Jump to content
Sign in to follow this  

Help! scared to pull apart my engine

Recommended Posts

So started riding a year ago and have an awesome 2006 KX 250F. Now if I could only have my feet touch the ground when sitting on the bike would be awesome but I have learned to deal. Anyway, the bike always started awesome. One good kick with the choke when cold or one kick with the hotstart once warm. Only reason it would take two kicks to start is when I am getting tired and gave it a crappy kick, or i fell over and flooded the carb. Still learning.  I went to take my bike out the other day and I couldn't get it to start, had no compression. Managed to get it running with two friends pushing it and me popping it into gear and it ran... ok... but would not idle and would die instantly.

 

Well come to find out (after we found out it wouldn't start of course) that my brother and friend (who didn't know anything about dirt bikes) took the bike out and was just putting around the property and ended up over heating the bike. I guess it required about 3-4 cups of coolant. Friend said that he stopped it as soon as he heard the cap pop and things boiling over and waited for it to cool a while. Then rode it about1/4 mile back to the house and put it away.

 

I know that there is going to be damage when I open it up but the most I have over done myself is general maintenance and rejetting the carb. I'm not very mechanical but I am wanting and willing to learn. I'm hoping someone on here will give me an idea of what type of damage I can expect and point me in the right direction. I have another friend that is willing to help along with my brother who are both very mechanical but they have a tendency to take over unless I have an idea of what is going on.

 

Thanks for help!

Share this post


Link to post
Share on other sites

I'm not sure about overhearing issues and what that could do but it sounds like there might be clogged jets and needs a carb cleaning. If you do a carb cleaning, make sure you flush the gas tank and install a fule filter.

Share this post


Link to post
Share on other sites

With the bike being overheated and loss of compression I would expect piston damage. Don't try starting the bike any more. You can remove the exhaust pipe and look in at the piston through the exhaust port. to check for damage. Look for scratches and ring damage while turning the engine over slowly. Get some experienced help if you pull the cylinder(not your brother or his buddy!) Not a big job but you need someone who knows what they are doing.

Good Luck!

Share this post


Link to post
Share on other sites

With the bike being overheated and loss of compression I would expect piston damage. Don't try starting the bike any more. You can remove the exhaust pipe and look in at the piston through the exhaust port. to check for damage. Look for scratches and ring damage while turning the engine over slowly. Get some experienced help if you pull the cylinder(not your brother or his buddy!) Not a big job but you need someone who knows what they are doing.

Good Luck!

no, you can't see the piston through the exhaust port....this is a 4stroke. If they over heated to that level then there could be damage to the piston and rings, maybe cam bearings too....it could be anything. You are going to have to drain coolant and oil, remove water lines, tank, cams, timing chain, then remove head nuts and pull head off, then cylinder. Use rings in a few places of cylinder to check ring end gap and see if the cylinder got warped. Put head on glass and measure any warpage by putting feeler gauges between head surface and glass. Get a shop manual and act as if your bike is a lego, they takes you step by step and as with any bike I've had in my 27 years of racing......don't try to rebuild without the manual, no matter how many you do or have done, model changes sometimes change certain specs and require you to know that. Don't remove a bolt without a shop manual.
  • Like 2

Share this post


Link to post
Share on other sites

no, you can't see the piston through the exhaust port....this is a 4stroke. If they over heated to that level then there could be damage to the piston and rings, maybe cam bearings too....it could be anything. You are going to have to drain coolant and oil, remove water lines, tank, cams, timing chain, then remove head nuts and pull head off, then cylinder. Use rings in a few places of cylinder to check ring end gap and see if the cylinder got warped. Put head on glass and measure any warpage by putting feeler gauges between head surface and glass. Get a shop manual and act as if your bike is a lego, they takes you step by step and as with any bike I've had in my 27 years of racing......don't try to rebuild without the manual, no matter how many you do or have done, model changes sometimes change certain specs and require you to know that. Don't remove a bolt without a shop manual.

..

 

My mistake! Thought it was a 2 stroke.

Share this post


Link to post
Share on other sites

Boiling over is not really an indication of catastrophic engine failure.  Loss of compression may be stuck valve.  Top off the coolant, clean the carb paying attention to the pilot jet, reassemble and try again. Have you popped the valve cover off to check the valves?  That should be done and check the compression release while you are there.  Do a compression test too.  Look to see if the valve tappets under the cam are all moving down and up evenly.  If the old 04 has any amount of time sell it for parts and get a newer one with lower hours.   Where in Oregon?

Share this post


Link to post
Share on other sites

Willamette valley.

I haven't actually done any work to it yet. The garage is currently being used replacing the bottom end of a yz450f. Didn't want to tear apart two bikes in the same area and risk getting the parts all mixed up. The bike is an 06 and really hasn't had a lot of tlc but also spent most if it's life sitting on a stand as a shop decoration. Guy sold it cause he only rode it once in two years. When I bought it changed all the fluids and rejetted the carb and the girl has run flawlessly! I love this bike and want to get it up and running again.

Thanks for the suggestions on where to start. I'll post what I find when I start working on her.

Share this post


Link to post
Share on other sites

Sounds good. I am on the coast, I know my ID says Alaska, but I live in Oregon for a little bit longer.

Share this post


Link to post
Share on other sites

How was the compression while running? What makes you say no compression? LOW compression on an 06 id believe, but if it ran with some pep its got compression. Lack of starting after starting good for awhile first of course tells us carb. Second tells us valves. Have they been measured? If theyre out of spec. Maybe just get the right shims in and see how it starts/runs. Then you could just get a compression test to give you an idea about getting new rings.

See, little work as possible. Least money in parts. If youre not racing. Just get it running. Valves tighten up and need new shims with time. See if thats it.

Thats what id do considering it was just running and starting. And ran when you jump started it.

Overheating is what they do. Go faster. Where was it coming out? You could get a higher pressure cap. Also replace ( should do whole right side) but replace gaskets and seals in water pump. Behind the impeller change that seal.

Those seals and shims, is less than 50 bux. * edit: oh yeah plus a 1.6 rad cap. Still under $50

Depends how bad you want/need/can afford new piston/cams/valves etc...

Try a valve measurement first

Edited by notoriousE-R-I-C
  • Like 1

Share this post


Link to post
Share on other sites

I say no compression cause I could move the kick arm down with minimal effort. Previously it always had good resistant when I kicked it. When I did get it to run it just seemed like it wanted to die if I didn't have enough throttle and if I gave it more it started to backfire. Sorry I'm not really good at explaining. I'm still learning more about mechanics.

Edited by themotogirl

Share this post


Link to post
Share on other sites

How was the compression while running? What makes you say no compression? LOW compression on an 06 id believe, but if it ran with some pep its got compression. Lack of starting after starting good for awhile first of course tells us carb. Second tells us valves. Have they been measured? If theyre out of spec. Maybe just get the right shims in and see how it starts/runs. Then you could just get a compression test to give you an idea about getting new rings.

See, little work as possible. Least money in parts. If youre not racing. Just get it running. Valves tighten up and need new shims with time. See if thats it.

Thats what id do considering it was just running and starting. And ran when you jump started it.

Overheating is what they do. Go faster. Where was it coming out? You could get a higher pressure cap. Also replace ( should do whole right side) but replace gaskets and seals in water pump. Behind the impeller change that seal.

Those seals and shims, is less than 50 bux. * edit: oh yeah plus a 1.6 rad cap. Still under $50

Depends how bad you want/need/can afford new piston/cams/valves etc...

Try a valve measurement first

 

I totally agree here.. sounds like its just the valves out of spec and was being rode really slow.. 🤦  fill the rads, 1.6 cap definitely will help and shim the valves, she will be good to go in no time at all. :ride:

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

Reply with:

Sign in to follow this  

×
×
  • Create New...