Quad not running properly

[farmboy]

Hi, got a Honda FM420 not running properly. Sometimes is fine but sometimes won’t Rev up properly and cuts out. Seems worse when it’s hot. Any ideas? Thanks

 

[quattro]

Hi, got a Honda FM420 not running properly. Sometimes is fine but sometimes won’t Rev up properly and cuts out. Seems worse when it’s hot. Any ideas? Thanks

Spark plug

 

[Timbo]

Spark plug

Or failing that, ignitor. Often symtpoms are perfect when cold but loss of spark when hot

 

[farmboy]

Thanks I’ll stick a new plug in it and see what happens

 

[livestock 1]

Fuel filter, fuel pump, relay

 

[Nae bother]

Sometimes a new battery makes a massive difference,did with my old Honda 350.

 

[Scholsey]

we’ve had numerous ECU issues with our 420

 

[Dry Rot]

Could be dirt in the carb. These days it is sometimes cheaper to buy a Chinese replacement (they make the for Honda anyway) than fiddle around with them.

But if you don't mind fiddling....

Here's a link to a good thread on carbs: https://www.trxforums.com/threads/carburetor-basics-thanks-to-saber6.286/

I've a new surplus ECU for a 2002 - 2006 TRX 350 here if anyone needs one.

 

[livestock 1]

420 is fuel injection