lowering kit

mzmasi

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Late follow up to lowering kit

Finally got it 2 days ago. Haven't had time to take the shock off until today. I'm not equipped to compress the spring, etc to change the end of the shock so I'm taking the shock to a shop for that. I'll still put the shorter side-stand on, raise the forks and put the shock back on myself. Their side-stand looks the same as the original quality-wise and the shock end better. The bigger foot is a genuine KTM part which I bought from them because they had them. Pretty cool that it came from the Isle of Mann too motorcycle racing history fans.
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Hi JKBC,
I am getting another RC390 for street instead of track only. How is the rear shock, and associated geometry working out?
2016 RC390 with a cup bike tail and foam "seat" on the way. On the track bike we dropped the front set and softened the rear shock, as well as replacing the tail with the cup bike one since the race seat is lower. Looking for a little more drop for rideability. With those changes on the track bike, I'm still barely tippy toe, but it doesn't matter because I only have to put my feet down when entering and exiting the track. I need to be able to put my feet down on the road. Any advice would help!
 

CDN Duke

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Hi JKBC,
I am getting another RC390 for street instead of track only. How is the rear shock, and associated geometry working out?
2016 RC390 with a cup bike tail and foam "seat" on the way. On the track bike we dropped the front set and softened the rear shock, as well as replacing the tail with the cup bike one since the race seat is lower. Looking for a little more drop for rideability. With those changes on the track bike, I'm still barely tippy toe, but it doesn't matter because I only have to put my feet down when entering and exiting the track. I need to be able to put my feet down on the road. Any advice would help!

(is it Diane?)

Are you running stock exhaust or aftermarket on the street bike? The T-Rex lowering link actually works quite well but it won't clear the factory muffler. Lowers rear 45mm. I've updated the forks to drop the front end accordingly as well. Quite pleased with the outcome...

More detail on the lowering here: http://www.ktmduke390forum.com/foru...49-t-rex-racing-45mm-lowering-kit-review.html

I'll find the link to my fork detail

Andrew
 
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mzmasi

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Hey Andrew! I am running the stock exhaust. Thanks for the links, I will read through them (there's a lot of info, which is awesome) and will figure out what we're going to do. Will post what we decide on. Diane
 

mzmasi

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Thought I'd give a quick update on lowering my bike now that it's all done. I'm 5'3", and I really needed to get my toes down at least, on both sides of the bike. Just went for my first ride and the set up worked pretty well. We changed out the rear set to the Driven TT rear sets. We used the T-Rex lowing link and kickstand. The combination of the new rear sets and the new kickstand meant that the kickstand interfered a little with my shifting on this ride I just took, but I think that should be easy enough to fix. Those rear sets are very adjustable and we can always bend the kickstand if it comes down to it. After lowering the bike we tried to bend the stock exhaust enough to provide shock clearance, but it just wouldn't work. Ended up getting Werks slip-on exhaust, and added a Biker's Choice 1.5" OD baffle turned down on a lathe to fit inside the header in order to quiet it a little, because it was really loud. We got the cup bike seat because I learned with my last bike that the cup seat is narrower than the stock seat (probably from the lack of actual seat padding!), so it allowed me to get my feet a little closer to the ground. We got the Tyga carbon fiber seat that holds the stock taillight assembly, and it's great. Seat height has ended up at 30.5", and stock seat height is listed at 32.3"
 

amirossi21

New Member
Is there any lowering kit available in the US or canada for the rc390?
My wife is only 4'11.
I found this on a UK website.
KTM RC 390 Lowering Kit -60mm

thanks.
I went to search a shorter spring that meant for 80 kg. After which I asked my local mechanic to change the spring to the existing rear shick and also hardened the preload. Done, cheap, perfect and met to my expectation. Also no more fish tail entering a corner. Can consider

Sent from my SM-G935F using Tapatalk
 

CDN Duke

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Copied from another thread...

Be careful with lowering it. I'm dragging a lot of hard parts at max lean. Now that's on track at full race pace, but if you lower the bike you may run into the issue at even moderate lean angles in the canyons.

Post #36 has a good illustration of what I'm dragging:http://www.rc390-forum.com/forum/track-days-racing/1327-race-bike-huge-review-4.html



This caught me out earlier this week. After the first session of the day, one of the Pro6 instructors came by to school me on body position as he heard my bike drag. Said I'll have to get off the bike tor reduce the lean angle. So, rest of day I did work on it and was getting more comfortable etc. Last session of the day I sat up a bit after getting passed by a couple riders then leaned it over again in next turn and touched down again. This time it lifted the bike enough for me to lose traction and low-side.

Bike is lowered ~45mm F&R. Probably never an issue on street but definite liability at the track. I touched the right side engine case bolt, ground down the case. So, a word of caution if lowering the bike and planning to track.

(Happily no injuries but good lesson learned.)


Before:

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After coaching:

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Damage:
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isaac_

New Member
Glad you're alright! Yes, lowered bikes aren't great for track. It not only increasing the chances of dragging hard parts but it also changes the geometry (i.e. handling) of a bike.

You look 10x better in the after coaching pictures! Keep at it. From there I'd add that it looks like your chest wants to point towards the tank. Make sure you don't get crossed up.
 

CDN Duke

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Here's the video: [video=youtube_share;cqnX-EJbHCk]https://youtu.be/cqnX-EJbHCk[/video]



I'd add that it looks like your chest wants to point towards the tank. Make sure you don't get crossed up.

I take it you mean I shouldn't be doing that and instead turning upper body to face where i want to go etc?
 

isaac_

New Member
Here's the video: [video=youtube_share;cqnX-EJbHCk]https://youtu.be/cqnX-EJbHCk[/video]


I take it you mean I shouldn't be doing that and instead turning upper body to face where i want to go etc?


Correct. Have they told you about kissing the mirrors? You want your spine parallel to the bike... not over it. The fluid that was coming out at the end... water?
 

CDN Duke

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Correct. Have they told you about kissing the mirrors? You want your spine parallel to the bike... not over it. The fluid that was coming out at the end... water?

Thanks for clarifying - yeah, several have told me to get the upper body down lower and over the grips/mirror portion.

Yup, coolant overflow on right side, just dripping off.
 

CDN Duke

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So update on the T-Rex lowering link.

If anyone has one installed, I would recommend checking the frame bolt to ensure it's not seized. I thought it was the red loctite I used on install that was preventing me from getting the bolt out, but it turns out the hardened steel frame bolt galled inside the aluminum link. I didn't lube the shaft when I installed it, probably would have helped. Bottom line, cost me 4.5hrs of machine shop time to drill the bolt out...

I had tried to remove it myself on a couple occasions previously but gave up and left it in. But since I had the airbox out for the intake runner install, thought I would finally deal with it. Friend helped me weld onto the bolt a couple times, I broke an extractor in the head, then took it to the machine shop.

For anyone running one today, check the bolt, make sure you can unscrew it and add some anti-seize to the shaft. If it's already seized, either leave it as-is, or if you want to remove it, plan accordingly and get some professional assistance to properly get a bite on the head before it strips out - may need to weld a proper bolt onto the head to get the leverage required depending on how corroded it is...
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SoCalRC

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Well now. Thx for scaring me with this last set of pics/nightmare. I'm looking at the T-Rex kit w/ sidestand for my daughter who is 5'2 and change. She can tap the top of her toes on both sides just barely. We will be putting this on her 2017 RC390 so supposedly the drop capability is only 1 inch instead of 2, which is kinda fine by me.

My plans to lower are the T-Rex shock eye, raise forks approx 15-20mm, some minor platform riding boots and some shorter sidewall tires and a corresponding sprocket change. And of course, backing out all the preload since she is only 110 lbs. This will get the bike down maybe 1.5" total and make it almost workable. Haha. She wanted a sportbike. Sure, there were some slightly better options regarding height like the 400 Ninja, but she and I both like this bike, and the RC is lighter than the Ninja by a worthy amount which I thought provided some benefit to offset the taller seat height of the RC.

I'll keep you guys posted but she just got the bike yesterday and is taking the rider course in less than 2 weeks time. Wish me/her luck! =)
 

SoCalRC

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So, the T-Rex shock eye kit only lowers 1" on 2017+ RC's instead of 2" on the 2016 and previous versions. I feel like I am limited on raising the forks because the front forks still need to move thru their stroke without the front render hitting the bottom of the running light/underside of upper fairing. This seems to be about 20mm or so I am guessing...give or take a few mm. I tool a couple clicks off the preload roday so now only one click out from lowest setting. Now, some may scoff but I am looking at putting a 130/70/17 on the rear. It is on paper just a hair taller but what is happening with the 150/60 is that the pinch is making the tire extra tall on a 4" rim. But a 130 on the same 4" rim will get more stretched pulling down the center of the tread for a lower dameter. Sure, a 140 is prob ideal for track use or aggressive riding, but my short term goal is to get the bike a bit lower for her to learn on while possibly sacrificing all out lean angle capability. I also could only find 1 tire in a 140/60/17... a Shinko which I am not particularly fond of that exact tire. I have experimented with this before on my old 636 when I put a 160/60/17 on the OE 5.5" rear wheel back when I was heavy in to wheelies and was trying to save rotating weight to get the nike up in the next higher gear without changing the gearing. There were no more chicken strips, but it was too the point where I didn't feel comfortable leaing it over too far because just like a flat earther sailling off the end of the ocean, that 160 didn't have enough rubber left to lean onto, and I was already at the edge of the tread pretty quickly where the sidewall meets. I think it will be a bit less severe with a 130 on a 4" than a 160 on a 5.5", but I think I can get the tire a 1/2" shorter to 23.5" or so vs the current 24".

Anyway, before I get into all this, I am going to play around with ratchet straps and simulate my intended effective ride height and if her reach to the ground isn't satisfactory, maybe we shelve the RC lowering idea and get her a 400 Ninja and then I inherit the RC. Haha.
 

SoCalRC

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T-Rex lowering link is on. Had to use an actual 12 ton press to get the bushing out. Wasn't coming out with the supplied hand-press tools. Bike is a 2017. T-Rex claims 2" lowering for 2014-16 and 1" for 2017. The pice itself lowered the hole to hole shock length by 29mm. But seeing as the shock is mounted at roughly a 45 degree angle, and the way the swingarm moves thru its travel, that shouldn't be the actual lowering number. I didn't take measurements prior but long story short, you WILL need to get the kickstand they sell or cut/weld your current one. We bought the adjustable kickstand, but I don't like how far the tab piece sticks out on the side so it will prob get cut off so it doesn't drag on the ground or chop the ignition if it gets bumped during riding/shifting.

She went from barely the very tips of both toes to a very comfortable ball on both sides. Her riding boots have a slight platform and a decent heel and the sole of the heel is maybe 1/2 to 1 inch off the ground. I feel confident now that her 5'2 1/2" frame can handle the bike at this point. Recommended, but just be prepared to have to use a press. Used anti-seize on the upper shock mount bolt and maybe another one or two bolts. Used a small dot of red loctite on the shock eye (Hopefully not too hard to remove in the future. Prob would just use blue loctite in the future as I don't think it needed it in the first place and it didn't have any from the factory, but the T-Rex instructions said to do so.

I initially dropped the front 20mm, but almost all the ride height improvement comes from the front, and I am worried about cornering clearance and speed bumps. I moved it to a 12mm drop up front, but will prob move it to 8 or 10mm front drop shortly after she gets aquainted with the bike.
 
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