More power?

[flyingpez]

I just recently got my xs400 bobber running reliable and most of all charging. Since I built the bike 2+ years ago Ive had a modern triumph bonneville and a 77 shovelhead. Now that Ive ridden other bikes that have more power I feel like the 400 cant even get out of its own way. Is there anything, I that can be done to get some more power? Can it be bored out or anything like that? Different carbs? Just wondering. I looked for a thread on this and didn't see anything off hand. sorry for my ignorance if there is one.

Keith.

 

[eric123]

Cheapest and easiest is to lose weight, both you and the bike. Exhaust and air filters is probably next, then carbs and then cracking open the motor...Make sure the bike is tuned as perfectly as possibly really makes a difference too...

 

[xschris]

For any real power you will need a bigger bike, seems you have already done that

 

[drewpy]

Cheapest and easiest is to lose weight, both you and the bike. Exhaust and air filters is probably next, then carbs and then cracking open the motor...Make sure the bike is tuned as perfectly as possibly really makes a difference too...

 

[Arclight88]

I rode my first XS400 from San Antonio to Denver then back once. I had plenty of power to cruise on the highway, but long hills took a downshift.

Using the one HP per cubic inch rule, these motors should be able to sustain a HP range of 22-26 HP (5% tolerance). I have seen a book that claims one model of this motor produced 37 HP from the factory. OK, but I bet my 30 year old wonder is not.

Someone once commented that until you are taking corners at full power you don't need more power. ;-)

 

[drewpy]

depends where you ride. The xs is great on twisties and I have seen off bigger bikes but they are not for that, but were designed as a reliable commuter.

 

[flyingpez]

Ive shed a good amount of weight and I am 6' 145lbs myself. I have pod filters and my exhaust is pretty much straight open. I guess I'm kinda screwed than.

 

[JARichmond]

You can of course sink waaay more money than the bike is worth in engine upgrades if really want to. Things like bigger pistons (Kawasaki GPZ1000s will bring the displacement up to 440cc), gas flowed heads, lighter internals, and more aggressive cam will give you mounds of extra power with well tuned carbs.
Look for some threads about power around the forum. I know that there are some mentions of guys on the German forum getting insane P/W ratios

 

[xschris]

For the work and money its just not worth it

 

[corruptmind]

I find the xs400 to be a fun light-ish small bike with enough power to play if wanted. As a bike for commuting to work its not bad, decent on fuel and works. Its also a good bike for customizing the look of. A lot of options if you're semi decent at fab work. Not a lot of bikes can claim they've been a dirtbike, cruiser, bobber, chopper, cafe racer, tracker, and/or more. But you have to take it for what it is... its a 30 year old bike that has a small displacement, limits, flaws, low rev range, and tight gear spread. There's tweaks you can do to help but there's a sacrafice. You can adjust your sprockets for more top end with a loss of acceleration or reverse it. You can open the air/fuel flow, etc. Or like has been mentioned, you can sink a lot of money into mods/upgrades which could be the price of something a bit more modern and powerful. Its a UJM.

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[OleDoc]

I rode my first XS400 from San Antonio to Denver then back once. I had plenty of power to cruise on the highway, but long hills took a downshift.

Using the one HP per cubic inch rule, these motors should be able to sustain a HP range of 22-26 HP (5% tolerance). I have seen a book that claims one model of this motor produced 37 HP from the factory. OK, but I bet my 30 year old wonder is not.

Someone once commented that until you are taking corners at full power you don't need more power. ;-)

That is probally at the crank.probally around 25-30 at the rear wheel

 

[flyingpez]

Is 40cc over the most you can bore it out to? If I can fine another engine for cheap it may be worth messing with. I know the bike is what it is and its not meant to be a rocket ship, Im not like most kids that want to make an R1 out out of the bike they could afford. I would just like a little more so when I am on the highway I am not going balls to the wall to keep up with traffic.

 

[flyingpez]

What is a gas flow head and where can I get more aggressive cams?

 

[JARichmond]

A gas flowed head is basically a port and polish. Cleaning up all of the rough parts of your head that would help air flow in and out of your engine smoothly. Cams can be found at megacyclecams.com however they aren't cheap. You also may want to invest in stronger valve springs if you get a taller cam. I don't know if it's absolutely necessary to do so, but I'd prefer not to risk floating a valve.

 

[JamesDavies]

there is always nos? fair bit of money but it will give you the bursts of power you want.

 

[OG-Rider]

A gas flowed head is basically a port and polish. Cleaning up all of the rough parts of your head that would help air flow in and out of your engine smoothly. Cams can be found at megacyclecams.com however they aren't cheap. You also may want to invest in stronger valve springs if you get a taller cam. I don't know if it's absolutely necessary to do so, but I'd prefer not to risk floating a valve.

It is FRIGHTENINGLY easy to float the valves on my bike. I think stiffer valve springs would be a must with a hot cam.

 

[OG-Rider]

You can of course sink waaay more money than the bike is worth in engine upgrades if really want to. Things like bigger pistons (Kawasaki GPZ1000s will bring the displacement up to 440cc), gas flowed heads, lighter internals, and more aggressive cam will give you mounds of extra power with well tuned carbs.
Look for some threads about power around the forum. I know that there are some mentions of guys on the German forum getting insane P/W ratios

Have you tried GPZ pistons yourself?

 

[Scorpio1963]

More power out of XS 400 is not worth pouring alot of $ to make it do so.It would be cheaper to get a bike that a larger engine no matter what the make or model is.Before I bought my bike I just barely missed the oppurtunity to get a Suzki 650 gs.The Guy was only selling it for $450 and I was on the way to go look at my XS that purchsed.He said his brother had just bought it.I was kinda bummed.I dont know how long Im going to keep my current 400xs but if I have the cash at the time and i can get a good enough deal next year Im getting something bigger.At least something that will do 90-100mph with ease.I havent never gone faster than 65mph on my bike and it seems to stumble after 60mph.I know my bike has carb issues which is probaly reason for that.Oh also I want something thats a tad bit newer with shaft drive

 

[OG-Rider]

I can't help but notice how often posters in this forum cry about money. I started building bikes with my father in the 1960's. Honda, Kawasaki, BSA, Suzuki, Triumph, Yamaha, and Harley Davidson all fell victim to my cutting torch and welder. I'm a good builder with 40 odd years of experience, and I've never built a really good bike without spending a bunch of money! Bike building is not about money in my opinion. It's about creating the bad ass piece of individualized art that my minds eye can already see.

I purchased an XS400 last September. Before that, I had a hopped-up Evolution Sportster with around 80hp. Before that, a shovelhead bobber with about 75hp, and before that. a shovelhead chopper with about 80hp. Before that, a CBR600 F4i rated at 115hp, and before that a Suzuki GS1100 that was pretty close to 100hp. All in all, it had been about 20 years since I owned anything that wasn't screamin' fast.

So ya, the XS400 seems down right anemic. That does not mean I can't make an XS400 perform the way experience tells me it's capable of performing. Yes, it's going to cost money; I estimate the engine build will cost me around $1200 dollars, and the rest of the build will run close to a grand. With the initial purchase I will spend around $3200. If you say, "It's not worth it," I will simply ask you "who else has an XS400 that will stand sraight up in the first 3 gears." Good fabrication and mechanical skills will take you along way, but the really cool stuff costs money even when you do most of the labor yourself.

 

[Scorpio1963]

Well some of us dont have 2-3 grand to throw around on making a comuter bike into a racing machine.Nor do we have to tools or shop to do the fabricating neccesary.Even if I did I would still just buy a faster bike.Oh and 1 other thing speaking about me personaly,what $ I do have is tied up in another project I have been working on with 4 wheels.