SuperMotard question - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 18 Old 12-16-2008, 02:38 PM Thread Starter
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SuperMotard question

Does a supermotard conversion (smaller diameter, wider front tire) help with high speed stability? I am toying with the Idea.
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post #2 of 18 Old 12-16-2008, 03:24 PM
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supermotard question

My two cents worth;
Not much difference going straight, though certainly not a gain of stability.
But in hard turns the loss a 'trail' is big. Trail is your feel, security and trust (or not) in the front wheel when leaning and turning. True sm bikes make up for this deficiency with special triple clamps to restore that loss of trail.

Stock your bike will have around 120mm of trail, 17" wheels puts that value to about 85mm. You can ride it, but not with abondon. You end up cornering slower, wondering where that good, secure feel went.

Any time you see a bike 'lose the front' it is for lack of trail. Like all those motogp stars you see on tv, tuck the front, yep, not enough trail for the available grip. period.

'08 KLR650,
'72 BMW R75/5 (Col. Klink),
'02 KTM 400 E/XC,
'05 ktm 125 sx (for sale)

"Hey, are you okay? Can you get up?
I thought you said you could ride"

All the best
Kent Soignier
www.gmdatl.com
the str8ner
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post #3 of 18 Old 12-16-2008, 07:47 PM
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Supermotard wheels on an '08... work great!

I just finished my Motard conversion on my '08 and I couldn't disagree more with Kent's diagnosis. I took a spirited 160-mile ride last Sunday morning and can say without a doubt that my bike is more stable at "sane" (under 90+)speeds than with the 21" hoop, also it now is much easier to initiate a turn or to make a mid-turn correction. There's a reason the SM guys use wide, sticky tires and it's called "traction". The bike is a whole different animal with these wheels on it. I tried to upload some pics but this darned forum won't let me even at the impossibly small size(s) specified. Check other KLR forums for more SM data and pics. Mike
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post #4 of 18 Old 12-16-2008, 09:17 PM
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Create an account at photobucket.com then upload your pictures to there. Once uploaded, have the forum open and your album on photobucket opened. You then find the pic you want to post and click on the IMG option under the picture, this copies it, then here in your post you just right click and paste. Do a preview of your post and make sure the pic posted correctly. I also found out you can adjust the size of your pictures uploaded to photobucket, I use the 1024x768 option on photobucket, this makes a really nice big picture to see. Make sure to have the size option set before you upload. Hope this helps...

2008 DL650 VStrom Yellow and Black
Previous ride was a 2007 KLR Black/Silver, I miss it..
Looking to get back into KLR's sometime soon.

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post #5 of 18 Old 12-17-2008, 08:46 AM
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motard question

It is okay for you or anyone to disagree with my comment, (not a diagnosis).
Besides our extensive geometry database of good and not so good handling motorcycles I base my comments on: All of our customer SM projects , using our good set-up with special triple clamps makes them several seconds a lap better than they went with the basic 17" 'motard set-up'. They tell me "it's like you gave me 20hp".
I have done the motard thing with a personal hotrod yz426, using 17" michelin roadrace rubber. Running very respectably lap times and racing in D Superbike, giving SV650's fits at little talladega. On one occassion I tucked the front at 80mph. crashed my brains out. 86.7mm trail on that particular set-up. I really needed special triple clamps, but I didn't want a dedicated roadracer out of my woods bike. I was just doing it for the fun of it.

Beware Emjayw and anyone else on 17" front wheels on dirt bikes:
Yes, the turn in is quicker, (because you have made the rake angle steeper with the smaller front wheel, and that is a benefit)you will tuck the front wheel at a slower speed and at less lean angle than with the 21" front (because of the loss of trail). fat rubber and all.

As I said previously, straight-line stability is not the problem. Deep lean angles, with tires near the edge of available grip is when it is deficient.
You wont get much warning when the front wheel tucks. It happens so quick.
Have fun and be careful.

'08 KLR650,
'72 BMW R75/5 (Col. Klink),
'02 KTM 400 E/XC,
'05 ktm 125 sx (for sale)

"Hey, are you okay? Can you get up?
I thought you said you could ride"

All the best
Kent Soignier
www.gmdatl.com
the str8ner
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post #6 of 18 Old 03-18-2009, 06:42 PM
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kent soignier ,

I was reading another post on this topic and wondered what you thought about it. This guy says he put a 17" wheel on the front so he could just carry one spare for both wheels, and also that with the 17" wheel and tires there is only a 1" difference in outside diameter.

I just wanted your opinion because it sounds like you know what you're talking about. I don't really understand the concept of rake and trail or why it matters. What's the difference between doing this on a KLR and an actual supermoto bike?

http://www.klrforum.com/showthread.p...ht=supermotard

Originally posted by: Rainier Tom

Quote:
Here's the reason I laced up a 17" front wheel. If/when I take an extended trip on my KLR, instead of carrying two different sized spare tires, I could carry one spare tire (4.50"x17") and use it for either the front or rear.
Quote:
The tire is a 120/90/17 Kenda K761 mounted backwards. A 21" front tire has an approximate diameter of 27 inches while the Kenda on a 17" rim has an approximate diameter of 26 inches (taller sidewall). You might want to build and install the front wheel first then decide how much to lower the rear.
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post #7 of 18 Old 03-18-2009, 07:18 PM
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I wont comment on a conversion but wonder why the question of stability at speed was posed.Ive had a couple of klr's my newest an 08 and never have had a instability problem.
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post #8 of 18 Old 03-30-2009, 06:54 AM
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supermotard questiion

sorry to be so long answering your question bethlehem. I have been at roadrace events for the last six weekends in a row, and full time at gmdatl. something like eight LONG days a week.

converting to 17 inch front rim so one spare tube fits both ends seems smart enough.
but I would not consider it a move for better handling until it is combined with the proper triple clamp offset to restore the LOSS of trail that comes with the 17 inch front rim.
Using a taller 120/90 series tire as someone mentioned will help reduce that loss but there is still a reduction of trail. I have not seen that combo so will reserve further comment.
if you don't intend to corner with roadrace style and commitment you will be fine.
the lack of trail doesn't matter
going straight, it really matters when you get down to extreme lean angles.
I have done this upgrade in chassis geometry for dozens of racers who started the process by simply lacing up the 17 inch front then telling me how wonderful it all is, then they lose the front end in a fast turn and crash.
after we put them on the Sweet Numbers their lap times improve to the tune of several seconds per lap. To a man they all did not realize how they had struggled to turn their bikes, since the tip in IS much better, but the TURN is not. I know that sounds oxymoronish, but trust ne on it.


remember, going str8 you'll be fine, turning at casual pace is okay too, the problems start when the pace escalates.
It is all in the numbers.

'08 KLR650,
'72 BMW R75/5 (Col. Klink),
'02 KTM 400 E/XC,
'05 ktm 125 sx (for sale)

"Hey, are you okay? Can you get up?
I thought you said you could ride"

All the best
Kent Soignier
www.gmdatl.com
the str8ner
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post #9 of 18 Old 03-30-2009, 10:54 AM
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I am in Kent's camp on this subject. His explanation is clear enough for a math challenged type like me to digest. I had no real understanding of 'rake & trail' until I started reading this thread.

Keep up the informative dialog Kent, I like the effect.

Ard

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Last edited by Hardyreels; 03-30-2009 at 11:02 AM. Reason: correction
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post #10 of 18 Old 03-30-2009, 02:16 PM
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Yes, thanks for the reply Kent. It's sinking in.

So I assume a basic rider like myself riding twisty backroads at the speed limit or slightly above would be OK? I don't lean corners like a pro or drag foot pegs and knees. I don't really understand how a triple clamp can help but it sounds expensive for someone like me who doesn't take too many risks anyway.

Last edited by Bethlehem; 03-30-2009 at 02:18 PM.
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