I just recently overhauled a 200 Scrambler 400 4x4. Tore it down to the frame but did not do the engine. It ran very strong prior to overhaul. One of the things I replaced was the throttle cable assy, since the bolt guide going into the oil pump was broken and I didn't want an oil pump failure. The scrammy has a pipe, V-force reeds & spacer, clutch kit, and K&N with modified airbox. The scrammy was jetted at 200 (I live at 5000 feet) and again, ran very strong.

I changed all fluids, tires, belt, replaced a hub seal and put on the new throttle cable. I also overrode the reverse limiter switch. I replaced the jet with a 210 since I knew I could get more air in with a clean K&N and airbox mods. Now I have a dead spot at 3/4 to 7/8 throttle? It almost feels like it is shutting down the spark? It runs strong to this throttle position and then you hear this WAHHHH from carb and it hunkers down coasting until I let off the throttle. I switched back to a 200 jet and made sure my air screw was right. I noted that at full throttle my carb slide is mostly wide open. It idles very well.

I went through the service manual and my next step is to override all the kill switches to rule out a lack of spark - that's what this thing feels like at 3/4 to 7/8 throttle. I still think this has something to do with the carb and the cable assy I replaced. My needle clip is at the highest (leanest) point as it was prior to the overhaul. I didn't not any washers on the needle as referred to in the service manual.

Help! Any ideas?

I am wondering if there are any carb components that, if missing might cause such a problem - there is a chance I lost something in replacing the cable assy. I didn't note a washer on either the needle, nor the main jet. The slide appears to go all the way up at full throttle. My oil pump seems to be working fine with the new cable and spring & lever.

Please help - I hate bringing it into the dealer - they haven't been real helpful in the past.

 

Is your throttle cable adjusted correctly??

 

I wouldn't know what a prperly adjusted throttle cable is. I did adjust it near the ETC box to get it to idle properly and I confirmed that the oil pump lever was opening when the throttle was just beginning to move. At full throttle, the carb slide appeared to be all the way to the top.

 

Try, taking it for a test ride with the airbox lid off, if its better, than its too rich.
And try pulling the choke on, while its acting up, if that makes it better, its too lean.
Id say having the needle down so low, itd be too lean. Id get it to the midpoint .
The mixture adjustment wont have any effect, once youre past 1/8 open.
Is the float level good? If it were too low, itd run lean on top.

 

This latest post sounds like a good idea. I'll work on it this week - anybody else got advice? Please!

 

Check the basics first. Double check your entire quad. Confirm your carb is securely into the intake boot. Double check your intake boot to cylinder bolts. Did you change out the fuel and oil filters (LH side of quad, viewed like you're sitting on it) Sometimes things can be shaken loose etc. Start with the simple basics first.

 

what is that thing running at?
you shouln't exceed 1150 dgree in the midrange,1250 at WOT.
anyway jetting become finicky with the stock airbox,wich plain sux.

 

How do you check the "float level" on the carb?

 

Also, when putting this thing back together, what if I didn't rotate my secondary clutch far enough on the helix? I did use the 2-2 setting, but was concerned I didn't rotate it far enough. Could this be limiting my RPMs and giving me this dead-spot effect?

Thanks!

 

If you did not get the rotation right it would take off like you were in quicksand for the first 50 or 60 yards. How is your compression? How are the crank seals? Is it a new plug?