Hey guys, Tim here, I'm just going into my second season, my xs400 was my first bike and out of the two others I've gotten it's still my favorite. I think its time to put some more power into it. Id like to beef up the engine, and turn it into a cafe, maybe stretch it a few inches but honestly, I've no idea where to start or even what I should be looking at. ALL advice, stories, tips welcome. Im excited to hear what you guys have to say.
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Noob, need all the advice i can get, want to beef my 83 up and eventually cafe
- Thread starter TcGrey
- Start date
jthiessen
XS400 Addict
Somewhat a thread hijack, but is it possible to bore and add a plus sized piston?
http://www.xs400.com/forum/showthread.php?t=9388&highlight=big+bore Check this thread out, post 3 and 4 for the dohc bikes. Not sure how he made out or if it ran well as no updates where done on this subject
jthiessen
XS400 Addict
Not sure how he made out or if it ran well as no updates where done on this subject
Red flags and alarm bells going off!!
Agree we need to see it work. With these kinds of mods you almost always run into some sort of issues than need to be fixed. I have always said if I want a bigger more powerful bike I would just get one that came that way stock. For the time and money it will be cheaper
hjennings
XS400 Addict
http://www.xs400.com/forum/showthread.php?t=9388&highlight=big+bore Check this thread out, post 3 and 4 for the dohc bikes. Not sure how he made out or if it ran well as no updates where done on this subject
Disclaimer: I'm a car guy that's just now getting into these bikes, so if this has been covered, I apologize.
Why couldn't a guy slightly overbore the block to fit in a slightly larger sleeve (thus using a larger piston)? Looks to me like there should be enough meat there.
XSLeo
XS400 Junkie
Yes, I think it's possible to bore out the stock sleeves or even bore the cylinders for a larger sleeve.
As xschris said there can be problems involved. A bit research might find awswers to that question.
I know that several places sell over bore kits for the XS650, Some just bore the stock sleeves to fit bigger pistons, this stretches the cc's out to 700 or a bit more.
There is a kit that you bore the cylinders out and use sleeves and pistons to make it a 750. Similar kits have big fin cylinders already fitted for the 750 sleeves and pistons.
Some one out there might sell kits for the XS400 that do similar things.
xschris also mentioned getting a bigger bike. The XS650 with all it's options is a good candidate.
Leo
As xschris said there can be problems involved. A bit research might find awswers to that question.
I know that several places sell over bore kits for the XS650, Some just bore the stock sleeves to fit bigger pistons, this stretches the cc's out to 700 or a bit more.
There is a kit that you bore the cylinders out and use sleeves and pistons to make it a 750. Similar kits have big fin cylinders already fitted for the 750 sleeves and pistons.
Some one out there might sell kits for the XS400 that do similar things.
xschris also mentioned getting a bigger bike. The XS650 with all it's options is a good candidate.
Leo
XSLeo
XS400 Junkie
I didn't know if there was. I don't know a lot about the aftermarket support the XS400 has.
Leo
Leo
hjennings
XS400 Addict
Rather than using a kit, I'm thinking just any bike (heck wouldn't even have to be a Yamaha) that has a slightly bigger sleeve (I'd rather bore the block and add a bigger sleeve than bore the sleeve) and fit it into the 400 block.
Not only would you get a few more CCs, but possibly move to a piston/ring size that is commonly available. I don't have access to a lot of motorcycle data (neck deep in cars mostly, new to the bike arena). But it'd seem all you'd need is to know the stock bore of the 400 block (the block, not the sleeve). Do some measurements to see what a save overbore would be, then search for stock sleeves in those sizes. Bore the block, press in the sleeve, and add new larger (and more common) pistons and rings.
Not only would you get a few more CCs, but possibly move to a piston/ring size that is commonly available. I don't have access to a lot of motorcycle data (neck deep in cars mostly, new to the bike arena). But it'd seem all you'd need is to know the stock bore of the 400 block (the block, not the sleeve). Do some measurements to see what a save overbore would be, then search for stock sleeves in those sizes. Bore the block, press in the sleeve, and add new larger (and more common) pistons and rings.
Im not sure you would want to take these bikes much faster than a well tuned stock 400 motor with pods, re jetted carbs and free flowing exhaust will already go? These frames have they're handling limitations and over a certain speed they will just start feeling a little on the hairy side 
But I guess for more torque or acceleration it could be worth pursuing. You could turn it into a mono mahine 
But having said that, if you find a relatively easy mod that isn't crazy expensive I am more than interested in the results!
But I guess for more torque or acceleration it could be worth pursuing. You could turn it into a mono mahine But having said that, if you find a relatively easy mod that isn't crazy expensive I am more than interested in the results!
if you want a faster bike, sell the xs400 and buy something else (or keep it, and buy another bike). You're not going to get amazing results from modding this one without running into many issues. These bikes aren't built for speed. With the right tools, skills, and parts anything can be done, but with this bike you'd end up replacing more than you'd be keeping. You can go a little way as suggested above with some pod air filters, an aftermarket exhaust and some rejetting, but even that should be more for the looks than the performance gain as it is a marginal improvement for the money invested.
Unless you want to do mods for fun. If you want to find out how far you can push a 30-year-old 400cc bike. If you want that custom modded bike that you built to your personal preference and you want to have your own creation to straddle
just my $0.02
Unless you want to do mods for fun. If you want to find out how far you can push a 30-year-old 400cc bike. If you want that custom modded bike that you built to your personal preference and you want to have your own creation to straddle
just my $0.02
hjennings
XS400 Addict
Isn't that what most of us want?
Seriously though... and not trying to hijack this thread... but I've thought of a slight bore/re-sleeve not so much for a power mod, but to allow for more common replacement parts (piston and rings).
I do not have the resources to search through all the sleeve inside and outside diameters like I do automobiles. But I'm put money on it that there is enough meat in the block itself to do a very slight overbore, press in a factory sleeve that is slightly bigger than the original XS400 sleeve, and then use the corresponding piston/ring combo that is common and parts are readily available for. Wouldn't even have to be a Yamaha part. A sleeve is a sleeve. As long as you did the right bore and pressed it in, once it's in it doesn't care what the part number is.
