Hello, I have recently done a whole top end on my 2006 klx125 and now when the bike warms up, it squeals and dies, I can keep it alive with throttle *the squeal changes with RPM* but the engine won’t go past 5000 rpm, before the top end rebuild it ran decently; but I replaced it due to smoke, any help would be greatly appreciated,
Maybe the valve timing is off? Is the timing chain on correctly?
- Thread starter
- #4
I’ve checked the valves, I don’t believe they are off any, unless the tdc mark on the flywheel is off,
- Thread starter
- #5
I did have to replace a small missing washer, but I found it under the bench after cleaning, also, the bike ran clean for about 3 minutes, then it began making noise, I’m stumped on this, out of the few rebuilds I have done (2 strokes) i Also don’t think anything else could have fallen in because when I wasn’t working on it I made a point to put all the covers back on and keep the engine isolated, (I rebuilt this in my basement so garage debris isn’t a huge concern) I’ll tear it back apart for the third time today, I’ll post some pictures of some stuff for you guys to look at.
edit; when I put a bit of two stroke oil into the cylinder the noise went away, it was just an attempt to see if it was the piston, the noise wasn’t there until the oil burnt off.
- Thread starter
- #7
It’s a single oil pump I believe, it may need synthetic? My father said to run petroleum non synthetic to break in the top end, but maybe that’s the issue?
truespode
Moderator / Wheelie King
- Jun 30, 1999
- 7,980
- 249
As long as it is good quality oil it won't cause the squealing. Something is rubbing that shouldn't be and not getting enough lubrication or air is flowing through something creating the sound.
I've ran Rotella in my CRF's back in the day and Mobil 1 and all sorts of others with great results.
Something happened on the rebuild that either is preventing lubrication from getting where it should or blocking off air flow of some sort or allowing air to flow where it shouldn't (maybe the exhaust is not installed correctly or piston in backwards (doubt that though).
I wish I could be of more help. We have some bright people who have built a lot of race engines in the past (I'm not one of them) and understand engines at the design level but they don't stop in every day. I have a message out to who I consider the best of the best and hopefully he'll get a chance to take a look at the thread soon.
I've ran Rotella in my CRF's back in the day and Mobil 1 and all sorts of others with great results.
Something happened on the rebuild that either is preventing lubrication from getting where it should or blocking off air flow of some sort or allowing air to flow where it shouldn't (maybe the exhaust is not installed correctly or piston in backwards (doubt that though).
I wish I could be of more help. We have some bright people who have built a lot of race engines in the past (I'm not one of them) and understand engines at the design level but they don't stop in every day. I have a message out to who I consider the best of the best and hopefully he'll get a chance to take a look at the thread soon.
- Thread starter
- #9
Okay thank you for that, today I put a small amount of oil in the cylinder and have discovered the rings are making the squeal, cause with lube they stopped the new question is now, why are the rings squealing? And it’s probably because they need a different type of oil, so I’m gonna try synthetic and I’ll keep you updated.
Sorry for the delay getting to this.
The KLX is a very simple engine design, very rugged but very simple. It won't care if you use synthetic or mineral based oil as long as it's even close to the correct specification.
If you put oil into the cylinder and your noises quieted down the odds Then there is unintended metal to metal contact.
The likely possibilities are the compression are fitted with too little end clearance. The compression rings have a small clearance space that needs to be verified in the barrel but off the piston. This clearance is necessary to make sure the ring ends don't butt together as the engine heats up and the metal of the rings expands. If they butt together this keeps the rings from compressing together enough to fit the bore basically making them oversized for the bore due to metal expansion. The manufacturers usually make the rings with too little clearance so they can still be used in excessively worn cylinders.
The other thing that comes to mind and what my guess is based on how many times I've seen it happen is the scraper rails or the spacer for the oil ring package slipped during cylinder installation and are now overlapped and doesn't fit the bore correctly.
For those not familiar with what a four-stroke piston ring package looks like, it usually consists of one or two compression rings that are similar in shape and function to what you're familiar with on a two-stroke engine. Underneath these compression rings is an additional ring package that consists of two very thin flat spring steel rings that are separated by a wavy spacer. The picture below should make it clearer.
When you're assembling the cylinder onto the new piston it's pretty easy to have the oil ring package squirm around a bit and overlap enough to cause the problem you're describe.
It's happened to everyone at some point if you put together a lot of four-strokes.
As painful as it sounds I'd HIGHLY recommend you take the engine back apart and look for signs of damage to the bore. High pitched noises from the engine that are cured with excess oil are a sure sign of some unintended metal to metal contact, Unusual wear marks will tell you the details of the story that you need.
Good luck, and don't feel bad about this. Every great engine builder from the guy at the local track to Byron Hines has been through this at some point. You'll learn from it and be part of a big club who acquired something valuable once you sort it out.
The KLX is a very simple engine design, very rugged but very simple. It won't care if you use synthetic or mineral based oil as long as it's even close to the correct specification.
If you put oil into the cylinder and your noises quieted down the odds Then there is unintended metal to metal contact.
The likely possibilities are the compression are fitted with too little end clearance. The compression rings have a small clearance space that needs to be verified in the barrel but off the piston. This clearance is necessary to make sure the ring ends don't butt together as the engine heats up and the metal of the rings expands. If they butt together this keeps the rings from compressing together enough to fit the bore basically making them oversized for the bore due to metal expansion. The manufacturers usually make the rings with too little clearance so they can still be used in excessively worn cylinders.
The other thing that comes to mind and what my guess is based on how many times I've seen it happen is the scraper rails or the spacer for the oil ring package slipped during cylinder installation and are now overlapped and doesn't fit the bore correctly.
For those not familiar with what a four-stroke piston ring package looks like, it usually consists of one or two compression rings that are similar in shape and function to what you're familiar with on a two-stroke engine. Underneath these compression rings is an additional ring package that consists of two very thin flat spring steel rings that are separated by a wavy spacer. The picture below should make it clearer.
When you're assembling the cylinder onto the new piston it's pretty easy to have the oil ring package squirm around a bit and overlap enough to cause the problem you're describe.
It's happened to everyone at some point if you put together a lot of four-strokes.
As painful as it sounds I'd HIGHLY recommend you take the engine back apart and look for signs of damage to the bore. High pitched noises from the engine that are cured with excess oil are a sure sign of some unintended metal to metal contact, Unusual wear marks will tell you the details of the story that you need.
Good luck, and don't feel bad about this. Every great engine builder from the guy at the local track to Byron Hines has been through this at some point. You'll learn from it and be part of a big club who acquired something valuable once you sort it out.
- Thread starter
- #11
Thank you for this, I’m fine with tearing engines apart again (nothing but time on my hands) and I actually bought two sets of the oil rings, scared of breaking them, and will be able to replace them, the compression rings came back to about 0.05 on a feeler, when I looked it up people said it was fine so I had assumed, never the less I shut the engine off the second the noise would start after figuring out it was top end, I hope that the cylinder isn’t scored, would it be? The first time I rebuilt it the cylinder looked fine, so let’s hope for the best.
Even if the cylinder is scored it might be salvageable. Hard to say until it's opened back up.
This question isn't meant to be insulting but it kinda needs to be asked at this point.
Do you have the FACTORY service manual for your engine? It's going to be super helpful in determining clearances and the proper ways to measure them. I've built a lot of engines over the years and the first tool I grab is the factory service manual.
Good luck and let us know what you find.
This question isn't meant to be insulting but it kinda needs to be asked at this point.
Do you have the FACTORY service manual for your engine? It's going to be super helpful in determining clearances and the proper ways to measure them. I've built a lot of engines over the years and the first tool I grab is the factory service manual.
Good luck and let us know what you find.
Did you resolve the problem ?
