I just installed a 416 piston in my bike. I did not do the cam or any other modifications. The piston is a wiseco 11:1 and I am running a 50 50 mix of 110 and 92 octane fuel. I took the bike to the dunes this weekend and had a hard time with the bike. It is not developing horsepower like I expected. I ran it against a freinds bike that I maintain by the way and his just seems to develop better and more hp. His bike is stock exept for a K&N and E-series with 12 discs. Is there anyone out there that has done a 416 without the cam? I have spent a lot of time jetting and doing plug chops. and I think I have it dialed in. The jetting changes have not made much of a difference in the performance of the bike. The low end of the bike has increased. There is a little more torque but the bike does not run up the hill any faster than before the piston install. Any help would be appreciated.

 

Going to a 416 is not going to give you much more HP by itself, I mean it's only about 18cc. that's not even a 5 percent increase in displacement. The real benefit or the 416 kit is the higher compression. High compression gives you more lowend power. Now combine the added lowend power from the high compession piston to other mods such as a bigger carb and a midrange-topend cam, which add to your top end but hurt the low end power, and you have a strong running bike.

In other words the reason it is usually not recommended to put a huge cam or carb on a stock bike is that it will hurt your low end power drastically. By raising the compression, you get back the low end power lost to these mods. The result, you get a machine that has the same low end power as stock (which is very good) but screams in the mid to top end. Plus you get the benifit of the increased cc, not much but I would say 1-2 HP

 

So Rob you would expect that with just going to a 416 11:1 piston that I would not pick up much over stock except some more low end torque.

 

You will get some lowend torque and just a little more overall HP, very little though. But this paves the way for you to add torque robbing mods that let you go fast. Some well built 416s will give me my R some serious competition when I have my MX gearing.

 

Just a 416, or just a 430 piston will NOT give you much overall "new" power.

A 416 or 430, with a more aggressive cam combined with rejetting/exhaust will give you a good deal more power right thru the whole powerband.

This 416EX is dead nuts with 250R's and LT250R's in pavement drags, and I crush the 250R's in sand/dirt drags.

 

MIA 416 could you tell me how many discs do you have in your e series? I started out with 12. But kind of figured that I needed to go with a few more with the new piston. Thanks for the great info.

 

You didn't list what type of airbox mods you have. I suspect that, and the fact that you don't have enough discs on your pipe are your problems. White Bros. recommends 18 discs on a stock motored EX for the most gains. That's what I am running. Stock piston, no airbox lid, White Bros. filter, Rev Box, and E-Series(18 discs). Bike has a lot more top end with 18 discs and a 165 main. [img]i/expressions/face-icon-small-smile.gif[/img]

 

This is a great topic!!!!! Could you guys please help me out too!!!!! I just ordered a White Bros. E-series pipe(just the silencer) K&N filter and jet kit. I believe the pipe comes with 6-discs(not sure, correct me if i'm wrong). I ordered another 6-extra discs to make 12 total. 12 is what "dirt wheels magazine" used to do the pipe test on the 400's in a issue a few months back. The said it was the best pipe out of a bunch they tested. Anyway, I do plan on running with no air box lid. My question is: Will this give me the LOW END & mid range I"m looking for? I"m very satisfied with the top end on my bike since I don't ride very fast and only ride in trails etc. If not, how hany discs should I be using?? I can't really find ANY info. on the disc systems on the the e-series pipes and how they work, or how many you should have, or what exactly they do????????? I hope anybody with knowledge and experience with the e-series reads this and helps me out. PLEASE HELP! Thanks

 

Your E-Series pipe will come with 12 discs. And that is what you should leave it at if you don't want to sacrifice any low end power. Your E-Series pipe will also come with a tuning manual that explains how the disc system works. If for some reason you don't get the manual, you can also get it on White Bros. website.

 

Thanks for all of the info. I have run no airbox lid and a K&N with outerwears. I am going to order the XR Cam pretty soon for it and I hope that helps some. The only other thing I could imagine is that the cam chain is off a tooth. I was very careful when putting everything back together so I doubt that is it. Can anyone give me there tuning setup with and E-Series stock headpipe, No Lid, K&N, XR Cam? I would like to know: needle position, Main Jet, Pilot Jet, and # of discs in the E-Series? Also does anyone know about the White Bros R-4 Pipe? I have had 2 E-Series crack and White Bros is really good about replacing them but that does not help me when the bike is down for two to three weeks for replacement. Thanks again for all of your help and knowledge.