Big Bore Kit

[daddy-O]

Has anyone had any real world experience with a "Yamaha XS1100 Big Bore 1196cc kit "9.8:1" CR pistons rings head gasket HP coated" as currently listed on eBay from Canada? Also, "IF" the kit is installed what about balancing the rotating assembly as the new pistons and other moving parts are larger?

Just beginning to investigate this possible rebuild. In the possess of reviving a NICE 1979 xs1100F that has been stored inside for a long time. Cold compression check shows #4 to be weak compared to 3 others. This improves greatly with t-spoon of Marvel Mystery Oil. Suspect that cylinder #4 may have had some surface rust as it ran very hot compared to the others. My plan is to run the bike for a while with Amsoil 2 Cycle Racing Oil (200:1 mixture) in the fuel to see if the rings will slowly reseal. If this doesn't work I will consider a complete tear down once I have the needed new parts in hand.

You comments and expertise most welcome.

[crazy steve]

Check the valve adjustment; my experience is that too-tight valves really affects the compression...

As to the big-bore kits, if it's a Wiseco piston kit, these are quality parts. No rebalancing needed.

[ViperRon]

I did the Japan 1198 kit bike runs smooth all RPM ranges no roar or vibration I can feel. As for the Kit you mention I can not say.

[trbig]

Bigger doesn't matter with the balancing. Your crank may be pushing one bigger piston up the bore, but it'll be pulling an equally bigger piston down at the same time and they offset each other.

As Steve pointed to.. That's if the machining is quality and all pistons are the same, but it would take a pretty severe difference to ever notice any vibrations from it.

Sadly, I can't attest for anything but Wiseco either.

[MPittma100]

Big Bore Kit

You also need to run a cylinder leaking test to verify what is responsible for the compression loss. Not doing so leaves you only a guess as to what is wrong.

There are 4 possible areas of leakage: Rings, intake valve, exhaust valve, head gasket.

If you do not have access to a cylinder leakage tester - buy one. If not, put about 90 psi compressed air into affected cylinder with piston at top and valves closed. Find the air leak by feeling/listening to various areas - exhaust pipe(s), around intake/carb area, crankcase vent tube/oil fill area.

You will find out what exactly is leaking and know what to fix.

I have had a number of dealings with Wiseco pistons. One of the factors of engine balancing is having all of the parts of the rotating assembly weighing the same (grams). The Wiseco pistons will weigh the same. Other brands? - maybe, maybe not. You get what you pay for with the Wiseco brand. When they first went into business many years ago, they were making only motorcycle pistons. They now have a piston for virtually any engine made.

MP

[TopCatGr58]

I didn't know CANADA had their own eBay?!

Okay, I found it, here's the description of the parts!

Note the BOLD TEXT below!!!! Looks they are taking a $100.00 set of cast big bore pistons and putting some fancy "stuff" on it! ?Snake oil? I don't know anything about what they are talking about!

T.C.

Yamaha XS1100 78-81 "1196 cc"

Big Bore Kit

This kit has 4 pistons 74.5 mm (2.933") and includes full floating wrist pins, clips, piston rings, matching head gasket and Ultra Slick assembly lube. These are quality high silicon aluminum pistons and rings imported from Japan and process coated in Canada. Composite head gasket is .046" thick. This kit will give you a compression ratio of approximately 9.8:1. Wrist pin oil holes have a special chamfer for improved pin lubrication. The only machining required is to bore and hone your existing cylinders to accept the 3mm oversize pistons. This kit will add lots of power to your XS1100 the coating really works. More cc's, less friction and better combustion.

Each set is inspected and weight matched during our process. Quality is guaranteed. Piston domes are coated with CBC1* thermal barrier and skirts with DFL1* high pressure dry film lubricant. Coatings are heat cured. Pins are coated with PKSX* dry film.

Good for all 1978-1981

Yamaha XS1100 models

Installation instructions and bore surface finish recommendation included

If auto shipping calculation seems high send us a message and we will get a correct cost

Coatings manufactured by TECH LINE*

CBC1*

- Ceramic thermal barrier coating

- Reduced piston temperature. Keeps heat in chamber longer, through the power stroke

- Increased torque and H.P. Increased combustion chamber efficiency.

- Reduced fuel consumption.

DFL1*

- high pressure lubricant with extremely low coefficient of friction

- reduces friction, galling and scuffing

- increases part life from up to 10 times

- ideal for piston skirts, cam lobes and any part subject to sliding or rotating friction

PKSX*

- designed for cylinder walls, lifter bores and valve guides

- extreme temperature and pressure lubricant

- reduces friction and wear

- bonds at 20 millionth of a inch

DFL1 is a thermally cured Dry Film Lubricant. DFL1 makes use of a unique binding system, to retain high temperature stability while reducing friction. The film thickness of DFL1, as applied, ranges from .0005" to .001".The lubricating ingredients in DFL-1 can lubricate at pressures above 350,000 psi. Part life increase is a benefit. Life increases from two (2) to ten (10) times what is normal can be seen. The dry film lubricants may burnish until they are no longer visible, however, the active materials are bonded into the pores of the part and continue to provide protection. Parts will run cooler. Engine oil and water temperatures have shown a reduction. DFL1 is a primarily a high pressure lubricant and is recommend for use on any part subject to sliding or rotational friction. Camshaft assemblies, piston skirts and bearings all benefit from application of DFL1.



CBC1 is thermally cured metallic ceramic coating designed to be used on steel, cast iron or aluminum combustion chamber surfaces, piston domes and valve heads. CBC1 is formulated to be used in all engines, both 2 and 4 stroke. CBC1 provides a hard, durable thermal barrier overlay to any component. Provides reduced part temperature, resistance to detonation, increased combustion chamber efficiency. More efficient oxidation of fuel also occurs, leading to increased power output. CBC1 allows minimal transfer of heat through the coated surface thus reducing part operating temperature. In general coating the combustion chamber surfaces will allow you to run less initial timing with no loss of power (usually a gain will occur). You may also be able to run significantly less fuel. You should be able to run smaller jet sizes. Obviously no specific recommendations can be made as every engine combination will be different. Testing has shown significant power increases on a dyno. In addition certain changes can be made in such areas as tolerances, timing, jetting, that will increase torque and H.P. and are only possible through the use of coatings. Horsepower gains in excess of 15% have been measured in independent dyno testing.

[BA80]

imported from Japan

Uhhhh.........so are our bikes TC.

[TopCatGr58]

Greg,

I was just showing that they weren't WISECO FORGED quality pistons which cost $500.00 + for a set. I don't know about the coatings and treatment that they are putting on them, and if that is worth $200+ bucks, vs. just getting the Japanese cast piston set like ViperRon put in his bike last year?!

T.C.

[BA80]

I'm pretty sure the pistons these bikes come with are Japanese cast pistons.

I know Maximan put THOUSANDS of bucks in his XJ and ended up with only like 15 more horsepower.

Is THIS the kit ViperRon got? Bigfoot got one of these but as of yet hasn't installed it.

[MPittma100]

Big Bore Kit

There is a big quality difference between a cast piston and a forged piston. The forged piston is a much better piece. Cast pistons are for everyday use - not so much a performance part. A forged piston is a performance part and is much stronger and requires less piston to bore clearance because they do not expand and contract a lot like the cast version.

I do not know if Yamaha used cast or forged in production. If they did use forged, your best bet is to use a forged replacement. If they used cast pistons, replacing them with a forged one is an upgrade - a good upgrade. If Yamaha used cast pistons, replacing them with another set of cast is a suitable repair.

Forged pistons are normally used in high performance, higher compression, higher revving applications. Typically, a forged piston set is made to increase compression. With the increase there will be a significant increase in power and you will likely have to start using premium fuel to feed the new ponies - just something to consider.

All of the "fancy" lubricants and treatments are used to enhance the cast piston's durability. They are not needed in forged pistons. The material used in the forged piston is much better than the cast material.

My 2 cents.

Mike

[BA80]

Absolutely Mike, I'm just sayin'

Unless you have DEEP pockets and don't care or plan to run your engine at 10 - 12 K all day long the forged pistons are completely unnecessary.

Some of the hottest engines I've built (automotive) were built with cast pistons. $$$ does not = HP or reliability. The forged pistons are only necessary if your pumping HUGE HP or RPMS. Then, you have the bottom end, trans, and clutch to worry about.

The BB kits were not intended to create HP, simply to repair worn cylinders.

[crazy steve]

...A forged piston is a performance part and is much stronger and requires less piston to bore clearance because they do not expand and contract a lot like the cast version.

Actually, the opposite is true; a cast piston expands less and needs less clearance. And while a forged piston is stronger, there's lots of cast pistons out there doing just fine in typical street motors. It's when you start running things on the very edge that forged parts become really needed.

[ViperRon]

I got the 150.00 set of pistons and gasket from Japan. I compared them with the ones from Yamaha and found no difference. I used calipers and all measurements were the same. Wristpins were a smooth tight fit and felt the same sliding in. I hung the pistons on a balance and they appeared perfect. The balance was for gun powder loads so pretty precise. I had an exceptional performance shop bore the cylinders and used highspeed precision hone on the last .001 of the bore. The only issue I have had is that when warm the new highcapacity AGM battery will barely turn it over. Cold compression values were even near 160 mark before the engine was started the first time. Head was slightly shaved no gasket on cylinder to engine side. So for me I have a normal good running bike now more power then it had new and I did not spend the extra 500 for a name. But I also do not plan on racing a 30 year old bike on the strip. Now that rings are seated I have the carbs running a little rich and at 75 to 80 get 41 per gallon on hightest gas.

I hate to think how quick it would be screwed up if that coating pealed off.

[BA80]

no gasket on cylinder to engine side

Not exactly sure what that means.

Did you have any cam chain issues with the shaved head?

[BA80]

Ohhhhhhhh! Ok, I thought about it a little and now I understand. You mean between the jugs and the cases.