getting 5% to 7% better.
I come from a background of Italian bikes so I am used to higher gearing which may be why it feels normal to me.
I thought that it might stop the front wheel lifting, but if anything it is easier to lift without the clutch as I extend the gears further. I can tell this will be a controversial statement. Lower gearing should mean easier lift. What I find though is that I am extending into more HP and the wheel comes up pretty naturally. I don't feel like I have lost a first gear to go to something that is 1/2 way to a sixth. |
Xoptimizedrsx
| | Posted on Monday, January 12, 2009 - 11:52 am: |
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i can see the nature of the effect your getting. as you stated. if your getting to the rev limiter with power to spare move the ratio if your just looking for speed.
if you race this will work on some track and not others. its a trial and error thing.
i personally just use chain drive to control mine. being i'm on a xb9 i was in need of more hp/tq.
i can easily jump up a few teeth on the primary to make further adjustments but its just more work than necessary IMO for me.
you are right moving it on one end will make it lift harder to a point. as long as the hp and tq is there. my finale is way down now so i now do not hit the rev limiter in 5th. i run out of power.
with the last work i'm doing i should just hit the limiter. which will be in the upper 140's i'll use the dyno to check this in a month or two. as well as play with gearing more to see the actual difference on the dyno.
having a dyno makes things so nice. even better having the tools and the dyno. which i do now.
mike |
Petebueller
| | Posted on Monday, January 12, 2009 - 12:20 pm: |
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For the track, the chain makes it much easier Mike.
I used to run different sprockets for touring and city on my Laverdas. I can't do that with the primary on my Firebolt, though changing the primary and (if it were possible) changing the belt pulleys would not be a big difference in effort.
For the Firebolt, 41 tooth primary works but there is a lot of slack to take up in the adjuster. 42 is perfect for adjustment and 43 is just too tight. 42 and 38 are really the only options. A chain gives you a lot more variety.
This is my bike Dyno'd in 4th. It is DIN not SAE. SAE is about 12% higher so it would be around 103RWH SAE.
It was pulling just over 200kph (125 mph) at the rev limit in 4th. I think it would come close to the 250kph in top.
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Xoptimizedrsx
| | Posted on Monday, January 12, 2009 - 11:42 pm: |
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i'll play with th4e dyno more in a few weeks as i'll have the engine back together.
i'll tune it in with the dual wide band in each cylinder. plus this way i can play with timing a bit more.
i'll see what the xb9 can get with my pipe. hopefully the work effort i have done will show up good. as i'll take a gas can that day. first i have to get 500 miles on it before high rpm dyno time. i need to seat the new top end. all stock just fresh rings and valves.
i can post the finale with the first. being a xb9 muy stock runs are only hp in the upper 70's
i'll see what it gains with the xb12 header and intake as well as retune. same home made pipes.
i have two different ones to test.
i'll post my weekends work.
give me a few weeks to get it ready.
no lies here a little xb9 thats it. all stock parts mix and matched from a xb12 to xb9.
mike |
Petebueller
| | Posted on Tuesday, January 13, 2009 - 06:55 am: |
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This may also be helpful Zerba. It is a picture of the Vincent Black Lightning breaking the 150mph barrier.
It is of Rollie Free, an American, riding on the Bonneville Salt Flats on 13 September 1948.
Free was determined to break the land speed record in the "Flying Mile." His first pass hit 148 mph (238 km/h), which broke the record, but Free was determined to break 150. Noticing that his riding leathers had started to come apart at the seams from the force of the wind, Free borrowed a bathing suit, cap, and a pair of tennis shoes and laid down on the bike. With the decreased drag, Free broke 150 mph, topping out at 150.313 mph (241.905 km/h), shattering his record of only a few moments before. That bike, also known as the "John Edgar Lightning" after its sponsor, is currently in the private collection of Herb Harris of Austin, Texas."
(Message edited by Petebueller on January 13, 2009) |
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Making ur top speed higher?