Boring a Head Pipe and Exhaust Manifold ?

[imabadfish]

Is there anything special about the way the boring on the exhaust manifold and b pipe head pipe is done? I'm considering taking my parts to local machine shop to get it done but I'm not sure what instructions to give them besides bore to 49mm. I don't want them to F it up but I really want it done so I can put my ski together.

Thanks.

 

[jaxrider]

not a big deal to do it by hand if you have a die grinder with some aluminum burrs and some sanding wheels

 

[imabadfish]

not a big deal to do it by hand if you have a die grinder with some aluminum burrs and some sanding wheels

best I got is a dremel, probably take me hours to do it with that lol

 

[JamesG]

send it to xscream

 

[BrightE's]

I was about 3 minutes away from asking this very same question.

So without a die-grinder, a machine shop will probably be the best bet? I'm looking to go out to 50mm.

 

[N3vrSat1sfied]

rotary file on a drill will work if your steady.

 

[BrightE's]

send it to xscream

Do you know what the bore service runs at xscream?

 

[Tommytunes]

Contact Jetmaniac.... let " Blue " do the work.... got mine done there and it came out PERFECT... ready to see what difference it will make once installed... !!!

 

[JamesG]

Do you know what the bore service runs at xscream?

I forget, not much though, it's a fairly easy job for them. That's where I got mine done

 

[Quinc]

How far can you bore these until you run into the water jacket?

 

[BrightE's]

How far can you bore these until you run into the water jacket?

X2

 

[VXSXH20]

I believe 51mm is as far as you want to go. Jetmaniac sells the Bpipe big bore gasket already. just buy one , set it atop your flange, trace it and work slowly and carefully.

 

[Tommytunes]

I believe 51mm is as far as you want to go. Jetmaniac sells the Bpipe big bore gasket already. just buy one , set it atop your flange, trace it and work slowly and carefully.

Just pay and let them do it... comes out perfect... !!!

 

[Quinc]

You can buy the cutting, sanding, and polishing dremel/die grinder attachments at McMaster for less then 30$ shipped. Then use them to polish inside your manifold etc

 

[Tommytunes]

You can buy the cutting, sanding, and polishing dremel/die grinder attachments at McMaster for less then 30$ shipped. Then use them to polish inside your manifold etc

Yeah but it will look like chit rodriguez.... mine from JM / Blue looks factory bored, but, better... you get what you pay for these days... true statements in life... !!!

 

[speedysprocket]

The exhaust gases don't care what's pretty, just whether or not something is blocking their way... I bore mine out by hand. Recently I put the die grinder burr in my drill press and hold the pipe to bore it out...

 

[DAG]

2 questions in regards to port matching

In respects to flow, is it more critical that the transfer between the cylinder and mani be the least restrictive (aka mani opened up larger than cylinder) or is it more critical that the charge coming back from the pipe is lease restrictive (mani smaller than cylinder). My guess would be its better to get the heat away from the cylinder but how critical is that step for the return wave? Are they each rated 50% as far as efficiency?

With the obvious answer you want them perfectly matched. What is the best way to confirm you have everything 100% matched?

 

[Harbor]

With the obvious answer you want them perfectly matched. What is the best way to confirm you have everything 100% matched?

My cylinder exhaust port is raised like almost 2mm, so I had a 2mm step down in the roof of the exhaust port as my manifold was not port matched and raised 2mm. I first port matched the gasket to the cylinder then transferred it to the manifold.

Then With the head removed and gasket and manifold temporarily mock assembled I could reach into the exhaust port via the cylinder and confirm my port match

I also bored the head pipe to 50mm and bored the manifold to 50mm, blended the 50mm into the runners and removed casting slag within the manifold runners and polished the ports.

Did I like the gain on my +8mm non PV 865 Lamey ?

No, all it did was soften the low end hit, made it smoother/softer, may have had a gain in mid range but all I noticed was less hit off the bottom. The smaller port seemed to lend itselft to low end.

May work better for bigger PV motors though

 

[VXSXH20]

Opening up to 50mm on a bone stock bore 61x will not yield impressive results.

-The early production FPP manifolds and B headpipes had an approximate opening of about 44mm and later manufactured at approx 47mm.

On smaller cylinders like a stock 61x, Gains on a 50 mm opening are minimal but can help the over all equation. It will help most on a ported larger cc motors with more air flow

-Opening the early manifolds up to 47+mm seem to help much better.

 

[Big Kahuna]

Porting something does not always give you more.......... Ask your builder...........