Hey guys,

Just bragging on myself . I rebuilt the motor in my 400 xplorer and it runs good wseco piston, bottom end bearings and seals, RCR head work and now I have a question. The book calls for my carb to be set at 200 main, 30 pilot, needle clip in the 3 positin and the air screw 1.5 out. It also calls for the 400 scrammy to have a 230 main and a 35 pilot. I hear they are the same motors. So what is different on the machines ? I know the exhaut is different. Niow I have 210 main 30 pilot,the needle raised one notch and the air screw one turn out. Is this a good starting point ? Thanks for all replies.

 

the exhaust is different.

 

ya its tuned down.

 

I really don't see why you would have to rejet at all actually. You didn't increase the airflow with a air box mod, the fuel flow hasn't changed, and the oil injectin rate hasn't changed. The only other thing required for combustion is a spark and you got that already. I may be wrong, but I don't think that the head work alone is gonna affect your jetting as much as you think it might. Now if you would have had the jug trail ported, that would be more drastic, but you only mentioned head work. Did you enquire from Rick if any new jetting is required, because if anybody would know, he would. Trust me on that one!
I would set everything back as it was before to get a good starting point and do a jetting test . Here's basically a summary of how the jets in the carb work, so if you already know this, don't laugh so hard that anyone else on the forum hears you. Just trying to help. If you have problems from 1/4 to 3/4, you might want to look at the needle. If you have problems from 0 to 1/8 throttle, then you may need to adjust your idle mixture screw and problems between 1/8 to 1/4 throttle might be adjusted with the low speed pilot jet. Just put in a new plug and check the plug for correct color at each different interval. Run it for a few minutes at each level, then shut it down using the kill switch before you chop the throttle (I believe that's how I use to do it) Somebody correct me if I'm wrong about that. Just remember that when you first rebuild the top end and change out the rings and piston, it's a good idea to mix in some additional oil into the gas for the first 2 hours of low level riding to break them in right and during this time it's impossible to jet it right with the extra oil in the gas. Just take ya time and don't take any chances as rebuilding the top end requires time. I just finished rebuilding the one on my Scram yesterday afternoon and it kills me that I just can't go out and pin the throttle. But good luck and sorry I rambled on so long!

 

[img]i/expressions/face-icon-small-smile.gif[/img]Good man Bayou, Not everyone knows this . I did. I'ts cool of you to take the time for this guy.[img]i/expressions/face-icon-small-happy.gif[/img]

 

It's always a good idea to richen the carb settings when breaking in a fresh engine, he did say it had headwork so it may very well need some extra fuel also. If you premix you will lean it out as you now have oil and gas flowing thru the carb instead of straight gas. Premixing is good but adjust the carb so you don't run lean....

 

First off thanks for the help guys. I did forget to mention that I was running 40:1 pre mix and the oil injector for the first few tankfuls. Thats why I went ahead and richened all circuits on the carb. I plan on doing some plug checks some time when it gets broken in. I also plan on getting a RCR stage one kit for this thing. If there are any 400 xplorer owners with this kit, please let me know your thoughts and if you would recommend it.

Chris