Need guidelines for porting 5b SS

Need guidelines for porting 5b SS
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Need guidelines for porting 5b SS - 4/30/2008 11:16:52 AM

P Bear

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From: Yelm, WA, USA
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As soon as they become available I will be getting a Baja 5b SS. Instead of getting the ported big bore kit right off the bat I thought I would try porting it myself. If I bung it up I was going to get the kit anyway. Being a machinist I already have the tools needed.

What I need is some numbers on what size to make the ports. A while back there was a article out on porting the Savage .25. I was wondering if anyone has any info on porting these gas engines.

RE: Need guidelines for porting 5b SS - 4/30/2008 12:00:38 PM

Foxy

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Porting a gas engine is a totally different kettle of fish than porting a nitro engine. I've never seen or heard of such guidelines to be honest, and I've also never heard of anyone 'having a go' on their own. I'm not sure, but I assume there is a much smaller margin for error on these gas engines.

Basically, the thing is, like I say, I never heard of anyone ever doing it on their own, and large scale guys are much more engineering/technically minded than nitro bashers, so I have to assume that it's either too difficult or too risky to DIY. I don't know to be honest, I wish you luck if you try.

There are some really good porting companies out there who might offer you some assistance, at least maybe in porting theory. Carlo from CC racing seems like a really good guy, is a member here, and is considered one of the top gas engine tuners out there, he has a number of gas powered 2 stroke speed records to his name.

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(in reply to P Bear)

RE: Need guidelines for porting 5b SS - 4/30/2008 12:17:16 PM

P Bear

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Yea, my post looks uninformed. I read this 2 Stroke Cylinder Mapping http://2wheelstuffs.blogspot.com/2005/11/2-stroke-cylinder-mapping-part-2.html and not only is it pretty scientific but seems most people who have studied this have their own ideas on how it should be done.

I will see what Carlo has in mind. Thanks.

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RE: Need guidelines for porting 5b SS - 4/30/2008 3:16:59 PM

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Not sure but I believe Earthsurfer (ESP Mods) stated that the CY heads aren't good candidates for porting because there's not enough excess material. He was referring to the 23cc but I would guess the 26cc would be even worse. But if your good with getting a head kit give it a go,won't know till you try!

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RE: Need guidelines for porting 5b SS - 5/1/2008 3:16:16 AM

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i have ported a weed wacker motor... if that helps you any. all you need to do is take a few thousanths off of the intake, and a little more off the exhaust. then maybe rejet the carb. thats what i did.

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RE: Need guidelines for porting 5b SS - 5/1/2008 3:57:14 AM

savagecommander

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i can try to send you a copy of the two stroke tuning guide. that has about every little thing you could think of in it.

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RE: Need guidelines for porting 5b SS - 5/1/2008 8:45:32 AM

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From: melb, AUSTRALIA
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to me it just looks like they dremel out the exhast port , but then they dont even polish it smooth , so i would like to do the porting myself one day too

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RE: Need guidelines for porting 5b SS - 5/1/2008 11:04:48 AM

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the boating gas forum has info in there . or i think its Jimsboatdock has a detailed artical

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RE: Need guidelines for porting 5b SS - 5/1/2008 11:49:48 AM

P Bear

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Yea, it's a neat idea. Do some grinding and go faster. I had a Honda Odyssey 250 with a carb twice the size of stock, port job, expansion pipe and big clutch. Drop the hammer below 20 mph and either the back wheels would spin or the front wheels would come off the ground. At least twice the power of stock.

That Savage .25 article gave exact dimensions as to where to grind to along with pictures. Brush on some Dykem, scribe lines and have at it. Everyone who reported back results liked it. Be nice to have something like that for the 23 to 30 cc engines that are common.

Thanks for the replies.

(in reply to cyclops1970)

RE: Need guidelines for porting 5b SS - 5/1/2008 4:14:12 PM

savagecommander

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well all i can say is there is a relation to how long the port is open vs how large it is=when it makes power. the trick is getting the ring not to snag, you have to be very careful on chamfering the edges.

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RE: Need guidelines for porting 5b SS - 5/9/2008 11:18:01 PM

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From: melb, AUSTRALIA
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well then can someone link us to that porting guide that was in the rc gas boat section , i cant find it

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RE: Need guidelines for porting 5b SS - 5/12/2008 1:43:45 AM

badz

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From: Syracuse, UT, USA
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quote:

ORIGINAL: P Bear

As soon as they become available I will be getting a Baja 5b SS. Instead of getting the ported big bore kit right off the bat I thought I would try porting it myself. If I bung it up I was going to get the kit anyway. Being a machinist I already have the tools needed.

What I need is some numbers on what size to make the ports. A while back there was a article out on porting the Savage .25. I was wondering if anyone has any info on porting these gas engines.

Porting is easy to do and there is no science to it

http://www.modelgasboats.com/Magazine_Content/Tech_Articles/Engine_Porting.html

< Message edited by badz -- 5/12/2008 1:44:11 AM >

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RE: Need guidelines for porting 5b SS - 5/12/2008 2:05:35 AM

hellya

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thats the one badz

..i knew there was a how-to on porting...I was looking for it at the dock

.....thanks man

< Message edited by hellya -- 5/12/2008 2:07:08 AM >

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RE: Need guidelines for porting 5b SS - 5/12/2008 3:34:29 AM

badz

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quote:

ORIGINAL: hellya

thats the one badz ..i knew there was a how-to on porting...I was looking for it at the dock .....thanks man

Yeah I couldn't find it on jims either, i think they deleted it cause someone once posted it on a goped forum and claimed they wrote it, linked the pics and all right from jims

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RE: Need guidelines for porting 5b SS - 5/12/2008 4:03:23 PM

savagecommander

Posts: 417
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From: , MI, USA
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quote:

ORIGINAL: badz

quote:

ORIGINAL: P Bear

As soon as they become available I will be getting a Baja 5b SS. Instead of getting the ported big bore kit right off the bat I thought I would try porting it myself. If I bung it up I was going to get the kit anyway. Being a machinist I already have the tools needed.

What I need is some numbers on what size to make the ports. A while back there was a article out on porting the Savage .25. I was wondering if anyone has any info on porting these gas engines.

Porting is easy to do and there is no science to it

http://www.modelgasboats.com/Magazine_Content/Tech_Articles/Engine_Porting.html

there is a little more to it than you think.

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RE: Need guidelines for porting 5b SS - 5/12/2008 6:05:09 PM

P Bear

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Joined: 1/5/2008
From: Yelm, WA, USA
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Thanks for the link Badz! I think what is really needed is before and after dimensions taken from a fixed point of a port job that is known to give good results. What we need is some one who will measure their ports. Electronic calipers are inexpensive these days and very handy to have for many uses. For example on the cylinders you can measure from the top of the roof/squish area/head or measure from the base of the cylinder to the ports and to the roof. Take lots of measurements, can't have too many.

Dykem is cheap. A carbide scribe will last a lifetime if not dropped. The other tools to do this aren't expensive and are good for other jobs also.

(in reply to savagecommander)

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