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Engine Modding - Porting and Reed Valves?

Discussion in HPI Baja Engine and Exhaust forum, started by swisstoni.

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Old 05-28-2006, 09:00 AM
swisstoni swisstoni is offline
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Engine Modding - Porting and Reed Valves?

Hi there guys,

I've fitted a K & N filter, that made a noticable difference but what's this I've been reading on reed valve kits....? What sort of power gains can I expect?

Also, I've read about 'porting', what does this involve? Similar at all to nitro based porting? I.e. a steady hand and a dremel!?



Cheers,

Ben
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Old 06-05-2006, 10:33 PM
gavinp gavinp is offline
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So the reed valve kit sounds like a winner. Any thoughts on which one fits this engine? I know they are around 80 ($152 (sorry about my conversion but the dollar's still sliding!))

g
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Old 06-06-2006, 01:23 AM
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I agree 100% w/badz on the K&N filter, DON"T DOIT if you want your motor to last. I have $500 into rebuilding the motor on my 4-wheeler because of K&N & it's not the first time, I was stupid enough to try it twice in my life & twice it burned me!! This time there was a clear dirt trail from the filter into the carb, no doubts.
There is no substitue for foam except dual foam like the baja filter!!
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Old 06-08-2006, 12:59 PM
alltoys alltoys is offline
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I am a welder/machinist. Does anyone know if there are instructions on how to port a 2 stroke engine. I will eventually boost the power of my engine just wondering if there is a step by step guide on how to do it. Porting seems to be a science that no one wants to talk about. I have reworked heads on my 4 stroke ATVs just curious if a 2 stroke is any different. :idea:
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Old 06-08-2006, 01:08 PM
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Hi alltoys, I am a tool & die maker. There is a very big difference in porting the 2 & 4 stroke. You're right, info is very hard to come by on the porting subject, people don't want to give away trade secrets, especially if they learned by trial & error & are making a living off of it. It would be nice if somebody on here had info on it (these motors in only)& would share it. I did alot of porting on my nitros & most of the time was very happy with the results. There is however alot of info on the net about ports in general & how they work.
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Old 06-08-2006, 01:58 PM
RC_King RC_King is offline
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Can anyone tell me what and how the reed valve kit works thats different to how the normal engine works?
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Old 06-08-2006, 04:24 PM
alltoys alltoys is offline
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Quote:
Originally Posted by TurtleRacing
Hi alltoys, I am a tool & die maker. There is a very big difference in porting the 2 & 4 stroke. You're right, info is very hard to come by on the porting subject, people don't want to give away trade secrets, especially if they learned by trial & error & are making a living off of it. It would be nice if somebody on here had info on it (these motors in only)& would share it. I did alot of porting on my nitros & most of the time was very happy with the results. There is however alot of info on the net about ports in general & how they work.
I believe there is software available to diagnose what to do for porting, exhaust tuning and such on 2 strokes. There is definitly an inner sanctum for head porting dyno tuning is about the best for tuning heads. I have seen heads flow very good on a flow bench and don't work near as well as stock heads on a dyno. It's funny I can get head porting done on my V8 chevy cheaper than my Kawi 700 twin cylinder. Size does matter, lol.
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Old 06-08-2006, 04:31 PM
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Ok, I'll try this, I understand it I just don't know if I can explain it properly. The motor "as is" uses piston/port timing to "close off" the combustion chamber for combustion, so that compression does not escape back through the carb.. The reed valve uses a flat plate, usually carbon fiber, to "close off" the intake. The reed is very thin & acts like a oneway "valve" to let the charge in.
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Old 06-08-2006, 09:54 PM
swisstoni swisstoni is offline
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I'm a model shop owner....!


The orginal filter certainly wasn't overoiled - I only ran it for a couple of minutes with the stock filter on, brought it back inside and stuck the K&N on, and it did make a notable difference! This is only on tarmac however, I appreciate what you say about dusty use.

I'm still liking the sound of these reed kits though, and the DIY porting info also sounds useful, we've a fair bit of experience with nitro's - but 2 stroke is something totally new. The engines aren't exactly that expensive, I'd really like a go at some DIY mods but I agree with the earlier comments that there appears to be a substantial lack of info on it.
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Old 06-09-2006, 06:23 PM
jd72cv11 jd72cv11 is offline
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hey all!!

here's a link to the article on the HPI S25 port:
http://www.rccaraction.com/rc/articles/htpporting_1.asp

hope this helps...

Johnathan

---edit---

found:
http://www.eric-gorr.com/techarticle...wo_stroke.html
pretty good info too...
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Old 06-13-2006, 04:50 AM
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Another option you might want to consider is purchasing a larger bore top-end, already ported.

More power and more speed, in a easy to install bolt-on configuration...

http://www.davesmotors.com/store/product494.html
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Old 06-17-2006, 12:45 AM
rcrcman1 rcrcman1 is offline
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here's a link to some tech articles I've compiled on my website. They're intended for nitro burners but the concepts and basics will give you guys an understanding of what is what...

http://advantageracingproducts.com/techpapers.php
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Old 06-17-2006, 02:45 AM
rcrcman1 rcrcman1 is offline
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rricks, I've cruised your site a bunch....I'm looking at getting the cylinder you posted....reed kits, etc.

I'm just wondering, what exactly the differences between the CY and Zen are. If its going to be cheaper to make more power I'd like to swap in one of the stroker big bore engines add reeds and be done with it. Also with the reed kits I would imagine the engine would rev alot faster? I've run nitro stuff for years and have a banshee for the dunes, so in my mind the reeds just make sense for the gas stuff.

And on a pipe....whats on the way? besides the jetpro.....thats the first obvious upgrade everyones after.....I'd hate to put the stocker on a rippin new motor

tia
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Old 06-19-2006, 06:03 PM
ddmdave ddmdave is offline
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Quote:
Originally Posted by rcrcman1
rricks, I've cruised your site a bunch....I'm looking at getting the cylinder you posted....reed kits, etc.

I'm just wondering, what exactly the differences between the CY and Zen are. If its going to be cheaper to make more power I'd like to swap in one of the stroker big bore engines add reeds and be done with it. Also with the reed kits I would imagine the engine would rev alot faster? I've run nitro stuff for years and have a banshee for the dunes, so in my mind the reeds just make sense for the gas stuff.

And on a pipe....whats on the way? besides the jetpro.....thats the first obvious upgrade everyones after.....I'd hate to put the stocker on a rippin new motor

tia
Zenoah makes a 32mm bore engine (G230RC) and a 34mm bore engine (G260RC). CY makes both of these also, as well as a 35mm bore engine (CY27RC) and a 35mm bore engine with a +2mm crank (CY29RC) and a 36mm bore engine (GP290).

Your best bet for COMPACT power (if you want to avoid the heat and weight of a pipe) is a larger displacement top end, reed, and some good porting. The reed greatly improves low-end response and adds power throughout the RPM range. For a compact exhaust, the X-can works well on setups like this.

I've seen ported, reeded engines with X-cans murder non-ported piped engines.

Jetpro pipe will be available in just a few days; not sure what other exhausts are on the way.
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Old 06-19-2006, 08:12 PM
rcrcman1 rcrcman1 is offline
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Thanks for the good info Dave...will you have the Jetpro in stock this week at your warehouse? If so I'll cruise by and pick one up. Also do you have reed kits?
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Old 06-19-2006, 09:56 PM
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I'm not sure of the exact delivery date of the Jetpro pipes but it should be soon. The reed kits are here:

http://www.davesmotors.com/store/product73.html
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Old 06-19-2006, 10:17 PM
USABaja5 USABaja5 is offline
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Can you post a pic of the Jetpro pipe? I hope its not the one I've seen with the whole area under the wing taken up with a huge pipe.
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Old 06-19-2006, 10:19 PM
rcrcman1 rcrcman1 is offline
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do you have the reed kit in stock?
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Old 06-20-2006, 06:39 PM
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You bet.

http://www.davesmotors.com/store/product73.html
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Old 06-20-2006, 06:47 PM
rcrcman1 rcrcman1 is offline
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sold.thanks Brad
forgot to get some extra plugs though

let me know when you get the jetpro installed on your 5b I'd like to check it out and hear it
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