RX4 520 Conversion

Lobo_2002 · 08-15-2021, 06:14 PM

I've been looking for a 520 rear sprocket for awhile and haven't had any luck, the custom shops seem to only use aluminum for custom orders, super sprox never got back to me. Going through many catalogs checking dimensions, I found the 2014 CRF450R rear to be almost Identical, except the bolt hole size and the 90degree cut on the bolt holes. The RX4 bolt holes are 10mm and straight cut, while the CRF bolt holes are 8.5mm with 90degree cut.

Fast forward 2 months later(I'm recovering from heart surgery) I ordered front 14T 520 RX4 sprocket from Ali express, 43T JT Sprocket (JTR210.43 ), and RK 108 link 520 chain. My neighbor drilled the 8.5mm holes to 10mm and installed everything for me, as I still have 4 months of recovery. Everything went on well, my only concern is the 90degree cut on the bolt holes, but everything is torqued down so I do not believe it will be an issue.

Results,
I have a 520 chain setup on my RX4 and an almost 3:1 ratio using a 520 steel rear sprocket. My stock was 530 13T front 44T rear. My neighbor rode the bike for me and noticed a difference over the ratio change and feels lighter, but I can't report much else since I can't ride yet. If you decide to do this, your doing it at your own risk. If you find a better solution, please I'm all ears!

The mind likes to wonder when the body can't move, so I figured this would be my recovery project, looking forward to getting on it and trying it my self!

db_moto · 09-17-2021, 12:19 AM

Admittedly the 530 chain is overkill for the size of the engine in this motorcycle. Why are you looking to downgrade to a 520 chain? A 520 chain will free up a minimal amount of weight from the driveline and be slightly cheaper to replace.

Lobo_2002 · 09-25-2021, 02:51 AM

The main reason at the time was, I couldn't get a 14T 530 front sprocket, the 2019 rx4 came with a 14T, but 2020 and onwards come with a 13T and I was struggling with speed in certain situations. I have fixed my speedometer with a speedo DRD, so it reads one off. (Reads 66mph, but goes 65mph) I haven't had a chance to ride it with the new sprocket setup, because I'm still healing from my heart surgery, but my neighbor said there is a difference in speed, which is what I was expecting.

And since this engine is used in other motorcycles around the world I can find a 520 in both 13T and 14T. So I went with the 14T 520 and next I looked around for a sprocket. And the rest is in my original post.

I'm probably making it sound more complicated than what it should be, but I'll see how it works out in the long run.

pyoungbl · 09-26-2021, 08:54 AM

I'm confused. CSC started selling the RX4 as a 2020 model, the one I have is SN #####4002 so it's probably the second RX4 brought into the US. You are saying that there were some 2019 models too, with a different front sprocket. I guess I'll have to count my sprocket teeth to see exactly what I have. So far I have been happy with the drive train, good power delivery and decent top speed for a 42 hp bike.

Lobo_2002 · 09-27-2021, 06:37 PM

They had small inventory for 2019, maybe?

https://adventuremotorcycle.com/news/2019-csc-rx4

Mine is a 2020 with serial #*****4063

pyoungbl · 09-27-2021, 08:10 PM

The model year is always confusing for me. There does not seem to be any set date for what model year one is buying. In this case CSC probably sold bikes in 2019 but as 2020 models. Some day I'll see if the actual production date is listed on the data plate. That's pretty common...probably required by law. At any rate I'll still count my sprocket teeth just to see what's going on.

pyoungbl · 09-27-2021, 08:13 PM

More thoughts...Joey told me that they had at least one bike that was used for DOT/EPA certification. After that process they could not sell the machine. I guess DOT/EPA required some minor changes. At any rate, that was certainly a 2019. The ones actually sold to customers were probably all 2020.

Lobo_2002 · 09-27-2021, 10:26 PM

Now I'm curious to how many machines came with a 13T front sprocket. For the manual does say it comes with a 14T. I was told they only had 13T in stock. Joey and I talked about possible KTM sprockets fitting or even just making a custom one. I did find a KTM one, but it was too wide for the nut to screw on effectively, and it was 15T barely touches the case. So 14T is the max. Same spline as KTM. I'll have to look at my note book to see which sprocket it was.

Chris_Top_Her · 02-05-2022, 04:40 AM

The 530 chain is not over kill considering the weight of the bike and the arc if the swing arm when doing bumps/jumps and offroad. I air my bike often and I would stretch a 520 chain much quicker.

Bob Kelly · 02-20-2022, 11:36 PM

My bike is a 2021 CSC RX4 with the new big dash and I love it , but it is tall for me
so I dropped it by the preload spring adjustment in back all the way to the top and then lowered the front trees on the front forks exactly 2"
..... now I can touch the ground flat footed with both feet while on it....if your bike it so tall that you can't touch flat footed ...for gods sake lower it before you kill yourself !
.... to lower the triple trees in the front I did have to buy some handle bar risers (the pivoting type) and move the handle bars back about 1/2" and up about an inch. that allowed the fork tubes to come up 2" and it could go more....
....
I am very interested in changing the sprockets on the RX4 for better top end speed
I think my front sprocket is a 14T but not sure. the rear sprocket looks great for dirt but not so good for highway speeds so I am looking for one with about 10 teeth less than stock..... re drilling holes is no problem as I have a lathe and mill but I don't want to have to re make it from the ground up either....
I've asked CSC about different sprockets for the RX4 and they said they didn't have ANY at this time.
.... I do have one complaint with the bike ... bouncing on the seat doesn't even deflect it at all it is rock hard the only thing that flexes is the tire !
I understand why they made it so hard but good grief ! that's too hard for my 185 lbs.
every bump in the road is felt and by the time I've gone 30 miles I'm beat to a frazzle !
LOL
.....I did get it up to 70 mph with the gearing that's on it but it was up there in RPM's
i think changing the gearing to be steeper would be a real good idea...
it's got the Uumph for the dirt roads in the lower gears but I think gearing it more for the highway is the way I want to go.
.... with 60 miles on it I got a long way till 1st oil change ! LOL
....
Bob........

ChopperCharles · 03-15-2022, 12:10 PM

Quote:

Originally Posted by db_moto

Admittedly the 530 chain is overkill for the size of the engine in this motorcycle. Why are you looking to downgrade to a 520 chain? A 520 chain will free up a minimal amount of weight from the driveline and be slightly cheaper to replace.

Not true. When I switched from a 530 non-oring chain and sprockets on my SSR Buccaneer 250i to an x-ring 520 chain and sprockets I saved 8 pounds of unsprung rotating mass. That's a big deal. Bike felt slightly peppeier, and when it's a 250 a little pep goes a long way.

Charles.

ChopperCharles · 03-15-2022, 12:14 PM

Quote:

Originally Posted by Bob Kelly

My bike is a 2021 CSC RX4 with the new big dash and I love it , but it is tall for me
so I dropped it by the preload spring adjustment in back all the way to the top and then lowered the front trees on the front forks exactly 2"
..... now I can touch the ground flat footed with both feet while on it....if your bike it so tall that you can't touch flat footed ...for gods sake lower it before you kill yourself !
.... to lower the triple trees in the front I did have to buy some handle bar risers (the pivoting type) and move the handle bars back about 1/2" and up about an inch. that allowed the fork tubes to come up 2" and it could go more....
....
I am very interested in changing the sprockets on the RX4 for better top end speed
I think my front sprocket is a 14T but not sure. the rear sprocket looks great for dirt but not so good for highway speeds so I am looking for one with about 10 teeth less than stock..... re drilling holes is no problem as I have a lathe and mill but I don't want to have to re make it from the ground up either....
I've asked CSC about different sprockets for the RX4 and they said they didn't have ANY at this time.
.... I do have one complaint with the bike ... bouncing on the seat doesn't even deflect it at all it is rock hard the only thing that flexes is the tire !
I understand why they made it so hard but good grief ! that's too hard for my 185 lbs.
every bump in the road is felt and by the time I've gone 30 miles I'm beat to a frazzle !
LOL
.....I did get it up to 70 mph with the gearing that's on it but it was up there in RPM's
i think changing the gearing to be steeper would be a real good idea...
it's got the Uumph for the dirt roads in the lower gears but I think gearing it more for the highway is the way I want to go.
.... with 60 miles on it I got a long way till 1st oil change ! LOL
....
Bob........

There's a shock spring replacement modification for the RX4, which makes it much more suited to normal sized people. I don't remember if it's on this site or advrider, but it looked pretty straightforward. And cheap too.

Charles.

Bob Kelly · 06-05-2022, 03:23 AM

Lobo 2002 : so the end results of your sprocket change was up one tooth in the front and down one tooth in the rear Right ? my experience tells me you will barely see a change at all.... 10mph at most for the same given RPM
front sprocket change is about 10mph per tooth
rear sprocket change takes about 10 tooth change to get 10 mph difference....( this one varies widely as some times it just takes 5 teeth to make 10 mph)
it depends greatly on how big the rear sprocket was to begin with....
.....
I did a Front sprocket change( and chain)and rear sprocket change on my 250R Ninja
a few months back and realised about a 20 MPH difference for the same RPM
If I recall correctly I went from a 14 tooth on the front to a 16 tooth and from a 45 tooth on the rear to a 43 tooth... something like that.... it was a drastic change but it made the bike much more pleasant to ride for me. I can cruse at 70mph without it being at 8k RPM now
I had to do some case/chain guard grinding to pull it off but the end results were worth it just to get the RPM down and stretch out the lower gears ... 1~3 were so closely spaced you had to shift 3 times to get to 30mph ! now it's much better...
I plan to also change the gearing on the RX4 as it is a bit buzzy at 70mph and I would like to get the RPM down at cruise as well.... finding the sprockets is a whole nother problem though !
....
Bob....

Lobo_2002 · 06-14-2022, 09:47 AM

Unfortunately it made a huge difference. The bike became gutless in 6th gear, it would not hold 65mph no matter what. I ended up switching to 14/46 set up and it is much better, the bike responds better at low and highway speeds, now I can get up to 85mph easy, without the side panniers (tourfella cases).

Bob Kelly · 06-14-2022, 12:14 PM

Humm, I wondered about that Lobo 2002 ! as at 70mph there is little in the way of pickup in top end speed when you burry the throttle.... it seems to get it's power mainly at the lower RPMS ! and though it will turn the Higher RPMS it's just not as strong there... there is a fairly large fall off there....
the answer MIGHT be ( I emphasize MIGHT) be a better result by going Much steeper
in gearing like 2 teeth up on the front and 5 teeth in the rear so you drop the RPM low enough at speed to have the RPM back in the powerband .
.....
I have to admit at 70mph it is fairly gutless pulling out and passing is terribly slow on the freeway.... and I think that if we got the RPM down enough back into where the real torque and power are the results would be alot better.... that's my thinking
its a big thumper and they usually make their power at the bottom end not at top RPM
and although this thing can reach fairly high RPM ...it's still a thumper and that is Not where the power resides at...... so gearing is the Key ! I think.
....
Bob......

08-15-2021, 06:14 PM	#1
Lobo_2002 Join Date: Mar 2021 Location: Idaho Posts: 16	RX4 520 Conversion I've been looking for a 520 rear sprocket for awhile and haven't had any luck, the custom shops seem to only use aluminum for custom orders, super sprox never got back to me. Going through many catalogs checking dimensions, I found the 2014 CRF450R rear to be almost Identical, except the bolt hole size and the 90degree cut on the bolt holes. The RX4 bolt holes are 10mm and straight cut, while the CRF bolt holes are 8.5mm with 90degree cut. Fast forward 2 months later(I'm recovering from heart surgery) I ordered front 14T 520 RX4 sprocket from Ali express, 43T JT Sprocket (JTR210.43 ), and RK 108 link 520 chain. My neighbor drilled the 8.5mm holes to 10mm and installed everything for me, as I still have 4 months of recovery. Everything went on well, my only concern is the 90degree cut on the bolt holes, but everything is torqued down so I do not believe it will be an issue. Results, I have a 520 chain setup on my RX4 and an almost 3:1 ratio using a 520 steel rear sprocket. My stock was 530 13T front 44T rear. My neighbor rode the bike for me and noticed a difference over the ratio change and feels lighter, but I can't report much else since I can't ride yet. If you decide to do this, your doing it at your own risk. If you find a better solution, please I'm all ears! The mind likes to wonder when the body can't move, so I figured this would be my recovery project, looking forward to getting on it and trying it my self! __________________ 2020 Zongshen RX4
	4

09-17-2021, 12:19 AM	#2
db_moto Join Date: Sep 2021 Location: Indiana Posts: 13	Admittedly the 530 chain is overkill for the size of the engine in this motorcycle. Why are you looking to downgrade to a 520 chain? A 520 chain will free up a minimal amount of weight from the driveline and be slightly cheaper to replace. __________________ 2020 Fleet: CSC RX4, Hawk 250 DLX, Moto Guzzi V85tt “You are not entitled to your opinion. You are entitled to your informed opinion. No one is entitled to be ignorant.” -Harlan Ellison- “The most terrifying words in the English language are: I'm from the government and I'm here to help.” ― Ronald Reagan-
	0

09-25-2021, 02:51 AM	#3
Lobo_2002 Join Date: Mar 2021 Location: Idaho Posts: 16	The main reason at the time was, I couldn't get a 14T 530 front sprocket, the 2019 rx4 came with a 14T, but 2020 and onwards come with a 13T and I was struggling with speed in certain situations. I have fixed my speedometer with a speedo DRD, so it reads one off. (Reads 66mph, but goes 65mph) I haven't had a chance to ride it with the new sprocket setup, because I'm still healing from my heart surgery, but my neighbor said there is a difference in speed, which is what I was expecting. And since this engine is used in other motorcycles around the world I can find a 520 in both 13T and 14T. So I went with the 14T 520 and next I looked around for a sprocket. And the rest is in my original post. I'm probably making it sound more complicated than what it should be, but I'll see how it works out in the long run. __________________ 2020 Zongshen RX4
	0

09-27-2021, 06:37 PM	#5
Lobo_2002 Join Date: Mar 2021 Location: Idaho Posts: 16	They had small inventory for 2019, maybe? https://adventuremotorcycle.com/news/2019-csc-rx4 Mine is a 2020 with serial #*****4063 __________________ 2020 Zongshen RX4
	0

09-27-2021, 10:26 PM	#8
Lobo_2002 Join Date: Mar 2021 Location: Idaho Posts: 16	Now I'm curious to how many machines came with a 13T front sprocket. For the manual does say it comes with a 14T. I was told they only had 13T in stock. Joey and I talked about possible KTM sprockets fitting or even just making a custom one. I did find a KTM one, but it was too wide for the nut to screw on effectively, and it was 15T barely touches the case. So 14T is the max. Same spline as KTM. I'll have to look at my note book to see which sprocket it was. __________________ 2020 Zongshen RX4
	0

09-26-2021, 08:54 AM	#4
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	I'm confused. CSC started selling the RX4 as a 2020 model, the one I have is SN #####4002 so it's probably the second RX4 brought into the US. You are saying that there were some 2019 models too, with a different front sprocket. I guess I'll have to count my sprocket teeth to see exactly what I have. So far I have been happy with the drive train, good power delivery and decent top speed for a 42 hp bike.
	0

09-27-2021, 08:10 PM	#6
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	The model year is always confusing for me. There does not seem to be any set date for what model year one is buying. In this case CSC probably sold bikes in 2019 but as 2020 models. Some day I'll see if the actual production date is listed on the data plate. That's pretty common...probably required by law. At any rate I'll still count my sprocket teeth just to see what's going on.
	0

09-27-2021, 08:13 PM	#7
pyoungbl Join Date: Feb 2016 Location: Portsmouth, Virginia, USA Posts: 632	More thoughts...Joey told me that they had at least one bike that was used for DOT/EPA certification. After that process they could not sell the machine. I guess DOT/EPA required some minor changes. At any rate, that was certainly a 2019. The ones actually sold to customers were probably all 2020.
	0

02-05-2022, 04:40 AM	#9
Chris_Top_Her Join Date: May 2020 Location: San Antonio, Texas Posts: 62	The 530 chain is not over kill considering the weight of the bike and the arc if the swing arm when doing bumps/jumps and offroad. I air my bike often and I would stretch a 520 chain much quicker. __________________ CSC RX4 2020
	0

02-20-2022, 11:36 PM	#10
Bob Kelly Join Date: Jan 2022 Location: Weed, California. Posts: 271	My bike is a 2021 CSC RX4 with the new big dash and I love it , but it is tall for me so I dropped it by the preload spring adjustment in back all the way to the top and then lowered the front trees on the front forks exactly 2" ..... now I can touch the ground flat footed with both feet while on it....if your bike it so tall that you can't touch flat footed ...for gods sake lower it before you kill yourself ! .... to lower the triple trees in the front I did have to buy some handle bar risers (the pivoting type) and move the handle bars back about 1/2" and up about an inch. that allowed the fork tubes to come up 2" and it could go more.... .... I am very interested in changing the sprockets on the RX4 for better top end speed I think my front sprocket is a 14T but not sure. the rear sprocket looks great for dirt but not so good for highway speeds so I am looking for one with about 10 teeth less than stock..... re drilling holes is no problem as I have a lathe and mill but I don't want to have to re make it from the ground up either.... I've asked CSC about different sprockets for the RX4 and they said they didn't have ANY at this time. .... I do have one complaint with the bike ... bouncing on the seat doesn't even deflect it at all it is rock hard the only thing that flexes is the tire ! I understand why they made it so hard but good grief ! that's too hard for my 185 lbs. every bump in the road is felt and by the time I've gone 30 miles I'm beat to a frazzle ! LOL .....I did get it up to 70 mph with the gearing that's on it but it was up there in RPM's i think changing the gearing to be steeper would be a real good idea... it's got the Uumph for the dirt roads in the lower gears but I think gearing it more for the highway is the way I want to go. .... with 60 miles on it I got a long way till 1st oil change ! LOL .... Bob........ __________________ It's too late when you've gone too far !
	0

06-05-2022, 03:23 AM	#13
Bob Kelly Join Date: Jan 2022 Location: Weed, California. Posts: 271	Lobo 2002 : so the end results of your sprocket change was up one tooth in the front and down one tooth in the rear Right ? my experience tells me you will barely see a change at all.... 10mph at most for the same given RPM front sprocket change is about 10mph per tooth rear sprocket change takes about 10 tooth change to get 10 mph difference....( this one varies widely as some times it just takes 5 teeth to make 10 mph) it depends greatly on how big the rear sprocket was to begin with.... ..... I did a Front sprocket change( and chain)and rear sprocket change on my 250R Ninja a few months back and realised about a 20 MPH difference for the same RPM If I recall correctly I went from a 14 tooth on the front to a 16 tooth and from a 45 tooth on the rear to a 43 tooth... something like that.... it was a drastic change but it made the bike much more pleasant to ride for me. I can cruse at 70mph without it being at 8k RPM now I had to do some case/chain guard grinding to pull it off but the end results were worth it just to get the RPM down and stretch out the lower gears ... 1~3 were so closely spaced you had to shift 3 times to get to 30mph ! now it's much better... I plan to also change the gearing on the RX4 as it is a bit buzzy at 70mph and I would like to get the RPM down at cruise as well.... finding the sprockets is a whole nother problem though ! .... Bob.... __________________ It's too late when you've gone too far !
	0

06-14-2022, 09:47 AM	#14
Lobo_2002 Join Date: Mar 2021 Location: Idaho Posts: 16	Unfortunately it made a huge difference. The bike became gutless in 6th gear, it would not hold 65mph no matter what. I ended up switching to 14/46 set up and it is much better, the bike responds better at low and highway speeds, now I can get up to 85mph easy, without the side panniers (tourfella cases). __________________ 2020 Zongshen RX4
	0

06-14-2022, 12:14 PM	#15
Bob Kelly Join Date: Jan 2022 Location: Weed, California. Posts: 271	Humm, I wondered about that Lobo 2002 ! as at 70mph there is little in the way of pickup in top end speed when you burry the throttle.... it seems to get it's power mainly at the lower RPMS ! and though it will turn the Higher RPMS it's just not as strong there... there is a fairly large fall off there.... the answer MIGHT be ( I emphasize MIGHT) be a better result by going Much steeper in gearing like 2 teeth up on the front and 5 teeth in the rear so you drop the RPM low enough at speed to have the RPM back in the powerband . ..... I have to admit at 70mph it is fairly gutless pulling out and passing is terribly slow on the freeway.... and I think that if we got the RPM down enough back into where the real torque and power are the results would be alot better.... that's my thinking its a big thumper and they usually make their power at the bottom end not at top RPM and although this thing can reach fairly high RPM ...it's still a thumper and that is Not where the power resides at...... so gearing is the Key ! I think. .... Bob...... __________________ It's too late when you've gone too far !
	0