Hard Starting ?'s

I bought the bike recently 03 WR450. It sat for 2 years, cleaned the carb, and now I am having an issue getting it to run. It will fire and run for a second at a high idle, but it will die right out. I have the pilot needle set at 1 3/4 turns, and I have no idea where the idle is set.

I havent adjusted the valves yet, but the motor feels to have good compression. I am probably going to adjust them tomorrow. I also dont have the battery in the bike which I read a thread on here with a question of does the battery affect starting even if I am kicking the bike?

Also the ACV diaphragm is not in the best looking condition but its my understanding it only affects decel. This bike has stock jets and has good spark. Any tips for something else I might be missing. I searched around and I know how to find TDC and kick it. I need some suggestions on getting the idle set at a good baseline.

I bought the bike recently 03 WR450. It sat for 2 years, cleaned the carb, and now I am having an issue getting it to run. It will fire and run for a second at a high idle, but it will die right out. I have the pilot needle set at 1 3/4 turns, and I have no idea where the idle is set.

I havent adjusted the valves yet, but the motor feels to have good compression. I am probably going to adjust them tomorrow. I also dont have the battery in the bike which I read a thread on here with a question of does the battery affect starting even if I am kicking the bike?

Also the ACV diaphragm is not in the best looking condition but its my understanding it only affects decel. This bike has stock jets and has good spark. Any tips for something else I might be missing. I searched around and I know how to find TDC and kick it. I need some suggestions on getting the idle set at a good baseline.

The carb is probably not clean. Sounds like an extreme lean condition.

The pilot circuit in the carb is tricky to clean. The pilot jet and passage has to be spotless to work.

You need to rejet anyway (way too lean stock), so check that carb again. If you used conventional carb cleaner, prepare to change the rubber stuff in the carb.

I went out and cleaned it for the 3rd time. I took the float bowl off sprayed all of the jets out, took the pilot screw out and sprayed the passage way good. Unless there is something beyond the obvious I think I cleaned the carb good, the tank was flushed out and I have fresh 93 in the tank.

I got it to fire first kick, and about the fourth it started. I gave it a little gas and it died out. It seems to fire better with the choke off. I couldnt figure out a good way to set the height of the throttle slide. The manual calls for 3mm I tried to get it close. I also have the pilot screw at 2 1/4 turns out now. I am going to jet the bike after I can get it running and see how it runs.

Thank you for the help.

I ordered the throttle slide o ring and the FCV diaphragm. Dealer had a used 48 pilot but it ended up being a short one. He didnt have any new 48's I will get one from the other Yamaha dealer when I put it all back together. I bought an adjustable fuel screw, I am going to thoroughly clean the carb, I found a good write up on another site, so hopefully this fixes the issues. I will go bigger on the main jet also while its apart. 150mj is way to lean I hear.

Until then I work on other stuff and wait for my 300$ with a badass discount bunch of parts to show up. Having dealer hook ups make it so much better buying parts less than anywhere around, it defenitaly makes doing a job right a lot more affordable.

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