Jump to content
Sign in to follow this  

93 RM250 rough running

Recommended Posts

Like i said it's a 93 RM250 and everything is set to stock settings as far as carb goes although the main jet is up by 5 i believe from stock at 150 from 145 maybe? id have to look to be certain, other stuff is it has full exhaust and upgraded reeds as well as a brand new top end. It is really a pain to start, spent hours kicking it and it will start for about 3 seconds everyonce in a while then die. Its extremely hard to kick ie high compression and it is getting fuel and spark just the carb isnt right at all. I can start it by bump starting it sometimes but when it does get going it runs terribly. Smokes alot more then it should and it just bogs when you give it anymore then the slightest gas until the rpms are up or you are in 2nd gear. When it is up to temperature you can start it with a few kicks to get it going again but idle is as if the throttle is half way open and cant figure out a way to lower it. It is like the throttle is fully open when the choke is pulled also. I have throughly cleaned the carb a couple times and the gas is new, as well as a new plug. The plug however isnt what the repair manual suggests because that plug is hard to find around here so it is a ngk which the bike shop said might work. the temperature is in the 50's at about sea level and very humid.

Is there a plug which would match up better for cold starts? what do i need to do to get the carb right?

heres a video of the bike once it was fully warmed up and it was having trouble finding the power to get to second gear...

thanks,

salts

Share this post


Link to post
Share on other sites

Yeah that bike is running really rich , Plus something doesnt sound right , and you said its humid so it will add to being rich , if it spilling fuel which some of your problems my 96 rm250 had , well its spilling fuel cuase your float is stuck or sticking so clean that carb very very well ! , If they are clean maybe there not set right to level And im not sure but you should be able to run a NGk Br8eg ? Is the air filter dirty ? Bad Reeds ?

anybody ?

This is what Pro circuit reccomends

mj 178 sj 52 needle 1471 clip 2ND airscrew 1 1/2

Share this post


Link to post
Share on other sites

yea well i think the float level isnt right or it may be that the floats dont even float that well anymore from just being old. Carb has been cleaned very well a couple times so i know that it is not dirty. The plug i was running is a NGK BR8ES. is there something that works better?

Air filter is clean and reeds are brand new. It was VERY humid that day, so much that condesation was collecting on the outside of the engine when we were trying to kick it over. jetting is set at

180-Main

50 Pilot

1471 needle in 3rd position

airscrew 1.5 turns out

also there is a spring missing connceting the exhaust to the engine, it seals it up pretty well but not enough that it still leaks spooge down it after it runs...

let me know.

Share this post


Link to post
Share on other sites

Being so Humid will add to smoke and rough running , Find a spring its just a spring that holds it in place , First try bringing up your needle clip up one see what that does. Br8es is a good plug"standard" next step better is a Br8eg and then Br8eix they say that the br8eg and br8eix are better and will add to easier starting . i know ive tried br8es and eg not much diffence .

Read this

http://www.thumpertalk.com/forum/showthread.php?t=412662

Share this post


Link to post
Share on other sites

I dont think so but i dont know ?

Put the floats in the water and see if they float if they dont float there not working

Share this post


Link to post
Share on other sites

You may need a new needle valve and set your float height right. If you have a PWK carb the float height should be 16mm.

Share this post


Link to post
Share on other sites

i have a PJ carb and the height shuold still be 16mm according to the repair manual. I adjusted the floats but what it appears to me is that 16mm is when the floats are resting flat upside down... i dont think thats right, so i adjusted it so that they are out a little farther and even though it was alot more then it was it still is pouring fuel out the bottom when i open the fuel peacock and its still very hard to start... what am i doing wrong? why is this bike so hard to start?

Share this post


Link to post
Share on other sites
sounds alot like the floats, ill try and fix those today, do floats go old and stop floating very well by anychance?

Yes they do!!!

Share this post


Link to post
Share on other sites

Thats exactly what it sounds like,The carburator is pouring fuel into the cylinder. You should not have fuel coming out of the overflow either.Thats why it's hard to start also.:)

Share this post


Link to post
Share on other sites
i have a PJ carb and the height shuold still be 16mm according to the repair manual. I adjusted the floats but what it appears to me is that 16mm is when the floats are resting flat upside down... i dont think thats right, so i adjusted it so that they are out a little farther and even though it was alot more then it was it still is pouring fuel out the bottom when i open the fuel peacock and its still very hard to start... what am i doing wrong? why is this bike so hard to start?

Yeah i got the PJ carb too not much of a fan :)

Share this post


Link to post
Share on other sites

ill try and crank up the floats and see if i cant get the boyency to be about right even if the floats are going out sometime today... ill let you know.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×