H/S on '03 WR250F do I need this.

I think this was my engine's lean running problem. I have checked, cleaned, and re cleaned every part that touches fuel from the tank down.

I'm no racer, @58 yrs old, but like to run a little hard.

I've been doing mechanic's and fabrication my whole life, and am a registered information junky.

Q= My plastic hot start threaded collar to carb ftg. has little to no threads left, would not stay put, so I removed it, and configured a stamped copper foil plug, and sealed the top 3mm of the hole in the carb. Not permanently.

Next, soldered a small brass finger screw to the tail end of the mixture screw to extend it, makes for quick adjustment. (45 pilot jet). Have not ridden it yet, just basic garage adjustments. Seems to run better, but I'm not sure how it will do under load in the hills.

*Do I need this hot start valve when I have electric start.

*Will the port suck fresh air if the cable fitting was loose, and not sealed causing the engine to stay revved up for a short while after throttle is closed.

*What is the down side to plugging the port.

Thanks for any feedback.


Well first you have to make sure it's plugged and not just capped. If it's just capped it's still going to pull air thru passage ways inside that hole. Do you need hot start? Not if your bike starts fine without it when warm. The only time I ever seem to need it is when I lay the bike down and need to start it right away. If I lay the bike down and rest for a little bit then I don't need it. If you plug the port you wont have hot start anymore. If it wasn't sealed, yes you could have a lean condition and that can cause a hanging idle

Thanks Swede, that's exactly the answer I was looking for. If I stall the motor while in a creek that's a couple feet deep, where does the H/S scavenge the air from? Will I suck up water if I restart while standing in a creek. I have re-routed the (4) carb air vents, two go down like stock, and two are teed to a tube routed above the carb and into the battery box. Makes sense to me.

Someone must make a metal collar and replace the plastic one.

Thanks again


Not sure where the air comes from but what you can do to find out is spray contact cleaner or something thru the passageways in that hot start orifice and see where it comes out at. I highly doubt it's from outside air that's not filtered. I would think it would be from the Venturi area before the slide. Don't know but would think

The air comes in through the carb bore, it is filtered air. The vent toubes just balance out the pressures in the float bowl.

Not Ron's post about the hot start nut.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now