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Front to rear weight bias

Old 08-09-2010, 02:47 PM
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Front to rear weight bias

Has anyone checked the difference between the weight on the front vs back wheel on there bikes. I have a 10mm shim on the rear and dropped the front about 10mm and I still have 236lbs on the rear and 226lbs on the front. From what I understand we want about 52% on the front. What have you guys done? So to get to where I assume I should be I need about inch more height in the rear. My sag is set correct at this time. So need some feedback on this ok.

Last edited by Stumpy; 08-09-2010 at 02:58 PM.
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Old 08-09-2010, 03:03 PM
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Well I will say that with that chassis geometry you are on the verge of being very unstable.

I would strongly advise a steering damper in your situation. Also if you just put a 10mm shim over the rear shock, make sure the mount didn't turn when you tightened it down, as the mount no longer hits the lip in the frame. Also does the bolt come all the way through the nut when you attach it to the frame? It has to be real close, so use some care with the installation.

You also need to understand that you are changing rake and trail numbers, not just weight when you make chassis adjustments.

Do you still have the stock exhaust on the bike? What else have you done to it? The reason for these questions is you would be better off moving weight around instead of going more radical with the ride height adjustment. But as always YMMV.
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Old 08-09-2010, 03:15 PM
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+10 mm on the shock translates to a lot more on the wheel... And that alone is enough to make a big difference in turn in... Drop the front as well and you are on the edge of what I'd feel comfortable with... Plus dropping the front more than 5-7 mm makes it scarily easy to grind hard parts like headers... Trust me, I tried it... And I got the dime sized hole in the header to prove it...

From your sig I can't see any aftermarket pipes? That would move at least 10 lbs of the rear... So yeah, that's an option I'd prefer if you still have the stock pipes...
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Old 08-09-2010, 03:59 PM
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Well should have gave more info I have Jardine high mount slip ons Removed most of the stock rear fender not sure if putting a lighter battery in would help or hurt. Yes the rear shock has threads all the way past the nut but not by much but past. No problems having anything drag except for my aftermarket belly pan I will have to take a photo of it tomorrow and place it for you to see. I was just looking to see if anyone has played around with the front vs rear weight to get some better ideal instead of just adding rear height as it is not unstable now at all for me have only had head shake one time when I came down with the wheel turned after a hard shift into 2nd. So any info would be much appreciated from you guys.
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Old 08-09-2010, 04:12 PM
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Well... Measure out your rake/trail, and you will most likely find the numbers to be in the zone where caution is advised...

The bellypan might touch first, but the headers are likely to hit on lean (possibly once you have ground of the belly)... Please note that I'm not talking about bottoming out when upright, but with 10 mm less fork length, bottomed forks and lean... Trust me, those headers are close to begin with, that doesn't help... I would recommend comparing your current ride height in the front to the ride height with stock forks (yours are revalved) and set it accordingly...

The battery is fairly neutral in it's placement, the balance point as the bike is, is roughly the top/rear engine bolts... With the bike on my stand suspended there I can lift the front with two fingers on the pillion... Altough that should be a bit harder on your bike, I have more weight forward with my longer swingarm...
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Old 08-09-2010, 04:18 PM
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I'm in the same camp with Tweety and 8541Hawk.

10mm at the rear shock is about 30mm at the rear axle. That will be fine, but you probably don't want to drop the nose, too. That's how I had mine set up (+10mm at the shock and stock front end height). I think I went +15mm on the shock with my RC51, but I don't have my notes. You also want to be sure you have the sag numbers correct. Even if you don't have stability problems, you will have trouble keeping the header off the ground, when you drop the nose.

As far as weight distribution, it takes a lot of redistribution of components to get that much weight up front. Look at a Superbike and you'll see what I mean. All of the electronics go up in the front. I put a coolant overflow bottle in the nose, put a light battery in and move the components forward in the tail. I also put a different wiring harness in, to get rid of the wiring for the lighting. I stil have a slight rearward weight bias.

The bike is way more capable than I am, so i have plenty of weight and good feedback from the front end.

Last edited by RCVTR; 08-09-2010 at 04:20 PM.
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Old 09-24-2010, 11:37 AM
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Move the battery in between the cylinders where the coolant overflow usually goes
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Old 09-24-2010, 11:56 AM
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Originally Posted by imp View Post
Move the battery in between the cylinders where the coolant overflow usually goes
Or replace it with A123 cells..
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Old 09-27-2010, 09:36 AM
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How much weight would that save me. I think there was a thread on that I will do a search. Those are the dewalt battery's right.
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Old 09-27-2010, 10:56 AM
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Originally Posted by Stumpy View Post
How much weight would that save me. I think there was a thread on that I will do a search. Those are the dewalt battery's right.
Yes DeWalt, or you can get them separate on Ebay, pre-built from speedcell or turntech etc.

My 8 cell battery weighs about 2lbs IIRC. Realistically a 4 cell would probably be plenty.. Tweety started his Hemi with a 8 cell battery, but I don't mind having a 900cca battery in the bike :P
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Old 09-27-2010, 11:10 AM
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4 cell works fine in the summer, but turned out a bit marginal in autumn on the bike... The 8 cell is spot on... The 8 cell started a Hemi but it was a bit marginal at best... 12 cells would have probably have worked fine, but it's running 16 to have some reserves...

The 8 cell is about 1.6 lbs actually, and the stock battery is 7.5 lbs, so it's 5.9 lbs difference... That would put you at roughly 226 front and 230 rear... Not all the way there, but closer...
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Old 09-27-2010, 02:27 PM
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what was the difference on the hemi battery. 3.2lbs vs ???
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Old 09-27-2010, 03:03 PM
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Around 40 lbs somewhere or perhaps more, so it's a 90% improvement or better... It was one of the normal to large size sealed lead batteries... Replaced fairly regular since they seemed to die from long sitting in the winter followed by being asked to turn over a high compression hemi...

Suffice to say the A123 one looks tiny in the big hole meant for the stock lead monstrosity... But the 8 cell one turned the engine over more easily than a the lead battery managed, even when new...
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