Lowering the 2021 CSC RX4 front and rear.

[Bob Kelly]

Ok the proccess of lowering a RX4 is not all that hard you just have to have the stuff to do it with.
to Lower the front I simply bought some pivoting handle bar risers that fit into the original handle bar clamps and provide a place to put the handle bars that is higher and further back
this gets the handlebars out of the way so you can raise the front fork tubes up in the tripple trees to lower the bike....
I lowered mine 2" by raising the tubes 2" in the tripple trees
.... for the rear it is much more complicated, as I've discovered that just backing off the preload which does indeed lower the rear , but it also bottoms out the shock and the only suspension you have left is the flex of the tire.
so that is not the way to go....
I've changed the rear shock spring to a 400~450 lb/in. spring to make it a softer ride but it could go to a 350lb spring I think.
....
after studying the rear suspension and the short stroke of the original shock
I've come to the conclusion that the only way to lower the rear is by making a new lowering link for the rear one that is longer than the stock one.
Right now I am in the process of making that link
I could not find any 1/4" bar stock so I bought 3 pieces of 1/8" thick x 1.5" wide bar stock and I cut 6 pieces out of it 10" long ( which I will trim to size later) I drilled a 17/32 hole 5/8" from the end on one end for the bolt to go through and then cut a piece of 1" o.d. steel axle to 3" long and drilled a 17/32" hole through that as well then bolted the 4 pieces of bar stock to the round rod.... with that the 1/2" of bar stock added too much width to the rod so I had to trim it down to fit the original links width where it connects into the frame.... now with that measurement secure I will drill another hole
in the bar stock at a distance that is equal to the original hole spacing plus 1.5" and that should be enough length to drop the rear 2"
...
EDITED:{{{ turns out 5/8" is about maximum length the thing can handle not 1.5"... i determined that distance by taking the lower link loose from the shock pivot and lowering the bike to a seat height of 28+ inches then measured the distance between the bolt holes, center to center.... any longer will not work as the swing arm's angle won't allow that but that is plenty low infact I had to add preload to raise it some !}}}
...
.....I will then take the pivoting link and bolt it together with the bar stock in place on the link to get it's width correct and then tack weld everything on place on the link sense the round rod/axle part is skinnier than the far end bolt hole hookup it is difficult to get everything just right so using the parts
they connect to is the key. there is a slight bend in each of the barstock sides I am making up and that is the main problem right now ...
do I bend the individual bars and then weld them together or weld them together and then bend them ? I plan on adding one more 1/8" piece to each side for added strength and perhaps a gusset or two not sure on that yet.
those bends are NOT necessary at all.... when assembled the link arms are straight (good to know if your making a lower link! ) see post below.
.....

that's all I have for now !
Bob......

[Bob Kelly]

I made an interesting discovery that makes this build much much easier.... I don't have to bend the arms at all.... because the material I am using is mild steel and not cast aluminum it doesn't have to be as thick as the aluminum and therefore the steel arms can be straight to the pivot link.
so I welded all 3 1/8" plates together with bolts in the holes to make sure the alignment didn't move and now I am circling up the bars with a weld all the way around the bars
so that is 3, 1/8" by 1.25" wide 9"~10" long welded together as a solid bar More than enough striength for this piece I am sure. I also welded them to the Steel bar that I drilled a hole through it that fits into the RX4 frame I will need to grind off the corners of the bars so it can pivot without hitting the frame and locking up but that is no big deal. I was really delighted to see that the bars do not need to be bent the pivoting peace that attaches to the shock between these bars I am making are wider than the original cast piece itself by a good 1/8" to 1/4" .... and there were scuff marks on that piece where the shock bolt did hit it.... so more clearance that what they had is a good thing.
.... I am waiting for the part to cool now after welding it then I'll flip it over and weld the other side then try to clean it up the best I can ...it's never going to be a pirty piece but I could care less about that , I just want the bike lower so I can sit on it and have both feet flat footed on the ground... the distance between the bolt holes is 6 3/8" center to center a little longer would drop the rear more. a little less not as much drop...
I am hoping for a bit more than a 2" drop but we'll see what I get
....
later.
Bob....

[Bob Kelly]

Well, in typical BOB fashion, I managed to screw up that one.... I had it all made and went out to the bike to put it on and it would not fit... not even close ... i went back in as it started to rain anyway... measured and discovered the end product was 1/4" wider than it was supposed to be... WTF ? and thinking back at what I had done explained it... when I discovered I could leave the bars straight I quickly added one more bar to the stack (3 on each side of the 1/8" x1.25" barstock) and then welded them to the center axle part and I didn't realise I had cut the center axle part for 2 bars on each side ...not 3 ...so that is why it wouldn't fit ! so I set about to salvage my screw-up !
I cut the axle part in half cut out about a 3/16" piece out of it and then welded it all back together again ran the drill through the holes one more time and then painted it ( again) this time when I measured it I had plenty of clearance ! but it was getting late and I called it a day...
so tomorrow I'll put it on and see how much lower the seat height is !.
I probably wasted 2 hours today trying to mill down both ends which didn't work and it took me another hour to grind the ends flat again on both sides... another hour wasted trying to find some way to clamp the thing to the band saw to cut it in half till I finally gave up and put it in the vice and grabbed the reciprocating saw and cut it that way !
that was the best way as on the second cut ( with a new saw blade ) I could cut it very evenly and I got a surprisingly parallel cut !.... bolted together and welded back together it looks a bit worse for the ware but is more than strong enough for the job
with the 3 bars on each side the gap for the shock to go through is just at the minimum
so that's not a problem.... Ali-Express has been sending me a link of their lowering link for the KTM and it looks like it would fit ,,, for 70 bucks but they give absolutely no information on anything they sell so I steer away from them every chance I get !
no information on how far the holes are apart or what size they are... just a picture of it's pretty Orange color ! it may well work but without any information on it I'll put my money on more steel ! ...LOL
I do know that I want a minimum of 6-3/8" between centers on the bolt holes !
and I have that on my home made one !
..... we'll see tomorrow how much it drops the rear of the bike ! ( I hope)
....
Bob......

[Bob Kelly]

Ok.... I put the home made lower link on there and it would not fit.... the bolt holes would not align.... so I swapped in and out the original lower link several times and took many measurments.... I then set the bike height by the scissor jack to where it looked about as low as I wanted it... and then measured the distance between the bolt holes center to center.... and I found that I could just drill 2 holes at 3/4" closer to the pivot and that would meet the requirements.... drilling those holes was very hard to do however as the welding of the barstock had hardened the metal really hard, and I had to sharpen my brand new drill several times to finally get through it on both sides.
then I cleaned up the rough edges and then put the new lower link on there and everything fit ! ....SUCCESS ! the new seat height is 29.5" (un-compressed)
and I can sit on it and be flat footed with both feet even with my slippers on !!!!! my knees are not straight either but only have a slight bend to them ....
all in all I will call this project a success ....
my rear wheel looks to have about 3~4" of travel before hitting the plastic inner fender well..... i expect in time that will get chewed up !
my side stand may well have to be trimmed again, as the bike now sets almost vertical
now on the patio.... ( 2'x2' pavers) on the dirt it isn't a problem as I can just pull back and let the side stand dig a hole, but on pavement ya' can't do that ! LOL....
so the end length was 6-3/8" Minus 3/4" which makes it about 1" longer than the stock one is all. but I went from 32" down to 29.5" in the seat height...
ground clearance looks mighty low now.... maybe 6" or so but I haven't got the skid plate back on it yet....
... I had to use a stack of washers to take up the slack of the original bolt ...I will most likely thread down the bolt ( I think I have that die now) and then cut it off to fit better.
but I wanted to see how it worked before I did that !
....
so tomorrow if it's not raining I will put the bike back together and see how it rides
I still have to put the exhaust header pipe back on ,crash plate and side plastic other than that it's pretty much back together now.
.....
Later All !
Bob....

[Bob Kelly]

So as for the lower link I made for lowering the 2021 RX4 the original link was 4-7/8" between centers on the bolt holes.
the one I made up wound up being 5-1/2" between centers...
a small difference of only 5/8" but enough to drop it 2-1/2"
.....
I didn't stay at the low height however as the tire was too close to the fender well on the rear... so I brought down the pre-load nuts to raise the bike back up a little.
the seat height now sits at exactly 30" uncompressed and as we all know the bike doesn't compress much when you sit on it ( biggest flaw of the RX4 in my opinion)
even with the lighter 400~450 lb spring in the rear it still doesn't compress !
so that is a 5/8" difference in size for the lower link.
.....
I hope this helps someone lower their RX4 as it needs it !
.....
lowering the front forks is easy once you get the handle bars out of the way....
you just slide them up in the tripple trees , make dead sure they are at the same height and then lock them down with their clamp bolts.
....
the handling is exactly the same as the day I got it as far as I can tell....it still likes to corner well.... LOL.
....
later All....
Bob.....

[Lukas]

You have not changed the oil in the shock absorber and it not be will run well, it cannot be avoided and concealing this fact will not give you anything I wrote you that the factory oil is of low quality

[Bob Kelly]

Originally Posted by Lukas

You have not changed the oil in the shock absorber and it not be will run well, it cannot be avoided and concealing this fact will not give you anything I wrote you that the factory oil is of low quality

OK so what oil do you think I should put in there and how much ?
about the only oil I have is automatic transmission oil at the moment LOL
and although it was used in the Early Triumph motorcycles for front fork oil extensively it's probably not what you had in mind hahahah !
...
if the stock oil is really thick I can see a problem where a thinner oil would give a smoother ride....with the same settings ....but that is why they have settings
if it rides too hard back out the screw to open the hole and more oil will pass through the passage way and make for a smoother ride.....it's not rocket science, even I can understand that portion of the shock... so I don't see any real benefit to changing the oil in the shock unless the oil is super thick but I have no idea what the oil is in the shock ! so I have left it alone.
....
do you know what oil comes in the stock shock on the RX4 ?
that would be helpful indeed but saying change the oil without saying what to change it to isn't helping to much ! LOL
Guessing only adds to the infinite number of variables and just complicates the issue !
....
Bob.....

[Bob Kelly]

ok I ran into a snag.... I got the bike all ready to do a test ride and moved it under power about 10' parked it and went inside, the next day I went out and gave the bike a good looking over and saw that there was a 3/4" wide black mark on the rear tire....
upon further inspection with my weight on the bike the tire is rubbing on the inner fender well.... so it needs to be jacked up a bit more...
.... so today I took the saddle bags off the bike and rt. passenger foot rest and then took my reciprocating saw and cut those attachment points off of the inner fender well for more clearance,( that gave me about a full inch more of clearance under there.) I also added about 1/4" more of pre load to the spring...
it took me 2 hours to do all that and get it back together I haven't set on it because I still need to put the seat back on it ...LOL
....
there is such a thing as too low ! and I am right at the edge of that right now ....
.....i want it as low as I can get it and it still funtions correctly.... having the tire rub the fender well isn't correctly ! ! !
.....
this has been a UP hill battle through this whole process but, the end is near !
...
Bob.....

[Bob Kelly]

I had to get away from that bike for a few days and the weather turned rainy so it was a good time to take a break from it....
I just went out and set on that heavy pig and set there for a few minutes taking mental notes.... it compresses about 1" when I set on it and that is the most compression I have ever got out of the bike before ! so that's good....
setting there with my boots on both feet are flat footed on the uneven ground of my back yard ( mostly flat with clumps of grass, but mostly bare dirt) and my Knees are slightly bent .... not much but some.
the RX4's seat is kind'a wide, which hinders you getting your feet down straight they must go out sideways at an angle to reach the ground... but they go about where I'ed put then anyway so the seat really isn't the problem , and there is only about 1" of padding on the seat pan I doubt I could get much off of it that my weight doesn't squish anyway.... so I think that option is a dead end.
....
my side stand is definitely too long still even after I shortened it by 1/2"or 3/4" I don't remember exactly. but to leave the bike I have to pull it back and let it dig a hole for the side stand every time... and that's not good ! so I may take off 3/8" more and re weld it again.... solid forged side-stand ! it could hold up a truck ! way way over kill ! and heavy !
.....
I haven't ridden it down my favorite bumpy road yet but plan to soon.... and we'll see if I have to give the pre load more adjustment or not ....
.....
Bob.......

[Bob Kelly]

I found a bigger hunk of steel so I am making another lower link for the RX4 but this one will have a bushing in it, the one on the bike just has a bolt through it that is well greased
is all.... the original lower link has needle bearings pressed into it, which is a good idea I guess,but really not all that necessary for my type of riding but a bushing would be nice
so now that I have the material I am making another lower link that has a bushing !LOL
...I will have to buy some bronze but that's all....
I have most of the parts already made now and will soon just be waiting for the bronze !.... I plan to get 3/4" bronze rod bore a hole the size of the bolt through the center with the lathe then press the bronze bushing into the lower link....
we'll see how that goes.....the last one gave me no end of trouble but so far this one has gone real good ! ( i know what I'm doing this time and not guessing about everything ! HAHAHAH)
.....
Bob.......

[Bob Kelly]

I'm going to "TRY" to post 2 pictures here.... one is the new link before welding, next to the original cast link.... the other which I doubt it will take is the welded up version...
....
I have the link almost done , I am waiting on some bearing bronze to get here and I'll make the bushing for it.
... there is only 5/8" difference between the bolt holes on this thing but that is enough to really drop the rear of the RX4 about 2.5"
.....

Bob.....

[Bob Kelly]

I just came back from a short ride on the RX4.... didn't get very far as the rear tire was hitting the inner fender well at every tiny bump.... so I turned around and went back home.
the seat height right now is at 30.25" which is actually just about right on level ground for me.... but it has to go up a good 2 " or so, which makes the original 31.9" seat height about as low as you can go on this bike.....
.....
I am at a loss as for what to do on this bike ! I've never ran into a bike I couldn't lower the seat height on..... till now !
....
I am seriously considering selling it and getting a much smaller lighter bike now....
I have less than 200 miles on it because of the weight and seat height....it's one that can't be modified to get a different seat height , but you can make it softer riding !
.... I suppose I should take that victory and be happy but I'm not..... because if that bike gets just a little off balance for me I can't hold the heavy thing up....
so to me that sounds like "sell it !"
....
anyone want to buy a 2021 RX4 ? with 126 miles on it ? $5000.00 you pay shipping or come get it !. ( yes I have all the original equipment that I've changed !)

[Lukas]

You give up easily dear friend i can see that chinese engineering has given you a hard time too i am standing on my toes on rx3 because of bad wheel arch clearance solution the only solution is to change the rear rim to a smaller one from the old rx3 but if you have new rims with that nice interlacing like on BMW it will look bad but it is a way out it will enable you to put on a smaller tire.I would love to buy this bike from you but i live in Europe and the shipping cost would be huge.

[Bob Kelly]

Yes there is that option this is true, I hadn't considered that because of the trouble of finding one that would fit.... but re lacing a smaller rim would work I'd loose the "Tubeless tire" ability that the bike comes with and that would be a big shame !
Yah shipping to Europe would be more than the bike is worth ! no doubt !
.....
I'm just tired of fighting this Brand new bike that isn't what I expected it to be !
its way too heavy for me, and it's too tall too ! if I were 30 years younger it would be no problem, but I'm not ! I've NEVER ran into a motorcycle that I couldn't lower before
but this beastie is already as low as it can go and there is no room to go any lower in the suspension.... even making a new lower link with the extremely short stroke of the rear shock limits the amount you can go !
I just had my Kid set on it with me watching it and it is compressing about 2.5" when it's upright.... so all of the movement is already being taken up by the weaker spring
or at least half of the total movement and that is no good !
.....
it Wasn't supposed to be a big heavy cruiser bike ! but that is exactly what it is !
I'll swap out the spring again and see what I have then, the new lower link may have lowered and softened the ride in one fell swoop who knows !
....
I'm not even considering the RX3 because it is also way too heavy ...especially for a 250cc and for me to ride the TT250 I would have to lower it as well.... a long way, as it's seat height is 34" stock.... we have the lower seat on it but it is still too tall for me
I just sat on it and I can only touch the ground with the balls of my feet... not flat footed. but I think I can shorten it fairly easily !!!
.... Ah well, it'll all come out in the wash ! LOL.....
.... Bob......

[tknj99]

Sorry it didn't work out for you. I had my foray with the new RX4 as well for a few months and also would up selling it.. for me it was a combination of the seat being uncomfortable, lack of power and too heavy.. its always a gamble buying a bike unseen and untested but its better to be happy in the end than not ride.