First mods, case reed engine - Page 7 - Pocket Bike Forum - Mini Bikes
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post #121 of 288 (permalink) Old 2 Weeks Ago Thread Starter
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Originally Posted by silverbullitt7 View Post
Sweet. It definitely measures bigger at the cylinder side. How big do you usually go? I don't want to go to big and ruin it.
If I'm keeping the base gasket I widen the port 1/8" on each side.

If I'm losing the base gasket I go 1/8" on each side plus double the thickness of the gasket dead middle then I taper it down to make the exhaust open and close progressively to enhance scavenging and velocity..

When done right the exhaust port takes on a half of a football shape..

If you go back to post #112 and to the last picture I posted you can see what I'm explaining...

The one in the pic has been more agressively ported because the engine was being used for alcohol as it was an ADA 15:1 alky headkit to start with.




For the power level you seek I'd go 1/16" or 1mm on the sides also raise the middle of the exhaust port only 1/16" if you're rolling without a base gasket..

Your half of a football shape wont look as pronounced as mine when you're done though which is totally OK.....

Like I always say small changes in small cc engines makes big end results.....

37 years ago when I converted my first chainsaw engine into a kart engine by myself with very lil help from my dad I felt like an engine master and wanted to buy up any and all chainsaws to build more..

My dad just shrugged his shoulders and said "Oh Boy" and "Oh Goodie". sarcasticly ofcourse...lol

Once you pull off your first one you'll be stoked to do more....

Good Luck
Well, I had originally planned on using the base gasket. If I didn't should I use anything or use Permatex or something?
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Re: First mods, case reed engine

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Originally Posted by silverbullitt7 View Post
Well, I had originally planned on using the base gasket. If I didn't should I use anything or use Permatex or something?
I use Permatex Moto Seal....They carry it in almost all Autoparts stores worldwide..

Its just as good if not better than Hondabond/Yamabond

It has a runny watery-like consistency for a gasket maker but it sets up pretty fast[15-20 mins]






Those decompression notches they put on the 44mm cylinder exhaust port staves off a lot of pressure that could be more effective to building power over long terms had it been de-void of that notch like on the 40mm cylinders...As the 44mm cylinder engine heats up the more compression bleeds off at higher revs so having as much compression as you can up front with a 44mm cylinder helps out a lot in the end result.....

I'd ditch the basegasket and utilize the 180psi you'll get without one....The increased compression will be the saving grace to the whole build by making the engine stout enough to rival the 4hp you seek..


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Last edited by CAM2; 2 Weeks Ago at 12:06 PM.
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Re: First mods, case reed engine

For the Dremel you need a $30 set of ten different shape cutters, high carbon steel, the China stuff is junk, good for wood, lol. It also depends on the shape of you head pipe hole, you match the outer cyld exhaust port to it. When the piston starts down, it sucks the unburnt stuff out of the pipe back into the cyld. CAM2 always says, smooth path from the carb thru the engine. I think the bottom of the exhaust port is tapered down a hair. My 47cc Boosted306 modified cyld engine has a canted exhaust port and 1 wide upper port .690" wide, and non-ported piston, its a scrappy little engine.

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Re: First mods, case reed engine

I see you have a digital caliper....

Take a piece of paper and map the cylinder remove the map and make the calculations....

I want to know how wide your exhaust port is and how high it is dead middle at the inner part of the cylinder..

Then the exhaust port measurements on the outter part of the cylinder..

Then I want to know the distance from the height of the exhaust port to the base of the cylinder not the bottom of the skirt...You can see the line that differentiates dome from cylinder..

I also want to know the height of the transferports from cylinder base to transferport top...

Last measurement is the full width of the transferports

I have a 44mm cylinder that's casted as 44TM78...TM cylinders are performance oriented cylinders..

The numbers on the cylinder I have are...

Exhaust port inner : 23.54mm's wide x 9.35mm's high

Exhaust port outter : 25.08mm's wide x 16.20mm's high

Top of Exhaust port to cylinder lip : 24.69mm's

Transferport height from cylinder base to T-Port top : 29.41mm's

Transferport width is : 19.27mm's wide

3rd boost port height from cylinder base to BP top is : 29.41mm's

3rd boostport width is : 9.38mm's wide

Theres plenty room for improvement even with this cylinder that's supposedly already casted for more performance...LOL

I'd make the Exhaust port inner 25.50mm's wide by 10.5mm's high

The exhaust port outter Id go 26mms wide by 20mm's high

Id widen the transferport to 22mm's thin down the center divider and polish them..

I'd raise the 3rd boost port .10" higher than the transferports..

When done the TM cylinder would be quite a ripper....LOL




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Last edited by CAM2; 2 Weeks Ago at 09:49 PM.
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Re: First mods, case reed engine

There's your map, you can leave the fingers, make them thinner and cut out material front and rear. If you look your piston rides on it, CAM2 has done that. You have to match the main transfer of the cases and cyld you modified.

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post #126 of 288 (permalink) Old 2 Weeks Ago Thread Starter
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Quote:
Originally Posted by CAM2 View Post
I see you have a digital caliper...….

Take a piece of paper and map the cylinder remove the map and make the calculations....

I want to know how wide your exhaust port is and how high it is dead middle at the inner part of the cylinder..

Then the exhaust port measurements on the outter part of the cylinder..

Then I want to know the distance from the height of the exhaust port to the base of the cylinder not the bottom of the skirt...You can see the line that differentiates dome from cylinder..

I also want to know the height of the transferports from cylinder base to transferport top...

Last measurement is the full width of the transferports

I have a 44mm cylinder that's casted as 44TM78...TM cylinders are performance oriented cylinders..

The numbers on the cylinder I have are...

Exhaust port inner : 23.54mm's wide x 9.35mm's high

Exhaust port outter : 25.08mm's wide x 16.20mm's high

Top of Exhaust port to cylinder lip : 24.69mm's

Transferport height from cylinder base to T-Port top : 29.41mm's

Transferport width is : 19.27mm's wide

3rd boost port height from cylinder base to BP top is : 29.41mm's

3rd boostport width is : 9.38mm's wide

Theres plenty room for improvement even with this cylinder that's supposedly already casted for more performance...LOL

I'd make the Exhaust port inner 25.50mm's wide by 10.5mm's high

The exhaust port outter Id go 26mms wide by 20mm's high

Id widen the transferport to 22mm's thin down the center divider and polish them..

I'd raise the 3rd boost port .10" higher than the transferports..

When done the TM cylinder would be quite a ripper....LOL




Great pictures, I was reading this just before bed, I will get those measurements mid-morning tomorrow. Thanks guys, I will Definitely be diving into this soon.
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Quote:
Originally Posted by CAM2 View Post
I see you have a digital caliper...….

Take a piece of paper and map the cylinder remove the map and make the calculations....

I want to know how wide your exhaust port is and how high it is dead middle at the inner part of the cylinder..

Then the exhaust port measurements on the outter part of the cylinder..

Then I want to know the distance from the height of the exhaust port to the base of the cylinder not the bottom of the skirt...You can see the line that differentiates dome from cylinder..

I also want to know the height of the transferports from cylinder base to transferport top...

Last measurement is the full width of the transferports

I have a 44mm cylinder that's casted as 44TM78...TM cylinders are performance oriented cylinders..

The numbers on the cylinder I have are...

Exhaust port inner : 23.54mm's wide x 9.35mm's high

Exhaust port outter : 25.08mm's wide x 16.20mm's high

Top of Exhaust port to cylinder lip : 24.69mm's

Transferport height from cylinder base to T-Port top : 29.41mm's

Transferport width is : 19.27mm's wide

3rd boost port height from cylinder base to BP top is : 29.41mm's

3rd boostport width is : 9.38mm's wide

Theres plenty room for improvement even with this cylinder that's supposedly already casted for more performance...LOL

I'd make the Exhaust port inner 25.50mm's wide by 10.5mm's high

The exhaust port outter Id go 26mms wide by 20mm's high

Id widen the transferport to 22mm's thin down the center divider and polish them..

I'd raise the 3rd boost port .10" higher than the transferports..

When done the TM cylinder would be quite a ripper....LOL




Hey. I measured the stuff twice , I could do it again if I have to. These measurements seem pretty big.

Exhaust port inner width - 26mm
Height - 13 mm

Outer exhaust port - width 25.55mm
Height - 16.5mm

Top of exhaust port to base of cylinder -
37.15mm

Transfer Port height from cylinder base to top - 29mm

Full width of transfer ports - 21mm
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I don't know if the pictures do it justice, but the port is so much bigger than the old one. I measured the old one And the width of the inner exhaust is 23.71 And the height is 10.3, outer Is 24.6 width and 15.56 height
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I don't know if the pictures do it justice, but the port is so much bigger than the old one. I measured the old one And the width of the inner exhaust is 23.71 And the height is 10.3, outer Is 24.6 width and 15.56 height
Ahh thanks for the initial measurements...Even though the new cylinder looks bigger than the old cylinder it still has room for improvements in every area to work as it really should on a minibike..

I'm very interested in how high the piston top is going to be protruding in the exhaust port at BDC...

When I see the side by side comparison it looks like the port of the new cylinder is casted too low...

What's the distance from the bottom of the exhaust port to the cylinder base on both cylinders...

What's the height of the transfer ports?

Last edited by CAM2; 2 Weeks Ago at 11:46 AM.
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I don't know if the pictures do it justice, but the port is so much bigger than the old one. I measured the old one And the width of the inner exhaust is 23.71 And the height is 10.3, outer Is 24.6 width and 15.56 height
Ahh thanks for the initial measurements...Even though the new cylinder looks bigger than the old cylinder it still has room for improvements in every area to work as it really should on a minibike..

I'm very interested in how high the piston top is going to be protruding in the exhaust port at BDC...

When I see the side by side comparison it looks like the port of the new cylinder is casted too low...

What's the distance from the bottom of the exhaust port to the cylinder base on both cylinders...

What's the height of the transfer ports?
Yes the bottom Of the inside exhaust port to the base of the cylinder is about 22 mm. And the old one was about 30 mm.
The transfer ports on both are about 31mm.the cylinder is casted 44-6
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Re: First mods, case reed engine

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Yes the bottom Of the inside exhaust port to the base of the cylinder is about 22 mm. And the old one was about 30 mm.
The transfer ports on both are about 31mm.the cylinder is casted 44-6
You are gonna need another cylinder...That one isn't gonna cut the mustard......

The top ring on the piston will be exposed at BDC which is bad...

You really don't want any more than this exposed at BDC..



Don't get from the same seller either....Get this cylinder


https://www.amazon.com/GOOFIT-Cylind...WPWMV6TWQWV0QR

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Last edited by CAM2; 2 Weeks Ago at 10:40 PM.
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Yes the bottom Of the inside exhaust port to the base of the cylinder is about 22 mm. And the old one was about 30 mm.
The transfer ports on both are about 31mm.the cylinder is casted 44-6
You are gonna need another cylinder...That one isn't gonna cut the mustard.....….

The top ring on the piston will be exposed at BDC which is bad...……

You really don't want any more than this exposed at BDC..…



Don't get from the same seller either...……….Get this cylinder


https://www.amazon.com/GOOFIT-Cylind...WPWMV6TWQWV0QR
That figures. All well, part of it. Well I finally got the flywheel off. It was a fighter.
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Well at this point, I decided I'm going to buy a brand new engine and modify that one. I wanted an extra engine anyway. This engines cylinder still has good cross hatching, I'm going to clean it up. Put new piston rings in and Port The old cylinder head a little bit. Slap this one back together as an extra slightly modified engine. I know I will use it. And it'll give me practice. CAM2 I will still order that cylinder head kit that you posted. That way I'll have an extra one laying around for when one of my engines needs a rebuild.
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I unburied my piston Port motor and found I had a second one. Maybe I will modify these after the case Reed engines
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Re: First mods, case reed engine

Here is one engine you were talking about in the PM. I can put a 3rd bearing clutch housing if you want, no charge.
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Last edited by EPR; 2 Weeks Ago at 03:08 PM.
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Re: First mods, case reed engine

Here is a second and third engine. The first has a modified stock crank, hogged out on the inside for more flow up the cyld. The second has a ported cyld and blue round alloy head.
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Last edited by EPR; 2 Weeks Ago at 03:16 PM.
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Re: First mods, case reed engine

Then there is the 49cc piston port engine with Cag full circle crank, a lot has been modified, has very high compression. See the silver alum compression cap, its was a 17 to 1 cap I made a little bigger, $215 shipped.
It has a Cag clutch housing, but many trans will bolt up, maybe even work in an X1 2 stroke bike.
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Last edited by EPR; 2 Weeks Ago at 09:07 PM.
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Here is a second and third engine. The first has a modified stock crank, hogged out on the inside for more flow up the cyld. The second has a ported cyld and blue round alloy head.
Very nice, Which one is the best? J/K I know they're all great.
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I finally went and pulled out my rotary tool. It is a flex shaft by Craftsman. I bought it so long ago that I had forgotten what it was. Should make things easy.
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Re: First mods, case reed engine

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Originally Posted by silverbullitt7 View Post
Well at this point, I decided I'm going to buy a brand new engine and modify that one. I wanted an extra engine anyway. This engines cylinder still has good cross hatching, I'm going to clean it up. Put new piston rings in and Port The old cylinder head a little bit. Slap this one back together as an extra slightly modified engine. I know I will use it. And it'll give me practice. CAM2 I will still order that cylinder head kit that you posted. That way I'll have an extra one laying around for when one of my engines needs a rebuild.
You'll be fine.....Stick to the rules and things will turn out better than expected..

Its kinda hard to mess these engines up modifying them unless you hogg the crapolitis out of them , you try building them the way they build MX racing bikes or you try building them blind like our mod does...LOL

Those piston ported engines look like good projects too....

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Last edited by CAM2; 2 Weeks Ago at 07:31 PM.
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