Hawk 250 Won't Start, Stuck Valve? - Page 2

Thumper · 03-01-2022, 09:04 AM

Quote:

Originally Posted by FatHead

My new Hawk 250 was running fine for about the first hour at the ORV park. Just gently riding some trails to break it in. Then it died, and couldn't be restarted electric or kick. I brought it home and checked everything from the spark plug to air filter and fuel. All good. The carb seemed fine too (though I'm no expert). I read on here about valve clearance sometimes being an issue, so I pulled the valve cover. As I was trying to find TDC I noticed that only the exhaust valve was moving. I've gone through several cycles and the intake valve never moves. The curved rod that pushes the rocker up and closes the exhaust valve moves freely, but the matching rod for the intake valve is barely visible (so I'm assuming it is stuck down) and therefore never pushes the valve closed.

Any ideas on how to fix this would be greatly appreciated. This is my first dirt bike since childhood, and I'm no spring chicken...I'm also no mechanic so please use small words lol.

You were obviously on top of this from the start. If you have no evidence of interference (valve damage) and you free the valve you will be faced with the choice of going to bat on a warranty head replacement or just reinstalling and getting it running right. Warranty may be an uphill battle if the valve is moving again. Then again, it could be fixed and without any significant damage to the valve seats. Good luck!

FatHead · 03-13-2022, 07:20 PM

So I don't have a way to host a url to the picture, but what I found when I took off the head was the intake valve was bent towards the rear of the bike. It is about a quarter inch gap between the head and the and the inside edge of the valve. It can't seat itself in the recessed are, and obviously can't seal.

There are what appear to be 2 strike marks on the valve from piston contact, but the piston surface is unmarred. I'm not sure it could have jumped timed and the piston whacked it twice before it was so far out of line that the engine died, or if it overheated and warped and the piston hit it then.

360Powersports is covering it under warranty and sending me a new part. Now I just need to make sure the problem wasn't timing...before I put it back together and have it happen again.

Megadan · 03-13-2022, 11:49 PM

Quote:

Originally Posted by FatHead

So I don't have a way to host a url to the picture, but what I found when I took off the head was the intake valve was bent towards the rear of the bike. It is about a quarter inch gap between the head and the and the inside edge of the valve. It can't seat itself in the recessed are, and obviously can't seal.

There are what appear to be 2 strike marks on the valve from piston contact, but the piston surface is unmarred. I'm not sure it could have jumped timed and the piston whacked it twice before it was so far out of line that the engine died, or if it overheated and warped and the piston hit it then.

360Powersports is covering it under warranty and sending me a new part. Now I just need to make sure the problem wasn't timing...before I put it back together and have it happen again.

If the piston is damaged you might want to see if they will send you a new one too. Timing is easy enough to check. You will need to remove the left side engine case and pull the flywheel, but you can look at the cam and crank teeth and see if the two dots align for TDC. The chances of this engine jumping timing are pretty dang small though. The cam is a tight press fit to the gear and located with a pin and everything is gear driven.

I would say the most likely scenario is just a valve failure that just didn't happen to break off. Wouldn't be the first guy to have that happen here. Not super common, but not unheard of either.

TheDarkMagician · 03-16-2022, 05:43 PM

Hello i literally just did my valve adjustment on my magician and i know EXACTLY what you are talking about with only the exhaust valve appears to move. Mine was the exact same way but mine seems to be runnibg fine. My bike only has around 200 miles just put on a new carb did the valves so i could dial in the new carb more accurately and it needed to be done. My magician seems to be running really well though? Im not as knowledgeable as the ppl who have already messaged on this thread but could it be possible these engines are like that? And i cant believe no one said anything but are you sure it is not the carb? When i first got this bike it ran fine at the dealer ( i actuallu got it from 360 while in texas) and i couldnt get it started when i got home and it took me forevwr to figure out it was the fuel system. The tank was low and it wasnt getting enough fuel pressure. It was so lean it wouldbt rven run if the tabk wasnt more than half full. The carbs are garbage anyways evdn though it was geting fuel when the tank ran low it wasnt getting enough which is what threw me off. Kinda worried i have a stuck valve now though. Wouldnt it be not running right if it was a stuck valve?

03-13-2022, 07:20 PM	#17
FatHead Join Date: Feb 2022 Location: Eastern WA Posts: 5	So I don't have a way to host a url to the picture, but what I found when I took off the head was the intake valve was bent towards the rear of the bike. It is about a quarter inch gap between the head and the and the inside edge of the valve. It can't seat itself in the recessed are, and obviously can't seal. There are what appear to be 2 strike marks on the valve from piston contact, but the piston surface is unmarred. I'm not sure it could have jumped timed and the piston whacked it twice before it was so far out of line that the engine died, or if it overheated and warped and the piston hit it then. 360Powersports is covering it under warranty and sending me a new part. Now I just need to make sure the problem wasn't timing...before I put it back together and have it happen again.
	0

03-16-2022, 05:43 PM	#19
TheDarkMagician Join Date: Feb 2022 Posts: 33	Hello i literally just did my valve adjustment on my magician and i know EXACTLY what you are talking about with only the exhaust valve appears to move. Mine was the exact same way but mine seems to be runnibg fine. My bike only has around 200 miles just put on a new carb did the valves so i could dial in the new carb more accurately and it needed to be done. My magician seems to be running really well though? Im not as knowledgeable as the ppl who have already messaged on this thread but could it be possible these engines are like that? And i cant believe no one said anything but are you sure it is not the carb? When i first got this bike it ran fine at the dealer ( i actuallu got it from 360 while in texas) and i couldnt get it started when i got home and it took me forevwr to figure out it was the fuel system. The tank was low and it wasnt getting enough fuel pressure. It was so lean it wouldbt rven run if the tabk wasnt more than half full. The carbs are garbage anyways evdn though it was geting fuel when the tank ran low it wasnt getting enough which is what threw me off. Kinda worried i have a stuck valve now though. Wouldnt it be not running right if it was a stuck valve?
	0