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Old 01-25-2005, 07:42 AM
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Default lowering suspension inch to 2inch's

     

got a 93 250 yz , how can i lower it like 2 inch's tops ??? Gimme some links or idea's thanks
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Old 01-25-2005, 09:45 AM
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Default Re: lowering suspension inch to 2inch's

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Originally Posted by dalifts
got a 93 250 yz , how can i lower it like 2 inch's tops ??? Gimme some links or idea's thanks

I have lowered one bike and I am getting ready to do it (albeit differently) with my next one.

I am at work right now, but I will post for you the results of my investigation tonight.
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Old 01-25-2005, 09:58 AM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by DCox
.

I am at work right now, but I will post for you the results of my investigation tonight.
Oh oh, be prepared for one of his long winded posts......but always informative.

Why don't you guys just wear platform soles on your boots?
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Old 01-25-2005, 10:39 AM
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Default Re: lowering suspension inch to 2inch's

Just put on about 50 pounds that would work thats how it works around here i just barly touch but when my dad gets on my bike he can sit flat footed. J/K I thing DCox will answer all you questions tonight. Good luck and enjoy the bike.
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Old 01-25-2005, 12:08 PM
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Default Re: lowering suspension inch to 2inch's

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Originally Posted by quadfather03
Just put on about 50 pounds....
Not really a good solution. My 2000 CR250 is sprung correctly for me, IF I cut off one leg. It doesn't handle nearly as well as my 2002, which seems to be pretty close to sprung correctly.

Trust me, if I can tell a difference, then something is really wrong. RC I am not.
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Old 01-25-2005, 09:17 PM
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Default Re: lowering suspension inch to 2inch's

I have had to look into this subject a great deal since I am 5'7" with a short in-seam. This fact has motivated me to read almost every post I could find on this subject in the various off-road forums and magazines. I have also chatted with as many people as I could to get information. I write all this to let you know that what follows comes from many different sources, so it will be difficult to give credit where credit is due in some instances.

The following procedures--sometimes in combination--are used to lower off-road motorcycles. I will give an overview of each as well as provide you with some strengths and weakness that you may encounter with each solution.

1. Seat Foam Shaving: I noticed that Carmichael's bikes were shaved in the seats. As I looked into it more, most factory riders have their mechanics customize their seat with respect to height, so that they might feel and ride as comfortable as possible. Transworld Motocross magazine has one of the best articles I have come across on how to go about shaving a seat yourself. Kawasaki factory mechanic Alex Ewing takes you through the process step-by-step, complete with pictures. You can access the online version of that article here.

Be advised, however . . . I have read some horror stories of shaving jobs gone awry. These individuals typically had no idea how to go about it though. The nice thing about shaving the seat is that you can have an upholstery shop put the seat cover on when you are finished for a nominal fee, and it will look quite professional. It will also keep all the factory ergos and suspension intact. In a worst case scenario, you simply have to buy a new seat (ca. $80).

2. Linkage Devices: Some people have been very happy with the installation of lowering devices for the rear suspension, such as those made by Kouba. In essence, the link brings the rear end of the bike lower, leaving the original front and rear travel height intact. The front end is lowered in a corresponding fashion by simply raising the fork tubes higher in the triple clamps. You can check the Kouba website and see that they make their products for many different makes and models, and installation is reported to be very easy and only take about 30 minutes. The links are also relatively inexpensive, running about $120.

I would not hesitate to use this method of lowering for a playbike for my wife or kids, or for something where keeping the precise balance of the bike is not crucial. Most people who go that route are very happy for precisely those kinds of applications. However, if you are concerned about maintaining precision in suspension balance, you may want to choose another route. As you undoubtedly already know, raising the front forks in the triple clamps can produce a better turning front end, but it likewise can lead to instability on high-speed straights (viz., "headshake"). For me, the only time I want to adjust the fork tube level is to find the best balance between these two extremes.

3. Front & Rear Suspension Revalve: This is the approach that I took with the KTM300exc I bought last year. Since most bikes come stock with four inches of unused sag in their suspension, this approach can be particularly helpful in lowering a bike without sacrificing the factory ergos or suspension balance. Since my KTM is a woods bike, the lowering of the entire bike actually created a lower center of gravity, which makes low-speed cornering and restarting on a slippery hillside a whole lot easier. One area that is sacrificed, however, is ground clearance. That may be an issue if you ride MX tracks with deep ruts, where you could potentially scrape bottom.

On page 81 of Eric Gorr's latest edition of Motocross & Off-Road Performance Handbook, he has a picture of Rich Rohrich with his lowered YZF and CRF. Gorr's comments in the caption are as follows:
"Rich Rohrich made his YZF and CRF motorcycles easier to manage by having MX-TECH perform the typical super-moto suspension setup, including limiting the travel and lowering the ride height, stiffening the spring rate, and adding more rebound damping. The result is a lower center of gravity and a bike that hugs the inside line on turns."
I posted a question to Rich Rohrich on DRN regarding this issue and his response to me was as follows:
"I'd give Jeremy Wilkey at MX-Tech a call Phone: 815.936.6277 and discuss your options with him. He's lowered 3 bikes for me and each one has worked great on an MX track, with my CRF450 being the best of all."
Gorr also added in this same thread:
"I'm 6'1" and I like riding Rich's bike on tight tracks, its turns so good! It doesn't feel much different on jumps but I don't go crazy airing it out, too much of a waste of time. The only thing you have to be concerned about is ground clearance and picking lines through deeply rutted jump faces and turns."
Their assessment appears correct. My KTM is valved for the woods instead of the MX track, but it does everything it was designed for very well. And the best part is that it fits me.

The downside to this approach is two-fold: You need to really make sure you get someone who really knows what they are doing, since this is more than just a standard revalve (which in itself requires expertise). From my research, the two sources I would trust the most to do this work are the one recommended above by Gorr and Rohrich (MX-TECH), as well as Factory Connections. I have heard excellent reports about FC's work in this application.

The second downside is expense. While I haven't check prices recently, you can expect to pay anywhere from $400-$700 for this type of revalve.

4. Lower Sub-Frame: This approach involves enlarging the hole in the lower subframe mount, or cutting the subframe and rewelding it, thus bringing it down several mm. As a result, seat height can be lowered a fews inches. The real downside to this approach is that the rear fender is effectively lowered while the travel distance remains the same. This means that the rear wheel can strike fairly hard against the fender in a bottoming situation.

There are some short people who exclusively ride MX and they have indicated that after a while they adjusted to the height of their bike without making any adjustments. I believe that they actually have. For me, however, it is more than just adjusting. I want to be able to restart my bike without having to find a little hill or something to lean against or stand on. Moreover, I have ALOT more confidence riding when I can touch the ground and the bike really fits me. It makes the entire ride much more fun, and that is ultimately what it is all about.

Interestingly, Carmichael's people do both suspension revalving as well as shave the seat on his bike to find that place of comfort and subsequent confidence. With the next MX bike I get, I believe I am going to follow the steps outlined in the article on seat shaving that I linked above, and if that is unsatisfactory, I am going to go with the type of revalve that Rohrich and Gorr recommended.

Good luck.

Last edited by DCox; 01-26-2005 at 08:13 AM.
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Old 01-25-2005, 09:35 PM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by DCox
1. Seat Foam Shaving: I noticed that Carmichael's bikes were shaved in the seats. As I looked into it more, most factory riders have their mechanics customize their seat with respect to height, so that they might feel and ride as comfortable as possible. Transworld Motocross magazine has one of the best articles I have come across on how to go about shaving a seat yourself. Kawasaki factory mechanic Alex Ewing takes you through the process step-by-step, complete with pictures. You can access the online version of that article here.

2. Linkage Devices: Some people have been very happy with the installation of lowering devices for the rear suspension, such as those made by Kouba. In essence, the link brings the rear end of the bike lower, leaving the original front and rear travel height intact. The front end is lowered in a corresponding fashion by simply raising the fork tubes higher in the triple clamps. You can check the Kouba website and see that they make their products for many different makes and models, and installation is reported to be very easy and only take about 30 minutes. The links are also relatively inexpensive, running about $120.

Interestingly, Carmichael's people do both suspension revalving as well as shave the seat on his bike to find that place of comfort and subsequent confidence.
I have simply gotten use to riding at that height. However, kicking on the wrong side of hill can be a little tricky .

I haven't gotten a chance to shave my seatfoam but will undoubtably do this mod in the near future. Very good step by step. Thanks DCox! I'm 5'8. :zap

For some reason, Kouba refuses to make links for the YZ? :

During the telecast of the Phoenix or A2 SX, Todd Harris and Cameron Steele were talking about RC's rear shock. They had mentioned that in years past, he had them shortened for his height. He felt that the shorter height hurt him on the whoop sections. This year he is running his rear shock taller. I guess it's working? Damn rain messed up his chances of a perfect SX season?
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Old 01-25-2005, 09:48 PM
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Default Re: lowering suspension inch to 2inch's

As usual, excellent write up, DCox.

You are 10ft tall in my book
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Old 01-25-2005, 09:51 PM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by DCox

I would not hesitate to use this method of lowering for a playbike for my wife or kids, or for something where keeping the precise balance of the bike is not crucial. Most people who go that route are very happy for precisely those kinds of applications. However, if you are concerned about maintaining precision in suspension balance, you may want to choose another route. As you undoubtedly already know, raising the front forks in the triple clamps can produce a better turning front end, but it likewise can lead to instability on high-speed straights (viz., "headshake"). For me, the only time I want to adjust the fork tube level is to find the best balance between these two extremes.
Great report Mr. Cox! I knew you would prove me right. Thanks.


DCox, I hear your concern on geometry but I don't agree with you. If you raise the forks by the same amount as you lower the rear you have not changed the rake or trail geometry of the forks. Plus it can still be fine tuned like a stock suspension by adjusting shock and fork clickers, further adjustment on fork height in the triples, race sag and static sag. You are not comprimising the handling characteristics of the bike. That is my take anyway.

Short legs is usually the reason for lowering the bike, if you have short arms to match the legs it may also be a good idea to use adjustable bar mounts to get the bars closer to the rider and also a lower profile bar. Once you get your machine's ergos to match you it can make a huge difference on how you can perform on the bike.

Last edited by Silver_Fox; 01-25-2005 at 09:55 PM.
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Old 01-25-2005, 09:55 PM
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Default Re: lowering suspension inch to 2inch's

Shaving the seat foam is about the easiest, least expensive way to lower the bike. Dont forget you lower the rear you might need to lower the front also to balance it out, which can mess with the handling of the bike if not adjusted right... just my honest opinion on the topic.

Brandon
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Old 01-26-2005, 08:09 AM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by Silver_Fox
DCox, I hear your concern on geometry but I don't agree with you. If you raise the forks by the same amount as you lower the rear you have not changed the rake or trail geometry of the forks. Plus it can still be fine tuned like a stock suspension by adjusting shock and fork clickers, further adjustment on fork height in the triples, race sag and static sag. You are not comprimising the handling characteristics of the bike. That is my take anyway.
Silver, I am only an "expert" at being normal height in an abnormally tall world .

However, if you can give me more information/details on what you are saying here, I would really appreciate looking at it, since the Kouba link would definitely be one of the cheapest and easiest fixes out there. Everyone who has actually used it has reported good results, but most people I have found in that category were women riding really tall KDX's etc., or kids riding bigger bikes. It's use seems noticeably absent from weekend warriors and serious racers (with some exceptions) who did not want to throw the geometry off.

Perhaps the reservations people have about losing the factory geometry are over-rated and this solution is easily over-looked in the process. The last time I looked at Kouba's webpage (months ago), they did have instructions on adjusting the forks to bring about that balance, but they were suprisingly silent about making any claims that this brought the bike back within factory specs. To be sure, I recall them even having a disclaimer/warning about the possibility of adverse handling. Of course, that could just be one of those liability statements to protect themselves from people who crazy-glue their eyelids shut and then blame the manufacturer.

One thing I forgot to add about the Kouba link that seems self-evident is it is 100% reversible within say, 30 minutes time. This means that if you don't like it, you are only out the cost of the link (which you might be able to sell on Ebay), or if you go to later sell the bike to one of the "abnormally tall" (5' 8" and above ), you can swap it out for better sales appeal.

Heck Silver, the more I think about the Kouba link, the more inclined I am to at least give it a shot. Would you buy me one for my upcoming 450? At least send me more info. that has convinced you . . . .
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Old 01-26-2005, 09:33 AM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by DCox

Perhaps the reservations people have about losing the factory geometry are over-rated and this solution is easily over-looked in the process. The last time I looked at Kouba's webpage (months ago), they did have instructions on adjusting the forks to bring about that balance, but they were suprisingly silent about making any claims that this brought the bike back within factory specs. To be sure, I recall them even having a disclaimer/warning about the possibility of adverse handling.
At least send me more info. that has convinced you . . . .
Yes I think it would be hard for them to make a claim as bold as promising factory specs as I am sure the average person working on their bike may not take all the steps to ensure proper geometry. The disclaimer is a smart move on their part.
As far as sending you more info to convince you......... give me your address and I can mail you a box full of common sense, I have some here that has never been used.
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Old 01-26-2005, 11:39 AM
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Default Re: lowering suspension inch to 2inch's

Silver Fox is correct in what he states about chassis geometry. It's only a problem if you adjust one end and not both. That changes the front end rake and will effect handling as a result. If you change both, the rake does not change and the bike will handle the same. I used to deal with this on my roadrace bike when changing from DOT tires to racing slicks. The slicks were shorter than the DOTs, which lowers the nose slightly and increases rake angle. Adjusting fork position to account for this difference eliminated the change and made the bike handle the same with the different tires.

Along the same lines, new suspension links change the behavior of the rear end since they modify the kinematics of the suspension system. Most are designed to be progressive and changing the length of the links will change the nature of the relationship between rear wheel travel and shock compression. If you'd like to work out how they change, find a engineering textbook on Kinematics and have a ball. Don't ask me as I don't do those kinds of calculations without getting paid for it.

As for RC's bike, he does shave the seat and did modify the suspension in the past. But the RM isn't lowered, other than the cut seat foam as twoofeach said, if you can believe the TV announcers.
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Old 01-26-2005, 12:20 PM
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Default Re: lowering suspension inch to 2inch's

Michael, if I understand your second paragraph correctly, the change to the behavior of the rear end is true even if a correct geometry is obtained through raising the front fork tubes. If this is the case, it may better explain the hesitation I detected from others regarding the use of these lowering links.

It would still be interesting to know precisely what could be affected in the suspension, and if it could be compensated easily. While a slow weekend warrior like myself does not require the suspension tuning that a serious rider needs, I can usually feel the difference if it goes too far in the wrong direction (read "garbage scow").

Quote:
Originally Posted by mtk
Along the same lines, new suspension links change the behavior of the rear end since they modify the kinematics of the suspension system. Most are designed to be progressive and changing the length of the links will change the nature of the relationship between rear wheel travel and shock compression. If you'd like to work out how they change, find a engineering textbook on Kinematics and have a ball. Don't ask me as I don't do those kinds of calculations without getting paid for it.
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Old 01-26-2005, 03:33 PM
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Default Re: lowering suspension inch to 2inch's

Well I ride Harescrambles....did the seat shave and had ProAction lower my bike 2 inches......this gives me 3 total inches. I have rode 2 different bikes from Proaction( buddies bikes) with no complains. My cost was 540.oo= respring and revalve. I shall see if it works on the mx track also. I will click up the compression clickers to find the perfect adjustment on the mx track.....then click back for the woods.
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Old 01-26-2005, 05:00 PM
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Default Re: lowering suspension inch to 2inch's

i had my 2004 yz250f lowered 3 inches at first, then went up to 1 inch, dont lower it to much you'll bottom out alot, but all in all its awesome i got mine done my Gary Borelli in Mendota, IL
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Old 01-27-2005, 11:48 AM
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Default Re: lowering suspension inch to 2inch's

Quote:
Originally Posted by twoofeach
During the telecast of the Phoenix or A2 SX, Todd Harris and Cameron Steele were talking about RC's rear shock. They had mentioned that in years past, he had them shortened for his height. He felt that the shorter height hurt him on the whoop sections. This year he is running his rear shock taller. I guess it's working? Damn rain messed up his chances of a perfect SX season?
That is interesting Twoofeach. I wonder if Team Suzuki did a combination of custom work to get RC's RM to fit him better. The pics where I have seen him sitting on it show a flat foot on the ground. I know Honda cut the subframe and rewelded it, as well as shaving the seat on his CRF450 this last year.

It would be very interesting to know what combination factory teams finds best for bringing seat height down for shorter riders.
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Old 04-04-2005, 07:19 PM
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Default Re: lowering suspension inch to 2inch's

something simple to get an inch or so is just to lossen up the triple calmps and slide the fork tubes up as high as you can. it may affect handling negatively, but it seemed to work okay for me.
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Old 04-04-2005, 10:29 PM
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Default Re: lowering suspension inch to 2inch's

I'd chop the seat long before I did anything to the suspension.

I bought a second seat for my CR for that exact reason. The stocker is going to get cut down. I won't touch the boingers on it if I don't have to.
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Old 04-05-2005, 01:01 PM
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Default Re: lowering suspension inch to 2inch's

the quickest method that wont give you fender drag is to cut off some front spring, and back off the preload on the back until you like it. if you find a height setting you like and the suspension does not seem too harsh, then make some top out spacers for the front and the rear. they would be the same as you cut and backedoff resepectively. remember when you cut a spring it becomes stiffer,,so you may need softer ones to make you happy when it is all done. Yamaha did some of that for you when they built the 94. it was an inch shorter in the suspension dept. public didnt like it i guess. simply dropping the fork in the clamp can get you a safe 3/4 of an inch drop in most cases,,but any more than that and you can catch rocks, mud etc between the tire and fender in a bottomout situation. This can lock the front wheel. If you don't like that idea, stick to cutting the springs. If you dont mind a softer ride you may be able to just got to softer springs and less preload etc.

as you drop further into the stroke, your valving changes too. some of it you may be able to work out with the "clickers" if your riding even detects it. I would be kind of hard pressed to tell someone with a 12 year old bike to go spend upwards of 300 dollars to revalve it right off the bat though.

as far as cutting the seat, it works, if you like how the pegs fit you afterwards,,,try sitting on your bike with some padding simulating the heigth difference.


cutting the subframe is pretty easy if you have access to a welder. the rear wheel will be closer to the seat base and subframe. make sure there is at least 1.5 more inches of clearance than you have travel, do this by actual measurement. move the wheel as far back as is needed to play with this one. even the linkage changes require at least measuring to see if you are going to get drag. in my case I dont mind light drag there,,just dont want the wheel to lockup. you would be surprised how much everything can flex in a hard bottom out,,from the wheel,,to the swingarm and frame to the subframe.
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