Hawk 250 won't stay on

Vipet711 · 05-31-2019, 09:56 PM

Ok so I know alot of things can contribute to your bike not staying on. Fuel spark and air. I am new here and new to motorcycles in general. I like to consider myself mechanically inclined, but not so much in any thing that has combustion. So I followed everything on China riders. Got my bike, built it, changed the stock oil, put a mikuni carb, change sprockets. And that's about it. For the first 300 miles it has been riding great. It wasnt until a co worker of mine wanted to ride it and I let him. So he was riding it and tried popping wheelies because apparently he has experience riding bikes. Unfortunately he crashed it into a parked car and I thought it wasnt a big deal because he was going about 5-10 mph. After he crashed it I started it and it started fine and I even rode it home with no problems, it felt like it was normal.

I'll add a paragraph here because that shit is building up. It wasnt until after I inspected it that the rim was bent but still fine at this point. So about 2-3 days later my brother takes it for a ride while I'm at work. As he was riding he said out of nowhere it felt like it started engine braking very hard and then just died. He couldnt get it to turn back on so he walked it home. After I inspected it the battery was dead, prob from all the time he was trying to start it on his way home. So I jump start it and started charging the battery with my car. I managed to charge it enough to get it to start but it wouldnt stay on. I have a mikuni carb so I thought maybe if I just adjust the idle screw it would help it like it has in the past. I keep adjusting it and nothing, until I had it all the way fully seated in. Still doesn't stay on. So I tell me buddy, the one that crashed it and been riding dirt bikes since he was a kid about it and he said he would look at it.

The first time he looked at it we figured it was just the carburetor jets were dirty. So we opened up the carb and changed the stock carb jet which I think was 100 on the mikuni down to an 80 because we are in south west Florida. And it was completely clear and clean. Decided to change the spark plug too. So did those two things and tried starting it and same shit was happening but this time the compression outside out the muffler feels much stronger and I noticed my oil went from yellowish- clear to black and there was like black smoke coming out the muffler. Didnt think too much of it but it didnt stay on, so he looked at it again but it's still doing the same shit he said he can adjust the throttle cable to keep it idling but I don't feel like it solves the underlying problem. Because all this happened every since he crashed it

So I googled what black smoke coming from the muffler and black oil means and says I'm burning oil so idk if all this shit happened from the crash. I just want to get it back up and running and want to know what to look for or what parts to replace. I dont want to just adjust the throttle cable to force the bike to stay on if there is a real problem with the engine that is not letting it stay on then I want to fix it.

Forgot to mention the Airbox was a bit cracked but noticed it after taking of the carb, looked like I could repair it so I got some high temp silicon but it did t seal it completley so I got this air filter
https://www.amazon.com/gp/aw/d/B000W...3C7LO58P&psc=1

please help idk what to do, I am new to bikes but am good with tools. If anybody has any ideas tell me what to check and what to look for. This bike was tons of fun and I just want to get it back on the road

RedCrowRides · 05-31-2019, 11:01 PM

I'm not saying it's not a carb issue of some sort but the symptoms you are describing are indicative of valve adjustment being too tight, which is a pretty common condition in Hawks. I get that the other mishaps couldnt/shouldnt have caused valve lash to change

but i feel like that might be coincidental , you mentioned it had 300+ miles on it and thats the neighborhood that new Hawks need the valves adjusted. There are tools to do this available from Chinariders member NZbrakelathes ebay shop , or you can improvise, it's not hard to do but it does require someone who knows how so if you dont feel comfortable with it then get someone to help who knows how.

Worst case is that isn't it , you wasted half an hour but at least you eliminated one possibility ,and you know your valves are good to go clearance wise. Best case is once you get them set right it runs like a champ for you again .

Vipet711 · 06-01-2019, 10:13 AM

What is a valve adjustment?

NzBrakelathes · 06-01-2019, 10:19 AM

Quote:

Originally Posted by Vipet711

What is a valve adjustment?

Best YouTube that question and for special tools n hawk stuff check out my eBay shop in the link below

Megadan · 06-01-2019, 02:24 PM

Quote:

Originally Posted by Vipet711

What is a valve adjustment?

It is known as valve lash. It is a small gap that is purposefully put in between the tip of the valve and the rocker arm to allow for the metal of the valve to expand as it gets hot. This ensures that the valve stays seated and sealed when closed to maintain proper compression and to prevent burning up the valves. It is a very critical thing to the proper operation of a 4 stroke engine.

05-31-2019, 09:56 PM	#1
Vipet711 Join Date: May 2019 Posts: 2	Hawk 250 won't stay on Ok so I know alot of things can contribute to your bike not staying on. Fuel spark and air. I am new here and new to motorcycles in general. I like to consider myself mechanically inclined, but not so much in any thing that has combustion. So I followed everything on China riders. Got my bike, built it, changed the stock oil, put a mikuni carb, change sprockets. And that's about it. For the first 300 miles it has been riding great. It wasnt until a co worker of mine wanted to ride it and I let him. So he was riding it and tried popping wheelies because apparently he has experience riding bikes. Unfortunately he crashed it into a parked car and I thought it wasnt a big deal because he was going about 5-10 mph. After he crashed it I started it and it started fine and I even rode it home with no problems, it felt like it was normal. I'll add a paragraph here because that shit is building up. It wasnt until after I inspected it that the rim was bent but still fine at this point. So about 2-3 days later my brother takes it for a ride while I'm at work. As he was riding he said out of nowhere it felt like it started engine braking very hard and then just died. He couldnt get it to turn back on so he walked it home. After I inspected it the battery was dead, prob from all the time he was trying to start it on his way home. So I jump start it and started charging the battery with my car. I managed to charge it enough to get it to start but it wouldnt stay on. I have a mikuni carb so I thought maybe if I just adjust the idle screw it would help it like it has in the past. I keep adjusting it and nothing, until I had it all the way fully seated in. Still doesn't stay on. So I tell me buddy, the one that crashed it and been riding dirt bikes since he was a kid about it and he said he would look at it. The first time he looked at it we figured it was just the carburetor jets were dirty. So we opened up the carb and changed the stock carb jet which I think was 100 on the mikuni down to an 80 because we are in south west Florida. And it was completely clear and clean. Decided to change the spark plug too. So did those two things and tried starting it and same shit was happening but this time the compression outside out the muffler feels much stronger and I noticed my oil went from yellowish- clear to black and there was like black smoke coming out the muffler. Didnt think too much of it but it didnt stay on, so he looked at it again but it's still doing the same shit he said he can adjust the throttle cable to keep it idling but I don't feel like it solves the underlying problem. Because all this happened every since he crashed it So I googled what black smoke coming from the muffler and black oil means and says I'm burning oil so idk if all this shit happened from the crash. I just want to get it back up and running and want to know what to look for or what parts to replace. I dont want to just adjust the throttle cable to force the bike to stay on if there is a real problem with the engine that is not letting it stay on then I want to fix it. Forgot to mention the Airbox was a bit cracked but noticed it after taking of the carb, looked like I could repair it so I got some high temp silicon but it did t seal it completley so I got this air filter https://www.amazon.com/gp/aw/d/B000W...3C7LO58P&psc=1 please help idk what to do, I am new to bikes but am good with tools. If anybody has any ideas tell me what to check and what to look for. This bike was tons of fun and I just want to get it back on the road
	0

05-31-2019, 11:01 PM	#2
RedCrowRides Join Date: Jun 2018 Location: Florida Posts: 759	I'm not saying it's not a carb issue of some sort but the symptoms you are describing are indicative of valve adjustment being too tight, which is a pretty common condition in Hawks. I get that the other mishaps couldnt/shouldnt have caused valve lash to change but i feel like that might be coincidental , you mentioned it had 300+ miles on it and thats the neighborhood that new Hawks need the valves adjusted. There are tools to do this available from Chinariders member NZbrakelathes ebay shop , or you can improvise, it's not hard to do but it does require someone who knows how so if you dont feel comfortable with it then get someone to help who knows how. Worst case is that isn't it , you wasted half an hour but at least you eliminated one possibility ,and you know your valves are good to go clearance wise. Best case is once you get them set right it runs like a champ for you again . __________________ 2001 Mustang GT 2004 Sportster 2018 VADER 2020 Orion RXB250L
	2

06-01-2019, 10:13 AM	#3
Vipet711 Join Date: May 2019 Posts: 2	What is a valve adjustment?
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