white smoke, bubbles in coolant, need a leak down test??? How???

cowasucky · Jun 27, 2009

2003 kx 250 has sputtery idle with large plumes of white smoke to go with it. I was told to check my open radiator after cranking it up and check for bubbles and sure enough the coolant was "jumping" out of the radiator. My coolant level hasn't dropped though, atleast not noticeably. I was also told to do a leak down test. How do I do that ? Is it fairly simple a? I'm no mechanic, but I recently rebuilt my clutch and did a fine job if I do saY so myself....so I'm capable just not very experienced. Does this sound like I'm facing a serious repair here??? The bike runs really goog.....really, really good, except for the smoke and sputtery idle. Please help, I can't afford a mechanic, but I love to ride my bike. I ride every weekend with my 11yr old son. And his 03 yz85 so I have to keep this bike in top shape. Thanks guys, y'all haven't failed me yet !!!

whenfoxforks-ruled · Jun 27, 2009

Did you fix the head gasket leak yet? You have found the source of your problem. You do not really need a leak down test for that. At least till you fix the head. O-rings or a gasket? Was the plug black?

_JOE_ · Jun 28, 2009

Yeah, you have a combustion chamber leak. Pull the head and visually inspect for a damaged gasket or cracks in the metal. Check the head for warpage as well.

A leak down test will just bubble the coolant which you know it's doing anyway. This test is more helpful to diagnose crank seals.

cowasucky · Jun 28, 2009

Uuugghhh!!!!!!!!!!!!!!!!!! I'm so freekin' bummed now......but I absolutely apreciate the hell out of all your help. So bottom line.....either the head is cracked, warped, head gasket is blown, or piston rings are gone ????? None of which I'd feel comfortable doin' myself, but a mechanic is out of the question due to lack of finances. Soooo I gues I'd better start reading up on how to do these repairs. Any suggestions on some good literature or " how to " websites ??? As far as the question about the plug......it's black and wet, but the black wipes right off. The plug looks pretty good (light tannish color). Also, I live in a residential nieghborhood that is full of -ssholes who looooove to call the cops on me everytime I crank up my bike so it's difficult to " try " anything. I wil,l however, crank it up and see if the exhaust feels wet as soon as all my nieghbors leave for church. I'll post the results as soon as I have them. Thanks again everybody for takin' your time to help a brutha out !!!

helio lucas · Jun 28, 2009

http://www.eric-gorr.com/

those are pretty simple and straight foward repairs to do... :cool:
if even i could do it anyone could... and requires normal tools, nothing special...
organized dismantle of engine are the secret. keep every thing in the same order as you take out and will be easier to put in.
cleaning is second step. every thing should be clean, tools, working area and parts.
service manual is invaluable and online micro fiches great when you have doubts.
a digital camera is also great help.

do it slow, and give atention to detail. it will only hurts for the first time :laugh:

whenfoxforks-ruled · Jun 28, 2009

You should not HAVE to pull the cylinder. Unless you have an idea the top end is worn/too many hours? If you pull the jug, you have to at least put new rings in it. It is nice to know exactly where the engine is at time wise/wear. All you do know now is the head gasket is blown. An easy fix as Helio pointed out, and sent you to a solid source.

rmc_olderthandirt · Jun 29, 2009

cowasucky said:
So bottom line.....either the head is cracked, warped, head gasket is blown, or piston rings are gone ?????

It wouldn't be the rings, although it is probably past time to change them anyway.

The odds are that it is just a blown head gasket. If you were intent on getting the bike running ASAP I would just buy a new gasket/O-ring, swap it out and give it a shot. I am not familiar with your bike but on my bike I could swap out the head gaskets in about 10 minutes using nothing but a 12mm wrench. Err, make that a 12mm socket and torque wrench. Which means you also need a repair manual so that you know what to torque the head bolts down to.

cowasucky said:
Also, I live in a residential nieghborhood that is full of -ssholes who looooove to call the cops on me everytime I crank up my bike so it's difficult to " try " anything.

Well, as a general rule you shouldn't be making noise past 9:00 PM. If you are testing mid day and not riding in the street I would let them complain!

Rod

cowasucky · Jun 29, 2009

I tell you what......when I firstbought these 2strokes I wasn't able to mix my own gas. The knowledge I've gained from you guys here at dirtrider.net is unreal ! I've learned general maintenace & upkeep, mods, ridding techniques, rebuilt my entire clutch thanks to a couple of you out there, and you've gotten me through another one here it seems. I just ordered the head gasket and thanks to you all I feel confident that I can get this fixed on my own and inexpensively. I am so very greatful to all of you who took the time to wiegh in on this. You wouldn't believe how much it means to me and my 11 year old son, who are desperately trying to get into this wonderful sport, to have so many people to turn to and get quality advice from in a moments notice. Really, I'd have problably been forced to give up due to mechanics costs if it wasn't for the advice I've gotten here. So thanks again !!!

TRexRacing · Jun 29, 2009

If you can do the clutch the head gasket will be within your skills.

julien_d · Jun 29, 2009

Head gasket is a breeze compared to rebuilding the clutch. You should have no problem at all, and a top end gasket set can be had for pretty cheap. That is indeed more than likely your problem.

J.

cowasucky · Jul 2, 2009

Allright guys..... I got my new head gasket, got the head off, removed the old head gasket, now what exactly am I lookin' for ??? How do I know if the gasket is bad ??? What else should I do or look for while I'm in here ???

TRexRacing · Jul 2, 2009

Can you post photos of the head,cylinder and old gasket?Usually there will be a small stain or discoloration where the coolant was getting by from the water jacket to the cylinder.Sometimes it's not so obvious.Check to see that the cylindr and head gasket surfaces are flat and clean them up well with 3M Scotchbrite.Take your time and torque the head.Run the bike through a heat cycle or two,let it cool.Re-torque.

cowasucky · Jul 5, 2009

Changed head gasket, couldn't really really find an issue with the old one and the head, piston, cylinder, and rings looked to be fine.......atleast from what I could tell from visually inspecting it down into the cylinder and through the exhaust port where I removed the pipe to replace the springs and o rings. Put it all back together and it still smokes. I have a carb rebuild kit from moose racing that contains all the jets, needle, screws, springs, gaskets and float valve. Could the issue be with the carb ??? Any more ideas ??? I've got to figure this out by vacation on the 26th so I can take ny bike with me HELP !!!!!!!

sr5bidder · Jul 5, 2009

try to torque the cylinder bolts (not the head, look lower) there is a gasket there too and the coolant passes through the cylider into the crank case to get to the water pump..

I assume you mean smoking bad as in more than a 2stroke ought to.

next you would need to disassemble and check for warpage with a piece of glass and a feeler gage

whenfoxforks-ruled · Jul 6, 2009

Leak down test. When you purchase the kit from motion pro, it comes with the hardware to seal up the engine, pump a few pounds of air into the engine, and time its release. It has been a longtime since I have done this. There are methods of jury rigging your own test, but the exact psi and time of release are whats important. Or maybe just the fact you can see what is leaking? There is a thread in here on this subject, maybe someone knows where its at? Looking through the exhaust port is weak, it does not show much, most of the damage can be behind your line of sight. And there are a lot of bikes that the base gasket does come into play for sealing the coolant system, and the water pump seal also!

cowasucky · Jul 6, 2009

Here's a seemingly stupid questiion, but if I don't ask and it ends up being a factor......that would be even stupider (if that's even a word). When my head gasket arrived in the mail it was kinda bent or warped lookin' and there was this " coating " like maybe a teflon or somthiing on it that was peeling off all the way around on both siides so I rubbed it all off with my fingers and it came off pretty easily. I put that gasket on and torqued it down very carefully. I added the coolant and left it to sit overnight. The next morning coolant had leaaked out and was pooling all around the top of the jug as well as running down the side. So it was way worse than before I ever messed with it. At the advice of a fellow rider, I took it all apart and added a high temp gasket sealant around the gasket on top & bottom, put it all back together and let it set over night again. The next morning.....no coolant leaking out , but it now smokes worse than before. Should I get a brand new gasket and just try again ??? Is that teflon like coating supposed to be on there ??? Help !!!!!!

whenfoxforks-ruled · Jul 6, 2009

OEM or aftermarket gasket? Did you check the head for being flat? Are you sure all the studs are all the way in?

cowasucky · Jul 6, 2009

whenfoxforks-ruled said:
OEM or aftermarket gasket? Did you check the head for being flat? Are you sure all the studs are all the way in?

It's an OEM gasket. Is there supposed to be a coating on it or should it just be smooth, shiny metal ? I laid a straightedge across at a few different spots and it looked to be flat. I did not try to turn the studs down any. Everything " looked " good, but I'm no expert....hell I really didn't know what to look for. A couple of the studs were rusty lookin'.....not on the threads, but at the bottom. I was worried about getting some of the rust down in the water jacket. This is my first " :head job" lol so I have no idea what a problem would look like. All I know is that it's worse now than before. The old gasket looks to have a black coating cause around the center hole the coating was flaking and worn. I ordered a new one so I guess I'll try again.

whenfoxforks-ruled · Jul 6, 2009

Take 2 head nuts and tighten them together onto the stud. Then check the torque from the top nut. Check each stud. You need a 400 grit piece of waterproof open sandpaper. Put it on a piece of glass, spray some wd40 on it, keep the head flat and draw a figure 8, lightly cross sanding the surface will show if its flat, or make it flat. 2 times and check how much of the surface is sanded. Just enough to make it flat. Bad seals can come from the top of the cylinder also, usually the head or studs though.

white smoke, bubbles in coolant, need a leak down test??? How???

cowasucky

whenfoxforks-ruled

Old MX Racer

_JOE_

cowasucky

helio lucas

whenfoxforks-ruled

Old MX Racer

rmc_olderthandirt

cowasucky

TRexRacing

julien_d

cowasucky

TRexRacing

cowasucky

sr5bidder

whenfoxforks-ruled

Old MX Racer

cowasucky

whenfoxforks-ruled

Old MX Racer

cowasucky

whenfoxforks-ruled

Old MX Racer

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