gas/oil ratio for 1990 rm 250

[markyb]

I have just purchased a 1990 rm 250 that is in great shape. I am new to the 2-stroke scene so I have a few questions. The bike has supposedly been ported and jetted and rebuilt with a wiseco piston/ring kit. The exaust is stock except the silencere has been shortened.(why would this be) As for mods those are all that I know. What gas /oil mix should I use. The previous owner said 20:1. Should I go leaner? Also does it help at all to use a higher octane fuel? Also I read somewhere that using a BP7ES plug can help lean the bike out a little. Is this true, if so, is it a good idea? I would appreciate any help. I plan to just trail ride the bike a few times a year so I just want to keep it running as smooth as possible.

 

[markyb]

a little help please!

 

[xcracer72]

i rose an 89 up until a few years ago. I mixed 32:1 with a br8es plug ( i think that was it?) The silencer was probably shortened in an attempt to get more exhaust flow and increase power. "FMF Shorty" "Pro circuit r309" etc etc. I only EVER use the suzuki premix. Never a problem. 20:1 sounds a little rich are you fouling plugs or spewing oil out of your exhaust anywhere? as far as plugs make sure any changes you make are identical (threads lenght of threads/diode) etc etc have your local shop reference it for you. when you decide to lean it out go in small increments ususally 6:1
ex. 20:1 26:1 32:1 I run 40: in both a 2003 an 2004 rm 250.

Anything else?

 

[markyb]

I have only riden it about 4 times for about 10 minutes each. I have not seen any oil yet. maybe a little at the silencer port. It does smoke (white) until it is warmed up and ran, then it does not smoke. Is that normal? The bike is a frick'in rocket. The last bike I owned was a old honda 100 back in the early 1990's. This thing will take some getting used to!

 

[xcracer72]

white is normal until it gets hot less than a minute is typical.

 

[markyb]

It is about normal then. Since this is my first 2-stroke I am very cautious about everything. Reading the horror stories about engine siezures and stuff, i want to make sure everything seems normal. Thanks for the help. I am sure I will have more question down the road.

 

[MXer]

I had an 89 RM 250 at one time. It was the first year for the case reed engine Suzuki used until 96. It was almost the same as the 90 RM 250. Riders would shorten the silencer to give the engine more power. I used a BR7ES plug. It is a hotter plug and it worked very well. I used that plug in all of the RM 250's I had. I ran a 40 to 1 mixture. It depends on how you jet the bike. If the person you bought the bike from ran 20 to 1 than that is a good place to start. As far a gas goes I would not run anything less than PREMIUM PUMP GAS. If the compression was raised you might need to run race gas or a 50/50 mix of race gas and premium gas.