Porting

99sr220 · Post by **99sr220** » 05:12 am Nov 10 2010

Sorry to hijack the thread, but my cylinder is ported and has been engraved by whoever did it. The mechanic says it's only been done 'a little'. It's a 220 and runs fine, plenty of power, especially low down. However I have nothing to compare it with.

The bike is very thirsty when running on open roads, where it drinks more than a mates YZ250. Does this sound normal? Does porting effect fuel consumption?

Post by **fuzzy** » 10:41 am Nov 10 2010

It surely can. A KDX will also run sickly rich, still be smooth, and not foul plugs, while guzzling fuel. How's your jetting?

99sr220 · Post by **99sr220** » 06:35 pm Nov 10 2010

fuzzy wrote:It surely can. A KDX will also run sickly rich, still be smooth, and not foul plugs, while guzzling fuel. How's your jetting?

The jetting is the next thing I need to look at, the bike had been poorly maintained and I've just got it running well. From memory it has a 152 main jet and a 42 slow jet. I'm riding from 20 - 400ft in the tropics were it's very hot and humid.

It seems strange that it drinks more than a YZ250.

Slick_Nick · Post by **Slick_Nick** » 09:25 pm Nov 10 2010

FRP ported my bike. From what I can tell, did a great job too. No overheating, pinging, etc here.

Post by **Mr. Wibbens** » 10:07 pm Nov 10 2010

Slick_Nick wrote:FRP ported my bike. From what I can tell, did a great job too. No overheating, pinging, etc here.

He sure did a crap job on carvrs

Budget_89KDX · Post by **Budget_89KDX** » 10:42 pm Dec 14 2010

I knife edged my intake ports like I did on my victor jr intake on my 5.0 don't know if id call it porting but it didn't hurt anything I can tell on my blaster or kdx.

Post by **fuzzy** » 09:22 am Dec 15 2010

Nah, cleanup stuff like that is most likely fine. Just don't polish anything. The size/shape of the ports is what's critical.

Budget_89KDX · Post by **Budget_89KDX** » 02:37 am Dec 16 2010

Had some funky looking casting flash and what not so I broke out the dremel and cleaned it up.but that was it I'm by no means qualified for major porting on these unfamiliar engines.I've done some old SBF heads that turned out well but there's so much info on exactly what to it went pretty easy.I now at the least gasket match all my engines prior to assembly but again those are SBF and I'm quite comfortable with them and confident of what I'm doing this is my first kdx so I'm not in a hurry to reinvent the wheel.

Post by **fuzzy** » 10:17 am Dec 16 2010

Porting on a 2-cycle should in no way be compared to a 4-cycle, FYI. Cyl porting on a 2-cycle is like the camshaft. You can generally go to town on cast iron v-8 heads.

Budget_89KDX · Post by **Budget_89KDX** » 01:54 am Dec 17 2010

True.so just out of curiousity who does actual porting on these engines that actually yeilds performance and isn't just some bull **** claims?I looked mine over with a fine tooth comb while it was apart and there's not much so whatever is done looks like there's NT much room for failure.either get it right or you've ruin.ed it and got a price of scrap.

Post by **fuzzy** » 10:01 am Dec 17 2010

The stock porting on a KDX is good. Just like a camshaft, it's give/take. If you REALLY want to wake up the top end and are willing to sacrifice bottom this is done easily. People have reported Eric Gorr's 'better everywhere' port job is good, and EG will admit that not much is done to the KDX cyl in particular. When it really comes down to it I don't understand a 2-cycle to this level. One of the best 2-cycle kart engine builders in the country (has made a billet engine from scratch) once said "A 4-cycle is an air pump to the point that the laws of physics identically apply. A piped 2-cycle has more in common with a saxophone than an air compressor"

Budget_89KDX · Post by **Budget_89KDX** » 04:04 am Dec 18 2010

Yea definately not like v8.

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Porting