Project Motor Swap

[FJ1200W]

Hey Steve, FYI here's a 11 year old post which might interest you...

http://www.fjowners.com/index.php?topic=712.0

Cheers!

My targets are 24 btc open / 53 abc close on the intake and 55 bbc open / 22 atc close on the exhaust

Stock should be 12 btc open / 41 abc close on the intake and 40 bbc open / 12 atc close on the exhaust

That was a good read, thank you!

[Pat Conlon]

I don't know the cam lobe duration on the stock cams** what would your targets be measured in lobe center degrees?

**assuming you are using stock cams.

[FJ1200W]

I don't know the cam lobe duration on the stock cams** what would your targets be measured in lobe center degrees?

**assuming you are using stock cams.

Not stock cams.

Stock duration is 233 degrees on the intake, 232 degrees on the exhaust. At .040" duration.

Stock lift is .315" and .313" respectively.

I have not confirmed the cam is not a special grind, but it should be .375" lift and .257 degrees duration on both sides.

The codes on the cam are for a Mega Cycle 26800 and I'm not sure if the MP is the machinist or some other code.

The 03.90 may be the date code.

I hope so, as there are rumors the early Mega Cycle cams hold up much better than the newer ones.

It's not a radical grind, I'm not sure why the titanium shim under retainers were installed, but it sounds like I'm going back to the stock shim over bucket set up for reliability.

Unless some wants to talk me out of that.

[RPM - Robert]

...but it sounds like I'm going back to the stock shim over bucket set up for reliability.

Only use genuine Yamaha valve shim on those cams. Many aftermarket shims are a different hardness and surface finish that do not play well with Mega Cams.

[FJ1200W]

...but it sounds like I'm going back to the stock shim over bucket set up for reliability.

Only use genuine Yamaha valve shim on those cams. Many aftermarket shims are a different hardness and surface finish that do not play well with Mega Cams.

Wait - you mean I can't sand down quarters and polish them with Simichrome? 

[FJ1200W]

USPS came through early

83mm 320 grit

[fj1289]

I don't know the cam lobe duration on the stock cams** what would your targets be measured in lobe center degrees?

**assuming you are using stock cams.

Not stock cams.

Stock duration is 233 degrees on the intake, 232 degrees on the exhaust. At .040" duration.

Stock lift is .315" and .313" respectively.

I have not confirmed the cam is not a special grind, but it should be .375" lift and .257 degrees duration on both sides.

The codes on the cam are for a Mega Cycle 26800 and I'm not sure if the MP is the machinist or some other code.

The 03.90 may be the date code.

I hope so, as there are rumors the early Mega Cycle cams hold up much better than the newer ones.

It's not a radical grind, I'm not sure why the titanium shim under retainers were installed, but it sounds like I'm going back to the stock shim over bucket set up for reliability.

Unless some wants to talk me out of that.

Stock shim over bucket works well with those cams - but I can only vouch for them up to 10,500 RPMs!

[FJ1200W]

Stock shim over bucket works well with those cams - but I can only vouch for them up to 10,500 RPMs!

That's good to hear and it is consistent with the majority. I'll keep in under 10.5K and call it good.

[FJ1200W]

Honed the cylinders today.

I can still see a couple of tiny scratches, it is what it is.

Good enough for this project!

[FJ1200W]

Glad to have an understanding wife.

[FJ1200W]

Randy has an eye for detail and he noticed it appear my pistons were too high. Deck height was off.

He was right.

The copper base gasket measured .60mm which is probably not 100% accurate, I'll check again.

I did measure it multiple times, but Cometic only makes them in .020" (.50mm), but the gasket could be from somewhere else.

The piston seems to be approximately .15mm (.005") above the deck.

Should it be even with the deck or below?

If so, can I use a fiber gasket with the copper gasket or do I need to use one gasket of the correct size?

And finally, for this phase, should I spray the copper gaskets with a sealant (Permatex Copper Spray-A-Gasket or )?

[fj1289]

Steve - you can stack MLS base baskets to get the thickness you need.  Guys are also known to de-revert MLS gaskets to remove a layer - so Ikd imagine you could do the same to add one or two layers if needed. 

I would THINK you could stack an MLS with the copper, but I'd run that by Randy first.   

I really prefer MLS gaskets over copper - copper used to be handy for one-off gaskets or thicknesses, but seems you can do the same with MLS now.   I seem to always get a "seep" from copper gaskets I do t get with MLS.   

[FJ1200W]

Steve - you can stack MLS base baskets to get the thickness you need.  Guys are also known to de-revert MLS gaskets to remove a layer - so Ikd imagine you could do the same to add one or two layers if needed.  

I would THINK you could stack an MLS with the copper, but I'd run that by Randy first.  

I really prefer MLS gaskets over copper - copper used to be handy for one-off gaskets or thicknesses, but seems you can do the same with MLS now.   I seem to always get a "seep" from copper gaskets I do t get with MLS.  

Good info, thank you.

I'm leaning towards ordering one Cometic C8598 base gasket which is .010 - That should put the piston a hair below.

Single-Layer Steel (SLS) gaskets feature a stainless steel core with embossed outer surfaces that create a heavy-duty seal between the center steel layer and the mating surface
Viton gaskets feature a stainless steel core with a 0.001" thick coating of Viton rubber on both sides

Or the C8241 .010 copper

Whatever RPM not only suggests - but sells!

[Old Rider]

I'm not a expert but the pistons have to be below surface .when i did my engine i used 2 steel-basegasket stacked to get pistons below surface. i think 1 gasket builds 0.25 millimeter when crushed .Maybe you need 3 steel-basegaskets stacked and that may make the piston flush.
I used this gaskets http://rpmracingca.com/proddetail.asp?prod=5EA-11351-00&cat=39  The gaskets have a spesial layer that glues them together and seals at first heatcycle.

The fibergasket i was told might bulge out and start to leak they dont make them with asbestoes anymore and that makes them weaker.
Here are a link to when i had the same question and Randy answered:   http://www.fjowners.com/index.php?topic=18143.240

What are you going to do with the pistonrings ?  are you going to reuse the old ones? if i where you i would use new rings since you have honed the bores or else the rings will not bed in and you get a oilburner.That is what i heard anyway.

And i also got a forgiving wife her is a pick from when i baked a cylindercake in the oven to get the cylindersleves in and had the sleeves in freezer  
It smelled enginepaint for some days and the pizza tasted a little engine .

[FJ1200W]

I'm not a expert but the pistons have to be below surface .when i did my engine i used 2 steel-basegasket stacked to get pistons below surface. i think 1 gasket builds 0.25 millimeter when crushed .Maybe you need 3 steel-basegaskets stacked and that may make the piston flush.
I used this gaskets http://rpmracingca.com/proddetail.asp?prod=5EA-11351-00&cat=39  The gaskets have a spesial layer that glues them together and seals at first heatcycle.

The fibergasket i was told might bulge out and start to leak they dont make them with asbestoes anymore and that makes them weaker.
Here are a link to when i had the same question and Randy answered:  http://www.fjowners.com/index.php?topic=18143.240

What are you going to do with the pistonrings ?  are you going to reuse the old ones? if i where you i would use new rings since you have honed the bores or else the rings will not bed in and you get a oilburner.That is what i heard anyway.

And i also got a forgiving wife her is a pick from when i baked a cylindercake in the oven to get the cylindersleves in and had the sleeves in freezer  
It smelled enginepaint for some days and the pizza tasted a little engine .

I'm reusing the piston rings as they have very little use and appear new. If it's a oil burner, I can bust back into it again, I'm on a budget of sorts. That being said, if there are major issues on the final check of ring gap, they'll be replaced.


I had hoped to hear from RPM sooner rather than later, and I could not find that specific base gasket on their web site, so I ordered one (C8241 Copper .010") off eBay.