?'s about Ebrothers speed kit

A good friend of mine is looking to buy a used 400ex. The one he is looking at has what the owner calls a White Brothers Speed Kit. I can't find any info on this kit as he names it. I think it consist of an E series slip on, K&N filter and Rev limiter. Is that correct and does anyone have opinions on these kits? What should he look for to make sure it is setup right? Thanks in advance.

[Texan32]

its called the "E" kit. Moto-Man sells one just like it. It does consist of the pipe K&N power kit and a rev kit.

Now, the ony thing you need to worry about is weither or not the previous owner actually installed the larger jets. With a e series, you can easily run a 160 main jet. Ask they guy who owns/did own it if he changed them. If not, that NEEDS to be done. Any thime you run a higher flow pipe, you need to ru larger jets or you will melt the motor. Also, i don't know if you are new to this page or not, but MANY people put in a 42 pilot jet. Along with the 42 pilot, you can remove the choke plate. the larger pilot jet eleminates the need for the choke. (it cold starts MUCH easier). On the pipe, many of the people here that run the e series are using only 12 discs. So, you might want to check on that.

Installing the pipe and rev kit are pretty much no-brainers. So I would mainly concern myself with the jetting issue. Oh, one more thing. With the rev kit...there are two types. Ones that give an extra 1000 RPM's and then there are unlimited RPM's. I would verify which one he has. If it is the unlimited RPM one, i would SERIOUSLY consider getting a different one. Too many people (and many on this site) have smoked motors from over reving the engines!

Any more questions, let me know....i'll see what i can do

Thanks for the useful information. I do have a few more questions though.

I have read that the 400ex stops producing hp at around 8000 rpm and that unless some serious motor tweaks are added installing the rev kit is a waste of money. True?

Second... the owner claims that the rev kit helps with low end torque as compared with a stock rev. True?

We just want to make sure the quad is setup properly and that the owner isn't blown smoke up our *****. When we tested the quad it seemed sluggesh when reving at the high end? Could that be the jetting?

[Texan32]

HP.....yes, the 400's peak hp is somewhere around 7500 rpm's. The rev kits claim to add hp by changing the spark advance curve. Personally, i think rev kits are worthless (unless your running a highly modded motor). I don't remember where, but i have seen actual dyno results of the WB rev box. It did NOTHING for the power curve. All it does is let the bike rev 1000 or so rpm's higher. But back to the 400's curve...it stops producing hp at 7500ish. So basically unless you are drag racing and need a few more rpms at wot to get that extra 2-3 mph, its just a waste.

There are many on this page that run rev boxes. And some claim higher output, some don't. I with what little power the box could produce...i wonder if its just in their head. You and i both know that if you spend $$ on something that is supposed to make power, you want to believe it so muchthe in your head you think you really feel a difference.

If its slugish on top end, it very well could be a jetting issue. Did the owner tell you what jets he put in? You need to find that out. If he doesn't know for sure, all you have to do is pull the carb. You could also check the plug. But, be leary about that. With all the gas additives, the plug could not be telling the whole truth. Also, how old is the plug? How long has the qud been sitting?

I don't know exactly what the guy is telling you, but i wouldn't say he's blowing smoke. An E series with a K&N and jet kit is a VERY common and well liked power booster around this site. As for the rev bok, thats just personal opinion. I have NO plans on changing my rev box, but if there is one on there, i wouldn't worry about it (except one thing...some rev boxes won't start if it is really cold outside...but i don't think you will have that prob in where ou live).

Let me know