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18' 450 sxf sprocket size vs chain adjustment

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On ‎7‎/‎28‎/‎2019 at 5:40 PM, BDubb106 said:


Those were my findings exactly with the switch so it is not just you. Give it a ride or two until the chain settles in and you will be able to bump it back a bit. I don’t notice any of those quirks that come from moving the wheel forward anymore.

Looking to throw a 49T rear on my 2019.  Can you guys confirm that the stock chain will  work as long as I flip my axle blocks around?  Also, I've found that running the rear axle any closer than 606mm (measured center of swingarm bolt to center of axle) starts causing issues in the way our bikes handle.

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10 minutes ago, KTMrider37 said:

Looking to throw a 49T rear on my 2019.  Can you guys confirm that the stock chain will  work as long as I flip my axle blocks around?  Also, I've found that running the rear axle any closer than 606mm (measured center of swingarm bolt to center of axle) starts causing issues in the way our bikes handle.

Was wondering if lowmass flipped the blocks with the stock chain also? 1 tooth on either sprocket only moves the adjust 5/32"

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2 hours ago, KTMrider37 said:

Looking to throw a 49T rear on my 2019.  Can you guys confirm that the stock chain will  work as long as I flip my axle blocks around?  Also, I've found that running the rear axle any closer than 606mm (measured center of swingarm bolt to center of axle) starts causing issues in the way our bikes handle.

Get a longer chain, the new 19's work well with the wheel back, imo.

That's why they made the slot longer :)

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Posted (edited)
4 minutes ago, BDubb106 said:

It will work but as yzrider said. They work much better with the wheel back.

So what size chain should I run? 116 link?

Edited by KTMrider37

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Posted (edited)

One longer than you have.

I can't remember what's stock. If it's 116, then 118 you'll need.

 

Edited by yzrider53
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11 minutes ago, yzrider53 said:

One longer than you have.

I can't remember what's stock. If it's 116, then 118 you'll need.

 

my 2019.5 came with a 114 so I guess I'll pick up a 118 and cut it down to 116..

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You'll be happy. I did that immediately, even with the 48. The 49 will be be in between the marks on the swing arm.

 

I highly recommend you get an O'ring chain.

 

  

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10 minutes ago, yzrider53 said:

You'll be happy. I did that immediately, even with the 48. The 49 will be be in between the marks on the swing arm.

 

I highly recommend you get an O'ring chain.

 

  

I'll probably opt for the D.I.D. VT2

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sorry dropped ball on this

I did use stock chain length with 49T BUT axle blocks turned and now axle almost all the way forward.

I never did try the 49T with axle all the way back and longer chain.

With the axle all the way forward I am not sure I like the handling. It seemed to be a better balanced bike with axle back farther about in center of adjustment. Ive lost some confidence at turn entrance and it seems a bit twitchy at speed.

I plan to eventually put the 48T back on and get axle back a bit and see if I notice a difference

 

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2 hours ago, lowmass said:
sorry dropped ball on this
I did use stock chain length with 49T BUT axle blocks turned and now axle almost all the way forward.
I never did try the 49T with axle all the way back and longer chain.
With the axle all the way forward I am not sure I like the handling. It seemed to be a better balanced bike with axle back farther about in center of adjustment. Ive lost some confidence at turn entrance and it seems a bit twitchy at speed.
I plan to eventually put the 48T back on and get axle back a bit and see if I notice a difference
 


I just did this test a month or so ago. The bike def wants to oversteer with the axle slid forward. I thought it was a suspension issue and then remembered that I had the rear pretty far forward. I didn’t notice the twitchiness at speed but I run my steering stem a little tighter in the sand (my track is pretty much all deep beach sand except for a few corners that I added clay) and never really got the chance to play with it on a decent “soil” track. I did however notice worse than normal arm pump (I don't suffer from arm pump very often so if I pump up it is either from simply holding on too tight or a crappy diet that week) when riding with the rear wheel forward so I am sure I was gripping tighter to try to compensate without noticing it. 

I have since replaced the chain (again) with a 120link chain as I have a 2018 and moved the 49T back. I have only spent a few minutes on the bike since then due to my electrical issues but the bike def seems to handle much better and is as predictable as it was with the 48 again. No issues holding a rut anymore.

Edited by BDubb106

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10 hours ago, KTMrider37 said:

my 2019.5 came with a 114 so I guess I'll pick up a 118 and cut it down to 116..

Yes you will have to add a link to run the 49T effectively and keep the handling characteristics. The wheel forward is not worth the handling trade off to me. I am sure there are some people out there that enjoy that "quick" handling but I am not one of them. I need the consistency and stability.

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Posted (edited)

yea not too surprised by that.  Interesting on the twitchy thing with axle far forward. Theres a section on one track I use to monitor the twitch. Its a long straight with washboard at end. So long as you are a bit more forward ( centered ) and on gas there is no twitch BUT if you are even 1/2 inch back it shakes.

I am a bit cramped on this chassis ( 5' 11" and long legs) so I think I need that 1/2 inch. 

also it just doesn't seem like the front is as well connected at turn entrance. As if I am having a harder time getting it to settle in a balanced way into a turn.

BDubb , can you give a comparison of handling between axle in middle of adjustment , verses axle all the way to the back? I didn't try that one

 

BTW on the 49T.  Once I opened the airbox, got rid of filtr flame screen and muffler screen, the power profile on map 2 now seems to have a fast enough squirt that I think the 48T may be the better tool on our local MX tracks. 

Edited by lowmass

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3 minutes ago, lowmass said:

yea not too surprised by that.  Interesting on the twitchy thing with axle far forward. Theres a section on one track I use to monitor the twitch. Its a long straight with washboard at end. So long as you are a bit more forward ( centered ) and on gas there is no twitch BUT if you are even 1/2 inch back it shakes.

I am a bit cramped on this chassis ( 5' 11" and long legs) so I think I need that 1/2 inch. 

also it just doesn't seem like the front is as well connected at turn entrance. As if I am having a harder time getting it to settle in a balanced way into a turn.

BDubb , can you give a comparison of handling between axle in middle of adjustment , verses axle all the way to the back? I didn't try that one

Yes... I will be putting in a few moto's today as I finally have the bike running right again and have some spare time. I just sent a reply to KTMrider via PM stating the same. I will compare axle all the way forward (flipped) with stock length chain, middle adjustment, and all the way back just for a back to back comparison. 

It's odd that you are getting a feeling that the front is not as planted with the axle forward. I feel the front is too heavy with the axle forward. I am having trouble with the front wanting to knife when I try to settle into a rut at speed. I know that the sand makes the bike feel that way anyways so maybe that is where our differences are. 

The sand develops more of a roller style holes than square edge chop like I am used to and as you describe, so I get over the rear anyways as the gas is my friend through the corners whether the wheel is forward or back. 

I too am a bit cramped on the chassis but it feels more comfortable than most bikes I have tried. At 6'4, I obviously have long legs but don't like the feel of low pegs or a tall seat. I will trade space for the natural feel of a chassis any day of the week because we all know that corner speed is what matters. 

 

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Posted (edited)

great I look forward to hear what ya think. Be careful to set sag each time...

yes it does seem strange that it feels less "planted" with rear axle forward, BUT with axle forward you actually have less weight on front wheel. This may show up more on harder tracks and maybe less on sand??

With axle in middle of adjustment the entrance to turns seemed more consistent , balanced, and predictable. I feel I can trust it more

 

 

Edited by lowmass
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5 hours ago, lowmass said:

great I look forward to hear what ya think. Be careful to set sag each time...

yes it does seem strange that it feels less "planted" with rear axle forward, BUT with axle forward you actually have less weight on front wheel. This may show up more on harder tracks and maybe less on sand??

With axle in middle of adjustment the entrance to turns seemed more consistent , balanced, and predictable. I feel I can trust it more

 

 

So I have tested the axle forward and full rear so far today. Sag was set at 106mm and fork pressures were reset before each ride (148psi which is my normal pressure on my track due to the sand) to ensure that results were consistent. Forward gave me the same feelings I remember. Over steer and arm pump. Still didn't get that twitchy feeling but I could not get the thing to settle in a rut to save my life. It was far better when squaring up corners which costs me speed in the sand. I did tip the bike over a few times in corners that I can typically hold it pretty much wide open through.

With the axle in full rear position, the bike was much more stable and felt more balanced. I flowed much better around the track and I could immediately feel myself putting less effort into riding a fast lap or two. It settled into ruts nicely and was much better railing the outsides than trying to drop into an inside line. If I tried to turn the bike too quickly (sharply), it felt like I had to fight the bike to keep it leaned over. It just wanted to stand up, but I had no issues climbing out of ruts. Just not a feeling I was 100% comfortable with. However I experience zero arm pump, so it was rather obvious that I was fighting the bike with the axle forward.

I am fat and out of shape so I need to take a breather before I head back out to test the axle in the middle position. So far I think I will try to end up somewhere in the 3/4 range based on results so but I will update once I test the axle in the center. I preferred the axle in the rear position far more than the front position. I still want to be able to get inside at times. Esp when I get out to some harder based tracks. 

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Rode with the axle in the middle yesterday evening, bike handled like a dream. It gave me the option to take any line I wanted without feeling like I was fighting the bike and it held a rut amazingly well. I would say anywhere from middle to rear is going the be the target range for just about any rider. I just can’t see many people liking the axle much further forward than 1/2.

Lowmass is 100% correct, you need to check sag every time you change the chassis geometry. It has a drastic effect on the way the bike chassis responds in various situations.

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Good job BDubb

BTW I just went back through your posts and realized I forgot to mention that every sense I put the 49T on with the axle all the way forward, I too have been getting arm pump. And now thinking on it I believe the added twitch  and lack of confidence at turn entrance has me holding on tighter. 

I dont have issues with arm pump unless out of shape or haven't ridden in months. I haven't had an issue with arm pump at all this year until I changed axle position to the front. 

Another interesting thing is the rear doesn't hold up in stroke as well with axle forward. It Gs out more. Strange as I thought with axle farther forward ( thus less mechanical advantage), it should G out less and be stiffer. I suspect however that with axle forward there is simply more weight on rear wheel ( engine and body now closer  to rear axle) and   that is overcoming the small change in mechanical advantage of a shorter swing arm ( axle forward) . If I move my ass just 1/2 inch farther forward the G outs stop BUT Im too cramped on chassis.

I learned a thing or two in this. Thanks BDubb for stayin on it ! 

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