going case inducted!!!

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mrfubs

mrfubs

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Jun 13, 2013
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michigan
Very nice job it looks pretty sick! cant wait to see a video of it!

I do have some advice. do NOT use your pistons rings if they are chrome. Im the one who tryed the chrome on chrome and ill tell ya what, all the hard work you did to the cylinder will be gone in 5 mins. i ran my for not even 2 mins and scored the walls majorly.

Save your self the grief and use a stock piston, there is no alternative piston with thinner rings right now. iv spend the past 5 months reseaching, calling, buying pistons and rings.

1977 mopeds lists motobecane 47mm 1mm thick rings non chrome, well they dont carry them anymore unfortunately.

Id just hate to see what happend to me happen to you. Hope i helped!
 
mew905

mew905

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Sep 24, 2012
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You'd need a real cylinder. Since you're doing all that work, you could probably ream and bush your crank out to 12mm to use more pistons. There's a kit Foureasy used to net 5hp with just that and a pipe. Proper plating means you could also ditch the kit piston (you cant buy just the jug unfortunately) and go with the Hoca minarelli.
 
Davezilla

Davezilla

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Mar 15, 2014
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that looks really wicked... I'd go with a better cylinder to get the most out of that setup as well... The Puch Athena kit Foureasy used did make some impressive power and there's another guy on youtube that used that Minarelli jug (Stage 6) and his bike really rips.. It looks like he used a 3/8" thick steel adapter plate to mate the jug to the cases, I got close up pics of that one from mrfubs and I'll have to dig them up if interested, his setup loks crude, but it's the quickest China Girl based engine I've seen so far... https://www.youtube.com/watch?v=HOK9DsKZ_KQ
 
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M

mech_engineer

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Mar 3, 2014
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Puerto Rico
Thank you for your advice i am thinking of using my old notch piston to test the duration of the exhaust and transfer ports. Then buy a new one and make the duration changes at the jug. I am waiting for the machine shop to finish the 3er transfer port and i need to fit the ktm expasion.
 
mew905

mew905

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Sep 24, 2012
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I see you've got a PHBG Carb. I've got one myself, waiting to go on my green bike (no reeds sadly, 40mm intake makes it too wide for either set of my RSE Reeds, which are too small anyway so meh...).

I've been wanting to, but havent had time, to screw around with the jug and see just how much I can cut into the transfers. I want to make them the right angle without making them smaller (JB Weld technique), but last time I used JB in the transfers it just melted and screwed up the flow (maybe not enough case pressure?). I highly recommend going with the Athena jug that foureasy used, just because it's got much larger, better angled transfers. The stock jugs lose a lot of power from short circuiting (shooting fresh intake mix straight out the exhaust), this reduces both scavenging efficiency (not blowing everything out of the cylinder) and reduces the amount to burn (a case reed 2 stroke should in theory suck the full stroke's worth of mix into the case, so you'll have inherently higher transfer pressures, but the transfers are just going to waste a lot of it). If you have some spare jugs laying around, you should see if you can get those transfers to a better angle.
 
rogergendron1

rogergendron1

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Sep 18, 2013
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woburn ma
mew905 said:
I see you've got a PHBG Carb. I've got one myself, waiting to go on my green bike (no reeds sadly, 40mm intake makes it too wide for either set of my RSE Reeds, which are too small anyway so meh...).

I've been wanting to, but havent had time, to screw around with the jug and see just how much I can cut into the transfers. I want to make them the right angle without making them smaller (JB Weld technique), but last time I used JB in the transfers it just melted and screwed up the flow (maybe not enough case pressure?). I highly recommend going with the Athena jug that foureasy used, just because it's got much larger, better angled transfers. The stock jugs lose a lot of power from short circuiting (shooting fresh intake mix straight out the exhaust), this reduces both scavenging efficiency (not blowing everything out of the cylinder) and reduces the amount to burn (a case reed 2 stroke should in theory suck the full stroke's worth of mix into the case, so you'll have inherently higher transfer pressures, but the transfers are just going to waste a lot of it). If you have some spare jugs laying around, you should see if you can get those transfers to a better angle.
Click to expand...
how ?

How do you get into the transfers up in the jug to alter the angle ?

I could barley get my dremal pen in there to clean up the casting flash arouns the transfer port opening to smooth it out let alone get a bit in there and change the angle!
 
M

mech_engineer

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Mar 3, 2014
175
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Puerto Rico
You can get rid of a little bit of aluminum from the lower part of the transfer port this will help to make your porting. I used jb weld to correct the angle but make sure to not go lean in the mixture this will increase the temps and melt the jb weld
 
mew905

mew905

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Sep 24, 2012
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I had a peek at my spare cylinder yesterday, looks like you can clean up the transfer angle using a drill bit (preferably in a press but a hand drill would probably do it too), then clean it up using a dremel. I prefer not to use JB as last time it melted. You need the case compression to stop the exhaust gases from melting it. Plus I'm not a fan of shrinking the already tiny transfers. I'm not sure how much you can remove just yet, havent done a test drill but I probably could today.

I have a very small dremel extension, the dremel branded one is too fat to get in there, I got one from Sears that's a small pen-like extender that can fit right into the transfer ports :)
 
M

mech_engineer

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Mar 3, 2014
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Puerto Rico
:-|| the engine started!!!!! But i am tired rigth now i will post video later ... faster throttle response... more power at high rpm and less vibration... a diferent engine...
 
mew905

mew905

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Sep 24, 2012
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I'm not surprised. The engine can actually draw the full stroke's worth of air (minus flow losses such as reed and intake restrictions). This, in turn, means more air to be compressed when the piston comes back down. That means higher primary compression, which blows into the combustion chamber at high RPM's more effectively and doesn't allow as much blow-down. This means more into the combustion chamber and less return. That makes it more efficient. This also means to combat the blow-through of the increased transfer pressures, you can increase secondary (combustion) compression. Getting a matching expansion chamber will maximise your power. :) Glad it worked out, what reeds did you use? I'm interested in trying this myself

I really want the Minarelli V1L reed set but I'm doubting it'll ever come back into stock, and that'd be jug reeds, case reeds would be far more effective :)
 
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Davezilla

Davezilla

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Mar 15, 2014
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rogergendron1 said:
how ?

How do you get into the transfers up in the jug to alter the angle ?

I could barley get my dremal pen in there to clean up the casting flash arouns the transfer port opening to smooth it out let alone get a bit in there and change the angle!
Click to expand...
I was able to get up into mine with a pneumatic pencil grinder and a 3" long carbide burr... The pencil grinders are about $20 at Harbor Freight and they need a good supply of air to run them but they spin at 54000 rpm so they can remove metal pretty fast using full rpm with a fine toothed burr and just use a light touch & let the tool's speed do all the work. http://www.harborfreight.com/18-air-micro-die-grinder-69745.html

These things are tiny so they will fit where a dremel won't, and I got the rotary files from browntool.com, but you can usually find long shank 1/8" carbide rotary files on ebay for pretty cheap. Dental grinders will also work but you'll need to make up some kind of air hose adapter and they spin a lot faster than the harbor freight pencil grinder I got. if you can find a dental grinder for a decent price, that would be the way to go as they are smaller and faster, but the pencil grinder will get in there when using the long shank burrs
 
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