Wiseco Big Bore Kit

[MPittma100]

This Wiseco big bore kit to 1179 cc seems to be a lot less $ than I have seen in the past. Is this too good to be true?

http://www.ebay.com/itm/Wiseco-Pisto...0e00d4&vxp=mtr

[crazy steve]

The listing is for just one cylinder.... X 4 would be $468.16...

[MPittma100]

Big Bore Kit

The listing is for just one cylinder.... X 4 would be $468.16...

Why would anyone advertise this way?????

[DGXSER]

So someone who is not looking close buys it, then finds they only got one, and concludes its cheaper to buy three more from them than to buy a complete kit.

[D0wn5h1ft]

There are cast piston kits for a similar price to that.

[IanDMacDonald]

I'm curious: factoring in machine shop costs, actual cost of the bore kit, etc, how is it justified to spend the money on a bore-over, versus finding another engine? It's like what, 79cc's for anywhere from $500-$1k? And, from my understanding, the big bore kit is not that breath-taking of an upgrade. Am I wrong?

[crazy steve]

Nope, you're not wrong. If you buy the Wiseco kit, you'll have at least $700 in it by the time you have a running motor. That will buy a couple of good XS motors at least...

But when the 'genuine' Yamaha parts were still available, they were about as expensive so the Wiseco kit was considered a decent deal.

[D0wn5h1ft]

http://www.ebay.com/itm/80-81-Yamaha...7486d7&vxp=mtr

I, personally, wouldn't get a new engine. I'd spend the money on some cast pistons before I bought a new motor and opened up that fun box of things I have no idea whether they work or not. Finding a bent valve, stripped gears, scored cams shafts...I'd just do that overbore and use something I now works. PLUS, it'd be a great time to port the heads and remachine all those surfaces.

[DGXSER]

And that is the big $1000 question. What condition is the used engine in? I had the experience of helping another XSive put a used engine in his bike some years ago. He had a mechanic he was dealing with, a guy known for XS650 build bikes IIRC.

So he got this used engine from him after his engine th guy had been working on for him imploded...ie..Ate one fo its exhaust valve heads, dropped it off the calve stem into the chamber, chewed it up and spit it out the exhaust port. Only after causing mucho head and piston damage. So back to the used engine....after we got it installed, we had no oil pressure. It had dropped the idler gear off the end of the shift shaft fork and it got chewed by the clutch gears. So we pulled the one off his old engine. Then the gears were bad, so we pulled the ones off his old engine. Then it had a bent valve, so, got a valve and replaced it.

Now, in this case, between me and another local XSive Doctor we took care of the mechanical skills and labor the owner did not have the ability to perform. So the labor cost were zero. But, if you did nto have that skill on hand, you can see how that used engine could have ran him into LOTS and LOTS of cash. And we never did get it running quite correctly, so there may have been more to find. It got burnt up in a fire before we ironed it all out. Even so, all of the internals were not new or fresh still.

Compare that to the 1179 kit, all new internals, or well documented internals, and clean fresh parts, head clean ad valves lapped. A lot better starting spot really.

Not that I have ever done one, or plan to. however, there are advantages to it.

[JCW]

It's good for us xs850 owners! we can just buy 3.

I wonder if the reason big bores don't work is because the cam, cam timing and head (valves, port, etc) aren't been optimaized for the extra cc's.

Although another 95cc isn't a whole lot.

And yes, I've searched Mr Hodges posts, and with headwork and megacycle cams and big bore he's pushing over 95hp at the wheel. That's not too bad.

[crazy steve]

...So back to the used engine....after we got it installed, we had no oil pressure. It had dropped the idler gear off the end of the shift shaft fork and it got chewed by the clutch gears. So we pulled the one off his old engine. Then the gears were bad, so we pulled the ones off his old engine. Then it had a bent valve, so, got a valve and replaced it..

But most if not all of this could have been addressed before the motor went in the bike. If a motor is out of the frame, I'll pull all the covers and take a look at what I have before reinstalling, making any repairs then. The only way I'd install a used motor without doing that would be if I pulled it out of a good running bike...

Catastrophic failures of these motors are fairly rare (Tod not withstanding... LOL) as nearly all main reasons as to why one is 'dead' consist of ignition/electrical, carbs, trans, or valve adjustment (usually lack of same) in some combination. If it's sat for an extended period, you can have issues with frozen cylinders but it's rare that it can't be 'unfrozen' with some effort.

If you have deep pockets and/or undying love for the bike, go ahead and spend the $$$. But a complete rebuild with pistons, rings, rod/main bearings (can rod bearings even be found these days?) and a few valves can easily top $1K if you can find all the parts. Unless the bike is in excellent cosmetic condition (and if it is, it's not likely to need a motor rebuild), it's probably worth less than $2K. Add in a fuel system rebuild, brakes, tires, battery, etc and it would too easy to have far more than the bike is worth into it.

I love these bikes and wish all this wasn't so, but it is what it is....

[MPittma100]

It's good for us xs850 owners! we can just buy 3.

I wonder if the reason big bores don't work is because the cam, cam timing and head (valves, port, etc) aren't been optimaized for the extra cc's.

Although another 95cc isn't a whole lot.

And yes, I've searched Mr Hodges posts, and with headwork and megacycle cams and big bore he's pushing over 95hp at the wheel. That's not too bad.

Yes, the reason that the big bore kits do not seem to work is because you have only succeeded to make more cc and add weight to the rotating assembly.

Everything has to match. Bigger bore (likely more compression), hence you need more flow in the heads and cams, more fuel and a matching exhaust upgrade.

I think that I would only do a bigger bore when I had a mechanical failure in one or more cylinders.

[crazy steve]

The Wiseco kits have been around for years, but the thing to remember is when they first appeared there were still parts/people around that could use these kits to build power. Different exhaust systems, multiple suppliers of cams, carb options, etc. But when Yamaha signaled that they were abandoning the XS motor with the introduction of the FJ in '83, everyone moved on to the next new thing and further development pretty much stopped dead. All of that is gone now, and this has become just a rebuild option.

[crazy steve]

I'll add that I suspect that the main reason rebuild parts are so hard to find is the brief burst of popularity these motors had as the 'formula' motor of choice for those midget 'Legends' race cars in the '90s. When parts started to dry up, they moved on the FJ motors.

[IanDMacDonald]

Rebuild parts, as-in bearings, etc.?