04 RM125 tuning info

marcusgunby

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#1
04 Rm125

eric good to see you back :flame: 

im not sure if you know but i have been coverted to the banana bikes by bruce, so i have a 04 rm 125 in my garage, however it doesnt match up against the EG133 KX i had, i dont want to go big bore this season and was wondering if you have mapped the ports on one yet?i ask because i feel there is some power hiding away as its not as fast as a KTM copy engine should be:(

 

Also assuming the ports need to be modified, whats the current turn around time appoximatly?

thanks marcus.

 

ive attached a dyno from a US mag-you can see the rm is the one with the least low end but big overrev.
 

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ochster

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#2
Hello Marcus,

Eric just did a couple of 04' RM125 cylinders for me. Looking at the graph, our impression of the RM did not really mimick the shown curves. Stock the bike was quite good down low, had a very nice midrange pull, but seemed a tad restrictive on top. Compared to a modded 03', the bike made very good lap times. This was with the needle moved down, and race fuel. It was good enough we decided against the 4-stroke right now.
 

marcusgunby

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#3
hi ochster,

did eric port them for more top or bottom?

I feel the curve isnt far off for my bike, ive rode a 04 KX and that was a reasonable amount faster than mine:( ive done the jetting and its running crisp.On its own the RM feels ok but when i ride the KX it feels lacking.:whiner:
 

ochster

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#4
Marcus,

It will be interesting to see what Eric sai's after scoping the dimensions out.

Both of our motors are being built for Supercross right now. Eric calls it "burst style" power. I was talking with a pipe builder who is working on these, and he was commenting how good the oem bottom end and pipe really were.

My only experience with the 04'KX is second hand. But I do know someone who has already sold thier's, and went back to yellow. There complaints were in chassis feel, and peak power. Some guy's won't put the energy into set-up.
 

EricGorr

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#5
Hi Marcus,

Its amazing how close that Suzuki copied the KTM. Perhaps now they can gain a foot hold in the shifter kart market. Was that a dyno chart or projected advertising revenues for the big socal dirt bike mags?

Although the RM125 uses a triple exhaust port, one main oval port with two sub exhaust ports, the timing is a bit mild. In other words there is plenty of room to raise the ports. The cylinders that I worked on for Ochster will be even flatter on top but in sx and ax clearing obstacles with a short take-off is paramount. I expect to do several iterations before I get it right.

For your situation, I think that raising the front transfers 1mm and the exhaust 1-2mm would be in order. Ochster is sending me some outdoor cylinders next. That set-up works well on the KTM so theres no reason to think it would be any different on the RM.

Turnaround time is quick on porting now, just a few days for a heavy hitter like yourself:laugh:
 

bclapham

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#6
marcus- i juust said it had good turning and suspension, dont blame me that you dont like the motor! :p

if the bike is a bit peaky, it might be worth back dating the clutch to the steel driven plates- i dont know what years has these though, maybe others do?

Ochster: what is your riderss name/#??? if you are doing the west coast rounds and need any help/tour guide in socal then let me know!
 

marcusgunby

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#7
LOL bruce-its not a bad engine, but if you are used to 36hp KTMs and such it feels a tad tame thats all.I still nearly holeshot on a huge start straight against the 450s.

 

Eric thanks thats just what i wanted to hear :yeehaw:
 

steve125

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#8
Bruce! the "and such" part in Marcus backpedal means remembering how fast my KX144 was when he rode it!!LOL
 

ochster

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#10
Bruce,

The rider is Ryan Abrigo #402, a very talented and dedicated individual.

If you are serious on your offer, I may certainly take you up on it. We will be living out of the race trailer for the entire west coast 125. Would be super if we could find some true supercross practice facilities, they seem to be rare.
 

marcusgunby

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#11
Ochester if you need any help with a outdoor setting let me know-hoping to learn alot on friday when i do some dyno work on the rm.
 

ochster

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#12
Eric's work is proving to be very potent! The bike is very strong, it will outpull the 250 fourstrokes. That is ofcourse with race fuel, an ignition, pipe, etc, but none the less, it is very competitive. Hopefully I will get it to a dyno when in Cali, any sources Bclapham?

I will be sending Eric some cylinders for outdoors as soon as I recieve them.

We have had some temps in the low 40's, wich has shown the oem needle to be a little lean on the od.

Thanks Marcus, and keep us informed. I will be spending the first six weeks of the season in Cali, in a trailer. Unless I can find some comfortable accomadations, with room for a 30' trailer. Not sure how I will feed my DRN addiction.
 

bclapham

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#13
Originally posted by ochster
Hopefully I will get it to a dyno when in Cali, any sources Bclapham?
i can do some homework, there are several around, i really should put my 144 on the dyno, but i doubt a piece of paper with a HP curve would get me any faster, and i dont really have the motivation to swap any more tires than i have to!

We have had some temps in the low 40's, wich has shown the oem needle to be a little lean on the od.
thats amazing- i constantly fought a rich condition on that tmx carby- what needles are the 04's running?

I will be spending the first six weeks of the season in Cali, in a trailer. Unless I can find some comfortable accomadations, with room for a 30' trailer. Not sure how I will feed my DRN addiction.
i can always run a cable down into my garage! Ochster- will you be warming up for the outdoors in socal also???
 

marcusgunby

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#14
Ochester i owe you a apology, the rm was as good as almost any std bike produced.That mag chart was wrong in some way(either there bike was std jetting or worn out)

Heres a chart of std vs a 2C pipe.
 

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