200+ HP would be great. For now I think I'm going try it out at around 6-8, hoping for around 140. I've owned this thing for 20 years, I maybe put on 150km in the past 10. She owes me nothing and not worth selling so why not make it different. I started taking it out to the local 660 drags last year , just for chits and giggles. Can not hook up for the life of me. A skid swap will be in order. This is only for fun, I don't care if I win or lose. I just love to see the old machines give er a go!
vmax turbo help
- Thread starter lunnex
- Start date
Sorry about all the questions, I am wanting to test drive this thing before I loose all my snow.
In the picture is the red thing the rising rate regulator? And am I correct in thinking the bottom is inlet, top is the outlet, side is for fuel pressure gauge, and higher up it boost reference.
What does the silver thing do? I know that line is for return to the tank.
toydoc
Member
NO. Your going to keep and use the stock fuel system just as it is. It needs to start, run and idle off boost. 99% of the time it's running, it will be off boost. No better setup then stock for that. Your adding extra fuel for 1% of the time you make real pressure. Tee into the tank feed side for elec feed. Tee into carb inlets. Wire up the pump. Then dead head the hobbs switch and check for leaks. Make sure your needle and seat hold pressure. Then set your fuel pressure regulator to the pressure you want.
Rising regulator haven't work on old two strokes. We dont have enough elec output to keep up
Srxftw
New member
Precisely, i appologize if you misunderstood what I was saying lunnex, you need your stock fuel system, with this setup your just putting more fuel in your carbs when boost kicks in, looks sweet, where are you located?
Srxftw
New member
I'm not sure what your silver peice is, maibe a check valve or something, looks like a second hose for a signal line but I can't see too well from the pic, I don't know to be honest, as for the regulator I'm not sure buddy
Toydoc, I think I understanding what your saying. The one percent of the time on boost the electric will kick in, but would it not just push straight fuel into the carbs? Or do you agree with removing the oil injection and running premix?
Srxftw
New member
I'm in bolton, your over by Ottawa right?
toydoc
Member
Keep stock oil injection.
When the elec pump kicks in, it does push right into the carb. It has to push harder then boost pressure. If not, your fuel flow stops.
Put a straw in pop can and blow. How much pop comes up the straw? Same idea with a stock 5lb pulse pump vs 6lb of boost felt inside the carb.
The flip side, you don't want so much pressure you blow past the needle and seat. So with engine not running.
I jump the hobbs, let the elec pump fill the crabs till the needle and seat close and set the red regulator pressure.
Sometimes the needle and seat won't hold so you replace them with good ones (not knock off).
Real high pressure, I switched to Gross Jets
toydoc
Member
It's another regulator. Takes excess fuel from the red regulator (that you set pressure with) back to the tank.
Really need a pic of the intake box and carbs installed to see if it's plumed right
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Thanks toydoc, I'll try to reinstall the airbox and fuel lines today. Then I'll take more photos.
the line coming from the silver thing that is wrapped in a spring has a threaded male fitting on it, do I have to use this fitting or can I just push a new line into the tank where vent hose comes out?
the line coming from the silver thing that is wrapped in a spring has a threaded male fitting on it, do I have to use this fitting or can I just push a new line into the tank where vent hose comes out?
Backwoods M Max
New member
If you try to return through the vent don't be surprised to find fuel coming out under your handlebars. There has to be a free exit of air to the tank, when you try to push back to the tank it will create a pressure in the tank very quickly then out the vent the fuel will come.
I found this out the hard way trying to piggyback a hydraulic motor case drain down the tank vent and the end result was a big hydraulic mess. That was a 1/4" line trying to dribble down a 2" pipe so there was plenty of room for the oil, it's all about the pressure.
I found this out the hard way trying to piggyback a hydraulic motor case drain down the tank vent and the end result was a big hydraulic mess. That was a 1/4" line trying to dribble down a 2" pipe so there was plenty of room for the oil, it's all about the pressure.
So today I got some good headway. Had to make a couple of plates for the instillation, ran boost and fuel gauges. Then I tested out my fuel system in a loop out of a mason jar of fuel. I jumped the hobbs switch like toydoc sudjested .The problem is that my red regulator is leaking fuel out of the boost reference port. So I took it a part and found that the diaphragm is worn out. Does anyone know what make or model it is? There is no marking's on it , maybe there's a rebuild kit. Or what is a good replacement? Also is there a way to test my fuel pressure gauge? I could not get it to read anything
toydoc
Member
Summit or Jegs has them and rebuild kits.
Your jumping the hobbs to test:
Gauge
needle & seat
elec pump & power
Gauge didnt show pressure. So now work backwards.
Did the pump power up. Did you have any leaks. Did fuel make it to the needle and seat. Did needle and seat hold, or is it pumping fuel into the case..
You can blow into the gauge to test it. Just keep it under 20lbs
Your jumping the hobbs to test:
Gauge
needle & seat
elec pump & power
Gauge didnt show pressure. So now work backwards.
Did the pump power up. Did you have any leaks. Did fuel make it to the needle and seat. Did needle and seat hold, or is it pumping fuel into the case..
You can blow into the gauge to test it. Just keep it under 20lbs
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The pump fired up with lots of pressure , although I had the leak at the regulator. I pulled the lines off the carbs to be sure the fueI was flowing, but didn't get a chance to turn up the pressure because my gauge didn't work. So I would have no way of knowing at what pressure the needle would hold up to. I did try blowing into the gauge with around 10 psi, but it would not move. I guess I will need a new gauge as well. once I get the gauge I can check the needle and seat.
I'm back with a progress update. Got my new Mallory regulator and set my base pressure to 6 psi. I used 1/4" lines everywhere and 3/8" for the return line. It's starts and runs fine on a stand,( no snow, so I can't trail test it yet). Still need to find 2 o-rings for the carb/ airbox connections. I should have them in a week or so. A question for you guru's out there, I have a t fitting at the output port on the regulator, one of the lines has about 3 inch's of air in it. Fuel is going past the air , like an inline fuel filter would, is this normal? Or do I need to bleed it?
Also with reving it upto engagement, 3800 rpm, I'm not seeing any boost on my gauge, should I? Tested the gauge and its good. I know I have the leek at the carb /airbox but should I not see something? Turbo is spinning freely, revs quickly seems good.
Also with reving it upto engagement, 3800 rpm, I'm not seeing any boost on my gauge, should I? Tested the gauge and its good. I know I have the leek at the carb /airbox but should I not see something? Turbo is spinning freely, revs quickly seems good.
So I disconnected the charge tube and found it was not pushing any air, so I removed the turbo and found lots of wet suet. Also noticed the arm for the VANE was very stiff. Then I removed the piston style controller and cleaned it . it has a silver spring in it. Any idea's as to the boost this represents? The stiff arm turned out to be the band that you loosen to rotate the two half's was touching the arm, easy fix! I think the wetness in the turbo is just from running too fat, what do you guys think?
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