125-200cc Cr144 cold seize oh my back !!! Advice?!?

What main are you running? Lean seizure?

Heath

460 main 45 pilot #4 slide clip is in the third slot. Bike didn't smoke much at all but I thought it was just jetted good, however I'm kinda thinkin it was sucking air somewhere. I sent my cylinder back for replating and my bottom end off to have new bearings and seals installed and I bought all new gaskets top to bottom. Oh my carb to reed boot looked a little cracked not much at all so I ordered a new one. Bought me a 490 main dropped a clip position and stepped up one size on the pilot. If this bike seizes again I'll unhook the fuel line and strike a match and watch it burn. I'm so aggravated with this thing. Oh the reeds looked new as well.

Wow.... I really think you need to really work on jetting that bike. I would also check your intake boot for crack or a poor seal. Rebuild it, rejet it and check for leaks. Go easy on the WOT for the first little while until you get things sorted. Consider a lectron carb too.

I know you will think this is crazy, but it is something I have seen some time back.
If you are running a synthetic gear oil and a petroleum based premix oil ( or vise versa) and you have a very small leak on the clutch side crank seal there can be a problem with seizing. The 2 different products can create a very strong glue under heat and pressure if they combine in a 2 stroke engine cause a seizure. The top of the piston seems to be showing this in the photos.
This may not be the issue, but I sure would at least check it out.

Paw Paw

If it's too lean, it will eventually sieze at wot. The leaner it is, the quicker it will go.

You can build a leak down tester for about $20, here is a link to one similar to the one I built:

http://www.3wheelerworld.com/showthread.php/96856-Make-a-leak-down-tester-for-about-20

That will let you know if your seals are good and if you've got a leak anywhere. If it does have a leak and you can't find it, spraying soapy water around the seals, carb boot, and cylinder base should help nail it down.

If it doesn't have a leak, your main jet is too lean.

Good Luck.

Thanks guys. I'll let you know how the rebuild goes. And that is some good info on the synthetic gear lube and premix. I had never heard that before. I work at a radiator repair shop so I'm set up for doing a leak test I'm gonna do one before I start it. Hopefully the carb boot and crank seals fix it because I love this bike. I think it's a seal though because it appears to have been stored for a long time. The o ring in the carb after you remove the float assembly was as hard as a goats horn and was leaking so I thought my float was sticking but anyway I replaced that and it does make sense that my crank seals could be in the same shape. It should be back together in a week but it will take me longer to find time to fiddle with it as my wife and I are expecting our first child in a few days. Thanks again everyone.

Oh and I'm at 500 feet elevation if that helps any. What type of oil do you guys run? I was thinkin about trying something else? Any recommendations?

Never seen a synthetic oil that wont mix with a mineral / petroleum based oil EVER !
Yep I stand to be corrected but it goes against everything I was ever taught and every engine builder that I have the pleasure to meet.
Ive even known people to put a little pure castor oil to their synthetic premix just for the smell with no harm done although I personally dont think it a wise idea, Castor likes to stick to the hottest parts of a engine but still wont turn to glue even in the worst cases.

Well I think I've got it figured out. The wet side crank seal lip was rolled out just a little so that could've been a factor. The carb boot was pretty poor looking and I changed my main from 460 to 490. It's just a little rich but I'm fine with it. It revs a lot further now. I spent 900 bucks over 60 bucks worth of seals, a 30 dollar boot and a 4 dollar jet. Thanks to everyone for the help. I was ready to put my old Honda cr250 in it and call it a day but I'm glad I didn't I really love this bike now that I've got all the kinks worked out. Now I've just gotta convince my wife to trade her yz85 in so I can get her a husky. Hehe

EDIT: Didn't notice the second page where you figured out your problem. Glad to hear you got it sorted out!!

It sounds to me like your jetting is way lean if you've seized your engine twice. Looking at your plug it would appear that this is the case, looks a little too clean. How long were you at WOT in 6th before it seized? You should be able to hold that thing wide open (once its warm) and not have it seize if it is jetted properly. Also, I'd make sure all of your intake boots/flanges/gaskets are sealed properly.

Lean isn't the problem with a 460 main and 45 pilot. I'm 460/30 with a #5 slide at the same altitude and my bike sees a lot of WOT with no issues. Has to be the seal

Yesterday the wife and I went on a little Mother's Day ride. I noticed my bike had some gas coming out of the overflow but I thought since we weren't going very far it would be fine. It was not however. You could ride it a mile and it would die as if we're running out of fuel. Then you could wait a minute or two and it would start leaking fuel again and the bike would start and run great for another mile and then it would do it again. If you only ran it under 1/3 throttle it would run all day but it would only leak after you shut it off not while it ran. Any advice? Does anyone know what the float height is supposed to be? I just replaced the o ring around the inlet needle because it was bad just before it blew up last time.thanks again.

Hello everyone and happy new year. At the end of May in 2017 I was so fed up with my cr144 I decided to sale it. A few bikes later I had the chance to buy it back and so tonight I did.

The fellow I sold it to was a little older and barely did ride it so it's basically in the same shape it was when I let it go. I did manage to jet it. It idles, starts first kick hot or cold. However there's still a huge problem. It has absolutely no power what so ever. It doesn't smoke like a crank seal is bad. It doesn't have any bogs or hesitations. It just has no power.

After owning many two strokes. Such as countless Honda 125s 250s and bad ktm 200sx. I know these things should have atleast enough power to pull a front wheel in 2nd but mine does not. Power valve is working, I replaced the reed boot twice. New carb seals twice. New crank seals. 2 pistons. The timing hasn't been tampered with. Cleaned the header pipe out, repacked the silencer and it still has no power. Any ideas? could the seizes( there were 2 of them) have hurt the crank bearings? It didn't feel as if it had any bad spots. I'm not lookin for a 450 killer here I just don't wanna get my ass smoked by a drz125. (Hasn't happened but one probably could right now) should I buy a new carb? Or just send the motor somewhere with a blank check?

you must have a good 2-stoke guy in your race club that could help you. these are great durable bikes

Do you have a compression tester? I would probably start there and test the compression. Try and eliminate the easy things first, then work up to the more complex. I have had bikes that had a partially clogged pilot or main jet(s) that ran much much stronger after I cleaned or replaced the jet(s). If those all check out ok, try a new plug and make sure the air filter is clean (take it off and check, maybe there is something clogging the air passage. You never know what the last owner did or forgot in there. Hope you find the culprit! If not, please sell me your 144. I'd love to have one of those! Hahaha

If the fuel is stale, that could be a problem too. Maybe put in some fresh gas?

I've done all of that except for the compression test. I've been through that carb so many times I'm pretty sure I could do it drunk and blindfolded with one hand. lol I've contacted Walt though so I'm pretty sure it'll be a screamer this summer. However if that doesn't work you won't have to buy it because I'll give it to you.

Check the power valve & linkage is working correctly Dave, How did the compression test go?