High performance Intake Manifold

GoldenMotor.com
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
Tired of grinding out the stock intake manifolds for better flow and port matching? I have been building these custom port matched intakes for the two strokes. Here is a shot of the manifold before I hit it with the scotch brite pad. Ported stock aluminum on the left, custom one on the right. I made a CAD drawing of the old flange perimeter and then carefully measured and drew up the cylinder port. Laser cut a bunch of cylinder matched stainless flanges. I then made a small die to press the round tube to the rectangle shape of the cylinder port so the flow path smoothly contours into the cylinder. Tig welded together. These manifolds really open up the two strokes. Seems to make the engine run smoother, also.


Here is a picture of one cleaned up and mounted to a Grubee GT5 slant head engine.
 
Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
2,784
26
36
Indianapolis
Sweet. Okay, now I have two questions: can you demonstrate performance or fuel consumption gains in any kind of numerical figures or stats? and how much would you ask for one?
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
I have evaluated the intakes using a digital speedo. Cruising speed is up 2-3 mph. Real difference is in how it smooths out the engine. There is a big difference. Fuel consumption? Well, if I burn more fuel to go faster then I am going in the right direction. So yes, your fuel consumption will increase! Think of it as a bigger straw. A bigger hand made stainless steel tig welded straw that costs $40. Want one?
 
diceman2004

diceman2004

New Member
Aug 26, 2009
564
2
0
Kitchener , Ontario
that looks real nice , just look at how mutch bigger the opening is , it has to flow better .
i did the same for my 97cc lifan , saved a mastercam file . made it out of stainless also .

OOPS ( edit ) that was for my exhaust .
 
M

mountain80

Member
Aug 8, 2008
260
4
18
Red Deer, Alberta
What is the OD of the tubing you use, accurately down to the thou that is? Does it place the carb in the exact same place as before and if not what is the difference? I have a dellorto with a mallosi air filter that is within a 1/16'' of touching my frame and has a custom bushing to mate the carb to the manifold so sizes are ultra important. I am interested once I find out the aforementioned sizes.
Cheers
 
Last edited:
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
My custom manifold is .75" (3/4") O.D. The I.D. is .62". The stock aluminum manifolds are approximately .745 on the O.D. and approximately .58" on the I.D. I say approximately because the stock castings vary widely. My manifold will fit the CNS and NT style carbs. The radius elbow I use is much more contoured then the abrupt angle the stock carb runs. I can really make any configuration I want, but the one shown in the pictures is formed to the shape of the stock manifold in the height and set back of the carb. The one shown installed on my Worksman is a little longer and does not raise the carb as much. The manifold shaped like the stock version may set the carb back another 1/4" but I can and will tighten up this dimension. Basically trying to make sure it will fit any bike that runs a stock manifold. A direct replacement. And hey, if it doesn't fit send it back. I can sell it to someone else.
 
Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
2,784
26
36
Indianapolis
Hmmm...a 2 to 3 mph increase in cruising speed, smoother running engine is a big deal, (and, yes, I was wondering if there was an increase in fuel consumption, expecting it somewhat). And $40 isn't to bad for what it is. I may be in touch.
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
GeneFiorot said:
Buy a Manic Mechanic Version made in Billet Alum. Cheaper too
Click to expand...
Compare the two then buy the cheaper one or the one that flows more. Oh, and mine clears the clutch linkage and has a proper rectangle to round transition. I can do custom manifolds as well but but need very accurate dimensions. Manic does good work, no doubt about it, but our manifolds are made differently. His are CNC machined and mine are hand fabricated.
 
stuartracing

stuartracing

New Member
Dec 9, 2008
488
1
0
62
Gainesville FL.
sportscarpat said:
Compare the two then buy the cheaper one or the one that flows more. Oh, and mine clears the clutch linkage and has a proper rectangle to round transition. I can do custom manifolds as well but but need very accurate dimensions. Manic does good work, no doubt about it, but our manifolds are made differently. His are CNC machined and mine are hand fabricated.
Click to expand...
I would love to try your`s also..Can you give me an address to send a payment to.....Just make it an inch shorter....
Thanks,
Paul Stuart
[email protected]
 
G

GeneFiorot

Member
Feb 12, 2009
170
1
18
Punta Gorda Florida
One of the major improvements in the Manic Mechanic Manifold is the O ring sealing gasket. This alone makes a world of difference eliminating air leaks and allows for excellent low speed idling and proper fuel/air mixture at all RPMs
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
GeneFiorot said:
One of the major improvements in the Manic Mechanic Manifold is the O ring sealing gasket. This alone makes a world of difference eliminating air leaks and allows for excellent low speed idling and proper fuel/air mixture at all RPMs
Click to expand...
I have ran the various carbs and manifolds out there without the o-ring and I never have this issue with air leaks. Besides, the air leaks happen at the end of the manifold where it seats into the carb. If you don't seat your carb correctly then all these manifolds will leak air. An o-ring on the manifold does nothing for a carb that is not seated correctly. My design does not need an o-ring that serves no purpose. My intent here is NOT to sell a manifold that competes with Jims manifold. What I have done is designed a stock replacement manifold that flows better than stock and fits in the same area, give or take a 1/4". A true bolt on performance gain. The fact that it is built from laser cut parts, smooth contoured fittings, and tig welded together is just icing on the cake.
 
stuartracing

stuartracing

New Member
Dec 9, 2008
488
1
0
62
Gainesville FL.
sportscarpat said:
I have ran the various carbs and manifolds out there without the o-ring and I never have this issue with air leaks. Besides, the air leaks happen at the end of the manifold where it seats into the carb. If you don't seat your carb correctly then all these manifolds will leak air. An o-ring on the manifold does nothing for a carb that is not seated correctly. My design does not need an o-ring that serves no purpose. My intent here is NOT to sell a manifold that competes with Jims manifold. What I have done is designed a stock replacement manifold that flows better than stock and fits in the same area, give or take a 1/4". A true bolt on performance gain. The fact that it is built from laser cut parts, smooth contoured fittings, and tig welded together is just icing on the cake.
Click to expand...
VERY NICE WORK....
I can`t wait to try one out.....
Thanks....
 
K.i.p

K.i.p

New Member
Nov 8, 2009
339
1
0
CNY
I think your product stands it's ground as a viable alternative. It looks like you might want to consider a couple standard variations; stock dimensioned, shorter than stock dimension, and an offset style. I fabricated my own offset manifold and machined the match to the carb obtaining a "snug slip". An o-ring was simply not necessary although I did apply just a smear of RTV for kicks before I tightened it up.

It would seem, although I might be wrong, that once you have the curfs calculated it would be fairly simple to fabricate the short and offset variations. Good luck!
 
S

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
Hi guys,
Thanks for the interest in my manifolds. I will not be making hundreds of these manifolds. These are hand made one at a time and they are expensive as compared to the cost of an engine or a stock manifold. They work great and will always be unique. They are stainless steel construction. The I.D. of this manifold is .64" and I do not know of any larger than this. It is basically the same raise and run as a stock unit so you will clear your clutch linkage and if you have a stock manifold now then it should fit. It might set the carb back an additional 1/4". If you want one you can email me at [email protected]. Paypal is prefered. They are $40. I have a few in stock for now.

 
You must log in or register to reply here.
Top Bottom