Hard to start RM 250

[kxrider125]

I just got a fixer upper 82 RM 250 that is very hard to start.It has a few major back fires before it starts.Once it does start it seems to run(idle) fine.I havent driven it yet as its the middle of winter here in canada and its my winter project.There is plenty of spark (ive tried a variety of different plugs and brands)and it seems like the carb is getting good fuel.I pulled the carb and cleaned everything (Starting jet,main jet,etc)by what my manual states...im a serious newbie at this.i asked at my local dealer if they had a carb rebuild kit and he said no that they would just replace any worn or damaged parts,well i could not see anything wrong,it was very clean inside.I even took a very fine wire and cleaned all the tiny openings and blew air through them.I also did a compression test and it read around the 98 psi mark,im thinking,and im probly wrong,that it needs a piston/bore job as its border line compression.my friends bike reads at around 125 psi mark(rm 125) thats with a brand new piston etc.
Its the only thing i can think of as,like i said i have sufficient spark and fuel.
Any ideas for a newcomer to the 2 stroke world.
Thanks
Tony

 

[MXSparx]

thats not borderline. thats way low psi

 

[wgwgoldwing]

You might have some fuel built up in the crankcase. Take the plug out and have a friend help you turn the beast upside down. Work the kick starter with your hand and you will probably get a bunch of black crude spray out the plug hole. It's a good "no-cost" something to try. Mine had a lot in it probably due to I really didn't know how to properly start it (kept kicking, and kicking and kicking - forcing more and more fuel into the crankcase).

A routine I use on my 86 RM250 (and for my 04 RM250 for that matter) is:

Engine cold:

Choke on, throttle closed, 4 swift "jab" kicks, usually starts. If not,
Choke off, throttle closed, 4 swift "jab" kicks, if still no start,
Choke off, wide open throttle, 4 swift "jab" kicks.

Engine warm:

Choke off, throttle 1/8 - 1/4 open, 4 swift "jab" kicks, usually starts. If not,
Choke off, wide open throttle, 4 swift "jab" kicks, if still not start,
Go to Engine cold procedures.

I think I needlessly spent alot of money on my 86, when it was just my inability to start the monster. I put on a new coil (tests determined it was borderline), silencer, played with numerous carb settings, did compression checks (which came up around what your's did), even did a top end (bored out and all). After the top end I was still having the same problem. After much trial and error, I finally got it right. The above starting procedures work for me just about everytime. If they don't, I usually have a fouled plug.

One thing that made kicking soooo much easier was a pair of good MX boots (since then I got all the gear), but when first starting I didn't want to throw down the bucks, just incase I didn't like the sport. New boots are pretty stiff and really help you direct the power straight to the kickstarter. I wish I would have bought some the day I bought my bike It would have saved a lot of pain and aggravation. When you kick, pretend there is a big hairy spider on the bottom of your foot, and you want to get that burger off quick.

Anyway, this was my experience with a hard to start RM 250. There could be many other contirbuting factors in your case, mechnical problems, restricted air flow (dirty fiter), etc. If it's just starting procedures, this may help. Let us know how it goes.

Good Luck,

wgwgoldwing

 

[TrackMaster2]

i would suggest like you said a fresh bore and a new piston kit, old bikes run really good but they require a lot of maintence. I used to have a 1986 yz80 that ate pistons.

 

[kxrider125]

quote.."thats not borderline. thats way low psi"

ok fine,but would that make it hard to start,coz it does run,ive had it running a few times.It may have something to do with the air screw setting but it is adjusted to what the manual says..all the way in and a turn and a half out(i think,i cant remember sitting here)I even checked the stator and its exactly on the mark it should be.If it has been running wouldnt that clean the crank case out if it was over full of fuel?
when its cold and it has some MAJOR backfires before it finally starts,the manual says that it could be the air mixture.Should i turn the screw out or in? for my adjustment.
Thanks
Tony
P.S why is there no idle screw on suzuki carbs,only air mixture screw?

 

[Vytas]

A 250 should have about 200psi.  I would check compression again, rebuild top end and then start tuning the carb. 

 

[yz250flash]

From what I have read previously a worn out top end can make a bike harder to start. When my YZ is cold I do the following: Choke on and throttle closed - 3 slow kicks (by slow I mean just push the kickstarter down with the minimum presure it takes to move it). The fourth kick is still with the choke on and no throttle, but fast like you would normally do.

You said you had the bike running a few times. Was it hard to start after it warmed up also?

 

[kxrider125]

yz250flash

Yes after it was warmed up i still had trouble starting it,i actually gave up coz,believe me my leg was sore!!
I am definatly going to replace the piston and get the cylinder polished and or bored.
When i had my carb apart i noticed that an o ring in the main jet(i think thats where it was,im not sure exactly sitting here typing)looked a little flat,would replacing that help as well.Like i said though the carb looked really good otherwise(to me anyway)and i know i did a thorough job in cleaning it up.

I had trouble keeping it idling as well,i adjusted my throttle to as far as it would alow,that made it better but it still wouldnt idle.but if i turned the throttle just slightly and held it, it idled nicely and sounded normal.after it warmed up a bit and i revved it,it bogged a little,but not too bad.
why is there no idle screw on the suzuki carb?? do i need to adjust my needle...remember im new at this.

 

[Fastcat1977]

Thanks to you my friend ...!!!!!!!

I just about killed myself every time I tried to start my 1986 Suzuki rm 250 , I thought since it was such a big bike that it needed a really hard long kick to start the beast , till i read your starting procedures about the short jabs instead of the long hard strokes , thanks to you I can start it about every time on the money within a couple of kicks .
:cool:
Hats off to you.... wgwgoldwing

You might have some fuel built up in the crankcase. Take the plug out and have a friend help you turn the beast upside down. Work the kick starter with your hand and you will probably get a bunch of black crude spray out the plug hole. It's a good "no-cost" something to try. Mine had a lot in it probably due to I really didn't know how to properly start it (kept kicking, and kicking and kicking - forcing more and more fuel into the crankcase).

A routine I use on my 86 RM250 (and for my 04 RM250 for that matter) is:

Engine cold:

Choke on, throttle closed, 4 swift "jab" kicks, usually starts. If not,
Choke off, throttle closed, 4 swift "jab" kicks, if still no start,
Choke off, wide open throttle, 4 swift "jab" kicks.

Engine warm:

Choke off, throttle 1/8 - 1/4 open, 4 swift "jab" kicks, usually starts. If not,
Choke off, wide open throttle, 4 swift "jab" kicks, if still not start,
Go to Engine cold procedures.

I think I needlessly spent alot of money on my 86, when it was just my inability to start the monster. I put on a new coil (tests determined it was borderline), silencer, played with numerous carb settings, did compression checks (which came up around what your's did), even did a top end (bored out and all). After the top end I was still having the same problem. After much trial and error, I finally got it right. The above starting procedures work for me just about everytime. If they don't, I usually have a fouled plug.

One thing that made kicking soooo much easier was a pair of good MX boots (since then I got all the gear), but when first starting I didn't want to throw down the bucks, just incase I didn't like the sport. New boots are pretty stiff and really help you direct the power straight to the kickstarter. I wish I would have bought some the day I bought my bike It would have saved a lot of pain and aggravation. When you kick, pretend there is a big hairy spider on the bottom of your foot, and you want to get that burger off quick.

Anyway, this was my experience with a hard to start RM 250. There could be many other contirbuting factors in your case, mechnical problems, restricted air flow (dirty fiter), etc. If it's just starting procedures, this may help. Let us know how it goes.

Good Luck,

wgwgoldwing

 

[arnego2]

Hopefully he's still around to read your thank you note :)