won't start

[87250rxrider]

i just finished my 250r buildup. i built this R from the ground up, but now that its done, i can't fire the engine(i've never fired it myself, but it ran before i got it). at first i had no spark, so i swapped out CDI boxes with another one i had laying around, and i have achieved spark. my wiring harness is in perfect condition, so i know nothing is wrong with that. my problem is, even though i have spark, the 250r won't fire, and it doesn't sound like its even trying to. i have a 69mm bore, with a 4mm stroker crank, and 4.5mm spacer plate on it, with pro design cool head and 21cc dome. it's compression is right at about 190PSI, so i know i'm good with that. the spark plug is brand new, but the spark almost looks a little weak. i'm thinking that the problem is with the CDI box i plugged in it(not new). could the stator cause the spark to be too weak, is the CDI bad, or is the timing off causing the spark to not fire at the correct time?? i would really like to get my 250r running ASAP, so any help is greatly appreciated. i would love to get a CR ignition from ESR, but don't have nearly enough money, so i need to get this ignition fixed.
thanks,
-Ryan

[wilkin250r]

If you have spark, try a little starting fluid or carburetor cleaner, just a quick shot into your carb or air intake tube.

[87250rxrider]

if you spray that stuff in, don't you risk breaking something in the engine?
thanks,
-Ryan

[wilkin250r]

Possibly, if you over-do it. You shouldn't need more than a quick shot, less than half a second.

[LT250Racer609]

check your coils on the stator plate...if one of them is bad it would cause a week spark that isnt enough to start the quad

[hondardr4life]

I'm no 250r expert, but check your magneto. I'm not sure if a 250r has one (it should, I've never seen a motor without one), but that would also cause a weak spark. I rebuilt an OLD motor once, and I couldn't get spark, so I popped off the flywheel and the magneto was all messed up, and I fixed that and it ran great.

[87250rxrider]

LT250Racer609, how exactly do i go about checking them, or do i have to take the whole side cover off to check them?

[hondardr4life]

You would have to pull off the left sidecase, and then pull the flywheel off, and then would be in there. They are just little magnets that spin around a coil of wires and cause electricity.

[ESR350r]

takes 3 things to make a 2 stroke go for the most part. i heard you talk about 2 of them and not the 3rd. Compression, spark and fuel. i had a week spark and i could still get mine to run so spark is a spark for the most part. compression wise that is good. if your plug has fuel on it try knocking down youyr plug gap to 18 thousandths. 16 is the minimum but 18 shoudl help. sometimes with higher compression and a weak spark the spark will get blown out so try that. try a quick shot of carb cleaner of starting fluid in the carb to help.

[Scott-300ex]

190lbs of compression, you need racing fuel

did you rejet after your bore and stroke and all that stuff?

if you didn't take the mag off it will be in time but check it like the other guy said, if you stick a screwdriver up to it it should hold the screwdriver on it no problem

plug gap, yeah

fuel, spark, and air, check all those

i'd check and see if your getting fuel, then ignition, those are kinda important, lol

[beerock]

you dont need race fuel for 190 psi, it is on the verge of race gas but is fine with 93 octane. even so the mtoor would run. you could try gapping the plug a little tighter then it is. but if you have spark compression all you need is fuel. are you sure the woodruff key was installed on the crankshaft for the flywheel? that coudl be a reason.

[Aallron]

I would check the magneto timing 1st.
You didnt mention if you had the motor apart or if you just took it out and put it back. If you just removed the motor and painted / powder coated the frame I would suspect that their is not ground for the motor. Clean the paint off of the inside contact point of the engine/frame horns and she should run.
Let us know what you find.

[wilkin250r]

Originally posted by Aallron
I would check the magneto timing 1st.

Ok, let's get some terminology straight. The 250r does not have a "magneto". It has a stator, and a flywheel. The flywheel has magnets on the inside, and it spins around the stator to produce electricity for spark, and also electricity for lights.

Timing is very simple for these machines. If the woodruff key is installed between the flywheel and crankshaft, then the engine is timed correctly. It's that simple, really.

However, ground is a very good thing to check. Clean any paint or corrosion off of the spots where your engine mounts to the frame. The easiest is the front engine mount brackets, clean the paint off of them where they attach to the motor, and also where they attach to the frame.

[87250rxrider]

hey guys, thanx for all the help. today, i placed a smaller gapped plug in it, and it fired on the first or second kick. sounds great when on the throttle, but it sounds like it idles too high and it also blows a lot of dense white smoke out of the exhaust. when the exhaust is white, that means its running rich, correct?? the only thing that makes that seem odd is that the carb i have(mikuni 38mm TMX slide carb) was last used on a 265R, while mine is a 290r, mx ported with 21cc dome. right now it has no airfilter or airbox on it, b/c i'm getting an esr airbox eliminator kit for it, so i just started it up a few times like this. if anybody has a video with a big bore 250r idleing, i would greatly like to see it, to be able to hear if my 250r is idleing way too high or not. i'm not used to 250r's, so i'd like to hear a big bore. any jetting help would also be appreciated.
thanks,
-Ryan

[beerock]

white smoke with a sweet smell is COOLANT make sure its not BLUE smoke? ok.....

check your radiator level you might have a leaky head gasket

[2FIFTYR]

smokey exhaust could be a number of things, leaky hg as stated above, tranny oil in crank case (cracked case or leaky gasket), too much oil, in gas or pipe, water may have gotten in the motor some how, take it for a small spin to see if it goes away or if it stays, down the street and back should be sufficient enough to blow it out, if it still smokes you have other issues. oh another thing is if you used any silicone to seal like a pipe or something it may burn and smoke. is it possible that the fiberglass in your silencer got wet? just some suggestions.. try adjusting the idle on the carb, for the idle issue. spray your gasket areas with carb cleaner while idling to see if there is an air leak some where, if the revs rais when you spray carb cleaner on it you have a leak.

but i would adjust idel first, or even the needle clip.

[Aallron]

What the difference between a magneto ignition and a stator ignition ?

[87250rxrider]

could a small amount of coolant in the exhaust pipe be the cause? i had a leaky head gasket before, but i just installed a new one, but b/c of the last leaky head gasket i think i got a small amount of coolant in the pipe. could that cause it to blow white smoke?? if so, i think that that is my problem. it didn't look like i was loosing any coolant, but i'll check again today. BTW, what do you guys use to seal your head gaskets?? i tried using gasket sealer on my first head gasket, but that is the one that leaked, so i didn't use any gasket sealer on this gasket(brand new TRX 3-layer gasket) and it never looked to have been leaking, but it could possibly be. shoot me some suggestions.
thanks,
-Ryan

[beerock]

permatex copper spray

[Scott-300ex]

white is lean

if its blue thats oil, but you can burn oil and its ok to have oil smoke cuz its a 2-stroke and you mix oil with the gas, so its supposed to burn it.

[250r rider 88]

check your grounds thats what was wrong with mine my mechanic said on these old quads with simple electric systems one loose ground can screw everything up jmo

[beerock]

Originally posted by Scott-300ex
white is lean

if its blue thats oil, but you can burn oil and its ok to have oil smoke cuz its a 2-stroke and you mix oil with the gas, so its supposed to burn it.

white is not lean, white is coolant period.
a lean motor will show barely any signs of smoke at all.

[LT250Racer609]

what you want to be aiming for is brown on the spark plug...not white and not black....

[rockman]

white is lean
WOW.... some people don't know jack do they?