2003 rm 125 tuning/jetting, who knows a lot about

[Chili]

I've never really done any jetting since the last few bikes we bought were pretty close so I have a few questions for when I start playing with it on the 03. First I have done all the pre-reading of the important jetting threads and think that I have a basic idea of what I'm up against but I have 2 main questions I want to clarify. First if I recall the special plug spec'd in the RM's is between an 8 and a 9 heat range and while I don't mind running a $20 plug for safety I'm certainly not going to sacrifice a case of them to do plug chops to work my main from a 560 to the 440-460 range most of you are running. So given that the heat range of the stocker doesn't really match an 8 or a 9 how do I proceed? Secondly for WOT plug chop I always thought that you warmed up the bike then changed plugs and then tried to find a slight uphill to put a load on the engine and then ripped it through the gears until you were WFO and then grabbed the clutch and killed the engine, however in a recent thread on jetting someone mentioned that you can get to WOT in 1st gear. Do I need to just pin it in 1st for 15 seconds and then kill it to get an accurate chop?

My plans for now are to break the bike in on the OEM brass, then deal with the pilot and needle before finally progressing to some WOT plug chops to dial in the main.

Our conditions here are 785 feet above Sea Level and on average summer riding is 70-80 deg with anywhere from 45-100% humidity. Plan to run the bike on Yamalube 2R @32-1 with premium pump or at best 50/50 pump/race fuel.

 

[bclapham]

Chilli:

i have been running the BR8ES plugs for all my riding so far, as have many others in their RM's so i think these are a good start for tuning. i will run a better plug once i have it dialled.

its a real good idea to run 50/50 race gas since these bikes really rev and have aggressive ignition, ive seen a stock 02 seize up on pump. it should help with jetting and give a bigger safetly margin.

for what its worth, those main 560 jets sound massive- around here 80-100deg and 1000-4000ft i have seen rm's running in the range of 430-490 but i dont know what physical differences there are with the bikes so take those comments with slight caution.

have fun!:)

 

[Chili]

Originally posted by bclapham
Chilli:

for what its worth, those main 560 jets sound massive- around here 80-100deg and 1000-4000ft i have seen rm's running in the range of 430-490 but i dont know what physical differences there are with the bikes so take those comments with slight caution.

Bruce that is what has me baffled I don't think there is any physical differences with the bikes other than the jets in the carb. I'm at work so i don't have my manual with me but it is worded something to the effect that if you have a USA model it has these jets if you have a rest of the world model it has these jets. Just seems odd to me that they wouldn't send the USA specs to Canada since the guy that buys one in Pembina ND is running under the same conditions as I am since we are less than an hour away. That being said I'm reluctant to just drop it from a 560 straight to the USA spec of a 460 so I will most likely work my way down through the jets over time.

As for the 50/50 race gas I should probably start this in another thread but the gist I got from another thread was that you were wasting your time and money running 50/50 unless you were simply trying to avoid detonation. Since I can't afford to run straight race gas given the amount of fuel Troy uses and the $15 a gal price tag of C-12 up here I've simply stuck to premium pump in the past. In discussion with a race mechanic I respect he's telling me that it would be a waste running straight VP as none of the bikes have high enough compression to need straight race gas so he recommends 50/50, feel free to color me thoroughly confused :confused:

 

[bclapham]

Chilli:

dont know what to say about those mains other than just try and find a field and take a box of jets and a box of cheap plugs and have fun- i would keep the expensive plug until youve done that since you dont want to foul it, if indeed the bike runs on the 560, LOL!

as for the race gas, $15 a gal of C12 seems massively high, but if that the cheapest you can find then thats a shame. although ive only been running race gas the last 6 months, i strongly disagree that race gas in a stock engine is a waste- a friend runs straight c12 in his yz250 and has got the jetting really set well (much leaner) and this bike runs great (power and crisp).

in addition, although the hydrocarbon gods may disagree with me, i see no probs running 50/50 if on a budget and i think it will be much better than just pump- some of my friends here do that and have had success with cutting C12 and our pump gas is crapolla-- a friend that didnt is still waiting to get his rm125 cylinder repaired.

good luck

 

[Chili]

Originally posted by bclapham
as for the race gas, $15 a gal of C12 seems massively high, but if that the cheapest you can find then thats a shame.

I'm going to do some serious shopping yet but I've checked pricing at the two most likely suppliers for VP and both were $75 for a 5 gal drum. I can get it for $11 a gallon if I buy the big drum but then I'm into worrying about storage and keeping it fresh. Keeping in mind these prices are CDN funds, with the $ improving of late it might be worth me making a trip down to the USA to get some fuel although I'd have to check into the regulations against transporting it across the border etc.

 

[marcusgunby]

The Uk bikes comes specced with the same massive main jet-however they soon foul plugs when left std.
A friend ran the suzuki dealer and got a good spec for our bikes
Main 480
needle 2nd clip
pilot 35 AS 2 turns
this is a good starting point for most people.

 

[Chili]

Marcus - thanks for the reply. Have been out of town and just noticed the post this evening.

 

[bclapham]

Chilli: this may be a long shot,:) but does the 03 manual list any needles leaner than 6bgy27-79????

thanks, Bruce

 

[Chili]

Bruce I'm at work for the night shift but I'll take a peek tomorrow when I get home and post back.

 

[Chili]

Bruce sorry for being tardy with the reply. The 03 manual lists the 6BGY-27-79 as the leanest needle, however I imagine that is simply the leanest available from Suzuki.

 

[nothing]

is there a place to order needles and jets for my rm125 online, my nearest dealer is 100miles away

thanks!

 

[kdx#627]

I Have A 2000 Yz 125 And Just Recently Switched To A 12/48 Sprocket Combo And It Works Great. At The Track Where I Ride I Was In Between Gears On The Turns 2-3. The New Combo Makes The Gears Closer And Now 3rd Is Perfect And Fast.
David