03/04 rm 125 rebuild and jetting

[chump6784]

ok i bought my wife an rm 125 off a forum not that long ago and the seller told me it was an 05. on that same forum there was a post from someone that said it was an 04 as it was their old bike. no big deal as its basically her first bike(she has ridden before tho) and i got it fairly cheap.

i looked up the vin number on the net and there was no info on it so i rang suzuki australia and they had no records of the vin or engine number and the vin number has a 0 for the tenth digit but it definately not a 2000 or 2001. after a lot of searching on the net and through service manuals i came to the conclusion that it is either 04 or 05 because of the features such as quick adjust clutch, rear master cylinder and linkage mount as these features changed in 04 and were the same for 05. it also has a flat top piston in it which came standard in 04 and the 03 had a dome top.

i was going to order a new top end kit for it when i started playing with the jetting and when i pulled the jets out i found it had been jetted to pro circuits specs for an 03 model. there is quite a bit of difference between the 04 and 03 jets. the jetting has never been spot on, rips up top but has a dead spot right off idle. went to a richer pilot jet and didnt seem to help

so now i am wondering if it could be an 04 chassis with 03 engine or has someone got the jetting specs for the 03 and thought "good enough". the only other clue is to look at the power valve as that changed from 03 to 04 but i dont know what the 03 one should look like to start with

so my question is there any way to tell if the cylinder has been modified to take a flat top piston for the 03 model or do i take it that they just stuffed up the jetting and it really is an 04/05

[TMKIWI]

Try this. I have used it alot in the past to check on parts.

http://www.alpha-sports.com/suzuki_parts.htm

[2T Institute]

The carburetor is a give away , RM's have had flat tops for some time.The cylinder head is the only thing modified with a flat top conversion.

[chump6784]

well i worked out it is not an 03. its either 04 or 05. had a look at the powervalve last night and that was the answer

[chump6784]

Ok so now that I have found it is definitely an 04 I am now focusing on the jetting.

At the moment it is running 37.5 pilot, 440 main and needle 2nd clip. Pro circuit recommend 35, 360, 2nd clip. At the moment it has a small bog just as you open the throttle but jails ass from bout 1/2 throttle on. would that be expected with the difference in jetting?

Guess I should order the recommended jets an give em a go.

[MyckMcClung]

Yes the bog on the bottom is a rich condition. 35 or 36  pilot ought to do ya, not sure if I'd go that lean on the main though, maybe 375-420. I'm pretty sure that Pro Circuits specs are developed at sea level, 32:1 using 104 octane racing fuel. If you are at a higher altitude or using a lower octane fuel you should stay richer on the main. and raise the clip 1/2or drop the needle 1/2 same thing just worded differently. Either way you move the clip up 1 and shim under the clip.

[chump6784]

where i live and ride is pretty much sea level although 77 degrees is about what we have in winter. i am running 40:1 ratio and using 98 octane. i found some charts from thumper talk and the guy that posted them seemed to agree with the procircuit specs so i have ordered that today. guess i will see how it goes.

when you say rich do you mean too much fuel? i was reading one magazine and they said that if the bike has a slight bog off the bottom it needs to go richer on the pilot. i did that and it made it worse so i am going leaner.

being lean isnt too much of an issue right now as its my wifes first bike the main issue is fowling plugs. she is getting a lot better tho. as soon as i get this thing running right she should do heaps better

[2T Institute]

Yes the bog on the bottom is a rich condition. 35 or 36  pilot ought to do ya, not sure if I'd go that lean on the main though, maybe 375-420. I'm pretty sure that Pro Circuits specs are developed at sea level, 32:1 using 104 octane racing fuel. If you are at a higher altitude or using a lower octane fuel you should stay richer on the main. and raise the clip 1/2or drop the needle 1/2 same thing just worded differently. Either way you move the clip up 1 and shim under the clip.

Try a 7 or 8 heat range plug, you can have rich or lean bog. Play around with the airscrew a bit, there isn't a big differencebetween a 35 and 37.5 pilot.
At sea level you will need a richer not leaner jet.

[MyckMcClung]

yes, rich means more gas
I would recommend more oil in your mix for a 125, especially if it's a single ring. 32:1 should be the minimum for a 125.
I recommend 24:1 for break in up to 4 hours.
I meant to say "lower altitudes" I was thinking about the needle clip while typing, sorry bout the confusion.

[chump6784]

thanks for the help guys. just waiting for the jets to arrive and will start playing