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44mm Webers N/A

3K views 35 replies 11 participants last post by  MetalAlien 
#1 ·
I still gotta see if Tom will sell these to me but I made a simple mount for the 44s to use with pumpgas N/A.

So for example, when I want to go duning, or go to choke cherry to have fun next year. Should work good with the 840.

You can see this is basically the same manifold that I used for the blower so it has a huge common plenum. I've already tested it and it seems to rev and ldle just fine. I do need to buy some jets though as right now I only have one set.



 
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#4 ·
Nice. So could I do something like that with my Brute? I think Big Kev makes custom intakes for brutes.
Good news Erik all my go fast parts are in and going together tomorrow. I'll be running some of the same stuff you have on yours including cams.
 
#5 ·
Not sure how different the frame is Randy. This manifold is made by recycling the blower intake I made for the webers. The adapter plate means it just bolts on in place of the blower. You just swap them out, change to gas, plug the pipes and go.

I don't know if having that huge common plenum will help or hurt but it doesn't seem to be a problem yet.

Good news on the parts.. You are running the same cams as me?
 
#6 ·
I think so. AMR 4X's
 
#8 ·
Ok I thought they were the same. Did you need the extended rockers also? Mine did.
 
#10 ·
Looky good :)

how long does it take to switch over

would be kinda neat if you could get it set up where you have your Devil carbs on the blower and then the Webers set up on another manifold so you could just lift the blower off and slap the Webers on, for playing around
 
#11 ·
Yea that is the idea.

4 bolts to remove the blower
Use those same 4 bolts to fasten the weber manifold.
Switch out the alky to gas
Plug the pipes
dune around.

If would be quicker if they both used the same fuel but you gotta do what'cha gotta do. :)
 
#13 ·
Just because it uses the fuel too fast. That is the only reason. It actually rides really nice, very controllable. I could plug the pipes and ride around but the tank would be empty in about a mile or so.

If I switched to gas it would last a little longer, but the engine is set up for alky so the compression is too high. I would need a greatly reduced timing map and for all that trouble, the fuel would still be gone very quickly.

It would be like Camo trying to dune around with the boost turned up.
 
#14 ·
Sometimes I dune with it cranked... makes for a hairier ride. :lol:
 
#15 ·
When I first put on the blower, back when it was only 10psi I tried to dune around on racegas. Rode very nice. That was before I knew how much fuel it was using.

The low fuel light would come on and I always knew that I had plenty of time. The light just ment that I had to remind myself to go back...

Did a few runs to the top of the hill and slowly start back... only for it to run dry. LOL

I did that a few times before I realized what was going on. :lol:
 
#17 ·
Chris that is always an option but I haven't tried it yet.

As for the webers. The large common plenum doesn't seems to work too good for N/A. It idles odd. You gotta crack the butterflies way too much and it tends to act like it has a vacuum leak but I sealed it all up really good.

It works, it's just seems to be the wrong direction so I am going to take that plenum off and weld a baffle in the middle. Then it will act like two separate plenums one for each cylinder and try again.
 
#19 ·
nitro is rough on crank bearing.. heck, it is rough on pretty well everything internal.
 
#20 ·
I didn't realize you were running it on alcohol when boosting. I turbo lot's of sleds here at my shop and we always just run race fuel. I've built lots of Yamaha 4 strokes running as high as 25lbs and ran them on 108 motor octane and had no problems. How much are you boosting?
 
#22 · (Edited)
Depends on how you build the engine. If you build it for race gas you can run it at high boost. But alky will run a cooler charge more consistently. So when it warms up and a lot of our races are very hot weather. The Alky will always be faster when using the boost.

I run about 18-20psi with 10 to 1 compression, stock timing for now.

I do have a secret plan to raise the boost quite a bit.

Camos bike using his 20 shot is probably what his bike would be like if it was set up for alky. At least in hot weather. When it is cold alky makes less of a difference.
 
#23 ·
Alky? I have never messed with the stuff. I wouldn't have a clue where to start jetting. I've been thinking about it for awhile now, just to try.
 
#24 ·
Good luck... sucks a lot, and I mean a lot more fuel... as a matter of fact, I would think you would have a heck of a time getting it to work with stock carbs... and spraying on top with alky is pretty well a no no unless you run a seperate fuel tank for just the nx and run race gas in it... you would have to go way up on your fuel jet to run alky as the fuel.....and that is tough to do assuming you don't clog up the noid....
 
#25 ·
I run a separate tank for the RG. More than likely...just make a few minor changes and leave it on RG. I don't want to take the dunablity out of it at all.
 
#26 ·
to be honest, metal would know better than me, but, my buddies on alky use about twice if not a bit more alky vs how much they would use if on race gas... so, to dune.. you might be in trouble with as much riding as you do....
 
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