[Gunner99honda400]

Hey first time post so sorry if it's hard to read but I just bought a 1999 honda trx400ex and it idles fine and starts fine but if I give it any throttle at all it dies out almost instantly. It has an aftermarket chinesium copy of the factory carb and I have about 80% of the factory carb but I'm brand new to quads and such any advice is appreciated.

 

[Here 2 help]

Not taking throttle is usually indicative of the carb being jetted too lean - the Chinese carbs may not have sizes embossed on the jet so you have no clue as the the size and OEM replacements jets may have different thread pitch and are typically not sized the same as the Chinese jets. There are two methods of sizing jets; one is the size indicates the diameter of the hole (i.e. a 142 is 1.42mm) and the other is the flow rate (i.e. a 142 flows 142cc of fuel per minute at 4 PSI of pressure) so there is no correlation between the two - to replace a flow rated jet with an orifice sized jet may require a 142 be replaced with a 170 or vice versa.

I suggest you find a used OEM carb and build one out of the two (here's one on Ebay for $200)or just buy a new one for a later model TRX400EX (new from Honda 16100-HN1-A41 for $285) - a sympathetic dealer (like me) would sell you the new carb for $220 and ship it to you for free.