Have you Decked the cylinder

[nakomis0]

This post just keeps getting better. Great info guys.

Ok I decided to assemble earlier tonight and since all I was able to get quickly was the stock .020 base gasket I am now looking at a comp of just under 12.5:1. I have been told that the stock rod and bottom end should hold up with the stock rev limiter, I guess we will see.

The only thing I am a little confused about is the above info on measureing squish and how a dome top piston would effect that info. I cant believe that I could be getting 12.5:1 with a squish of 55 is this right? I am also considering having the dome reduced and getting the lighter piston pin and lightening the piston when its real cold here in Jan and Feb so this may be temporary if it doesnt really kick.

Well there is still some final assemby and set up to be done and I hope to get to break it in late on friday and will post what happens etc.

Well here is the final info:

Cylinder Head Volume (cc)38.000
Cylinder Head Vol (cubic in.) 02.318
Piston Head Volume (cc)-8.600
Piston Head Vol (cubic in.) -0.525
Gasket Thickness (in.)00.025
Swept Volume (cubic in.) 26.637
Gasket Bore (in.) 03.508
T.D.C. Volume (cubic in.) 02.325
Cylinder Bore Diameter (in.)03.508
Gasket Volume (cubic in.) 00.242
Deck Clearance (in.) .030
Note: Neg. nubmer above deck, Pos. number below deck Deck Volume (cubic in.) 00.290
Stroke (in.) 02.756
COMPRESSION RATIO 12.457

[dhines]

Thanks for the replies, gents. I was hoping that maybe Ross or JE would have updated their pistons to reflect the information that you guys have assembled.

Matt, thanks for the recommendation on the Ross piston. I expect that's exactly what I'll do when it comes time to rebuild. What gasket combo would you recommend to get the best compression/squish?

On the cam issue, I actually tried running the GT Thunder cam several months ago (which I believe is essentially the same thing as the Web 450/451) and it just killed too much bottom end for my tastes (I'm running the JE 10.8-1 with a Sparks pipe for cross country racing). I've thought about trying either the TC XC cam or the Web all-around. I don't know anything about the 479. Would it provide more bottom end than the 450/451?

I am also seriously considering the FST oil cooler. I just need to see how it mounts up to make sure it won't interfere with my WER steering damper.

Thanks again for all of the information. 440EX4me, good luck on that engine!

Best,

Dennis

[Dave400ex]

If you want an Oil Cooler, Dave at Dirt Mods makes one that fits where the stock cooler goes, it's just bigger. I would rather have that setup over a FST.

[Matt Fisher]

Lenny,
Don't sweat the .040 vs .055 squish. Just ride it and see what you think. Like you said, you can always take it apart again...

Squish is independent of the dome. The dome affects quench. In theory, the best scenario is having a very small area in the combustion chamber for the "explosion" to occur in. On the other hand, with multiple valves, it's nearly impossible to do so. You sacrifice combustion chamber efficiency for more airflow.

A good example of where squish is more important would be on a 2 valve V8 motor. Look at the current SBC heads. They're all closed chamber, with a fairly large squish area. A "pocket" around the valves makes up the combustion chamber. Quite efficient, but a 4 valve version will flow more air. There's some caveats to that, but you get the idea.

dhines-
What displacement are you running? Yes, the GTT cam is the Web 450/451, W Bros Track Cam (and probably some of the tuners "custom" cams). Hopefully I'll be able to give everyone a very specific compario of the 479 Vs 450/451 soon, as my friend's motor has the 479. It should provide slightly better bottom end, a little better mid, the same top-end, with more throttle response than the 450/451.

You could easily change the mounting arrangement of the FST cooler. It might require welding some tabs on the frame elsewhere, no biggie.

On the Ross pistons- unless you want to start milling cylinders/piston domes/combustion chambers, just assemble it and ignore the squish. That's the trade-off to having a domed piston. Nothing's free.

WarriorMan-
That's a great idea, a larger main cooler would work great. The FST cooler cools the oil going into the head, which is rather important considering the RFVC head is known for creating excessive heat. This causes detonation, and (possibly) is responsible for the rocker issues that plague high-lift cams. I'd suggest both, truth be told.

I think I may have been confusing squish and quench again :Grr But now my brain may have been gettin more "squish" too.

Dhines I know what you want but as much as I had tried to get a "fits all" solution to this the more it was apparent that there wasnt any.

The best thing I can offer from my experience with this never ending project is that you need to decide on what you want and start it going. So get the kit you like or purchase the parts seperate (my preference) and have the boring done and assemble the piston rings and cylinder and take some measurements. Then you will know if you need to do any decking or gaskets changes etc. and also you will have all the info to work out the numbers for what ever design changes you like.

You have to get the basics and go from there. Not the easiest way but the better way.


There was some very good info on cams earlier in this thread so take a look there too. It was interesting to find how many of the different branded and "builders" cams were off the shelf web cams.


I decided to take some time and get this thing fired up today so the fingers are crossed.

[Dave400ex]

Matt, If I went for cooling products I think I would get the XR's Only big fin head fit and that Dirt Mods bigger stock replacement cooler. How do you think that would work? Heck XR's Only says 30 degrees with the big fin head and I'm sure that cooler would do that or more.

[Matt Fisher]

A larger main cooler is quite appealing. I almost used the OEM cooler for the cam, and my custom one for the motor.

Although the big fin kit probably works great, I wonder if it would be as effective as the oil cooler. On a dirtbike, the room for a cooler is quite limited, but we don't have that issue. Since the FST design places cool oil directly into the camshaft's center, I'm thinking it will do a better job of cooling that component. I believe FST claims a 50 degree drop in oil temp. After seeing how small the OEM lines are (and therefore how long the oil is in the cooler being cooled), I tend to agree with that.

-I would not be excited about the cooler running out of oil (by mounting it upside down), because it would be quite some time before enough oil made it to the cam.

I was unable to find the big fin kit on the xrsonly site, what's the cost?

BTW- I got my sleeve from Advanced Sleeve. They also supplied me with the Cometic gaskets. Around $40 for everything, if memory serves me correctly- It was much cheaper than LA Sleeve and Cometic directly.

[Dave400ex]

The Big Fin kit is $250. Oldnumber7 has it and really likes it on his 465. He said during his dyno runs that they had to turn off the fans because it was running to cool. I think they would be well worth it, and look trick.

Its ALIVE !!!

Had made some time on Thurs before I left for a day and got the balance of the motor etc assembled and fired her up. Sounds good so far and may get some break in/seat time tommorrow if the weather holds out and will let you all know what I find.

Ended up with the 12.5:1 (dbl .012 and .020 base gaskets) and loaded it up with some 112 cam2 and now its smeeling better too.



As far as the aux oil coolers go does anyone have recomendations on where to get a "replacement " cooler and what is it from? (honda chevy etc.) I am thinking on just creating my own set up and am not crazy for the tranz cooler set up.