RM 500 - jetting help please

[subarumy98]

HI

Looking to help another buddy of mine here in South Africa.
Looking for some jetting specs for a 1983 RM 500.

Any numbers with corresponding altitude will help, as we can correct for the local conditions.

Thanks in advance



Trevor

[seego]

is the carby off a rm500 

[jady]

I am also looking for jetting tips for an '84 RM500, similar to the '83 model. After finally getting the bike together following years in pieces in the shed, it is running poorly but I can't clearly explain how. It won't rev out cleanly, sort of gurgles & chokes, yet when idling seems to build revs higher and higher (perhaps there's an air leak, better check), so here's an opportunity to learn about jetting, as I've never tackled jetting before.

The spark plug was black so that means too rich...? Perhaps it is rich in full throttle and too lean down low?

1st step is to return it to standard 1984 jetting which I believe is:
Pilot 40 (1983 std pilot jet was 50)
Main 300
Slide 2.0
Needle Jet 6FM46
Jet, needle R-4

For some reason my bike had this jetting:
Pilot 50
Main 330
Slide 2.0
Needle Jet 6FM46
Jet, needle Q-8

Unfortunately Suzuki have discontinued the standard needle jet & jet needle so will have to try somewhere else to find them...

I'll keep posting what I find out in case it is useful to anyone else.

cheers Jady

[D project]

Hi Jady, I had the same problem with my 500D and changed the standard jetting to what they had in the VMX article.I think the main changes were 280 main and I went to a R-0 needle jet which is still available from suzuki. It seemed to help out.
Also I think I was up against you in the pre 85 125/250. I was on the 125X.
Regards Jason.
Viper 620.

[jady]

Thanks Jason I might give that jetting a try... Can you remember which article it was, maybe the one with Brad lackey on front cover? I'll dig through my MX magazines, it is hopefully in the shed somewhere.
Yes I probably ate some of your dust on Sunday in the 125/250 races. The track was fantastic but a little hard on a 125, getting up the hills. The 500 made it much easier!
cheers jady

[JohnnyO]

You'll be able to get the mikuni jets you need from T.D.Hatrick in Townsville.

[D project]

Jady, it was in the aussie vmx mag a few issues ago #34.

[LWC82PE]

also for mikuni parts/jets this place is highly recommened www.iwt.com.au (Mikuni guru and well respected 2 stroke engine tuner, is experienced with motorbike engines too, not just karts)

A bit more about us ......
As Australia's major MIKUNI motorcycle carburetor supplier, our inventory covers nearly everything in this brand's range, both 2-stroke and 4-stroke, road and race. New carburetors, jets, spare parts, manifolds and expert tuning advise is available. We may only work on 2-strokes ourselves now, but we can assist with most enquiries on Mikuni's.

all contact details including international ph/fax numbers on their website.

[jady]

Thanks for the tips. I'll try TD Hatricks & IWT next week.

I finally found the VMX article after getting completely sidetracked reading through old VMX mags. What an encyclopedia you would have if you had them all!! They suggested:
Main: 280
Needle Jet: R0 or R2
Pilot: 45

I also found a Motocross Action test of the 1984 RM500. They suggested
Main: 300
Needle Jet: R4
Pilot: 35
Maybe this was for a USA model bike.

cheers Jady

[subarumy98]

Thanks very much boys

I have passed the info on and will advise the results.

In the meantime, I need to go and wrench. We have the first round of our VMX races this weekend.
Bit of a roadtrip to get there, abot 800km I think...