Topic: Biggest bore in stock block with big sleeves???

[dragracer]

Alright, looking to the old time experts on this question; What is the biggest possible bore in a stock cylinder with big sleeves??? I've seen 73mm, but how much bigger can you go in the stock block with aftermarket sleeves???

[Jerry Rxman Griffin aka MuthaF'er]

Here's a partial assortment



Measuring at the bottom of the skirt the big boy comes out at 73.59mm

[NalleyRacing]

Superbike Mike Keyte's big valve, stroker motor, used 78mm pistons in a stock SOHC block if I'm not mistaken.

[Bill/BentON Racing]

Yes to 78 mm. Stock block.....? Hmmmmm. Bill

[dragracer]

Yes to 78 mm. Stock block.....? Hmmmmm. Bill

Taking a stock block with big sleeves out to 78mm must have created some problems near the studs. Anyone on the forum go this big before???

By the way, what's the minimum allowable thickness of a sleeve after boring???

[754]

I would  think the sleeves  would need flat spots on them, almost no support from the cylinder with sleeves showing everywhere.

[Bill/BentON Racing]

Yeh, I'll go on Facebook and ask Superbike Mike, Bill

[dragracer]

Yeh, I'll go on Facebook and ask Superbike Mike, Bill

Thanks Bill. I'm just going through the winter crazies and running some wild thoughts around in my empty head.

[NalleyRacing]

Yeh, I'll go on Facebook and ask Superbike Mike, Bill

Thanks Bill. I'm just going through the winter crazies and running some wild thoughts around in my empty head.

Same here buddy

[Bill/BentON Racing]

Lets go BIG? 

[bear]

I know we run our motors for a different application to you blokes, but.

We mill the sholder of our sleeves @73mm.

Lets not forget the head is the limiting factor here if your running N/A.

Our hp curve goes flat at about 7'500 rpm, just can't get enough air into it after that.

Cheers,
Brian

[MRieck]

I know we run our motors for a different application to you blokes, but.

We mill the sholder of our sleeves @73mm.

Lets not forget the head is the limiting factor here if your running N/A.

Our hp curve goes flat at about 7'500 rpm, just can't get enough air into it after that.

Cheers,
Brian

Is that with a 33.5 intake Brian or are you up 35mm or something?

[dragracer]

How large a bore will Mikes billet block go with nikasil.

[dragracer]

I'm pretty sure the major concern is the limitation of the intake port, even when its maxed out. I doubt a spigot head like Kenny has will stifle a 78mm bore.

[bear]

I know we run our motors for a different application to you blokes, but.

We mill the sholder of our sleeves @73mm.

Lets not forget the head is the limiting factor here if your running N/A.

Our hp curve goes flat at about 7'500 rpm, just can't get enough air into it after that.

Cheers,
Brian

Is that with a 33.5 intake Brian or are you up 35mm or something?

We're run 35mm intakes and shave .5mm or 1mm off the exhaust Mike.

I'm pretty sure the major concern is the limitation of the intake port, even when its maxed out. I doubt a spigot head like Kenny has will stifle a 78mm bore.

I'm pretty sure your right there Frank and Johno is on the case for me on that front down here, fingers crossed.
But at the moment I have not been able to come up with a "usable" head down here that will flow much more than 80cfm and still give me enough velocity for my road racing motors.

Cheers,
Brian

[TurboD]

I'm pretty sure the major concern is the limitation of the intake port, even when its maxed out. I doubt a spigot head like Kenny has will stifle a 78mm bore.

Yes the intake port is the limiting factor, for example if the intakes will only support 100 HP increasing CC's will not gain much if any in terms of lowering ET.

[MRieck]

How large a bore will Mikes billet block go with nikasil.

I do not recommend anything over 72mm.

[kmb69]

Little off subject, but.......

Frank,

Mike was telling me you have external oil returns on your F dragster. I guess I didn't look close enough every time I have seen your bike in person. Would you mind posting some pics?

Keith

[dragracer]

Little off subject, but.......

Frank,

Mike was telling me you have external oil returns on your F dragster. I guess I didn't look close enough every time I have seen your bike in person. Would you mind posting some pics?

Keith

I'll see if i have any pictures on my lap top. If not. I'll get a few posted on here for you.

[dragracer]

Here are a few pics of the oil drain lines. Hope it helps.

[dragracer]

Lines in the  block.

[kmb69]

Very nice!!! Thank you sir.

Did you do that because of the oversize studs?
Are you still draining down the studs as well?

Look like pretty big buckets - 73's?

[dragracer]

If you look carefully at the pictures of the head, you can see that I've plugged the drain holes in the head. I used liquid metal with hi temp silicone smeared on top. It was done due to the oversize sleeves exposing the oil drain passages in the block. Dang thing leaked like a sieve til this was done.

[dragracer]

Very nice!!! Thank you sir.

Did you do that because of the oversize studs?
Are you still draining down the studs as well?

Look like pretty big buckets - 73's?

72mm bore/1030cc. MTC pistons. RC steel rods, stock unlightened crank, F2 ported head with stock valves, titanium retainers, APE valve springs with RC327 cam.

[Bill/BentON Racing]

Nice! Real nice! Can't wait for April, 2 in the 10's, 3 when undercut trans goes in Purple Rain turbo bike! K. Bill