Big bore kit

[blkryno]

How can I tell if my XS11 has a big bore kit in it?

[Tonyxs11]

How can I tell if my XS11 has a big bore kit in it?

pull the head off and measure the bore.

[blkryno]

thank you, do you know off hand what the measurements are for stock and big bore.

[Tonyxs11]

thank you, do you know off hand what the measurements are for stock and big bore.

standard bore 71.5mm. big bore depends on what size has been fitted !!!!

[LAB3]

Unless you picked the bike up from an unknown source such as an auction or a salvage type sale my best guess is you'd know if it where a big bore since that would be a selling point to increase it's value in most cases.

[Ranger_xs1100]

How can I tell if my XS11 has a big bore kit in it?

Assuming that you have ridden other XS11s, wouldn't you be able to tell if there is a performance difference in a big bore bike? I have zero experience with big bore kits, but isn't that the whole purpose? Increased performance? If not noticeable, then it seems like the expense may not be worth the benefit. Can anyone with big bore experience comment please? I'm just curious. Thanks.

[Bonz]

Main thing a big bore will do is add to your torque. Of course you'll gain some horsepower as that is a function of torque and RPM. However down low and mid range is what I understand you will notice.

[cajun31]

Assuming that you have ridden other XS11s, wouldn't you be able to tell if there is a performance difference in a big bore bike? I have zero experience with big bore kits, but isn't that the whole purpose? Increased performance? If not noticeable, then it seems like the expense may not be worth the benefit. Can anyone with big bore experience comment please? I'm just curious. Thanks.

Bob, I have never installed a big bore kit on any of my Yamaha's. I have done a bit of research on doing that with my Harleys. Just adding bigger jugs and pistons gives the Harleys increases in both torque and horsepower. Not to the extent they will run with the xs11 but you can feel the difference.

[speedlimit85]

I had a 79 standard with an orient express big bore kit a long time ago. 1179 cc with a power band -at high rpm the bike would really take off. I would bury the needle in the red.

I would know by riding what I have.

[blkryno]

Thanks everyone for the feed back. I have a 79 Special and the 81 has always seemed to have more to it. The story is I bought the 81 new in June of 81. Within a week the cam chain snapped and locked up the engine. We were on the highway at the time. When the back wheel locked up I was able to use the clutch to keep control and coast to the shoulder. When I contacted the dealer about it they were great. They fixed it 100% and gave me a loner 750. When I picked it up I seem to remember that the mechanic said that he had to bore the engine. I wasn't very mechanical at that time so I didn't really ask that much about it. My valve cover still has the groove on the inside where the cam chain tore into it. So it being winter right now I just got to day dreaming about what I need to do to the 81 for summer. And I remembered what that mechanic had said. So I knew this was the place to ask questions about it. Thanks

[bikerphil]

Maybe look in at the piston with a boroscope thru the spark plug hole, that may tell you something.

[LAB3]

Even going up one size on the ring and piston combo to clean up scored cylinder walls is going require a rebore. After reading your story I'd find it difficult to believe that on a bike getting warranty work done that there'd be aftermarket parts used, I'm pretty sure Yamaha didn't offer a big bore kit, not for a street bike anyhow.

[Tonyxs11]

Even going up one size on the ring and piston combo to clean up scored cylinder walls is going require a rebore. After reading your story I'd find it difficult to believe that on a bike getting warranty work done that there'd be aftermarket parts used, I'm pretty sure Yamaha didn't offer a big bore kit, not for a street bike anyhow.

yeah I agree, but a dealer should of replaced the cylinders and pistons with new standard ones. but if a new cylinder wasn't available at the time i suppose a re-bore would do. 1st over size doesn't make it a big bore though.

[LAB3]

yeah I agree, but a dealer should of replaced the cylinders and pistons with new standard ones.

I wouldn't have settled for anything less, better yet an entire new bike. Hard to do 40+ years after the fact.

[LenB]

Like to share a similar experience.....

About 10k kms my '80 11G started to burn oil like crazy. Still under warranty, I took it back to the dealership. What they discovered was it had been fitted with intake guides made of a soft metal that wore quickly. The wear then allowed oil past the valve stems and into the cylinders. Stem seals were also suspect. This, compounded with rusted-out axle detents in the mufflers (worked close to home and the exhaust never heated up enough to burn off the condensation) and riding behind the factory Vetter/Yamaha fairing made for a very fume-filled ride. Torn down, it was discovered that there was enough cylinder wear to require a one-over bore c/w pistons & rings. Assumed it was all factory parts as it was all under warranty. I was handed back a sweet running 11, not using any oil anymore. So, as per my rough calculations, I'm still riding an 1109 cc (?) classic Yamaha. Anyone else out there ever had a problem with premature valve guide wear?