Holy Grail of XS400 Big Bore Pistons

I think this would be the fastest xs400

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Like I said if anything invest on something else vs engine mods on a 400cc engine. Bike will do 90-105 stock, what do you want 110mph lol. My zx10r does 108 on gps in first gear tall! Seriously if your doing it to add performance, I wouldn't waste my time with a twin!
 
Like I said if anything invest on something else vs engine mods on a 400cc engine. Bike will do 90-105 stock, what do you want 110mph lol. My zx10r does 108 on gps in first gear tall! Seriously if your doing it to add performance, I wouldn't waste my time with a twin!

:laugh::laugh::thumbsup:
 
Like I said if anything invest on something else vs engine mods on a 400cc engine. Bike will do 90-105 stock, what do you want 110mph lol. My zx10r does 108 on gps in first gear tall! Seriously if your doing it to add performance, I wouldn't waste my time with a twin!

I own go fast toys. The XS is just fun to ride.

I am fully aware of the 'buy something different to go fast, save your money' mentality, I preach it quite often. When it comes down to it though, does it really matter? People race old 350's and put some insane money into them, when the class has no where near a payout to cover the bike. They could have just bought 3 or 4 stock liter bikes with that money. People buy cars that are worth 5 grand with underpowered V8's, put thousands and thousands of dollars into them to get some pretty nice power and have lots of fun with them... But wait, they could have just taken all that money and bought a 500 horsepower Ferrari 456 for $35,000.... I can keep going, but I'm sure you get the point I'm trying to make.
 
That would still be one of the slowest 400cc bikes made:wink2: A modern (street legal) 400cc would still be a better buy imho if that is what you are going for.

I've already talked to My local KTM dealer. I'm first on the list for the RC 390 when they get delivered:thumbsup:
 
If you have an xs400, you should just get the 1190 rc8r! I got a chance to do an open track day with one last season! I just say it was a beast to ride...still love my cbr,zx's though!
 
I am fully aware of the 'buy something different to go fast, save your money' mentality, I preach it quite often. When it comes down to it though, does it really matter? People race old 350's and put some insane money into them, when the class has no where near a payout to cover the bike. They could have just bought 3 or 4 stock liter bikes with that money. People buy cars that are worth 5 grand with underpowered V8's, put thousands and thousands of dollars into them to get some pretty nice power and have lots of fun with them... But wait, they could have just taken all that money and bought a 500 horsepower Ferrari 456 for $35,000.... I can keep going, but I'm sure you get the point I'm trying to make.

Cheezy Quote of the day: Sometimes it's not the destination but the Journey to get there!:bike:
 
If you have an xs400, you should just get the 1190 rc8r! I got a chance to do an open track day with one last season! I just say it was a beast to ride...still love my cbr,zx's though!

Now that I can't afford, otherwise I would. I had the chance to take one for a slow lap at Mid-Ohio a few years ago, that engine tone is something else.
 
my two babies! just added the xs400 to the stall! wanted a project/small bike to putts on!:thumbsup:
 

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So I've done a little more playing around in solid works, and stroking is a no go. Even if I could find some rod journal bearings that would work for me, the crank just wont hold up. Guys with ME degrees that have been doing this for over 20 years convinced me its a worthless endeavor, and said even if the crank holds up the piston speed will be too fast for anything over 5000rpm.

So carry on with the big bore talk :)
 
So I've done a little more playing around in solid works, and stroking is a no go. Even if I could find some rod journal bearings that would work for me, the crank just wont hold up. Guys with ME degrees that have been doing this for over 20 years convinced me its a worthless endeavor, and said even if the crank holds up the piston speed will be too fast for anything over 5000rpm.

So carry on with the big bore talk :)

or forced induction ;)

thanks for the info
 
Might have found a piston that will work on our bikes with no modification, other than switching to the XJR rods. Just bought a used piston from ebay, will need to find a used rod somewhere, then I can get to measuring.

The nice thing about these pistons? They are readily available in sizes from 69 to 73mm, and can be grabbed for cheap. Only downside is having to switch the rods. But for a $200 rod change, it may be worth it to be able to use readily available, cheap pistons. Before I say what they are from I want to make sure that no piston crown modifications are needed. they do have valve reliefs, and they look right, but the angle may be totally different for all I know. I'll report when I can find a junk rod.
 
Might have found a piston that will work on our bikes with no modification, other than switching to the XJR rods. Just bought a used piston from ebay, will need to find a used rod somewhere, then I can get to measuring.

The nice thing about these pistons? They are readily available in sizes from 69 to 73mm, and can be grabbed for cheap. Only downside is having to switch the rods. But for a $200 rod change, it may be worth it to be able to use readily available, cheap pistons. Before I say what they are from I want to make sure that no piston crown modifications are needed. they do have valve reliefs, and they look right, but the angle may be totally different for all I know. I'll report when I can find a junk rod.

keep us posted :)
 
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