the PVC manifold didn't go so well so now I'm making one from copper plumbing parts

[canuckxxxx]

View attachment 1

I see on the bottom of that Mikuni flange there is a thin raised part that is probably there to make a good seal with the head. Because the bolt holes on the GW intakes are offset a bit toward the centre of the motor this bead might not contact the head all the way around. I would suggest that you take a look at this. It would be nice to have that bead to make a good seal so maybe you could elongate the holes in the Mikuni boot to achieve this.

Brian

 

[joedrum]

hmmmmm ... opcorn:

 

[canuckxxxx]

I really like this PVC idea. Looking at the fittings at Home Depot, they are very cheap. I also like the fact that the plenum is very low volume...would like to see how that affects throttle response.

Has anyone every put a 2 to 1 adapter on the top of one of these and mounted a DFT carb? Would really like to see how that works.

I wouldn't worry about the heat from the head affecting the pvc. I think those rubber Mikuni boots will isolate them from the head.

Brian

 

[joedrum]

i think someone dose .. i how for sure chillidawg dose on a manifold with smaller volume than this one ... and he also using ..32-36 weber and last i heard it was bogging under hard twist on throttle

 

[slabghost]

canuckxxxx » Mon Nov 03, 2014 9:13 am[/url]":1ur69lf0]
View attachment 1

I see on the bottom of that Mikuni flange there is a thin raised part that is probably there to make a good seal with the head. Because the bolt holes on the GW intakes are offset a bit toward the centre of the motor this bead might not contact the head all the way around. I would suggest that you take a look at this. It would be nice to have that bead to make a good seal so maybe you could elongate the holes in the Mikuni boot to achieve this.

Brian

Looks like the mikuni mounts are a bit offset too. Seems to me they seal up fine installed right.

 

[chuck c]

The PVC parts are cheap but the flanges are $20 each. However from what I've done so far they are worth every penny. They eliminate the 7* angle of the stock intakes and that makes a HUGE difference. They make using the pvc parts a snap and makes it possible make a really solid working manifold with no more than a hacksaw. I didn't hit my desired cost limit but I exceeded my ease-of-build one! My hope was to come up with a design that didn't require much in tools or skill, no heat, no welding or brazing, that a guy could buy some parts and make on his dining room table. I'm really close to that goal.

 

[dan filipi]

Could tape on a vacuum hose, with the valve closed spray water around the edges. Any leak will suck the water right in. Should see it happen.

 

[canuckxxxx]

joedrum » Mon Nov 03, 2014 7:25 am[/url]":1c0urvol]
i think someone dose .. i how for sure chillidawg dose on a manifold with smaller volume than this one ... and he also using ..32-36 weber and last i heard it was bogging under hard twist on throttle

hmmmmmmm.... :headscratch:

 

[chuck c]

dlk, who put me on to flexpvc.com where I found the 5-way, urged me to go 1" instead of 1-1/4". He said throttle response would be better. That's counter to what I'd think. The 1-1/4" is very close to the ID of the OEM parts and I'd think the engine would have to pull harder and longer to get what it wants from a smaller diameter. The flip side is the velocity of the mix, it will already be moving faster though the smaller tube and that counts too.

Also in this complex set of variables is the engine RPM when you twist the throttle. At what RPM do you want that good response? Is it at idle or already going 4000 cruising down the highway? The intake runner length and diameter can only be optimized for one or the other.

Here's the true beauty of this design: it makes it really easy to build and test both in a true A-B way- same bike, carb, road, rider, altitude, and even weather. I can make a 1-1/4" manifold the same way and switch them in literately minutes. It's 5 hose clamps and the carb doesn't even have to be disconnected from the fuel line!

I will also get an indoor/outdoor thermometer and check the temperature of the gas inside the runners to see how much the temp drops and make sure the pvc isn't getting too close to the point where it would soften from engine heat. All that will be next season, right now my goal is "running".

 

[dan filipi]

canuckxxxx » Mon Nov 03, 2014 6:53 am[/url]":35vxzcyk]

joedrum » Mon Nov 03, 2014 7:25 am[/url]":35vxzcyk]
i think someone dose .. i how for sure chillidawg dose on a manifold with smaller volume than this one ... and he also using ..32-36 weber and last i heard it was bogging under hard twist on throttle

hmmmmmmm.... :headscratch:

Yeah, smaller volume than this one??
How do you get smaller volume than this that's basically straight into the runners?

 

[dan filipi]

Is it at idle or already going 4000 cruising down the highway? The intake runner length and diameter can only be optimized for one or the other.

I have to disagree somewhat on this since mine with 1" runners pulls strong and even from idle to redline. At freeway speeds 70-85 mph running 4000 rpm + with a slight twist in the throttle I go into passing mode.
The difference here is I'm running the VW type 4 manifold along with the 2 to 1 adaptor and I have no experience what effects not having a manifold to add volume would do.

 

[chuck c]

canuckxxxx » Mon Nov 03, 2014 10:13 am[/url]":2x4dl1zh]
View attachment 1

I see on the bottom of that Mikuni flange there is a thin raised part that is probably there to make a good seal with the head. Because the bolt holes on the GW intakes are offset a bit toward the centre of the motor this bead might not contact the head all the way around. I would suggest that you take a look at this. It would be nice to have that bead to make a good seal so maybe you could elongate the holes in the Mikuni boot to achieve this.

Brian

I will double check that. That little ring you see is 5.5mm bigger than the flange ID. The ID of the Mikuni flange matches the intake port but it's holes are centered. The Wing's are maybe 2mm off center. That can all be taken up by the holes being 8.5mm and the hardware being 6mm. I can shift the flange to line up on the port and still get the bolts in. But you are absolutely right, it is also possible to shift the flange the wrong direction and loose that seal over the edge of the intake port. There's nothing preventing that. Thanks for the warning, I'll put them on and center them first, then make the plastic fit where they fall. When it's all lined up well I can trace scribe the flange profile on the head so it can be lined up easily with the pvc blocking the inside view.

 

[chuck c]

dan filipi » Mon Nov 03, 2014 11:08 am[/url]":3d2d7c02]

Is it at idle or already going 4000 cruising down the highway? The intake runner length and diameter can only be optimized for one or the other.

I have to disagree somewhat on this since mine with 1" runners pulls strong and even from idle to redline. At freeway speeds 70-85 mph running 4000 rpm + with a slight twist in the throttle I go into passing mode.
The difference here is I'm running the VW type 4 manifold along with the 2 to 1 adaptor and I have no experience what effects not having a manifold to add volume would do.

YES! My instinct tells me that's the best of all setups. 1" runners for good velocity and a plenum holding a reserve of fuel/air mix hanging around waiting to meet instant demand. I think the plenum full of ready-to-burn mix is doing more for that good response than the runner diameter!

Which means my zero reserve volume manifold will probably not have good throttle response. If that turns out to be true the nifty 5-way PVC part will need to be replaced with something that has more volume. I was already thinking about that. They do make larger diameter 5-ways, I think there was a 2". If that will still fit it could solve the problem.

 

[chuck c]

Plug for flexpvc.com. The box contained a pocket copy of the Constitution. :clapping: for them.

5-ways
https://flexpvc.com/cart/agora.cgi?product=PVC-Fittings-5-ways-side-outlet-Cross
1" is $2.69
1-1/4" is $4.68
1-1/2" is $7.10
2" is $14.95

 

[joedrum]

dan filipi » Mon Nov 03, 2014 10:58 am[/url]":e1qbaj0z]

canuckxxxx » Mon Nov 03, 2014 6:53 am[/url]":e1qbaj0z]

joedrum » Mon Nov 03, 2014 7:25 am[/url]":e1qbaj0z]
i think someone dose .. i how for sure chillidawg dose on a manifold with smaller volume than this one ... and he also using ..32-36 weber and last i heard it was bogging under hard twist on throttle

hmmmmmmm.... :headscratch:

Yeah, smaller volume than this one??
How do you get smaller volume than this that's basically straight into the runners?

it is made with a one pipe ..of abpout 5" or more ...and then carb it cantered here ...like a T connector then u off there on each side to the cylinders... like the LDwingnut manifolds that he sold for awhile that used the vw single barrel carb ....unlike this set up where all runners come to carb .... witch in my opinion flows more ...than what chillidawg set up dose

 

[chuck c]

Fitted and ready to glue! Notice the air cleaner is at the same level as the gas cap.

It's very close but it clears.

 

[slabghost]

should be able to mark all the connections with a sharpy magic marker so you glue it exactly as it is.

 

[joedrum]

you could also ..keep it as is ...like it in a jig ...and glue one piece at a time from the 5 way out ...one runner at a time ....

 

[canuckxxxx]

dan filipi » Mon Nov 03, 2014 8:08 am[/url]":2dtal8xr]

Is it at idle or already going 4000 cruising down the highway? The intake runner length and diameter can only be optimized for one or the other.

I have to disagree somewhat on this since mine with 1" runners pulls strong and even from idle to redline. At freeway speeds 70-85 mph running 4000 rpm + with a slight twist in the throttle I go into passing mode.
The difference here is I'm running the VW type 4 manifold along with the 2 to 1 adaptor and I have no experience what effects not having a manifold to add volume would do.

Dan, I'm glad you posted that because I had forgotten the success you had using the 1" EMT runners. I was looking at copper pipe at Home Depot the other day and thinking that the 1" copper tubing would be pretty easy to make runners with and they have a good selection of fittings. But it looked so small even compared to my 1 1/4" grab rail runners. Googled EMT sizes and copper pipe sizes and the ID of the copper is less than 1/16" smaller (1.049" for the EMT, .995" for copper). :read:

Your bike is a 1200, mine's a 1100 so I'm thinking, the copper might work good. :headscratch:

Brian

 

[chuck c]

joedrum » Tue Nov 04, 2014 8:53 am[/url]":1crxz1hd]
you could also ..keep it as is ...like it in a jig ...and glue one piece at a time from the 5 way out ...one runner at a time ....

That's what I had in mind. I'll do the pipes in the cross then work out. 2 and 3 first (the ones with the cut down connections) then 1 and 4 worked well. I actually got 1-1/8" of pipe in the cut-down connections so they are very strong with 9/16" in each side. I think 1-1/4" pipe and fittings would still work, they would have to be cut down a little more but there's still probably enough socket to make a good connection. I've got the pipes cut so they are a pretty tight fit when in the right length but when the glue is on they will go a bit deeper. I'll scuff the OD of the pipes and ID of the connectors with sandpaper and clean all connections with solvent too.

The Mikuni flanges lined up on the head ports perfectly when they were pushed to one side of the bolt holes. I just had to put the screws in loose, push one way into they were touching the screws, and bingo. Got to watch tightening the screws. There's a recess around the holes on the mating side (visible in pics) to be sure of good contact everywhere else. It's easy to lift one side of the flange when bringing down the opposite screw. I had to light finger tight them first and tighten them evenly to be sure they made full contact. No gaskets- nice!