Help RS125 NF4

[husaberg]

you could be right there; can't be assed walking out to the shed to look at the box that it came in.

Fair enough i hear the winters are tough up North.

[Bert]

Fair enough i hear the winters are tough up North.

yea mate (1 degree is just too cold for this white boy) inside by the fire is where its at; esp when motogp is on....

[cotswold]

I have been driving myself nuts searching the Web for the dimensions for the spline of a RS125 Honda.
Does Anyone Know or have one they could measure.
I am trying to find a suitable sprocket to match these dimensions but only in 415 or 420.


The closest i can find in a suitable size is this but it will need some careful hacking.

I know you won't get anything in 415 as i have spent 6 months looking for the exact same size ( gp125 )
There are a number of chinese pit bike sprockets that are the right size but in 420, Red Dot a company in the UK sell them on E Bay. There is also an option of getting some made by a company in the States and if you fancy going in that direction let me know as i may be keen on splitting the cost (depending on how high the cost) http://www.rebelgears.com/sprockets.html

[jasonu]

Thanks for your reaponse but i am now even more confused.
So are you saying the RS125 NS4 is the same spline as an early 80's Cr125? .

Why be surprised, the NF4 is a CR bottom end.

Wanting to fit a 415 as preference (as i have a number of 415 sprockets) still at my house...
I could live with 420. but not 520 which is STD.


Are you sure you machined a 428 to 415 and not 420 to 415?
I thought the rollers or bushes were different diameter (as below) even though the pitch is the same?

I have several of both and never had an issue.

I know you won't get anything in 415 as i have spent 6 months looking for the exact same size ( gp125 )
There are a number of chinese pit bike sprockets that are the right size but in 420, Red Dot a company in the UK sell them on E Bay. There is also an option of getting some made by a company in the States and if you fancy going in that direction let me know as i may be keen on splitting the cost (depending on how high the cost) http://www.rebelgears.com/sprockets.html

Don't do that. Simply buy some cheap as chips 420's with the correct spline and get them surface ground.

Plus a bit of filing as well to get the splines out to 5mm

Good luck with that mate, they are as hard as fuck.

[husaberg]

Why be surprised, the NF4 is a CR bottom end.

because the splines on the cr changed spline nearly every year.

I have several of both and never had an issue.

428-415?



Don't do that. Simply buy some cheap as chips 420's with the correct spline and get them surface ground.



Good luck with that mate, they are as hard as fuck.

I have filed and ground them before after annealing them so am i
And yeah thanks for running the northern hemishere sprocket storage operation Jason

[jasonu]

I have filed and ground them before after annealing them so am i
And yeah thanks for running the northern hemishere sprocket storage operation Jason

I have had both 420 and 428 ground to 5mm thick which makes them the same as 415.
I remember someone posting here that 428 are different somehow but I have not had any problem using them.

[F5 Dave]

Would have been me as they are different, the rollers are different sizes. On a rear sprocket that will mean that you can't run a 428 vs 420. On a front you can probably get away with it but it is much kinder to run a 420 & 420 sizes are usually available for most things, unless you have a particularly queer Honda (my MB is only slightly ghey & MB50 sprockets fit).

Think 4.8mm is a bit more clearance. Don't forget to add the bevel on the teeth, I've seen people try to run flat sided sprockets, the munters. You can imagine what happens, or tries to happen.

[jasonu]

Would have been me as they are different, the rollers are different sizes. On a rear sprocket that will mean that you can't run a 428 vs 420. On a front you can probably get away with it but it is much kinder to run a 420 & 420 sizes are usually available for most things, unless you have a particularly queer Honda (my MB is only slightly ghey & MB50 sprockets fit).

Think 4.8mm is a bit more clearance. Don't forget to add the bevel on the teeth, I've seen people try to run flat sided sprockets, the munters. You can imagine what happens, or tries to happen.

IIRC the 428 rollers are wider than the 420 but still have the same pitch so if you are grinding them thinner to suit the 415 chain (same pitch as 420) then it doesn't matter.

[F5 Dave]

I think the rollers are a larger diameter so same pitch yes, but require a larger scollop in the sprocket. or run other way around may have some more slop.

[quallman1234]

Nothing much, Just replacing the rivnuts that hold the coil on as the bolt that holds the earth wire/coil fell out at Manfeild last month, DNF ;-(
Been getting the KR's ready for sale so left the RS at work so I had some room. One KR sold today

Oh yeap! I had the exact same thing replaced during nationals.

See you at round 3!

[cotswold]

IIRC the 428 rollers are wider than the 420 but still have the same pitch so if you are grinding them thinner to suit the 415 chain (same pitch as 420) then it doesn't matter.

Um this is what I found with a 428 chain and a 415 sprocket, it may have caused a few issues?

[jasonu]

Um this is what I found with a 428 chain and a 415 sprocket, it may have caused a few issues?

Lucky for me I was using 415 chain on 415 rear sprockets and a mixture of 420 and 428 ground down front sprockets. I will be sure to have another look before my next race meeting...

[husaberg]

Would have been me as they are different, the rollers are different sizes. On a rear sprocket that will mean that you can't run a 428 vs 420. On a front you can probably get away with it but it is much kinder to run a 420 & 420 sizes are usually available for most things, unless you have a particularly queer Honda (my MB is only slightly ghey & MB50 sprockets fit).

Think 4.8mm is a bit more clearance. Don't forget to add the bevel on the teeth, I've seen people try to run flat sided sprockets, the munters. You can imagine what happens, or tries to happen.

I have had both 420 and 428 ground to 5mm thick which makes them the same as 415.
I remember someone posting here that 428 are different somehow but I have not had any problem using them.

Lucky for me I was using 415 chain on 415 rear sprockets and a mixture of 420 and 428 ground down front sprockets. I will be sure to have another look before my next race meeting...

Or could have been me too Dave
i posted the roller sizes vs width a page back.

Wanting to fit a 415 as preference (as i have a number of 415 sprockets)
I could live with 420. but not 520 which is STD.

This is the STD NSR125 Front Sprocket



Are you sure you machined a 428 to 415 and not 420 to 415?
I thought the rollers or bushes were different diameter (as below) even though the pitch is the same?

I am not sure how much difference the roller size makes to the tooth profile though but the sprockets are different to look at even accounting for the width.
The reason i checked was when i was going to send you the spare KX85 ones and i couldn't figure out why they looked 420 size but the 420 chain would wrap around them.

[husaberg]

OKay this is what i have found out i think there was some confusion with my two pics that i missed......

RS125 Hondas sprokets are the same spline as a RG125 FXR150 and GP125 so anyone wanting to do a 415 conversion buy these.
AS confirmed by Diesel pig (thanks Neil)

If you have a Honda NSR125 well you will have to modify something to work......bugger

[Bert]

OKay this is what i have found out i think there was some confusion with my two pics that i missed......

RS125 Hondas sprokets are the same spline as a RG125 FXR150 and GP125 so anyone wanting to do a 415 conversion buy these.
AS confirmed by Diesel pig (thanks Neil)

If you have a Honda NSR125 well you will have to modify something to work......bugger

Yip had the same issue with the TZR but found the mx 85 splines met the requirements (and a bit of time on the surface grinder)...

So is the cr85 the same???