Quote:
Originally Posted by Mychel
I have issues with my hawk 250 , I live in IL.
Mods are Exhaust system.
Mikuni carb jetted to a 115 Main, needle is at middle position. I have. 17t front 40t rear I drove it wide open at in 4th gear it stopped pulling at 50mph. In 5th gear the bike had no pull at all . I came to a stop and my engine would not idle. I rev it up engine sounded like a miss fire. I got gas let it cool down and it ran a little better.
I need to know who else has 17 40 gearing and your top speed?
I need to check my plug, and any ideas on my jetting?
Thank you.
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First off, as Jerry mentioned, have you set the valve lash?
Secondly, how many miles on the bike? If it has under 1k miles, it isn't going to have a ton of top end yet, especially if you are around or less than 500.
As far as jetting, what size pilot jet do you have? I always recommend a good starting point for the Mikuni clones with an intake and exhaust with a 25 pilot, needle at the 4th notch, and 115 main. With full mods even the 25 can prove to be a touch lean so a 27.5 works better.
From the symptoms you describe, it sounds to me like you started to overheat the cylinder. Fueling will play a big role in this, and if you are at a low enough altitude you may need to step up the main jet size. I would begin with the previously mentioned jet settings though. Air cooled motors like fuel when pushed hard, it helps control cylinder temps.
A side suggestion - if you are going to push this motor that hard with tall gearing it would be a good idea to invest in an oil cooler. It makes a pretty good difference.
Quote:
Originally Posted by JerryHawk250
I run 17/40 gears and have done 75 mph+
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bear in mind we also have ported heads and he doesn't. Anything past 70 is a tall order for a stock Hawk with just an exhaust and mikuni clone.