Winter plans?? Vmax boost on gl1000

[ericheath]

I hate the word "winter." Up here we have spring, summer, fall, and THIS SUUUUUCKS!! My plans are to tear the carpet out of the downstairs family room (kids are gone and I don't have a garage) and bring in the two 77's and start rebuilding. I have been playing with this fantasy of having a gl1000 that can kick a**without the high costs of a supercharger. (Anyone else have this fantasy?) I have been trying to learn how the Vmax got its power and been wondering if this couldn't be an easier mod to give a shot the gl1000. My understanding is that the Vmax uses a carb setup similar to the Goldwing but has a tube connecting the intake runners with a throttle plate in it, one on each side of the engine. It is controlled by a servo motor that gradually opens beginning at 5750 rpms which is triggered by a signal from the ignition pulses. The Vmax has a 1200 that develops 145 horsepower stock. The way I understand the theory is that at the higher rpm, opening the throttle plate to other carb allows it to pull in a little more properly mixed fuel as that carb is not pulling any in at that time. (intake is closed) I think I read that it opens on gears one through four and not in fifth. Is this a mod that could be done on a GL? Yesterday I picked two throttle valves from old Hyundi. Intake diameter is a bit larger than the 31 mm for my 77's. I plan to slice off everything but the butterfly and throttle axle. I hope to find a way to connect them between the runners, and then see if I can get some electronics to control their openings. I was thinking I could use vacuum to open them, but the vacuum would be pulsing between the connected cylinders. I am a complete hack of a mechanic, and electrician. Not my profession. But lately it has been a passion. From all the guys who are mechanics, is this futility? Reading other articles on the older GL's, most suggest that getting more fuel and air in is the problem with getting more power. BTW a used Vmax setup is too rich for my blood. Maybe this will generate some other winter tinkerers who can help us all upgrade this already great performing bike, in reasonably inexpensive way. If this would work, it would probably boost the 78, 79's,1100's and 1200's while allowing them to keep the torque at their lower ends. All comments welcome by me. I love reading this forum and getting all the advice of fellow owners. I expect a good volley of discussion, although maybe has already done it.

[TAZA2]

We have toyed with the idea of putting throttle bodies on older hondas, my son does have a friend who understands the set up for programing the bikes for injection, there are changes that that have to be made, sensors that have to be installed, just ideas rattling around in our brain, was not trying it on the GL, was going to try it on the smaller twin cylinder bikes.

[ericheath]

MAybe I should clarify. The throttle body is only to use as the butterfly to open between the two carbs. It is not going to add any fuel via fuel injection. The choke portion of an old carburetor could do the same. I just came across the throttle bodies first in the junk yard. This is a way to add "properly mixed" fuel and air, not just fuel like an injector would add, and it's taking it from a carburetor that is basically just waiting for the next pulse from its side of the motor.

[sunnbobb]

Very interesting... and I am stealing this over to the Underground forum...

[wingless1]

interesting idea.
I have always been fascinated by the vmax system. after reading an article somewhere in the early 90's where someone was setting up an intake on a ducati, and found that optimum length was very long for low rpm torque (18" at 8000rpm, around 2' for 5000rpm), I got the idea to play with the 2 concepts: tuned length and crossover linking 2+ carbs to one cylinder. I used a yamaha xs650, put together a setup using abs tubing that put the carbs behind the frame downtube (about 4-6" longer intake runners than stock) and with about 2" diameter crossover tube between the intake runners (no valve in there though). I tried it for an hour or so up and down the road, trying different jetting and getting a feel for the idea. Results: significantly increase top end power, drop (likely jetting related) in bottom end. The abs got eaten by the gas, so it was only a short term trial. Have often thought of doing it again with a longer test, but would want to do it on a twin for simplicity. I think 4 cyls would be a lot going on for tuning purposes.
On the wing I would think it doable, and the way I would try it would be with 2 larger carbs, one for each side pair, running into split intakes for simplicity. I think that running 4 carbs, into 4 intakes, into 4 cyllinders, with valves and crossovers in between them would make the intake length long enough to be a problem, but would generate the best of all worlds: big intake volume at high rpm, high velocity at low rpm, and long runner for torque at low rpm.
For better though: 4x36mm keihin fcr-mx with long, convergent runners and a free-flowing filter/airbox would allow whatever other power mods you had done to work to potential.
something to look at: "boost bottles" on 2 cyl snowmobile intake systems.

[ericheath]

I see the newest Vmax uses a telescoping set of intakes to accomplish what you have described above. I though that aI read it to be the other way around though, long on the lower rpm and short at the higher rpm. I saw the "boost bottles" but have yet to read up on them.

[wingless1]

long for low, short for high is right.

[ericheath]

Does it matter if the intakes are longer ahead of the carbs? Older drag cars had taller intake stacks. Was that to help with low end torque? If so, they could be installed within the air filter compartment.

[wingless1]

the butterfly and venturi shape of the throttle ass'y of the carb will act like the closed end of a tube causing a sound wave to reflect back away from it, so the intake length can only be tuned from the valve face to the carbs (gently diveregent from head out to maintain velocity and minimize boundary layer). what you put on after that has little effect except at large throttle opennings, where they should be fairly short, divergent and equal length.

[78AZWing]

Wow! That all went right over my head! Whoosh!
Isn't that all basically what we are doing with the Weber two-barrel conversions?

[sunnbobb]

interesting.. any progress?

[ericheath]

I have some butterflies picked out. They're off a Hyundai!! Hah. They have about 1-1/2" openings. It is a tight squeeze between the existing runners. I chopped them off and soldered little stubs on them. They look like I'll be able to hook them up to open mechanically first, then try and get them coordinated to open only at higher RPM. The little I've read of those who fool their V-Max's into opening earlier, just pour gas in with no benefit. I don't have a welder, and I am not sure how good my aluminum welding would be. I am toying with dropping $50 to use some kind of rubber plumbing fittings to see if it will work. If it does, I'll look into fabricating something more permanent. I doubt I will get any rubber that the gas won't deteriorate. I saw that someone here was welding up aluminum runners for the Weber's, so it can be done. Anyone try welding the pot-metal aluminum runners we have? I have to get ready for the snow flying here. I can't believe it hasn't yet. I am hoping to pull two bikes inside and play this winter. I have to pull up carpet in the family room to make room for the wing family. I will post if there is any success. Unfortunately for me, I will not likely be able to run them until next April to find out. I also picked up a 1200 block to put the assemblies on, so that is in order and the frame I have needs repair as, well. The furnace will be taking all my extra cash for the rest of the winter, and OPEC will go nuts again. I listened to Donald Trump one night and he was suggesting how that OPEC would raise the price and lower the price in accordance with stock market. That has been in the back of my head ever since, and so far he has been exactly right. He thinks we have to do something to keep that price stable to keep everything else stable. Oh no, V-Max to politics!! But if I V-Max my wing and it works, it'll consume more gas and OPEC would be happy along with me. It's Friday, and it's five o'clock somewhere!!

[ericheath]

It was KR Bobber who did the welding on the aluminum runners. But it looks like he can weld a lot of things.....well.

[Track T 2411]

If you look at Vagrant50's build, he used marine grade exhaust tubing (rubber like) to connect his custom manifold to the runners. I've pondered the possibility of a "crossflow" type intake, with carb(s) on the left feeding the right cyls, right side feeding left. It would give additional length and room for the V-Max type crossovers. I know, way out there...

Good wrenchin'
Todd

[ericheath]

I guess the real question is, will this bring performance, or is Vmax's design just smoke and mirrors and the power is really elsewhere, the cams, the higher compression, timing? I tend to think it's the carburetion because the same basic motor is the Venture series and had far less horsepower. I only know what I read here, on the web. From reading the Venture sites, the Vmax motor does have different cams and higher compression, probably to enable the extra fuel mix to burned for additional power. The rubber I am thinking of is a 1-1/2" Tee connector. It is actually more like a "Y". It would have to be able to stretch enough to get over the rubber on the top of the wing's intake runners and be able to tighten up still. With that, you could easily drop in a butterfly to connect the intakes. Getting them to open at appropriate times will be the real challenge. I am thinking a timer working off the ignition pulses could be done. Then some small servos to open them. If I get the 1000 heads on the 1200 block, I should have the increase in compression to help this. Hopefully the 1200 will stand up to the higher revs. This has been an obsession for me, don't know why. I am a school teacher and an absolute hack of a mechanic, but I always wanted to mess with motors. In the late 60's and early 70's my dad forbid me to work on cars, lawnmowers and everything. This is the same guy who I found changing the rocker arms in our 283 chevy wagon wearing dress pants and a white dress shirt. He only rolled up his sleeves. He wanted me to get an education and a job that paid a living wage. He wouldn't help me much at all with anything mechanical even though he could have. He claims he knew that I would have been happy working at the Texaco pumping gas and changing oil. I thank him now as I can walk away from problems, not have to fix it because that's my job. I wonder how many mechanics of that era got burned out as the auto industry went high tech with all the electronics on cars today. Guys who were wrenches and could fix anything, suddenly had to learn to use the computer. It must have been rough on some of them. Okay... wayyyyy off topic.