Idea: Cylinder spacer

mew905 · Sep 3, 2013

I know someone made one of these before but I've never seen them for sale. The HT cylinders are about 2mm too low and the piston covers half the transfer port when its at BDC. My idea is to use a cylinder spacer with two towers reaching into the transfer ports. The spacer would uncover the whole port and increase the power band, and the towers reaching into the transfers are simply to stop short circuiting by aiming transfer flow toward the intake side of the cylinder.. I've been toying with a potential product but lack the CAD skills to have one made. If someone could make one out of aluminum or steel ($20 would be an ideal price range for something like this), it would make an amazing mod. I can get measurements if needed, I just need someone who can actually produce these for us.

Here's a quick sketch I did, hopefully this explains it a bit better.

MotorBicycleRacing · Sep 3, 2013

The somebody was 4easy? from AZ and he hasn't been on this forum in a long time.

Huffydavidson · Sep 4, 2013

Meanwhile back at the compression gauge the numbers are dropping .

mew905 · Sep 4, 2013

Huffydavidson said:
Meanwhile back at the compression gauge the numbers are dropping .

Yep, thats the drawback, youd have to shave the cylinder head mating surface to gain back compression, but in all honesty i havent noticed much of a boost to begin with going to higher compression. Itd have to drop big numbers to affect performance greatly. The question is would the added efficiency overcome the compression loss and give you a net boost?

Scott.D.Lang · Sep 4, 2013

The spacer that 4easy made was for a puch china girl hybrid so he needed to raise jug because of piston height, if I rember right

Huffydavidson · Sep 4, 2013

Well I search the member list and there is no member user named "4 easy" or" Easy 4" unless he past and staff removed that name.

MotorBicycleRacing · Sep 4, 2013

Huffydavidson said:
Well I search the member list and there is no member user named "4 easy" or" Easy 4" unless he past and staff removed that name.

Close enough .......

you woulda found him if you searched for "easy"

http://motorbicycling.com/member.php?u=10721

He ain't been here since 2011.

Huffydavidson · Sep 4, 2013

Thanks MBR, I found him and your right he hasn't been on since 9/7/2011 .just a quick read over , he had bought a house and the bike was taking up to much time , so he said he was hanging up the bike . His adapter plate was for a Puch top end . Not really that big of a deal. But what I did come across that was reallllllyyyyyy interesting these guys about two year back that TURNED THE JUG 180 and apparently got great results . brnot

maniac57 · Sep 4, 2013

Josh moon has a reversed jug bike...moonerdizzle I think?

mew905 · Sep 4, 2013

yep, jug reversal is an idea that's definitely not new. All ya gotta do is match the transfers and it works well. It's more for aesthetic reasons, our little motors dont go fast enough, nor suck enough air to get any benefit from ram air. As for the spacer, now that you mention it, yeah I remember it being a puch cylinder. It'd probably work out much better than ours as the timing is good for mid-low end power, but the piston covers alot of the ports at BDC, raising it would raise the exhaust/transfer timing and reduce intake timing (unless reed ported), reducing low end power AND compression, but giving more flow area for exhaust and transfers.

maniac57 · Sep 5, 2013

I'd love to see a simple bolt-on swap to a better cylinder like a puch or similar.
The aftermarket stuff is too pricey for me.
But the bottom end becomes the limiting factor quickly.
Maybe on a DAX balanced lower?
Let's see one of you mad scientist types swap a good cylinder onto a chinagirl...affordably!

mew905 · Sep 5, 2013

It would be beneficial for sure. Better ports, better plating, better transfers... Too bad im so bad with CAD, i could have a prototype by next week...

dmb · Sep 5, 2013

turkman has one that he's been working on. hopefully it will be ready for the grange race. neil kinda outlawed it for the china motor class so i hope bob didn't loose interest in it. really nice motor with a lotta time and money in it. too bad. it might be a nice race motor that didn't blow up or need rebuilding after a day of racing like the china racers do. dennis

MotorBicycleRacing · Sep 5, 2013

dmb said:
turkman has one that he's been working on. hopefully it will be ready for the grange race. neil kinda outlawed it for the china motor class so i hope bob didn't loose interest in it. really nice motor with a lotta time and money in it. too bad. it might be a nice race motor that didn't blow up or need rebuilding after a day of racing like the china racers do. dennis

I didn't outlaw nuthing.

I said he could race it in the PRO class last June and lets all talk
about future rules for the PRO class at one of the races in person.

Turkman never finished the motor.
Bring it out to the race this Sat Sept 7th or the Oct 19th race at
Grange Motor Circuit.........

PS: Dave at Arrow Motorized Cycles built the special stroked crank for turkman's motor.

Kioshk · Sep 5, 2013

mew905 said:
Too bad im so bad with CAD, i could have a prototype by next week...

Gimme the dimentions and I'll mock it up for you.

Dan · Sep 6, 2013

Kioshk said:
Gimme the dimentions and I'll mock it up for you.

Purty awesome Kioshk. It really is folks like you who make "here" such a great place.

To "mock it up" is a good deal of work and really great to see/read some one offer to help a buddy like that.

I pull my hair out trying to write cnc and mastercam programs, lol.

.flg.

mew905 · Sep 6, 2013

Kioshk said:
Gimme the dimentions and I'll mock it up for you.

for sure, if you have a spare base gasket for a 66cc lying around, thats the overall design, then on the exhaust side (narrow side of the transfers) it just cuts in triangularly, at a slightly deeper angle than the intake side. the spacer needs to be 2.5mm high (with a base gasket on both sides to seal it, it'll raise the cylinder 3.5mm higher than stock), I'll include an image of what I mean in a minute (sadly I dont have an angle finder, but thats ok, the angles on the base gasket block the transfers anyway). Using this means you have to remove 3.5mm from the cylinder head mating surface. But, in simple terms, that means make the part that sticks out from the top of the cylinder perfectly flush with the top fin. this will set the piston at the same height it would be stock, meaning you wont lose compression... but it'll take a really, really long time to sand that off, best use a lathe.

The transfer towers are the tricky bit, they'll need to be sanded down on a per-case basis as the grubees have 1mm higher transfers than the type D's. so make em stick up 36mm from the topmost area, and it has to be a smooth transition from the stock transfer shape to the towers to gain maximum effect. I'll have these 3D printed in stainless steel and the minimum wall needed is 2mm.

If you can do this for me, I'll for sure have one made and test it out.

dmb · Sep 7, 2013

neil, i said ''kinda'' and the other neil at first said something to the no effect, but they changed their minds then the third neil overruled the other neils and will let it run unless it was too fast. where the first neil's ruling overrules the second and third neil. OK? now that thats cleared up i'd sure like to see bob's motor run as i'm sure two outta three neils would like to see the same, maybe. wow talk about a brain teaser, i'm tired

MotorBicycleRacing · Sep 7, 2013

dmb said:
neil, i said ''kinda'' and the other neil at first said something to the no effect, but they changed their minds then the third neil overruled the other neils and will let it run unless it was too fast. where the first neil's ruling overrules the second and third neil. OK? now that thats cleared up i'd sure like to see bob's motor run as i'm sure two outta three neils would like to see the same, maybe. wow talk about a brain teaser, i'm tired

Damn, I didn't realize that you were that in love with me. laff

dmb · Sep 7, 2013

not just you, all three of you! i dont get along with #4 thou. but thats OK with me. 3 outta 4 aint bad love dennis ... sorry about jacking this thread i wanted to give you some info about other top ends on the china that have been done. thanks guys

Idea: Cylinder spacer

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