RX125 Tuning - Jetting

[AndrewStroud]

Really Andrew, an FXR150 is what your boy needs, then you could race it down here in the MotoFXR class! A Brother Suzuki FXR150, done in black and white, awesome!

Yea an FXR would be good too. With at least 4 of the 7 kids wanting to race I need a bigger shed and lots of bikes. They already do some mx and also race bmx and now looking at buckets.......... It' like starting all over again

[koba]

It started with a 125 which I assume is standard. I suppose it was lean from having a k&n and also through the oil pump being disconnected. Apparently when u run oil with the gas the jets get a fine coating of oil so need to be a fraction bigger. I modified an RD 400F when I was about 16yrs. I spent some time at school reading Graham A Bell's book on tuning 2 strokes, then got right into it with some porting, plainned the head, designed and made chambers. So it's testing the memory a bit but I think I'd quite enjoy getting some more power out of an RX motor. Might look at the squish next as that makes a fair difference. I'd expect u could take off 0.7mm or so. I don't mind the standard pipe at this stage because it's quite.

Be sure to check out the ESE thread the links are great, it has much reference to all the good books too.

[AndrewStroud]

Be sure to check out the ESE thread the links are great, it has much reference to all the good books too.

Thanks for that.
Man there's plenty of reading to do there. Good stuff though, I'll have another look later. zzzzzz

[Muzzab]

Interesting, I just Googled tuning an RX 125 and this thread came up :-) On Thursday my son rode a bucket at Mt Wellington with a RX 125 standard motor and std exhaust but had a K&N filter. I rode it and it didn't run that well. It went flat with the throttle wide open but went better when I backed off the throttle a bit. This usually indicates it's lean. It was pretty flat mide range as well so I lifted the needle max by dropping 2 clips and put in a 135 main jet and it went heaps better. AS

Brought a 130, 135 and a 140 jet this week. Today I fitted the 135 and dropped the clip on the needle. Can't wait to give real a test. But just giving it a bit of throttle stationary, it seems to rev up much quicker from idle.

Cheers
Muzza

[bucketracer]

Thanks for that.
Man there's plenty of reading to do there. Good stuff though, I'll have another look later. zzzzzz

The links on the ESE thread are re posted in two collections one page 80 the next page 90 and if you use the thread tools tab at the top of the page you can view all the pictures in the thread (13 pages) then click the post key on any picture to read the post that goes with it.

.

[Muzzab]

Here's some pic's of Tickled Pink,

http://www.kiwibiker.co.nz/forums/al...ictureid=32947

http://www.kiwibiker.co.nz/forums/al...ictureid=32948
http://www.kiwibiker.co.nz/forums/al...ictureid=32949
http://www.kiwibiker.co.nz/forums/al...ictureid=32950
http://www.kiwibiker.co.nz/forums/al...ictureid=32951

[AndrewStroud]

Brought a 130, 135 and a 140 jet this week. Today I fitted the 135 and dropped the clip on the needle. Can't wait to give real a test. But just giving it a bit of throttle stationary, it seems to rev up much quicker from idle.

Cheers
Muzza

Let me know how it goes. I suppose we need a straight a little longer than what's at the go cart track to do a reasonable plug chop. Better be my next little exercise as I ended up getting a bit keen last week ( 4 this time of the yr anyway as I should be sorting Superbike instead). I took off cylinder & Steve Bridge took off 0.7 and gave me a bit of solder to check squish. I filed out the exh port some - until I got bored with it (now 26.5 mm from top of cyl and 39mm wide. Checked squish and was still 1.3mm so left out head gasket and Yamabonded it. now 0.8mm squish. Definately more power now though doesn't rev out still with std pipe. Sure it'll be fine for the kids anyway - for now :-)

[Muzzab]

Let me know how it goes. I suppose we need a straight a little longer than what's at the go cart track to do a reasonable plug chop. Better be my next little exercise as I ended up getting a bit keen last week ( 4 this time of the yr anyway as I should be sorting Superbike instead). I took off cylinder & Steve Bridge took off 0.7 and gave me a bit of solder to check squish. I filed out the exh port some - until I got bored with it (now 26.5 mm from top of cyl and 39mm wide. Checked squish and was still 1.3mm so left out head gasket and Yamabonded it. now 0.8mm squish. Definately more power now though doesn't rev out still with std pipe. Sure it'll be fine for the kids anyway - for now :-)

We're going in the Greymouth Street Races this weekend, so will find out if it makes a difference. After this I probably won't be racing for a bit so intend having a look at the ports, I don't know if anything has been done to them previously. I found out recently one of the guys I work with is a bit of an old hand with two strokes and he mentioned "squish". So may get him to show me how to measure it and take it from there.
Cheers Muzza

[F5 Dave]

Yes, very useful for making Orange juice & fitting record amounts of oiled volleyball team members into a mini.

Seek you Graham Bells's two stroke tuning book & read it. Do a search, there are links on this site, but ultimately go buy the book, you will reference it again & again. + feel good that you are helping in his retirement.


ohh look the search got easier still with free delivery even.

Best $55 you will spend on your bucket

[Muzzab]

Yes, very useful for making Orange juice & fitting record amounts of oiled volleyball team members into a mini.

Seek you Graham Bells's two stroke tuning book & read it. Do a search, there are links on this site, but ultimately go buy the book, you will reference it again & again. + feel good that you are helping in his retirement.


ohh look the search got easier still with free delivery even.

Best $55 you will spend on your bucket

Funny you should post this, last night while searching squish came across
Graham Bells book on the net (I find this funny as well, my brothers name is Graeme Bell), had a good read about squish. But plenty more to have a look at. I have not had the top off my motor so may find it had already been tinkered with, time will tell. Cheers Muzza

[Muzzab]

Bike got a good testing on Sunday in the Greymouth Street Races. The jetting and needle adjustments seemed to give give the bike more pull from lower revs. It seemed to get off the line better and rev out a bit more. The bike is too high geared for the street circuit though. Will have to get a couple of smaller front sprokets to experiment with. Had a great time, wish I had discovered bucket racing 20 years and fifty pounds earlier.
Cheers Muzza

[Anmic]

Hi Muzza,

Ive just picked one of these little things up to set up as a racer over in Australia. Ive been hunting for onfo on an expansion chamber. What did you end up using for yours?

Cheers,

Anmic

[Muzzab]

Hi Muzza,

Ive just picked one of these little things up to set up as a racer over in Australia. Ive been hunting for onfo on an expansion chamber. What did you end up using for yours?

Cheers,

Anmic

Hi,

This thread is going back a bit, haven't had the RX125 for a while, brought a FXR150 motor and bolted it into
a RGV250 rolling chassis and been playing around with that for a fair while now.

I don't know the origin of the chamber on it, but people had suggested using ones from the likes of RM125 motocross bikes (made to fit of course).

Have fun.

Cheers
Muzza

[TZ350]

First pic is of the RG250 pipe, second pic is the cut-out front section we found we could use as it was very close to the RM specs.

Third pic is the RG/RM spec pipe, fourth pic shows where we cut the flange end off and turned it down in the lathe to fit the GP cylinder. Cutting it here made it easy to re-align the pipe to fit onto the GP.

Last pics are a comparison between the original RG pipe and the RM spec one. Thomas made the RM spec one in the original heavy gauge metal to better withstand the argy bargy of Bucket racing at Mt Wellington.

You will have to follow the link back to the original post to see the pictures.

A RG250 pipe works well and it can easily be modified to 80's RM125 spec found in Bells Book

We got 18 hp using the RG pipe then 22 with the pipe modified to RM spec.

[koba]

You will have to follow the link back to the original post to see the pictures.

A RG250 pipe works well and it can easily be modified to 80's RM125 spec found in Bells Book

We got 18 hp using the RG pipe then 22 with the pipe modified to RM spec.

22 is more than I've ever had...