I have two 2003 Raptors that are set up exactly the same.

They both are stock except for they both have a White Brother's R4 Silencer on them.

They have few hours on them, have the plugs and oil changed, and valves adjusted.

Both are very well maintained and still look like brand new.

One is about 10% faster in a straight drag race when the riders are the same weight.

We even tried allowing the rideers to switch and had the same results.

They are ridden at sea level in Mexico.

Both are jetted at 150/155, stock Needle position, 25 Pilots.

Idle mixture is at 3 turns out.

When the slower Raptor winds out, it seems to sputter just a bit at the very top end.

I am looking for suggestions how to get this one running better so they even out in performance???

Thanks in advance!

 

maybe the slower one is running too rich and thats why it sputters on top end?

 

you might want to check your bowl Float level. i had a similar problem. my quad ran fine other than on long straight sections where i was topped out, it would cut off , sputter. i just raised the level of fuel and it ran great in top end.
i had that problem for almost a month( only run on sundays) i took off my inline filter thinking it was that ,changed the top for teh gas tank. changed my spill proof brether line cleaned out my carbs 3 times. until i found what it was. wish you Luck my friend Raptor Carbs Are a pain in The azz.

 

Wouldn't I want to increase the size of the jets to provide more fuel?

 

If you are running out of fuel it won't matter how big of jet you put in. Check the floats, then think about changing your mains.

 

to increase the gas going in to the engine yes. if theres not enough fuel in the carb, its gonna starve it and act like its running lean.

 

How do I check/adjust the floats?

 

just take out the carbs, whe theyre upsidedown measure from the bowl mating surface to the top of the float it should be 0.51 inches. theres other good links for that. maybe soemone here can hook it up.



Set Float Level

 

HHHHHEEEEELLLLPPPPPP!!!!!

I tried everything suggested and they still crap out on top end.

Tried new gas, plugs, different jetting, different type of airbox modifications, etc.

I had the valves adjusted several months ago at a Yamaha shop in Phoenix.

Could a poor valve adjustment creat this problem?

 

A valve thats too tight will do it. Raptor intake valves tighten up and don't seal. Remove the plug on the side of the case, put a 19mm socket on the crank and turn it CCW to feel the compression. There should be significant resistance on the compression stroke. Compare to the other quad. If there is a difference, then there is proabably a valve too tight.