Eric Gorr Porting

Questions and Answers about the best carb and Head mods available for the KDX.
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Post by green_passion »

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fuzzy wrote:DFIII reeds will be even better for your lost low-end. Is your carb done? Leaking head gasket won't help either. :wink:
That's my next upgrade since the stock reed cage got melted when the head gasket blew.

Update

Well, I got my cylinder back last Thursday from EC and the mechanic worked for two hours on the bike only to discover that one of the head studs are stripped. :cry: :cry:

So, I didn't get a chance to ride it up at Kennedy Meadows. Which is a shame 'cuz it rained just enough up there to perfectly water the trails all three days we were there. Instead I was on his CR250 that made me miss my KDX even more. :roll:

Stay tuned...I'm aiming for some seat time later in the Summer. Meanwhile I'm going to try-out some scuba diving while I can. :mrgreen:
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Post by canyncarvr »

???

Stripped? I suppose that means the cylinder threads..not the stud threads, right?

Who is taking them out/putting them (studs) in on the cylinders trips to EG? USC wants to see the cylinder with nothing in it..no KIPS, no studs, no locating pins, no nothing. EG is doing that? Or is 'the mechanic' doing it?

Don't recall if this was covered before or not..and didn't go looking, but a lubricant should be used on those threads. SOMEthing to prevent dissimilar metals corrosion. Even using a threadlocker would be better than using nothing.

IMO and all.......

What was the upshot of the last EG stint? What did it take to 'fix' it?

AND...is there a relationship between the hole (assuming it's NOT the stud) stripping and the coolant loss/gasket 'failure'?

Thanks for the ongoing updates! Much appreciated!!

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Post by green_passion »

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canyncarvr wrote:???

Stripped? I suppose that means the cylinder threads..not the stud threads, right?

Who is taking them out/putting them (studs) in on the cylinders trips to EG? USC wants to see the cylinder with nothing in it..no KIPS, no studs, no locating pins, no nothing. EG is doing that? Or is 'the mechanic' doing it?

Don't recall if this was covered before or not..and didn't go looking, but a lubricant should be used on those threads. SOMEthing to prevent dissimilar metals corrosion. Even using a threadlocker would be better than using nothing.

IMO and all.......

What was the upshot of the last EG stint? What did it take to 'fix' it?

AND...is there a relationship between the hole (assuming it's NOT the stud) stripping and the coolant loss/gasket 'failure'?

Thanks for the ongoing updates! Much appreciated!!
I believe it was the stud threads but I'll have to ask him to be sure. All I know is that we are looking into just throwing in the towel and buying a new stock cylinder 'cuz of everything that's gone wrong. :roll:

He's been taking everything apart before we ship it. I recently found out that EC doesnt (you'll get a kick out of this C) use US Chrome anymore due to issues he was having with them. He now uses a local shop where he lives. The last time we mailed in the cylinder he asked that we send him everything with the cylinder, including the bolts, power valves, and head. He fixed it for free as a "warranty repair" so that wasn't an issue.

Your welcome and like I said, I'll be posting a more cohesive ride report, complete with new reeds within a few months. :)
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Post by canyncarvr »

I COULD say I just got a cylinder off ebay for $80. Of course...it's just a puke 200...not the Kingly 220, but you may well find a deal there.

RE: 'He fixed it for free...'

Meaning...it was stripped/replated/honed again?

Did the cylinder threads come out with the stud on disassy...or they were just ratty enough to not hold this time?

BTW...that does 'just happen'. I've seen bolts come out of quite new aluminum (not old..not sitting for years...not corroded that I could tell) complete with an intact spiral of every speck of aluminum that used to be part of the hole.

Hence...SOME kind of agent..lubricative or locking.

Someone at EG could have noticed the threads were bad..and helicoiled it for 'ya!

Well...I'm assuming that would work. Possibly the head is thin enough in that particular area that the hole required to take the helicoil would get too close to a water jacket. I dunno......

Good luck!

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Post by Jeb »

I'm lookin' forward to hearing your report with the porting. I wish I understood more about how which porting dimension affects what and on which port(s). It's mesmerizing to consider how things could change by shaving a few mm here or there . . .

out of curiosity you mentioned riding a CR250 - are you talkin' the R (two stroke)? Would you care to comment on how its power feels compared to the top end of the recently ported cylinder?
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Post by fuzzy »

I'm betting not even close. I'm sure it's a nice difference though.
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Post by green_passion »

Meaning...it was stripped/replated/honed again?

Did the cylinder threads come out with the stud on disassy...or they were just ratty enough to not hold this time?

BTW...that does 'just happen'. I've seen bolts come out of quite new aluminum (not old..not sitting for years...not corroded that I could tell) complete with an intact spiral of every speck of aluminum that used to be part of the hole.
It was just honed again. Nuthn' to serious.

I think a combination of both. After some further investigation, it looks like my cylinder was helicoiled by the previous owner. The odd part is that when we did the first top end on my bike, it had a stock piston in it. :blink:

Ah well, Matt's (the mechanic)has the parts on order and he's going to get my bike (hopefully) put together for this weekend's race.

I'll let y'all know how it goes after our Friday test ride. :roll:

>|<>QBB<
Jeb wrote:I'm lookin' forward to hearing your report with the porting. I wish I understood more about how which porting dimension affects what and on which port(s). It's mesmerizing to consider how things could change by shaving a few mm here or there . . .

out of curiosity you mentioned riding a CR250 - are you talkin' the R (two stroke)? Would you care to comment on how its power feels compared to the top end of the recently ported cylinder?
Yes, the "R". Matt has had his CR ported for more bottom end by EC as well so it's pretty tame compared to a stock CR. The porting in my opinon is comparable in power but the CR has just a bit more "omph" to it when I need it compared to the KDX. However there were several times when we were whipping in and out of the trees at Kennedy Meadows that I'd wished I'd had my mellow-n-nice 'lil easy to throw around KDX. Of course there's issues with the power band on the CR that creates its challenges while riding it. :roll:

I'm still not sold on any other bike to own other than my KDX. (Although I'm going through a love/hate relationship with it right now. :wink: )
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Post by ebeck »

That is pretty mild porting. Or so it seems. Really want to hear the ride repot. A I correct in that this upgrade has been going on since April?

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Post by Curious George »

If you raise the exhaust port itself slightly , wouldn't the KIPS wedge still keep most the low end below 6000 rpm's where the KIPS kicks in ??

Any time you can clean up the intake burrs and casting flaws your going to get more air / fuel into the cylinder. The optimum idea is to pack it as full as possible.
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Post by Mr. Wibbens »

Ya ever hear anything positive with porting a KDX, do let us know :wink:

Seems to only cause problems as I've ever read about
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Post by fuzzy »

I remember plenty on that other site that were happy with EG's 'better everywhere' porting which is a real mild job. Ma Kaw got these cyls pretty perfect from the factory though. I think the 220's can benefit more as they are not so perfect (from engine builders mouths), but at the same time not a lot can be done because to 'fix' the 220 cyl you'd have to put back material that's gone already. This is why the 225cc (built from 200)is reputadely the ultimate 22x cc combo. Have heard of some detonation issues w/ this combo though so maybe that's why the 220 is the way it is. :rolleyes: Shame the 220 isn't simply a stroked 200 with say 10cc's coming from the stroke and 10 from the bore.

Most benefit especially for the money is in the head, reed cage, and carb.

Nothing wrong with a little cleanup, but don't polish anything. Turbulance is good in this case. Everything is give or take, just like a camshaft on a 4T. Raising the exhaust port will gain top end and lose low. Plating damage can also occur while port grinding, and IMHO it's all best saved for during a replate.

Still wish they made a true KDX250...Fully based off KX chassis...With motor based off 200, and most the increased cc's as possible coming from the stroke. For that matter this would've been nice right before the production run ended w/ a 200 as well....All KX based. Hell it would've saved them money to stop producing an extra chassis. Ala orange bike's lineup. Bet they would've sold like hotcakes. Lots of people out there want an enduro 2T without going euro.
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Post by canyncarvr »

Re: 'but don't polish anything.'

I get a kick out of some noob's idea that he's got the hot ticket, 'cuz HIS machine is 'ported and polished'. ASK that noob how that effects fuel suspension and air/fuel delivery, I doubt he will have a coherent, cogent response.

I'm not a cylinder porter...OR polisher for that matter, but I do know that removal of metal necessarily results in an increase in volume, said increase is going to reduce stream velocity and that can well reduce cylinder charge. There's a helluva lot more to it than removing 'stuff'.

Which is why it's generally called 'FM'. :wink:

A BTW...I asked EG if he could use a 220 head for a 200-225 job. His response was, 'No problem..it's got the same bolt pattern'. That concerns me. That a 220 head bolts up to a 200 means squat. Now...I could assume he is fully aware of the differences in the heads..he should. But..assuming such things generally leads to a fool running an errand.

:hmm: When was the last time you saw the word 'errand'?

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Post by fuzzy »

Yeah, that's intersting. Having not seen a 200 and 220 head side by side who knows which one would be compatabile with the other in realation to a 225....and like you said it may not matter (ie either one gets everything machined out). We do know for a fact that the porting between the two is way different and the end-result 225 would be way different when compared directly.

'porting and polishing' this is for 4strokes. I have seen some crazy polished 2-stroke stuff, but the were 100-125cc's that turned 21k RPM, and make about 45hp at 15k, and about 10hp at 8k...LOL. Not exactly a trail engine.

I should add this quote I like to spread around. It's from a guy who is pretty much the Don Garlits of the karting engines I just mentioned above..."A 4stroke is to an air compressor so much that the rules of physics apply directly.....A 2stroke has more in common with a brass or woodwind instrument than the latter." After reading that I decided to forever care less about closing the 30-40% lack of knowledge I have of them. While 2x simpler parts-wise, design/physics wise they are 3x as complex. Don't ever trust your local dude (or even a gold medal winning rider) to hit that thing with a grinder....Unless you KNOW that he knows his ****....Or at least has a port-mapping template from someone who did. :grin:
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Post by canyncarvr »

I have a bit of a pick about that.

I DID know a guy that I was SURE knew what he was doing. He had wrenched on RD motors for about ever, was the touted guru of everything 2T-twin-yammy. My RD being due for a rebuild, I asked if he could do a 'tune-up' on my cylinders. Nothing drastic, would use the stock pipes, the bike was a ROAD machine, not a track screamer.

He said he knew exactly what I was after..and he could take care of it.

What I got was a damn-near case inducted intake ports..and a bike that didn't run for crap below about 6000rpm. Fuel efficiency took a huge hit, and that was critical considering I had to be looking for fuel with the OEM setup at around 100 miles already. With new rules for gas stations and the liability insurance required to own one getting ridiculous, LOTS of little mom and pop places were closing. That 100 mile range got real iffy..the port 'tune-up' made it necessary to carry fuel with me. I wasn't crazy about that.

There are a whole lott'a folks that DO think they know what they're doing. They don't.

That engine didn't last. Crank seals got ett..and that was a long ways from home! Ended up with a stock engine from the salvage yard. What a relief it was to get back to 'stock' on my RD.

Ended up giving the thing away to a then-friend of mine that always ogled my little tweaker (he had gone through several of 'em in a handful of years. Always seemed to blow'em up). Had about 70,000 miles on it at the time. Went a lot of places on that thing.

The point is...if you are not extremely cautious when it comes to 'port-n-polish'ing your bike, you will likely be disappointed. And..you may be anyway regardless of how much care you put into getting it done.

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Post by fuzzy »

Agree with the THINK they know what they're doing....I should've phrased "Do research, and know for yourself if that person truely KNOWS what they are doing." This is especially true of the KDX as the are a pretty rare bike to cross a porters bench I'm sure, and it's vastly different than the run of the mill 125/250/etc. I know of a lot of people out there that do port jobs, and are renowned for their work, yet at the same time I know they don't know **** about 2-cycle port theory/etc. They have port-mapped someones work who knows more than them (STOLE it). This makes them a machinist with a map...Not like that's the end of the world if you want a RM/KX/YZ 250 cyl setup for MX/Desert racing (90+ % of the common port work, by guess), but could be a drastic mistake if you send your 200 in there. Hell, CC has a butch job from someone who is supposed to be the king of these bikes.
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Post by canyncarvr »

Re: 'Hell, CC has a butch job from someone who is supposed to be the king of these bikes.'

Hey! It was SUPPOSED to look like that (and perform like it, too)!! :lol:

Ahhh well.

...which is why I'm really pondering the Wibbiness (Why bother?) of it all concerning a 225 setup. I am pretty curious about it, though. Nothin' to lose but (another) $400 and maybe a (nother) year or two of trying to make a silk purse....

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Post by Mr. Wibbens »

I think you should then maybe your bike will gain some GRUNT and I won't hafta wait at the TOP of the hill for like an HOUR! :lol:
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Post by Curious George »

Did I ruin my cylinder my raising the center exhaust port by .030 ?
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Post by fuzzy »

No, that should be fine. You might not even notice anything.
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Post by canyncarvr »

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Mr. Wibbens wrote:I think you should then maybe your bike will gain some GRUNT and I won't hafta wait at the TOP of the hill for like an HOUR! :lol:
Yeah. Or maybe I could put on a couple hunnert pounds....

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