First of all I am new here so bear with me. I recently aquired a 400 Scrambler and I am having a little trouble. The bike runs great with about 1/2 throttle but it cuts out at full throttle. I am kind of thinking it is the jetting but I would really like some opinions. I am having problems with the throttle cable sticking because part of it was rusted, I have a new one on order, but I don't see how this could be the problem. Also the oiler is not being used the guy I got it from said it didn't work but as far as I am concerned I would rather mix my own gas anyhow. I am thinking this may be the problem I have heard that if you unhook the oiler you have to jet it different. Is this true and what do I need to rejet it too, elevation is not an issue I am in Oklahoma? Also I would like to know where I can buy the oiler block off kits I went to the hot seat website and they are like $35, can't you get them cheaper. Is not having the oiler blocked off a big deal, at least until I get a block off kit which will be as soon as possible? I am mixing my gas at 40:1 is this right that is what I always used on my dirtbikes or is this wrong and making me foul the plug? Any input would be greatly appreciated. Thanks.

 

i would clean your carb really good. sounds like a port is clogged causing it to bogg at full throttle. the jetting doesnt need to be changed if you premix. no need to get a block off kit. take the oil pump off and pull the shaft out of the hole and then put the pump back on. and the 40:1 mix is fine as long as its not bored or ported (bigger surface area and it would require more oil)

 

The carb looked clean when I took it off before but I will take it off again and make sure that all the vents are clean and everything. Thanks for the help I will let you know if it doesn't work.

 

Looks mean nothing. can have 1 piece of sand clogging jet. take jets out and used compressed air / cleaner. G/l!

 

Take the jets out and clean them,be sure the air filter is extremely clean.If this doesnt fix let us know

 

Okay sorry it took me so long I had to wait for my throttle cable to come in. Well I have cleaned the carb and no luck. I am wondering if this could be because of the reeds or something like that? Are these powervalve motors? The guy I got it from said he put new reeds in it but I have not checked them. Thanks.

 

is the exhaust clogged up?
have you checked your clutches to see if they have any wear? they tend to control RPM's too

 

I haven't checked the clutches or the pipe. I guess if the clutch has wear it will be noticeable? I do get a back fire every now and then if that helps at all. I have not found any air leaks or anywhere that it could be sucking in any extra air either.

 

Sounds like a clogged silencer to me.

 

Silencer looks clear.