RM125A jetting specs

[bigk]

Hello all,
Can anyone tell me the jetting specs for 1976 RM125A? Standard engine.
Cheers,
K

[cyclegod]

On the stock 32mm Mikuni

Pilot jet = #30
Needle jet = R-0 (R-3 is the go though)
Needle = 60P5-3
Main jet #250-260 (factory options range from #210-#310)

[bigk]

Cheers, That will be our starting point.
Thanks,
K

[Graeme M]

I haven't the specs to hand, but I don't think it'd be a 60P5 needle - I'm guessing 6DP5.

*Edit: I went off for a search to see if this is correct, and in the process found this very useful page. Scroll about halfway down, plenty of tech bulletins for RM series from 75-77 or so. Includes the change from R-0 to R-3 for the RM125A.

http://www.ozebook.com/compendium/techbuls/index.htm

[rm1976]

trying to jet my 125s bogs badly down low pilot 20 main 180 needle top clip plug looks grey white any ideas

[TT5 Matt]

VERY LEAN up the jetting on all stages,check float level,check for manifold air leaks

TT5 Matt

[rm1976]

great idea mat ...the thing is bike has new case seals,float levals checked, manifold is good and if you try to go richer anywhere its un rideable?       half to full throttle is great its just down low it wont pull
any ideas ?

[Lozza]

Learn how to read a plug, check ignition and what heat range is the plug?

[rm1976]

ignition seems to be working good plug is b9es and is grey/white after a hi speed run ?

[Maico31]

20 pilot is too small.. try a 30 or 35.

[Freakshow]

Check the CDI.  got a spare you can swap in for a test.  I smell zoki black box

[Lozza]

What check ignition means is to put a timing light on it and see if the timing mark correspond with the manual settings, not taking it out of the head and kicking it and watching the sparks!Your way to lean on the main should be around the 280 main jet.DO a plug chop when it's bogging and read the plug.

[rm1976]

hey guys thanks verry much for the input i think we are almost there, I went for a ride today and the bottom end is a lot better in fact verry good specs are mainjet 170 pilot 27.5 needle 3rd clip mixture screw2.25 turns.plug B8es grey in colour..............
its still a little doey down low but hey its a 125, and flat out in top gear it seams to hit a bit of a wall like it hits the rev limiter, maybe i am reving it too hard and expecting too much

[TT5 Matt]

still too lean,plug should be tan colour    start rich and go down better than holed or siezed piston because of excess heat caused by leaness not to mention lack of power and flat spots,go play some more with the jetting

TT5 Matt

[rm1976]

18o main makes it run like a pig  i will try different pilot jet(thanks mr hattrick)

[suzuki27]

Have you checked the output of the coil/plug lead; stator high/low speed coils etc with a multimeter.It still  might be worth doing a "leak down "test, if you still can't get it right.Also,check that your choke is sealing properly-that had me stuffed for ages on an old RM-someone had changed the choke and it wasn't sitting /sealing off completely when it was turned off-when that was fixed,a very rough running bike ran like a train.

[pmc57]

RM1976,
Your're still way to lean on the main for a RM125S. If you're running out of legs at the top, the bigger main should help, or like said earlier, you may end up witha hole in the top of the piston. Are you sure you have an S, they have a 34mm carby.

Standard carby spec's for a S is:
Main #280
Pilot #35
Needle #6DH3 (third clip from top)
Needle jet P-3
Air screw: 1 turn out

[rm1976]

Thanks for your tip about the choke on the carby but it all seems fine
Jetting is now 270 main 27.5 pilot 3rd clip 11/4turns out
I will check the resistance on the hi & lo speed coils
Racing at Tamborine this weekend lets see how she goes

[rm1976]

all jetting questions have been answered little rm is flying
holeshot buddy rode the last race at tamboreen and won by a mile
think i might retire and just build bikes for russ buddy