80-81 1196 Big Bore piston kit

[WMarshy]

You crazy kids have a serious need for speed, talking about big bore kits and lopey cams and port/polishing and such. I thought this bike was beastly enough as is, especially with the tractor gearing.

Then there's the turbo bike that got posted, for God's sake.

You guys are nuts! Thanks for the good read, it's facisnating to see what you can do with these little engines!

You know what they say... If it aint broken, modify it!

So I called up an old Yamaha dealer near my home town to see what NOS parts they might have on the shelf and found they have an entire crank bearing set! All of the brown color bearing were gone from the kit but all of the others were present. The guy I spoke to was like "we haven't rebuilt one of these in about 20 years!". I asked real quick what they can do on price and said the bearings still sell from Yamaha for about $18 a half! but he said they could take 10% off. I asked if they could do better and he said likely but his manager was busy with customers at the moment and I told him not to worry about it until I know what I needed and was ready to buy... From what i can see, bearing halves are selling for about $13 on ebay. There are a few auctions of guys selling an entire set but I dont know yet if there is a savings over buying then individually (from ebay). I might be able to convince the dealer to cut me a really good deal...

Any of you guys ever replace con rod and crank bearings while installing your big bore kit?

[petejw]

You know what they say... If it aint broken, modify it!

Any of you guys ever replace con rod and crank bearings while installing your big bore kit?

hey marshy, if ur going to buy new bearings go for the
blue coloured ones they're the thickest u can get
and will suit better on a used crank.

[BA80]

Any of you guys ever replace con rod and crank bearings while installing your big bore kit?

The con rods are unobtainium but I've never really seen any worn too bad, you can still get main bearings. Those are the ones that usually go bad in these engines.

The over bore kits I've seen running really don't make that big a difference. The oversize pistons weren't intended to increase performance anyway. They were to repair engines with worn cylinder walls.

[WMarshy]

hey marshy, if ur going to buy new bearings go for the
blue coloured ones they're the thickest u can get
and will suit better on a used crank.

From the way he explained it, the crank has a number on it and each con rod has a number on it. There is some math involved and the resultant number you get will tell you which color bearing you have to use to achieve factory spec clearances... I will have to wait to get it apart to determine what shape the crank is in and if it needs a clean up (doubtful but need to check). Too tight of a clearance will starve your journal of oil so, tighter clearances are not always better. I will have to wait for disassembly..

The con rods are unobtainium but I've never really seen any worn too bad, you can still get main bearings. Those are the ones that usually go bad in these engines.

The over bore kits I've seen running really don't make that big a difference. The oversize pistons weren't intended to increase performance anyway. They were to repair engines with worn cylinder walls.

Same idea, they will be check upon disassembly. Hopefully I wont need any but if I can get my hands on them for reasonable price I would like to replace them. It looks like the crank bearing were used in the early FJ motors so they can still be found.

Regardless, increasing the bore will result in increased power. As mentioned prior, significant gains wont be made without changes to valve/cam timing. Cams will have to wait but I plan to slot the cam sprockets... My plan it to use the later model head these pistons are made for b/c I want to take advantage of the bigger valves, but use the '78 cam (s) like Mr. Hodges did. Its going to be a long project so I'm going to talk to my Dad and see if he is willing give me his old E that needs an overhaul. I cant give up the bike I ride daily.

[petejw]

mate u dont need to go to all that trouble,
those figures are for a brand new crank,
the thickness between the bearings isnt much,
this was all covered well on the uk site, maybe
1 of them mite chime in.

[BA80]

I've ridden and do ride with people that have both the 1179 and the 1196 and the difference is really insignificant.

If you want to spend the money though poke around in HERE you'll find what you want.

[BA80]

I found THESE on fleabay too Wade.

[WMarshy]

I found THESE on fleabay too Wade.

Greg go back a page, I purchased the cheap 1196 kit this thread was started about... $178 delivered to my door...

I'm inquiring about the bearings b/c the motor has 48k miles and ai would like to make sure the bottom end is fresh.

[BA80]

Went back and missed it again, but good.

You can come across some con rod bearings once in a while on fleabay if you watch. Generally though they are OK.

[TopCatGr58]

Hey Marshy,

When I did my rebuild, I did just the top end because the bottom had been working fine when I had parked it 10 years earlier. My odometer had crapped out ~900 miles after I got the bike with 17 on it, just used the tripometer for gas monitoring and trips. I calculated that I had at least 50K miles on it before the rebuild. That was in 2000, I've put some 15-20k miles on it since then with no signs of con/crank bearing problems....no knocking or such. As stated, there is a bit more power due to the increased cc displacement, but not earth shattering, and the reports of these engines going 100K + miles I figure it'll be good for a while, especially the way I ride it only putting on a few k miles a year!

But it's your $$, time, labor, and eventually peace of mind!
T.C.

[WMarshy]

I received my piston kit today and everything looks like good quality. Shipping was FAST! Came all the way from Japan and didnt take but a week, seemed pretty reasonable. I also found a seller on ebay that is selling crank bearings and con rod bearing sets for $50 each.

[Rettic]

So, how well does the dome fit in the SF head? Will they work without pushing the compression to high? May be getting a set as well for my SF since my cylinder got messed up.

[MPittma100]

BB Kit

Don't waste your money or time installing anything other than a forged piston(s). And as everyone has stated, Wiseco is best. Cast pistons are "NON-PERFORMANCE" pistons.

You have to be certain beyond a shadow of a doubt that the piston you are putting in your engine has the correct dome cc, compression height, pin location, etc. The Wiseco kits are engineered to these exacting tolerances.

You get what you pay for.

My Two Cents, MP

[WMarshy]

Don't waste your money or time installing anything other than a forged piston(s). And as everyone has stated, Wiseco is best. Cast pistons are "NON-PERFORMANCE" pistons.

You have to be certain beyond a shadow of a doubt that the piston you are putting in your engine has the correct dome cc, compression height, pin location, etc. The Wiseco kits are engineered to these exacting tolerances.

You get what you pay for.

My Two Cents, MP

At some point ya have to ask yourself if what your paying for is worth what your getting..? For some it may be but for others its not. Although I believe the Wiesco pistons are high quality, I personally cannot justify spending $700 for pistons on a 33 yr old bike that I paid twice that amount for. Just keep in mind, the stock pistons are cast ...

You are correct, cast pistons are not performance parts nor do they claim to be. The set for $150 on ebay were engineered to resemble the 80-81 engines with the higher dome pistons. If used in the 78-79 engine, should be good for a few more points of compression. There is a member right now working on installing a set on his rig and he is going to cc his heads and clay the pistons to make sure no interference issues exist.

[trbig]

You have to be certain beyond a shadow of a doubt that the piston you are putting in your engine has the correct dome cc, compression height, pin location, etc. The Wiseco kits are engineered to these exacting tolerances.

The Wiseco piston domes don't match either the early or the late model domes. More of just a happy medium between the two, so I wouldn't call it "Exacting". And as stated, most of us have gotten some pretty decent performance from the stock CAST pistons. I wouldn't really call an engine that redlines at 7500 "Performance" though. If it was a modern sport bike and was expecting them to turn 15-18k rpm.. then maybe. There will always be some nay-sayers with anything new tried.