Porting the 394xp

Well I got back to my 394 that I tore apart. It was slated to get a 2101 piston, but had no luck getting someone to machine it for me yet, I just want my own lathe, and do my own work, it'll have to wait till I get my own. Anyway, I got the exhaust all done, widened it to .100" to skirt edge, didn't raise at all, I'm looking for torque, I flattened out the top a little, it still fairly roundish. Now I just have to open up the muffler to match it, don't think I'll do much to the intake besides smooth it out some. I'll work the transfers a bit too, I don't have any tools to get down to widen or raise the transfers at all so that part will stay stock, I'll just do some blending on them.

Sorry for no pics yet, it'll have to wait till tomorrow.

Good idea,,, I have a 394XP also,,,, I'll have to keep an eye on this tred to see how it goes!!!!! opcorn:

Yup, after porting a 371xp, I'm addicted. I'm heading back out to the garage now for something, so I'll take a few pics.

Waiting for pics.



Mr. HE

opcorn:

Here are a few mediocre pics, I need a better light source.

Needs a little more polishing up, to get rid of the last of the scratches, but in reality it probably doesn't matter that much.

parrisw said:

Here are a few mediocre pics, I need a better light source.

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So please excuse my ignorance but did you use a dremel? Only widen the top surface correct?

ropensaddle said:

So please excuse my ignorance but did you use a dremel? Only widen the top surface correct?

Click to expand...

I actually used a rotozip, a little bigger. Widen the sides of the port, then blend into the top of the port, I also made the top of the port a little more flat then stock.

hey man that looks good...nice work

parrisw said:

I actually used a rotozip, a little bigger. Widen the sides of the port, then blend into the top of the port, I also made the top of the port a little more flat then stock.

Click to expand...

Thanks I am going to look into porting my own soon do you use a caliper to mic the removed material?

Looking good brother! Can't wait to see the video.

lovetheoutdoors said:

hey man that looks good...nice work

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Thanks.

ropensaddle said:

Thanks I am going to look into porting my own soon do you use a caliper to mic the removed material?

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I use some digital calipers. I mark the piston with the cylinder installed, then measure to the edge of the skirt, that'll tell ya how far you can go. Just be careful, each side can be different.

CHEVYTOWN13 said:

Looking good brother! Can't wait to see the video.

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Thanks, I'll make a vid, have to get some wood to put it in.

Looks pretty good - a fair bit better than when I widened the exhaust port on an '81 CR80 with a B&D drill and 1/4" bit. (true story)

Would offer that it sounds like you've got the right idea on the porting approach. Have you radiused the new port edges to help stop ring snags? It's kind of hard to tell from the pics.

Looks good. Dremel makes a fine grit stone which has a cone taper to it so that you can reach in there to give a chamfer to the edge around the port. You can use the stone in your dremel, foredom or a drill. Should be able to pick one up at Walmart or a hobby/craft place for $3-4.

Best wishes,
Bob

Haven't champhered the port edge yet..

from what ive seen of your work, and from the size of that thing, and that "great casted 2101xp piston in a blue box that had an exorbatant shipping fee on it"(lol....inside joke/hint about an identity crises...lol), i imagine that will be a bad bad bad mo fo!!!


seriously tho, those are some bad bad saws!!!

Brownpot Deaton said:

from what ive seen of your work, and from the size of that thing, and that "great casted 2101xp piston in a blue box that had an exorbatant shipping fee on it"(lol....inside joke/hint about an identity crises...lol), i imagine that will be a bad bad bad mo fo!!!


seriously tho, those are some bad bad saws!!!

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Ya, I'd love to get that piston in there, it'll have to wait for now, until I get a lathe, for now it'll be run with stock piston, and ported cylinder.

parrisw said:

Ya, I'd love to get that piston in there, it'll have to wait for now, until I get a lathe, for now it'll be run with stock piston, and ported cylinder.

Click to expand...

Ya know I was going to wait on modding my new 395 but my modded 372 seems to hand it its azz. Granted the b&c 24" vrs36" make a difference but shoot 75 cc should not smoke a 395 but I have to say it does. Anyone else have this problem I am going to put an 8 pin on it first!

ropensaddle said:

Ya know I was going to wait on modding my new 395 but my modded 372 seems to hand it its azz. Granted the b&c 24" vrs36" make a difference but shoot 75 cc should not smoke a 395 but I have to say it does. Anyone else have this problem I am going to put an 8 pin on it first!

Click to expand...

Ya, I got a modded 372, I love it, its still just getting broke in now. It really need the muffler opened up though, its really restricted. I'll be doing that after I get this back together.

Here are a few last pics of porting. I got it all finished up today. Starting to go back together now.