2019 Hawk, ~700 miles, broken exhaust valve
 

I bought my Hawk in April, looking for a good bike to get back into riding for the first time in 20 years. It went together well, with really no issues or complaints until yesterday. on a street a couple of miles from my house, while riding home, i heard a metallic pop and the engine quit. no ability to restart, and with the fast crank, i could tell there was no compression. I tore into it tonight to get more info on the failure and found that the exhaust valve broke and dropped into the cylinder, causing all kinds of fun stuff to happen. needless to say, I'm not too happy about the bike anymore.

I'm working with the dealer I bought it from as it's still under 90 day warranty. I will let you all know how that goes if your interested.

I have some video of the carnage posted on my YT channel, and will give the link if anyone's interested. but since I'm semi-new here posting, I didn't want to spam unwanted links just yet.

You had a very rare failure. I wouldn't let it tarnish your view of the motor or the bike. Just bad luck really. Hopefully they decide.to replace the whole engine.

Thanks, I appreciate your response. I'm actually pretty happy with the bike until now. it is fun to ride and is/has serving it's purpose of stoking my interest while keeping me out of trouble. I am even at a point where I don't mind putting in some wrench time to get this back up and running.

I'm doing the back-and-forth now with the dealer to determine next steps. Can't say I'm unhappy yet as they ask for information to support my claim.

here are a few pics of the damage:

These engine are pretty solid. My Hawk is over 3 1/2 years old with close to 8,000 miles. Still running strong. More than likely it was just a defective valve that gave away. Hope the dealer takes care of it. If not, you can get the top end parts from Brozz250. https://shop.brozz250.com/eshopdetai..._250_Parts.htm

There was some metal chunks in the oil and filter screen, so it looks like the damage went through the piston and potentially further. i'm wary of the bearings eating themselves later because of that. Any thoughts from folks who have been through this motor on bearing tolerances and rebuild issues I should watch for?

I'd just strip it down and see what you've got to deal with, it's possible that the bottom end is perfectly fine.

Thanks, franque. I'm hoping that's the situation as well. If the bottom end is ok, I would be looking at a parts list to replace of:
-cylinder head with valves, springs, retainers
-head gasket
-cylinder jug
-base gasket
-piston, piston rings (and potentially connecting rod, wrist pin and retainers)

am I missing anything that jumps out to you or anyone else? again, not sure yet, going to tear into it more tonight.

These connecting rods are pressed on, you won't easily be able to just get the rod, crankpin, etc. It'll be easier to just get a whole new crank, and usually the bearings come with it!

pressed on... at the wrist pin? or at the cap on the crank? i'm wondering now if the crank has to come out, how deep this rabbit hole goes...

Me, personally, I would push for a new motor. If that metal got into the oil, then it also got into the rollers and needle rollers of the bearings, and the number one cause of roller bearing failure is metal particulate. That doesn't mean your motor couldn't be put together and run for a long time, but it would be a gamble. The crank bearings also just got slammed a few times by trying to compress a valve with the piston and head.

Yep, I'm with Dan on that. The crank is pressed together, the wristpin is a slip fit. Hopefully they'll get you a new motor!

700 miles, less than 90 days? yes, you deserve an engine assembly to make things right.

The dealer I bought this from, who is several states away from me, has indicated their reluctance to provide an engine assy replacement so far. My plan is to tear it down farther to see the damage and get some pictures and video. if the con rod cap is pressed, I'm imagining that the crank, con rod, and piston all come as one assy?

If you don't mind asking, who is the dealer? They clearly need to replace the engine.

I haven't named them yet because I'm not wanting to advocate for or against them just yet. I will name them once I receive direction on this claim and am able to judge their level of assistance. but I think it would be unfair to them until i get a proper, final response.