weantright

XT suspension

54 posts in this topic

15 hours ago, weantright said:

Thanks for trying, $150 for helicoils,,,, ouch!

Seat height, one inch means a lot to a female! Power is the biggest thing that would cost more to get to then upgrading the XT's suspension for our needs. Right now our XT's power is like a CRF230. Plus we already have the XT with options, would be too much to convert over or buy again. I would hold on to these forks if they weren't so dam cheap.

Agree with this. I think it would cost a bunch to lower/tame  a RR to a lowered XT. We had to lower the XT an additional 2" for the little lady, and could go another 1", easy. I just did the K-9 fork upgrade, along with the Fox shock, and the bike is vastly improved. If the bike was just for me, sure, I would have got the RR. But now this bike is fun for both of us.

Share this post


Link to post
Share on other sites
9 hours ago, canamfan said:

Boana racing has just released a cartridge kit for both forks, so you have 2 springs and two cartridges one for each fork and rebound adjustment on the left forks top, and compression adjustment on the right forks top. Sierra motorcycle supply has them listed in Boana race parts. $800 bucks, so kinda expensive but I've ordered it, only thing is I had rotator cuff surgery 3 months ago so it will be awhile before I can test it. While I'm off I'm doing some upgrades.

Buuuuuuut you still have to deal with the cheap china casting which will or may break in time. Also as posted in other forums these Olle forks are not long lasting. A bit more then $800 and you have KYB swap either OC or CC.

4 hours ago, drumiv said:

Agree with this. I think it would cost a bunch to lower/tame  a RR to a lowered XT. We had to lower the XT an additional 2" for the little lady, and could go another 1", easy. I just did the K-9 fork upgrade, along with the Fox shock, and the bike is vastly improved. If the bike was just for me, sure, I would have got the RR. But now this bike is fun for both of us.

Yep if this bike was mine it would be a RR but it's not. First it's the lady's then a back up which has proven to be majorly under suspended even for my 145lbs son. I was going to update with cartridges for him but this latest issue killed that. The direction I am headed is OC KYB unless Beta will have a set-up tailored to the XT come October.

Share this post


Link to post
Share on other sites
30 minutes ago, weantright said:

Buuuuuuut you still have to deal with the cheap china casting which will or may break in time. Also as posted in other forums these Olle forks are not long lasting. A bit more then $800 and you have KYB swap either OC or CC.

Yep if this bike was mine it would be a RR but it's not. First it's the lady's then a back up which has proven to be majorly under suspended even for my 145lbs son. I was going to update with cartridges for him but this latest issue killed that. The direction I am headed is OC KYB unless Beta will have a set-up tailored to the XT come October.

Since you have the fork off, measure the lug offset like this:

I did this for my conversion, works well.

(example dimensions are from '11 Yamaha YZ250F KYB SSS)

Dim A = dia of the lower thin wall part of the foot, should be 33mm
Dim B = height of the small casting rib on the rear of same foot section, approx .25mm  (if applicable)
Dim C = axel bore. easy at 25mm
Dim D = the distance from the inner ID surface of the axel bore to the top of the small rib on the rear of the foot, approx 36.5mm

The idea is to get good numbers on easy to measure surfaces and calculate the tough one to actually measure accurately.
Offset is the distance from fork tube center to axel center, so we use the dia of the foot and axel to calc them, and reference with D minus the rib height. The KYB is much easier due to the smooth casting, but same principle applies.

ex: Offset = D-B-A/2+C/2
=36.5-.25-33/2+25/2 = 32.25mm  (for my 32mm lug KYBs)

Tube upper and lower dias. are easy.

Stock fork length from cap to axel center.  Its easy to shorten a longer fork. 

The hardest thing to measure is the stock triple clamp offset, top clamp has to be removed from the bike to do it accurately.  perhaps there is a spec somewhere.

Once you know this, it narrows things down with respect to fork choice, and will define what clamps to use.  Trust me if you alter offset things can get ugly with handling. 

Caliper carrier should not be a problem, and spacers will have to be custom or modified.

Considering the use, a nice set of older KYB OC 46s might even work well and be a very affordable solution if the #s work out to use the stock clamps.  I have a set on my kid's KX125 I revalved and they are great for a moderate pace in the woods. 

1 person likes this

Share this post


Link to post
Share on other sites
21 hours ago, ossidog said:

I have owned both, I think you are talking 6 pounds if that and one inch.

The XT really is a horrid frame too 

From what I have seen following a guy on the trail I tend to agree, at least with the stock bike.  Top 3rd gear speed if the trail is a little rough the bike looks spooky, and scared the crap out of the rider several times.  I think the frame angle is steeper and for what the bike is intended for it makes sense.  Its not a low seat height race bike.   Still a lot of room for improvement in suspension, just keep things in perspective.  I wouldn't expect any kit, suspension option from Beta to be a great value.  Put an appropriate Japaneese fork on and call it done.

2 people like this

Share this post


Link to post
Share on other sites
52 minutes ago, GP said:

Since you have the fork off, measure the lug offset like this:

I did this for my conversion, works well.

(example dimensions are from '11 Yamaha YZ250F KYB SSS)

Dim A = dia of the lower thin wall part of the foot, should be 33mm
Dim B = height of the small casting rib on the rear of same foot section, approx .25mm  (if applicable)
Dim C = axel bore. easy at 25mm
Dim D = the distance from the inner ID surface of the axel bore to the top of the small rib on the rear of the foot, approx 36.5mm

The idea is to get good numbers on easy to measure surfaces and calculate the tough one to actually measure accurately.
Offset is the distance from fork tube center to axel center, so we use the dia of the foot and axel to calc them, and reference with D minus the rib height. The KYB is much easier due to the smooth casting, but same principle applies.

ex: Offset = D-B-A/2+C/2
=36.5-.25-33/2+25/2 = 32.25mm  (for my 32mm lug KYBs)

Tube upper and lower dias. are easy.

Stock fork length from cap to axel center.  Its easy to shorten a longer fork. 

The hardest thing to measure is the stock triple clamp offset, top clamp has to be removed from the bike to do it accurately.  perhaps there is a spec somewhere.

Once you know this, it narrows things down with respect to fork choice, and will define what clamps to use.  Trust me if you alter offset things can get ugly with handling. 

Caliper carrier should not be a problem, and spacers will have to be custom or modified.

Considering the use, a nice set of older KYB OC 46s might even work well and be a very affordable solution if the #s work out to use the stock clamps.  I have a set on my kid's KX125 I revalved and they are great for a moderate pace in the woods. 

Will do a more precise measurement but so far the offset is around 32mm. This goes against a spec one magazine posted that the XT and RR have the same 27* rake and 22mm offset. Using the Boano/Beta Sachs fork kit theory I should buy everything but the forks. This will let me drop in many brand forks of my choosing which is a big savings. Problem is no one has including Beta returned any emails. For the money 48mm forks work the best since the 46mm will not fit into the stock clamps. 43mm KTM 85sx forks are the closest to fit the stock clamps, overall length and stroke. This route a new axle, spacers for wheel and calibrator will be need.

Share this post


Link to post
Share on other sites

 

 

 

 

Will do a more precise measurement but so far the offset is around 32mm. This goes against a spec one magazine posted that the XT and RR have the same 27* rake and 22mm offset. Using the Boano/Beta Sachs fork kit theory I should buy everything but the forks. This will let me drop in many brand forks of my choosing which is a big savings. Problem is no one has including Beta returned any emails. For the money 48mm forks work the best since the 46mm will not fit into the stock clamps. 43mm KTM 85sx forks are the closest to fit the stock clamps, overall length and stroke. This route a new axle, spacers for wheel and calibrator will be need.

 

 

 

 

 

Even if the 2stroke RR and XT are the same rake and clamp offset, the RR uses 35mm lug offset. 3mm is a huge difference, and makes the bike hyper sensitive.  I know, I first put 32mm offset KYBs in 20mm clamps.  Once the bike initiated a turn things happened way to fast.  This might explain some of the XT character if indeed the lugs are 32mm. 

 

Share this post


Link to post
Share on other sites

Shock is not as bad as the forks but with this setup one change to either ends will unbalance the bike quickly. Shock is coming,,,,, well shipping soon which means +/- week (s).

Share this post


Link to post
Share on other sites

Posted (edited)

3 hours ago, GP said:

From what I have seen following a guy on the trail I tend to agree, at least with the stock bike.  Top 3rd gear speed if the trail is a little rough the bike looks spooky, and scared the crap out of the rider several times.  I think the frame angle is steeper and for what the bike is intended for it makes sense.  Its not a low seat height race bike.   Still a lot of room for improvement in suspension, just keep things in perspective.  I wouldn't expect any kit, suspension option from Beta to be a great value.  Put an appropriate Japaneese fork on and call it done.

 

GP, you provide some pretty good info, but I wonder if the guy you were following had his bike setup properly.

I'm not getting the bad-handling lots of folks are talking about with the XT.   I weigh in at less than 150 lbs without gear.

I'm used to tight-handling bikes though, as I trail-rode and raced heavily-modified KDX200's and 220's for about 15 years. But my XT isn't heavily modified, I just set the sag and worked the clickers (and put in heavier fork oil) - I ride mostly horribly unforgiving worn-out trails with big ruts, pot holes, and stutter bumps and although the bike is not as smooth as others in such situations at higher speeds, it certainly isn't scary either. I've also found that the stock tires are a weak link for dry terrain riding - which can contribute to handling issues on rough trails.  What I try to do when setting up a suspension is very simple; I look for a compression vs rebound rate (both ends) that is the most comfortable and controllable for the type of terrain I'm going to ride - by that I mean do I need more compression vs rebound or less...do I want the bike to come up faster or slower as a unit and how will it respond to trail trash vs a big hit at speed.   It is imperative that both ends move smoothly in concert so the bike stays level off of jumps, waterbar hits, etc. 

I have done a dozen or so front end swaps, mostly with the KDX's...and it can be a fairly expensive and time-consuming proposition to get the bike to handle properly.  Whatever forks are used, in addition to geometry issues, they have to have the correct spring rates to match the rear end, as well as the rider's weight.   If you choose to swap an entire triple, you need to be aware of the relative bar clamp positions (forward or rearward), as they can vary greatly from bike to bike.  The damping rates for MX forks are rarely worth spit for off-road use, so you need to at least revalve the compression stack.  And....if the forks were originally built for a heavier bike, you'll likely find that just putting lighter springs in will bring up another problem...too much rebound damping...even when fully backed out.

I've yet to overheat the stock shock (damping fade) in the most demanding of rides, and the single-spring light weight of the front fork design I consider a plus - of course, there will be some riders who will benefit from major suspension changes, but for the vast majority, including some fast guys, massaging the stock suspension is probably a better option, especially if time and money are a consideration (try the new cartridge drop-in first).

Just my perspective.

Edited by kawagumby
1 person likes this

Share this post


Link to post
Share on other sites

Kaw - Obviously you don't know GP as he is very knowledgably about this type of swap and has done it with several bikes. Also in my past I have done a fork swap and know all about the little stuff. Second did you read about my issue with the threads?? This problem makes swapping cartridges a big negative as the casting problem can't be fixed cheaply. So if I do this OEM way correctly I will have close to $800 into a fork with one side adjustable cartridge or just over a $1000 for duel sided. As for valving, there's a tuner somewhat local that already has done an XT KYB conversion with great results. I leave the valving to people that do it professionally, too much testing for the different brands I have.

My son is 145lbs w/out gear and has crushed this suspension several times on the trail. This is another reason to update vs. just make good. I can't see anyone hitting a water-bar at anything over an idle safely. Then again my water-bar maybe bigger then yours.

Share this post


Link to post
Share on other sites
1 minute ago, weantright said:

Kaw - Obviously you don't know GP as he is very knowledgably about this type of swap and has done it with several bikes. Also in my past I have done a fork swap and know all about the little stuff. Second did you read about my issue with the threads?? This problem makes swapping cartridges a big negative as the casting problem can't be fixed cheaply. So if I do this OEM way correctly I will have close to $800 into a fork with one side adjustable cartridge or just over a $1000 for duel sided. As for valving, there's a tuner somewhat local that already has done an XT KYB conversion with great results. I leave the valving to people that do it professionally, too much testing for the different brands I have.

My son is 145lbs w/out gear and has crushed this suspension several times on the trail. This is another reason to update vs. just make good. I can't see anyone hitting a water-bar at anything over an idle safely. Then again my water-bar maybe bigger then yours.

Forgive me if you thought I was talking about you specifically, since this is a forum read by many persons who own or may own an XT, my response was in general terms simply to show another perspective.  You wouldn't want someone interested in the XT to think that a major suspension upgrade was necessary to enjoy this bike, would you?  Believe me, I understand where you are coming from and your frustration with the casting issue your bike has (mine doesn't have that problem, for example).  So, again, I'm not arguing with you, simply showing another viewpoint.  

2 people like this

Share this post


Link to post
Share on other sites
21 minutes ago, kawagumby said:

 

GP, you provide some pretty good info, but I wonder if the guy you were following had his bike setup properly.

I'm not getting the bad-handling lots of folks are talking about with the XT.   I weigh in at less than 150 lbs without gear.

I'm used to tight-handling bikes though, as I trail-rode and raced heavily-modified KDX200's and 220's for about 15 years. But my XT isn't heavily modified, I just set the sag and worked the clickers (and put in heavier fork oil) - I ride mostly horribly unforgiving worn-out trails with big ruts, pot holes, and stutter bumps and although the bike is not as smooth as others in such situations at higher speeds, it certainly isn't scary either. I've also found that the stock tires are a weak link for dry terrain riding - which can contribute to handling issues on rough trails.  What I try to do when setting up a suspension is very simple; I look for a compression vs rebound rate (both ends) that is the most comfortable and controllable for the type of terrain I'm going to ride - by that I mean do I need more compression vs rebound or less...do I want the bike to come up faster or slower as a unit and how will it respond to trail trash vs a big hit at speed.   It is imperative that both ends move smoothly in concert so the bike stays level off of jumps, waterbar hits, etc. 

I have done a dozen or so front end swaps, mostly with the KDX's...and it can be a fairly expensive and time-consuming proposition to get the bike to handle properly.  Whatever forks are used, in addition to geometry issues, they have to have the correct spring rates to match the rear end, as well as the rider's weight.   If you choose to swap an entire triple, you need to be aware of the relative bar clamp positions (forward or rearward), as they can vary greatly from bike to bike.  The damping rates for MX forks are rarely worth spit for off-road use, so you need to at least revalve the compression stack.  And....if the forks were originally built for a heavier bike, you'll likely find that just putting lighter springs in will bring up another problem...too much rebound damping...even when fully backed out.

I've yet to overheat the stock shock (damping fade) in the most demanding of rides, and the single-spring light weight of the front fork design I consider a plus - of course, there will be some riders who will benefit from major suspension changes, but for the vast majority, including some fast guys, massaging the stock suspension is probably a better option, especially if time and money are a consideration (try the new cartridge drop-in first).

Just my perspective.

The bike was pretty new, and the trail was rocky but flowing.  My buddy on a 350RR was leading with the XT behind,  pretty good pace for a trail ride. I got in behind the guy and was pushing him a bit, trying to get by.  The bike just could not deal with rocks at the speed we were going.  I have no idea what the setup was, but its obvious its not in the same league as the RRs, Huskys, and GGs on the ride.  No shame, its not a woods bike made for faster riding.  I have gnarly trail near my house its perfect on, I know my neighbor has one.

As far as swaps I have KYB SSS on my 250RR, lengthened shock, and my own valving at both ends.  Quite pleased.

1 person likes this

Share this post


Link to post
Share on other sites
1 minute ago, GP said:

The bike was pretty new, and the trail was rocky but flowing.  My buddy on a 350RR was leading with the XT behind,  pretty good pace for a trail ride. I got in behind the guy and was pushing him a bit, trying to get by.  The bike just could not deal with rocks at the speed we were going.  I have no idea what the setup was, but its obvious its not in the same league as the RRs, Huskys, and GGs on the ride.  No shame, its not a woods bike made for faster riding.  I have gnarly trail near my house its perfect on, I know my neighbor has one.

As far as swaps I have KYB SSS on my 250RR, lengthened shock, and my own valving at both ends.  Quite pleased.

Doing your own valving is the only way to go!:thumbsup:

Share this post


Link to post
Share on other sites
5 minutes ago, kawagumby said:

Doing your own valving is the only way to go!:thumbsup:

I have been spoiled in that I have/had very good tuners nearby, one was a sponsor of my son. The one I deal with now rides the same type of trails and knows his $hit. Small shops with big passion and knowledge helps cut down the on the testing. Same day turn around!

Share this post


Link to post
Share on other sites

It will be interesting to see all the numbers on this bike(offsets, fork length, etc).  Then it might explain why it handles as it does, and provide a path to tweak it, if desired. I know its the best seller, but can't help but think a lot of people buy it for the lower seat height and then realize its not a shorter RR.  If my wife was still riding I'd get her one for sure.  She rode a GG Pampera 250, very light but the trials motor had a stiff kick.  if I rode that bike like my XCs at the time I would destroy it as it had lightweight trials hardware.  The XT solves that issue.

Share this post


Link to post
Share on other sites
2 minutes ago, weantright said:

I have been spoiled in that I have/had very good tuners nearby, one was a sponsor of my son. The one I deal with now rides the same type of trails and knows his $hit. Small shops with big passion and knowledge helps cut down the on the testing. Same day turn around!

For years I had Les at LTR do all my stuff.  Great guy.  NJ to WA just too far though for mid season changes or service.  Steve at PlusOneperformance/Afterhours in MI does a great job too, but I like to learn and solve my own problems if I can, plus its a LOT cheaper.  After a few tries, testing, and watching video of the bike in action its not too hard to get exactly what you want and understand why it works.  I rode my brother's Husky with a set of KYB CC forks he picked up done by ProTune and they feel VERY close to my setup.

Share this post


Link to post
Share on other sites

According to Owen Lock, who has owned and raced several iterations of both bikes, the stock RR and XT front suspension share the same total offset.

300 RR is 20 mm clamp offset + 35 mm fork foot offset, for 55 mm total offset.

300 XT is 21 mm clamp offset + 34 mm fork foot offset, for 55 mm total offset.

Share this post


Link to post
Share on other sites

Thank you, I'm sure weantright appreciates it too.
So, many options now.

1 person likes this

Share this post


Link to post
Share on other sites
12 hours ago, wwguy said:

According to Owen Lock, who has owned and raced several iterations of both bikes, the stock RR and XT front suspension share the same total offset.

300 RR is 20 mm clamp offset + 35 mm fork foot offset, for 55 mm total offset.

300 XT is 21 mm clamp offset + 34 mm fork foot offset, for 55 mm total offset.

Thanks, that's a great start to my project. Will be working on the bike tonight getting some finial numbers.

I attempted to use KTM85sx forks but the clamping diameters are smaller (enough to need a spacer) and shorter. Between these two a new triple clamp would be warranted witch pushes toward full size forks.

1 person likes this

Share this post


Link to post
Share on other sites

Assuming this info is correct, you are in a good spot considering you have to buy clamps anyway. You either go with 20mm (2stroke RR) clamps and 35mm lug Husky KYBs(CC or OC), 35mm lug Yamaha KYB SSS, Honda CRF KYB, or 23mm (4stroke RR) clamps and newer 32mm lug KYB SSS.  Really it may come down to the best quality/lowest hour fork you can find for the $$, OC or CC.  You can make the KYB SSS fork as soft or as firm as you want, it can be made to do anything.

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with: