250-500cc urgent help needed please, WR300 seized

My rekluse stays engaged on decel/downhills. It does not freewheel unless I touch the back brake, and then reengages when I take my foot off the brake. I am probably skidding the back wheel when it disengages.

Back a few years ago when my son was # 1 in the desert on a YZ 85 He would have it pinned all day he would never lift. If he needed to slow down he hit the kill switch. Amazing to watch pinned across a open area and at the end never lift just keep it wide open and hit the kill button. Did the same up and down hills to. Raced the YZ 85 for years and never seized it. We would mix around 32 to 1 with race gas. To give you a idea of how fast, I was a senior expert # 2 in the desert on a YZ 450 and he passed me a few times flat out across the desert on a 85. Ask Factory Husky racer Jake A. Jake will tell you Cameron beat him every time in the desert and never blew a motor back when they were racing 85s
I personally have never seized a 2 stroke some say not to do it but on long pulls instead of lifting which will cut off all fuel to the piston. I keep it pinned and hit the kill button. Works for me but many say do not do it.

back on the subject.. why is my piston so black but the head is spotless?


what does it say about jetting and all?

How long was that motor together? What does the underside of the piston look like? A black piston top is usually the sign of good or heading toward lean jetting. The crown of the piston gets hot enough to singe oil to its top and sometimes a spot on the bottom. Too rich jetting will show more "piston wash".

The real question here is why are you wearing a Breitling while working on your moto???


Here's mine. Was running good. Just off to check the O-rings when I had a coolant leak. Probably at 125 - 150 hours.

Thanks! 50 hours on engine. Forgot to check underside of piston, engine is still at dealer. Just wanted to check if that piston top does not point to other problems.

Ahmm.... . Because I forget they are there . And than my hands are to dirty to take them off

I also work in gloves . Box of 500 for $10 at harbor freight

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The piston top on the right corresponds w the piston underside on the bottom. The one on the right runs strong top to bottom and didn't get so hot that it burned oil to the bottom side...hope this helps. The pistons to the left were the stock jetting. The one all the way to the right is the jd kit. You can see the patterns left by the transfer ports on the piston to the right. They are mostly symetrical. This is a indication that they are flowing equally or close to it. If one side flows more than the other it will push the pattern to one side or the other. There is a bit of a safety margin in my jetting because two of the hs races i do involve sand, and we all know what that means..WTFO!!! Lol

Thanks, I asked dealer to save piston, so will check on the bottom.

Just want to make sure that nothing other than my stupidity caused seizure

Lol. Shit happens!!! If you don't learn from it, then it's just stupidity!! Ha

All,

Just a little info concerning engine temps. I have a 2003 KX 250 and a 2014 WR 300 with the thermostat installed. Both have the Trailtech Voyager on them so I get real time data on radiator/water temps. The sensor is mounted in the hose coming from the head going to the radiator so the reading will be at it's hottest. I have been using the Voyager for 1.5 years now, and these numbers are consistent and repeatable every time I go ride.

On a cold engine in an ambient temp of approx. 70 deg. F, after the initial start and 2 to 3 minutes of idleing, both bikes will have a water temp of approximately 100 to 110 degrees F. Generally, it takes 4 minutes or so for either bike to get to 130 - 140 F when idleing.

When riding, many times neither bike gets much above 150 - 160 even at 90 deg. ambient when we are riding some of the faster trails. When we hit the slower trails and single track both bike temps will climb into the 170 to 180 range and stay there with even the slightest amount of air flow. Only when we are basically crawling with no air flow will the temps approach 200 deg.

I guess I said all of that to say this. 2 minutes of idleing is not near enough time to heat the engine and allow proper expansion, expecially on a cold ambient day. After seeing these numbers for 1.5 years, I now start my bikes and let them idle for a good bit while I'm getting my helmet on etc.... and even at 140 degrees, I take off slow for a couple of minutes before throttling it.

This is only my experience, file it where you wish.....


Edit: This is with a 32:1 mix ratio and JD Jetting on the WR and stock jetting on the KX. As a side note, I've never seen an engine die from to much oil but have seen plenty die from too little oil...... YMMV.

many thanks GhostRider!! it was about 75F on that morning.

This area here... is actually quite cool this time of year.

not lacking power any more I am waiting for things to get sorted out with that new rod. I am monitoring that thread in your section. I am changing to something other than 50:1 for sure now..

I am running and planning on continue to use Amsoil interceptor.

Good oil. Just use more next time.

My truck takes 4 1/2 quarts, but i'm only going to use 2 1/2. Who needs all that stupid oil sloshing around in there and making things slippery!!!