Help PLEASE! My R is a smoke factory!

[Davemx250r]

I just rebuilt the motor on my R and we coated the piston with oil when we stuck it in. I started er up for the first time today and took it out. But its smoking so bad it wont even open up all the way. Are fresh motors suppose to do this? It just seems extremly rich, and i havnt changed the jetting or anything since last time,just bored the cylinder and put in a new piston. Has anybody else experienced this?

[kxrider]

did you forget to put your main seal in, or you may have blown it, do you notice any oil, or coolant leaks? try running it realy lean, and see if it does it, if it does then you are suckin crank case oil into your piston, or best case it may just not be broken in yet?????????????????

[Davemx250r]

no i know all the seals are in,i even added honda bond to them. It might not just be broken in yet, it only has about 5 minutes on the motor. i just didnt know if they smoked this bad when they were fresh

[300exazzkikr]

usually they smoke a little especially if you coat the cylinder walls but not a lot. What's your premix?

[Davemx250r]

32:1 i held it wide open down our road too,it will stay clean for maybe 3 seconds then when it idles down it smokes really bad unless you open it up again.

[300exazzkikr]

it sounds like it's your jetting then. I would keep an eye on your crankcase oil to just in case the seal has gone bad, if the oil level starts to drop then you know that it's sucking crankcase oil.

[Davemx250r]

Its not sucking crank case oil im posative, we seals that up water tight man. But i dont see how it can be jetting either because im running the same jetting i was before the rebuild, and its not like i went from 250cc to like 330 that i would need to change jettin, it should stay the same with a normal bore job. Im hoping it will go away after i break it in.

[airheadedduner]

When you put a motor back together all you need to lube it is a coat of wd-40 in the cylinder. It should not smoke on break in like that. Mine only smokes a litle heavy for maybe 30 sec and it then burns clean. Is it a blue smoke or a white smoke? If it is blue you are loosing tranny oil into the cyl. White is coolent.

For break in you need to put it through some heat cycles and torque everything down after it is cold. Then ride it for like 20-30 min never going over 1/2 throttle. You can't just ride it after slappin it together.

And it is not jetting, from 250 to 295 didn't change my jetting that much.

[phatswinn]

sounds to me like its just not broken in yet, the rings probably wont set right until you have about an hour of riding time on it
or the gaskets havent heated up and sealed yet

[Bean]

if you coated the piston with oil, the rings probably havent seated yet, keep on running it real smoothley, if that doesnt work, try taking the airbox lid off, or taking the airfilter off, and see what happens

[Davemx250r]

i fixed it, for some reason it was rich. i stuck a 162 main in there and it ran fine, it had a 168. Hey anybody ever turn there gas off while the engine is running to drain the carb of gas? well i did that and usually when it starts runnin out it will rev on its own a lil and die. well this time it revved a lil and kept on reving till it hit the limiter, i wasnt even touching the throttle. so i pulled the kill switch and it didnt die. finally i clicked it in gear and held the breaks and lugged it to die after about 5 seconds of full rpm rev. I found out then when you do that it makes the motor runn lean at the end and make it rev on its own,but fresh motors have so much compression i was told they can run with out spark or sumtin like that. It scared the S*** outa me because it was my new motor and it was reving with out me touching anything. Anybody had this happen on their R before?

[ESR250R]

U just leaned it out. i personally dont think your gonna get that much time outta this piston and ring. from what i heard u have done no heat cycles and u have been giving the engine he!! to get it to run right. i went from stock to a lrd ported cylinder and a milled head (milled for race gas) and i had hella compression. btw u popping your transmission into gear at WOT is really bad on the dogbones in your transmission. even with the clutch pulled in it still rounds (can even brake) the dogbones. u shoulda did a little investigating before just rebuilding and starting up the engine and riding. u need to be run though 2 heat cycles were it completely cools down. then u need to run 1/2 tank of gas between idle and 1/2 throttle. and the last 1/2 tank between idle and 3/4 throttle. when your doing the heat cycles your also supposed to tap the throttle every 10-15 seconds, so u can let the water pump do its job. if u let it idle it will overheat and possibly seize up.

[Ryan]

If you do have that problem where you can not shut off the engine without putting it in gear again, Turn down the idle screw untill the engine stalls. I had a similar problem with this. I later found out that the Manufactor had the head gasket in backwords :huh (Don't ask) :rolleyes: .

For it to stay revved like that, it could be as simple as a air leak in your head gasket. It may had not of been sealed properly.

[Davemx250r]

lol esr250r. Dude its had plenty break in now, iv road it a good hour not going over half throttle. Honda told me i dont have to do all the fancy crap you were talking about. they said just take it easy for about and hour and then ride the he!! out of her. And the revving deal wasnt my fault. i asked honda bout that too and they said if you have a shaved head it will do that once in a while because the extra compression makes it run on its own some how(dont ask) And i didnt just pop it in gear. I pulled the clutch in,shifted,held the breaks and slowly let out the clutch till it died, i had no other choise, the kill switch wouldnt kill it, what do you want me to do, let it keep reving till it runs out of gas? So see all that extra 1/2 tank of gas half *** throttle is a waste of time. Honda even told me so, just dont go above half throttle for about an hour or less and also you can hold it open during break in but only for 3 seconds at a time. Chill out dude, iv been around quads since i was born, i know a thing or too. And im pretty sure honda knows a lil more bout them than you do.

[ESR250R]

i have been to about 8 honda dealers in my area and ive talked to most of the mechanics and from what ive seen i wouldnt take anything of mine to 7 of those. i was told by a repubatable engine builder (lrd specialities) that was the proper way to break in a 250r motor, i wont listen to some stupid ***** honda mechanic but if u want to more power to ya. even if u did pull in the clutch the dogbones had to engage when u put it in gear and when the engine is reving that high it rounds the dogbones when the gears engage. i just thought i would let u know since i had to just spend $1800 to rebuild my bottom end because of this.

[Davemx250r]

Your talking about the shifting forks right? Iv got all new shifting forks. when i rebuilt my motor,i did the bottom end too, all new bearings and seals,new crank, shifting forks,and got baldwin second and 3rd gears. And i do trust my local honda dealer because their head mechanic used to race 250a national, on top of that hes my 2nd cuzen, i trust what he says.

[ESR250R]

no not the shift forks. the gears have dog bones actually on the gears. the last few races last year i would go to powerslide around the corner and i hit a few small bumps in the corner and it would just pop into neutral. i took it to the honda dealer and replaced all the cases (except stator) all new gears (89) new dogbones, new hinson clutch, new clutch, all new bearing, etc. the place i took my bottom end to told me that the gears occasionally werent engaging all the way from all the years of neglect.

[Davemx250r]

i get what your saying. But there was nothing else i could do to shut the dang thing off. i wasnt evem touching the throttle, i was standing a good 5 feet from the bike. And the kill switch didnt kill it either. But i know why it happend. i wouldnt have clicked it in gear and lugged it to kill it if i didnt have to, but i didnt wanna fry my new motor by lettin it sit there and rev till i could figure out how to shut it off. :rolleyes:

[ESR250R]

ya that is wierd i would think that cutting off the spark would stop it. i probably would done something stupid like pulled the wire off the plug or something:eek2:

[Davemx250r]

Its something to do with it leaning it self when it runs out of gas. It wont shut off because theres hardly any gas to run it anyways but theres enough to mix with the air, that some how makes it rev very high. Something about the compression i was told is why you cant cut it off by spark. They said choking it when it does that usually does the trick but not always.:rolleyes:

[lil400exman]

this is what happens to me when i run r/c race trucks with high compression motors and they would run what i did waspush them backwards in gear to make them stall out and osmetimes this would stick them at tdc (top dead center) and would have to take the glow plugs out and "reset" then engine by taking a small dowel rod and sticking it through the glow plug hole and pushing it down but after you break in a motor well it doesnt so that..........:)

[Ryan]

Dave, if you have this problem again, turn down the idle screw untill the engine stalls.

[wilkin250r]

You motor ran on on it's own because it got too hot, which was caused by the lean condition.

When you compress air, it heats up. If it heats up enough, it can cause the gas to ignite on it's own (which is bad). This is why you need a higher octane gas when you run higher compression. People think higher octane gas is more explosive, but it's not, it's more stable at high tempuratures.

When your engine leans out, it runs hotter. This can cause something (usually the end of the spark plug) to get VERY hot and glow. Now, when you compress the air and fuel mixture, the glowing end of the spark plug has enough heat to ignite the fuel, which will heat the end of the spark plug again. Basically, because your engine is so hot, you have an ignition source that doesn't need a spark, it will just run on it's own. This is why your engine didn't shut off when you pulled the kill switch, it doesn't need a spark at this point.

This is the same principle that makes a diesel engine run. Diesel engines don't have spark plugs, they have glow plugs.

You can prevent this by either running a higher octane fuel, or just don't let your engine lean out.