Hard Starting WR 450f (2003) when warm

I have got a 2003 WR 450f.  When I am out riding and it is warm it can be difficult to start.  Using the electric start, sometimes it starts right up. Other times it seems to take a lot of cranking to start it up.   I use the hot-start lever and that sometimes seems to help but not always. 

Seems like if it doesn't start on the 1st try, it takes quite a bit to get it going. 

Any ideas on what would be causing this?

2 question or thoughts:

1.  How would I go about testing the 'hot start' lever to verify it is working properly?

2.  Could this be a carburetor issue?  I bought the bike last year and have not had the carburetor apart yet.  Could it be a cleaning issue? or an adjustment issue?

Use hot start while running. Motor will change if working

Got same bike. Does same thing. Pull hot start , starts right up

I'm not an expert, but here's the 3 things I would do if it was my bike that i just purchased.


1. Clean the carb.  You can get the gaskets for $20 if you buy the gasket kit from honda.  Take a look at honda part # 16010-MEB-671


2. Get the JD Jet Kit & fuel screw.  I've had 2 WR's that were a pain to start until I got the JD Jet Kit.  They consistently start first kick after I installed the JD Jet kit.


3. Check the valves.  Hard starting can be caused by valves that are out of spec.

Thought wr450f was Yamaha not Honda. My mistake

The WR450f is a Yamaha. The Honda CRF's and WR's use the same carb - the Keihin FCR-MX.  Honda just makes the gaskets a lot cheaper than Yamaha does :)

Read the FAQ section

Uncork, and rejet the bike, including the YZ specs and blocking of the ACV in the carb

Then it will run correctly, and you can adjust the fuel screw correctly

Thanks guys. Markjo2013, I will give that a try with pulling the hot start while it is running.

Sounds like a carb rebuild is in order and that never hurts.

Krannie, I am not on this site much, where do I find that FAQ info?

Can anyone explain exactly what that hot start lever is doing

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