Bigbore kit for xs1100?

[mrbsyammy]

Is it worth the time and money to go the bigbore kit on the xs1100 79 special? seen seller on flea bay selling pistons rings wrist pins n head gasket for $150 plus s+h??
Till then Mr.Bill

[IanDMacDonald]

Based-on discussion here, not unless you have a reason to.

[natemoen]

You don't really gain any power from it. So unless you need to bore the cylinders for some reason, it is not really worth it.

[mrbsyammy]

Based-on discussion here, not unless you have a reason to.

No reason except I want it to be faster I'm old but not dead..
usually more cc creates more HP and torque.
Till then Thanks Mr.Bill

[natemoen]

No reason except I want it to be faster I'm old but not dead..
usually more cc creates more HP and torque.
Till then Thanks Mr.Bill

And changing to a K&N filter adds 10 hp......

[Bonz]

My $.02

You are gaining decent displacement, but doing nothing to the intake or exhaust to make it breathe/flow better, raise compression or headwork. You are not gonna get more in or out of the cylinders than stock unless you increase flow in from the carbs or out through the exhaust. Larger displacement in the case of the XS is not gonna do much, if anything.

I would suspect any gains are from the fact it is a fresh engine build and feels new under the butt dyno.

Example: And Yes, I love the ZRX....My ZRX 1200 has a totally stock internal engine. Stock pistons, stock cams, stock compression. By upping the ability to breathe with a jet kit, header system and exhaust slip-on, I have raised power from stock 110hp/79 ft/lbs to a current 125hp/83 ft/lbs. These numbers are even better now (but not dyno'd yet) with adaptation of larger carbs from the ZZR1200. It's not so much the overall numbers but the fact the power is from way down low all the way to the top. This engine carries 70ft/lbs from 3k rpm up to 9500 rpm with a peak of 83 ft/lbs. 66ft/lbs at 2500 rpm... As much as the XS1100 is rated at the crankshaft by the factory on its best day... All because of making it breathe better.

[jetmechmarty]

The smart money says enjoy the XS11 for what it is. If you wanna go faster, buy something else.

[mrbsyammy]

And changing to a K&N filter adds 10 hp......

already did that soon as I bought it but thanks

[mrbsyammy]

The smart money says enjoy the XS11 for what it is. If you wanna go faster, buy something else.

Nice bikes. Well the only way I would get a another bike is if someone bought it being disabled and getting $800 per month does not allow for new toys.

[mrbsyammy]

My $.02

You are gaining decent displacement, but doing nothing to the intake or exhaust to make it breathe/flow better, raise compression or headwork. You are not gonna get more in or out of the cylinders than stock unless you increase flow in from the carbs or out through the exhaust. Larger displacement in the case of the XS is not gonna do much, if anything.

I would suspect any gains are from the fact it is a fresh engine build and feels new under the butt dyno.

Example: And Yes, I love the ZRX....My ZRX 1200 has a totally stock internal engine. Stock pistons, stock cams, stock compression. By upping the ability to breathe with a jet kit, header system and exhaust slip-on, I have raised power from stock 110hp/79 ft/lbs to a current 125hp/83 ft/lbs. These numbers are even better now (but not dyno'd yet) with adaptation of larger carbs from the ZZR1200. It's not so much the overall numbers but the fact the power is from way down low all the way to the top. This engine carries 70ft/lbs from 3k rpm up to 9500 rpm with a peak of 83 ft/lbs. 66ft/lbs at 2500 rpm... As much as the XS1100 is rated at the crankshaft by the factory on its best day... All because of making it breathe better.

I was told that the xj has bigger valves and just a better top end is this true and would this be the way to go keep in mind I am on a limited income being disabled and getting $800 per month. I do have an extra 1100 xs engine so I would do whatever mods to it since I want to be able to go back to original if I ever decide to sell it.
Till then thanks Mr.Bill

[IanDMacDonald]

Are you doing all of the work yourself? Otherwise, your mechanic bill for doing any engine work will eat a big chunk of that fixed income. My bike is faster than many, and I love it! However, the work did not come cheap.

[IanDMacDonald]

Nice bikes. Well the only way I would get a another bike is if someone bought it being disabled and getting $800 per month does not allow for new toys.

Is that Pee Wee's bike?

[crazy steve]

Yamaha detuned the XS/XJ motor over the course of production, with 'improvements' being attempts to regain power lost due to emission factors. As designed, Yamaha didn't really leave anything on the table.

The XJ head does have larger valves, but also has a larger combustion chamber, so the loss of compression is only partially offset by the larger valves. The XJ also has milder cams (another reason for the larger valves) that helps with the midrange but hurts top-end power.

So as a power-adder, a big-bore really won't add much power (a few HP) unless you also improve the breathing, and things like a professional ported head and aftermarket cams are definitely not lo-buck. Very careful tuning is the best path to power on a budget, with particular attention paid to ignition timing, both initial timing and the timing curve.

Search for posts by Dan Hodges for more info.

[jwhughes3]

Burnt orange and white gave me a HP boost!

No seriously - the '81 Navy bike has a big bore kit and has a noticeable increase in seat of the pants power over stock - that being said - my 78 was very close.


John

[BA80]

I was told that the xj has bigger valves and just a better top end is this true and would this be the way to go keep in mind I am on a limited income being disabled and getting $800 per month. I do have an extra 1100 xs engine so I would do whatever mods to it since I want to be able to go back to original if I ever decide to sell it.
Till then thanks Mr.Bill

The 78 and 79 engines are quicker than the 80 - 83 and they have smaller valves.

Burnt orange and white gave me a HP boost!

No seriously - the '81 Navy bike has a big bore kit and has a noticeable increase in seat of the pants power over stock - that being said - my 78 was very close.


John

That engine doesn't run any better than the stock 79 engine in my bike. I rode with Russ a lot when he was on that bike. 97cc doesn't make much difference in the grand scheme. The Navy Bike has also been converted to the 2H7 TCI and has a centrifugal advance. It would run a lot better with a good exhaust on it I think