Hawk cuts out

[DSAdventures]

Got the Hawk on the freeway yesterday and had some issues with it cutting out like it was either starving for fuel or an electrical issue. The bike is an X-Pro produced in the summer of 2023 with about 100 units off measure on the odometer. The odometer seems to record something between kilometers and miles. The bike has at least 15+ heat cycles on the engine however this was it's first "high speed" run.

The bike is stock other than fresh oil and a valve adjustment prior to starting. At an indicated 57-60mph the engine would randomly stutter like electronics were cutting it out, starving for fuel or water in the fuel. I thought I might be bumping against the rev limiter but didn't think I could hit it at an indicated 57mph which is probably a true 54mph. In theory it has fresh ethanol free fuel so I am not suspicious of the fuel. It seemed to vary a bit where it might buck at 57 but then be okay at 59 then not okay at 58 but okay back at 57. Because of the speed variations I was thinking it probably isn't the rev limiter, or is there a random range with these things?

Still running the stock Torch plug so I am suspicious if that is it. Or possibly there is a ground lose however I would expect to see it happen at lower RPMs too.

Is there a common issue that causes this or is it a bit of troubleshooting to work through the fuel and ignition systems?

[bigdano711]

I'm guessing this is the carb'ed version? It sounds like it's lean, starving for fuel. Is it the stock carb? If so, good luck. It can be re-jetted, and the fuel mixture screw can be gotten to, but it's more of a pain than it should be. I recommend you ditch it in favor of a Nibbi PE28FL.


Anyway, it's the main jet you're looking for. My PZ30 (stock carb) came with a 40 pilot and a 105 main. If that's what yours has, it's probably lean for sea level. It actually did pretty good at 6000'.

[zero_dgz]

Before going bonkers on complicated stuff, check the float height in your carb. Rule of thumb is, it should let fuel through when the arm on the float is parallel with the split between the carb body and bowl, and shut off if it's raised above that. If it's shutting off way early, you'll have a low fuel level in your bowl and will starve it during sustained open throttle events -- like riding on the highway.


My Bashan's carb had the float height whacked in such a way from the factory, and caused similar issues. "Adjustment" is typically as simple as just bending the little tab on the float that engages the valve slightly until it's about right.


You can bench test these by sticking a short length of tubing on the inlet and filling it with a small amount of water or, if you're paranoid, kerosene. That'll let you see at which position it shuts off or flows through.

[buzz]

Bigger jets my friend,its that easy and cheap.2021 TBR7 8500 miles stock carburetor.

[DSAdventures]

Yep i should have included it's got a carb. Glad you hear you guys are saying fuel related vs electrical. I'd rather chase a fuel issue and it is definitely a lean running bike. One reason I bought the Hawk is that it is so well known and that there are usually multiple solutions to a problem. Thanks for the tips.

[jsumd]

Mine would do this with the stock carb. If i got on the throttle too hard or was getting in the higher speeds it would stutter and almost quit like it suddenly ran out of fuel, which is basically what it was doing since the carb couldn't keep up with it what I was asking from it. I switched to a nibbi and haven't had anymore issues. I highly recommend just doing that instead of tinkering with the crappy stock carb.