Homemade Reed Kit

europorsche914

New Member
Jun 18, 2008
168
1
0
Lancaster, PA / Newark, DE
Well after porting my motor, and installing an expansion pipe I started looking for another performance upgrade that will increase driveability at the same time. I read another thread about a bike with a custom pipelyne reed kit: http://motorbicycling.com/f35/spy-pics-team-boxers-full-suspension-243.html. When purchasing the reed kit from them you must supply your own carb, the one they use is the Walbro HDA-63: Lawn Equipment | Lawn and Garden Accessories (quick search: hda-63-1). Their solution is a great design from the pictures i have seen but I can not see spending $120 for their reed kit plus $57 for a carb when the engine kit cost $160. The only way I could see spending this amount is if I was planning on racing the bike. Now to fabricate your own reed kit is a lot of work and those who do not have the fabrication skills should support the small business and purchase their kit but if any of you are like me and enjoy tinkering I decided to fabricate or purchase the parts I couldnt fabricate to create my own kit.
Their kit consists of a reed valve, reed, and manifold. I first sourced the carb and the reed valve.
I decided to go with the same carb used as Pipelyne. The carb is a diaphragm design with adjustable hi and low fuel mixtures and idle circuit. This carb is used on many chainsaws.
The reed valve is basically a check valve for the intake that only allows the flow of air in one direction. Some valve designs integrate a limiting plate that prevents the reeds from opening too far which inturn causes premature reed failure. I located a reed valve with reed, limiting plate and valve body from ebay for $16: eBay Motors: Geely Moped Parts JL50QT 49cc (50cc) Reed Valve (item 170198754808 end time Oct-29-08 00:59:26 PDT).
After all of the parts arrived I began analyzing the adapter plates required to mate all of these parts together. First to mate the carb to the reed valve, I used a piece of 1.5x.125 flat stock and drilled the bolt holes, and intake hole. next i drilled the holes for the carb to mate up, and welded studs into these holes. I bolted the adapter plate to the reed valve then cut the heads of the bolts enough to allow clearance for the carb to seat flush. I sealed the adapter plate to the reed valve with copper gasket sealant. Next I fabricated a mounting flange for the manifold I was going to create to the reed valve. Next I used flat sheet metal to fabricate a manifold to house the reed valve and provide smooth air flow to the engine. I also fabricated a flange to mate the manifold to the engine. I then welded the two flanges to the manifold. Next fortunately or unfortunately this carb is of diaphragm design which requires a crankcase pulse, so we have to tap into the crankcase. I first seperated the head from the engine and set it off to the side. (This is a perfect opportunity to modify the intake and exhaust ports which I have already done which incredibly smooths out the engine at all rpm.) Next I took some 3/16" ID S.S. tubing and enlarged one end slightly. I drilled a hole the same size as the smaller section of the tubing, into the left side transfer port section of the crankcase (only space I could find to install it with out splitting the case). I used a shop vac to prevent shavings from falling into the crankcase. I tapped the tubing into the hole from inside the crankcase until flush with the larger section of tubing on the inside (I placed JB Weld on the outside of the tubing before I installed it.) I then took a washer and placed it around the outside of the tubing on the outside of the engine and tack welded it in place to prevent the tubing from falling inside the engine. I then closed the engine back up. Then I mated the carb to the manifold and then sealed it all with copper gasket sealant. I then used some rubber fuel line to mate the crankcase pulse port to the carb port. I then followed the instructions for setting up the carb and test fired the engine. Before I ran out of time I got a chance to ride up and down the street a little bit and it accelerates so smooth but need to tune the high mixture more this weekend because the engine bogged down at 16 mph. I also could get the engine to idle very very slow and still have it accelerate away which was amazing. Also this weekend I will need to fabricate a way to mount my performance air filter to the carb. More pictures to come this weekend. :ride2:
 

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joe-craft

New Member
Aug 6, 2008
46
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0
hi just wondering what the tube out of the engine block was for? Dont know much about the reed system?
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
12
38
N.M.
That would be for the diaphragm fuel pump in the walbro carb. It needs engine pulse to work the diaphragm , which in turn makes the internal path ways of the pumper carb work correctly to the jets.
 

speedracer831

New Member
Oct 13, 2009
7
0
0
santa cruz
how much for you to make one of these for my ht? also, what model was the walbro- it looked like the 167a but thats way to small for a motorized bike engine.
 

speedracer831

New Member
Oct 13, 2009
7
0
0
santa cruz
ohh i know what carb. didnt read closely enough. the hda 63. just ordered it, ill do the same thing as you but with a 4 petal reed valve once i get a little more money to order it. nice reeds are a bit expensive... for a 4 petal carbon fiber reed its like 70 bucks!
 

scott83

New Member
Oct 23, 2009
34
0
0
Indiana
Anyone know if theyre are known issues (blowing crank seals) when adding reeds with just port matching and polishing?
 

DanielMaia

New Member
Jun 24, 2009
309
0
0
Portugal
How did you make that hole to the pulse of the carb? You drilled a hole directly to the motor? And if you one day put back the old carb?

thanks
 

captainrichhill

New Member
May 31, 2008
203
0
0
If he wants to go back to the original carb he can just put a screw in the old hole that was drilled into the motor. No big deal.
 

europorsche914

New Member
Jun 18, 2008
168
1
0
Lancaster, PA / Newark, DE
Look, how did you put the pulse to the carb? You drilled a hole directly to the crankcase?
Yea i drilled a hole into the transfer port but a hole could be drilled anywhere into the crankcase that would expose the port to a crankcase pulse. Then I epoxied a piece of tubing in place so I could attach a hose to the port. I had the top end off the motor so I could prevent the drill shavings from remaining in the engine after the mod. To reverse the mod either epoxy the hole shut or insert a bolt into the other end of the tubing... -Justin