More power for my Xr 400

[RIGGS72]

I like my 400, but it needs more power.

[RIGGS72]

I have a Big Gun pipe and the pumper carb. Those are both good mods but I still would like more power. I would like suggestions on big bore kits and cams.

[ThumperTDC]

yes and yes with what you currently have, you will have plenty of power. Not any CRF450 power, but it's usable power.

[JoeBlow Kokomo]

Why don't you just buy a 650????

[kaufman xr400]

could put a cam in. put one in a stage one hotcam after i did a titanium 4 w/ staintune header, mukuni pumper, and opened up the airbox. all in all i am very glad i did it, cam is simple,(2 hours) for me and im no expert. but MindBlower has a point...

[RIGGS72]

I'm lucky to have this bike so a 650 is out of the question.

[stan_97]

gordon mods, easiest and cheapest power you can get, after that it gets expensive.

[kaufman xr400]

I'm lucky to have this bike so a 650 is out of the question.

thats understandable. but if you have done gordon mods and have a carb and exhaust, then theres only so much more you can do outside the engine. once you get in the engine its a new game. How much money are you looking at spending? hi, medium, or low? thats the biggest question, cause you can get more power, it just cost cash.

[UncleCrusty]

All i did for my xr was put in a twin air filter, change the spark plug, and mess with the exhaust tip. It's a lot easier to pop it up in 3rd now.

[JoeBlow Kokomo]

and probably reliability

[JoeBlow Kokomo]

I'm lucky to have this bike so a 650 is out of the question.

how so? I bought my (this summer) 400 for 2,500 (2003). Sold my 650 for 3,200 (2004 and plated)

Aint' MUCH difference in what they go for.

[kaufman xr400]

Reliability will be affected, alot more stress on the 400's motor with a 440. however i guess you could go to stock bore with higher compression (11.1), even then youll add stress. and its a pain in the rear end to kick.

i know that my dad paid only another 150 bucks for his 650 and loves it, but i find the 400 holds a different value to me, soooo much more comfortable (more race like?)

[RIGGS72]

Is anybody out there running the 426 kit with 11.1? Thats the kit I was looking at but if it does not make a big difference then I don't want to mess with it. The 650 is a great bike but I don't like the weight. I rode a TT600 for years. I loved the power but I like the Xr400 feel.

[Dwight_Rudder]

I suggest you look into one of PowRoll's 440cc kits. Either the Big Bore 440 kit or the Big Bore + Stroker kit. The stroker will have the most power and torque increase. I have used both and both are very reliable.

Dwight

[SparksXR426]

Is anybody out there running the 426 kit with 11.1? l.

Thats what I run in mine and its fine. I was running stock bore at 11:1 and had to go into the motor so while I was in there bored it. The difference in terms of real world power and torque while keeping the same compression was surprising. It did lose maybe 1000 rpm or less but the trade off was worth it. The motor also had the old White Bros. "all around" cam and the high rev ignition kit. This bike has always been a good runner.

[JoeBlow Kokomo]

Is anybody out there running the 426 kit with 11.1? Thats the kit I was looking at but if it does not make a big difference then I don't want to mess with it. The 650 is a great bike but I don't like the weight. I rode a TT600 for years. I loved the power but I like the Xr400 feel.

ok, there ya go. I understand that. I liked the 650, but like you, I prefer the smaller bike feel of the 400. I'm old enough that I don't really miss the big power any way. I've seen a lot of love for the 426 with seemingly a lot less problems than the 440.

[RIGGS72]

Is there a big difference in price between the 426 kit and 440? I have read that with the 426 kit I can have my sleeve bored. With the 440 I will have to have the sleeve changed out. Does that cost about the same? Also which cam should I run? I want to take the auto compression release off so I think I should just change the cam. I use the bike in the mountains and desert.

[ThumperTDC]

Is there a big difference in price between the 426 kit and 440? I have read that with the 426 kit I can have my sleeve bored. With the 440 I will have to have the sleeve changed out. Does that cost about the same? Also which cam should I run? I want to take the auto compression release off so I think I should just change the cam. I use the bike in the mountains and desert.

A Hotcams Stage 1 cam is the way you should go if you are wanting an aftermarket cam........more low to mid range power. As far as which bore size, the 426 will only need a bore to your stock cylinder. A 440 will either need a to have the work done to your stock jug, or on ebay they have a bolt on kit for roughly the same amount you you would be paying to have someone do the work to install it. I picked one up off of ebay for $325 and am planing on installing it this week.

Which ever way you go, stock compression ratio is 9.3:1 with a higher compression ratio you will definately notice it. I had a 416 kit in mine that was 10.8:1 comp ratio and the added power was noticable.

[RIGGS72]

A guy is selling a 440 big bore kit on Ebay that includes the cylinder and piston. He does not have the manufactures name in the ad. Is there a big difference in the manufactures of these kits and is that a good price? Also has anybode purchased anything from atvunlimited?

Edited December 17, 2009 by RIGGS72

[willxr415]

This is what I've got into my 400: Opened up airbox (snorkel revoved), K&N filter, 36mm Mikuni Pumper from Xrs Only, match porting, hotcams stage 1 cam, powroll 415 hi comp kit, fmf power bomb header and powercore 4 exhaust.

Its been forever since ive done anything to the bike besides ride it...I'd say 4 years of trouble free riding...

I will say that the above mods were not cheap!!! Between engine mods and suspension/body mods, I've spent more money on upgrades than the bike originally. BUt than again I picked up the bike in 2001 and still rally on it today!!!