I'm back guys. I picked up a 2009 last weekend. Its got 19,000 miles on it and was advertised as needing a rebuild or parted out. I got it for $550 and figured I would make it a 351 or replace the whole motor depending on the issue. Here is where I am so far.

I've got the carb cleaned (new jets) and new battery installed and got the KLX250s put back together. I checked and adjusted valve clearance so I know they are in spec. The bike also has a manual cam chain tensioner that I adjusted so I know its not cam chain noise. I believe its coming from the piston area of the motor and may be the piston or rings.

Symptoms:
Hard starting (need starting fluid if cold start)
If you take the choke off before its really warm it dies

Here is a video I took with the choke on and the bike running around 4500 RPM


Here it is at idle


What do you think? Should I do a compression or leak down test? I don't have the equipment to do that, so should I just tear the motor down to the jug and piston and see?

 

That almost sounds familiar...
Pull the oil filter and cut it open-if there is a pile of metal get ready for a new crank.

 

I just pulled the filter and cut it open. No metal other than from where I sawed it in two. Although I don't know when the oil was changed last so metal could have been in a previous filter.

I'm afraid I'm probably just going to have to drain all fluids and start removing parts till I find the issue.

 

Is splitting the cases required to inspect the crankshaft gears?

 

I would look at the piston first, the crank would be the last thing to go...almost.

 

I spent all day yesterday tearing into the motor. I started on the clutch side of the bottom end and removed the clutch basket and plates so I could get an eye on the crankshaft gear that drives the cam chain. All was good there an no broken teeth like I have seen a couple other post in the past. So I decided to go in to the top end and check out the piston and cylinder. Those both looked pretty dang good for a bike with 19,000 miles on it. I removed the piston and checked play on the rod, very little side to side which I have read is normal and no up and down play. At the end of the day I did not find anything out of the normal.

Where should I go from here? I think about the only think left that it could be would be the crankshaft bearings, but I couldn't feel any play in the crankshaft when using the rod to try and move it.

Should I just put it back together and ride it? I'd like to do a 351 but am kind of hesitant to spend that kind of money and then have something severe happen.

 

First I would measure the piston and cylinder bore to find what clearance it is at. Many times parts can look great but be running with huge clearances.

 

Get a cheap stethoscope and try to find out what part of the engine the noise is originating in. https://www.harborfreight.com/catalo...&q=stethoscope

The cam journals are known to get wiped out when the oil level drops to far.

Ride on
Brewster

 

I don't think it matters any longer. I screwed up. You can see in the bottom left hand corner of the picture the bolt hole is busted. I did not reach the recommended torque value listed in the manual before this happened. I new head is $700+, a used motor around a grand. I'm not sure its worth it. I could just part it out.

 

None of the pics are displaying for me.

At least you don't have much money into it. Should be able to recoup your investment pretty easily.