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You sure that's oem? Where did you order it from?
Who's making fun of BB kits! Mahle just joined the club!!!
- Thread starter CHEVYTOWN13
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CHEVYTOWN13
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Scot, I'll be starting this afternoon. I'm at work right now. I'm starting off cleaning the edges from the piston first. Then I'll be using a router to clean up the areas in question on the jug. Then it's time to bust out the used foredom I got from Adam:greenchainsaw: and go to town on the ports. Finally a little work on the transfers.
Using the metal gasket for a slightly tighter squish.
Here we go!!!
Using the metal gasket for a slightly tighter squish.
Here we go!!!
tdi-rick
Addicted to ArboristSite
Naa. The Rickster wont mind
The lower transfers can be matched to the base and one area that the BB can then match the Mahle cylinder is to generously radius the entry of the rear most transfer from the cylinder wall into the duct/port.
Have a look at this pic
compared to the very sharp 90* entry on your jug above.
Anywhere you are turning air/mix you want the transitions to be smooth for as little flow disruption as possible.
If you had access to a Foredom or similar, I'd at the least cleanup the transfers where they enter the cylinder and make the port exit uniform too.
Watch what Rick does, it will give you some good ideas.
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AUSSIE1
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Thanks for the info, can you please post some before and after shots?
Same principals applied to other saws can be applied to this saw.
The Husky's are very similar for example so plenty of information and pictures on these for you in the meantime if you do a search.
thanks for all the info guys, I know most here say don't port the bb kits but mine looks better than I was expecting. Im going to see what chevy does and others have done and try to do a little to my jug and see what I can learn. It will be a week or so untill I have the time to dig into this so Ill try and soak up as much info as you guys will share in the meantime.
AUSSIE1
Al.
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I would of thought most would have said PORT the BB kits.
I've found most times the size and No's of the ports could do with some work.
If you have the means it would be worth the effort.
SawTroll
Information Collector
I'm very disappointed with the stock 7900 OEM cylinder and piston that showed up today!
Was it a bad batch? Done on a Monday?
I'm porting it and can reshape the flaws, particularly on the piston as that looks like trouble to me. So I really don't care in that aspect, but dang, there's been a lot of talk about BB kits being bad and this OEM crap shows up. I'm glad I'm porting this cylinder, because if I had to run this stock, I'd be bummed. AREA 51 to the rescue:greenchainsaw:
That just looks horrible........:jawdrop:
in the photo of your piston it looks like the ring has a solid single surface like most rings Ive seen. The ring that came in my kit has a grove that makes it seem like two slim rings in one. Is this normal or should I look for a different 54mm ring?
Henry G.
ArboristSite Guru
I would send that junk back. Retailers are going to continue to accept crap like that unless customers complain/demand refunds in mass. QC at Baileys or wherever you bought should have caught that before even bothering to ship it.
AUSSIE1
Al.
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You've got a point, but there is a good chance he could end up with similar issues with the next kit.
Maybe a call to the supplier to make them aware.
Plus the turn around could be 1-2 weeks.
There will be no evidence once he finishes working on it.
The most is it looks ugly, but you would find it would run fine.
I'd have to clean up that skirt with like a racker file prior though.
THALL10326
The Champ
How dare you say that. That is a Mahle sir, you know, the best thing since chicken soup, I want Mahle on my pro saw,blah blah blah,(LOL) only Stihl makes a horrible looking kit, therefore you must overlook that ragged cut horrible looking POS in those pics,oooops, that slipped, anyway its AS correctness we're talking about here,:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:
CHEVYTOWN13
Addicted to ArboristSite
This jug is taking a ride in one of the General Motors Gangster Cars
I'm not going to say who it was. I don't think they are liable. Just picked it off the shelf like one wood do.
I don't really care as it's not a stocker no mo
For a stocker, not cool for school man...
Simple jig and some wood. I took off too much in one pass as you non journeymen can hear the chattering.
The Mex Port in action
<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf?file=http://vid701.photobucket.com/albums/ww11/CHEVYTOWN/365suddenacceleration.flv">
See you all later cuz the rest stays in the AREA Fitty One files:greenchainsaw:
PS...listen to Alstar and Slick Rick:greenchainsaw:
I'm not going to say who it was. I don't think they are liable. Just picked it off the shelf like one wood do.
I don't really care as it's not a stocker no mo
For a stocker, not cool for school man...
Simple jig and some wood. I took off too much in one pass as you non journeymen can hear the chattering.
The Mex Port in action
<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf?file=http://vid701.photobucket.com/albums/ww11/CHEVYTOWN/365suddenacceleration.flv">
See you all later cuz the rest stays in the AREA Fitty One files:greenchainsaw:
PS...listen to Alstar and Slick Rick:greenchainsaw:
CHEVYTOWN13
Addicted to ArboristSite
Angled towards the intake.
Hand porting to finish it off.
Hand porting to finish it off.
CHEVYTOWN13
Addicted to ArboristSite
Here is the picture from earlier just flipped to give you an idea of what it's going to look like from the perspective of the jug on the saw.
Should be FLOW time. I'm not touching the transfers that much, so velocity will be maintained.
Should be FLOW time. I'm not touching the transfers that much, so velocity will be maintained.
AUSSIE1
Al.
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Hey Rick, I've got a wood lathe...............Hmmmmmmmm popup pistons?
Now I'm confused...are we supposed to overlook the Stihl turds, or the Mahle turds?
That Mahle is, unquestionably, a horrible piece of work. It would be nice to know what the response would be were it to be returned. Someone needs to be embarrassed about that.
OR...maybe it is a new development in flow dynamics! I'm headed to the basement to open my transfers with a ball peen hammer and find out. Of course, if it isn't a new development, it looks like my options for replacement cylinders has narrowed considerably.
porting
I hit the send too soon. It looks like you enlarge and smooth the entrance to the transfer ports, but don't increase the size of the ports as they go up the cylinder. But you could enlarge carefully the intake ports into the cylinder as well as the exhaust port?
The old Mac 20 Go Kart engines had factory finger ports up the back side of the cylinder, so there were intake ports on three sides (270 degrees) and exhaust on one side.
Willysmn
I hit the send too soon. It looks like you enlarge and smooth the entrance to the transfer ports, but don't increase the size of the ports as they go up the cylinder. But you could enlarge carefully the intake ports into the cylinder as well as the exhaust port?
The old Mac 20 Go Kart engines had factory finger ports up the back side of the cylinder, so there were intake ports on three sides (270 degrees) and exhaust on one side.
Willysmn
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