Any info on a Hawk 250 dirt bike.

Weldangrind · 02-17-2015, 03:00 PM

You're welcome. There is a rev limiter built into the CDI, but I wouldn't want to defeat it. You can buy a no-rev limit CDI, but these pushrod motors have only so much potential. Believe it or not, there is only one cam lobe, and it bumps both valves. That means that neither valve can be optimized for lift or duration, but it's a wonderful motor for low end grunt and longevity.

Since most of these machines are lean from the factory, you're likely just running out of fuel at the top end. Fattening it by two sizes will likely produce results.

The Mikuni will have the wrong jets for your application, but they're cheap and plentiful. It will have a 100 main and a 20 slow jet. I'd recommend a 110 main, and at least a 25 slow if you're at any amount of elevation. If you're at sea level, try a 30 slow jet.

02-17-2015, 03:00 PM	#16
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	You're welcome. There is a rev limiter built into the CDI, but I wouldn't want to defeat it. You can buy a no-rev limit CDI, but these pushrod motors have only so much potential. Believe it or not, there is only one cam lobe, and it bumps both valves. That means that neither valve can be optimized for lift or duration, but it's a wonderful motor for low end grunt and longevity. Since most of these machines are lean from the factory, you're likely just running out of fuel at the top end. Fattening it by two sizes will likely produce results. The Mikuni will have the wrong jets for your application, but they're cheap and plentiful. It will have a 100 main and a 20 slow jet. I'd recommend a 110 main, and at least a 25 slow if you're at any amount of elevation. If you're at sea level, try a 30 slow jet. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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