Engine Tune MAJORLY effected by Tank fuel level
 

HEY GUYS....
Oh and i decided to revisit RCtech after a LONG time away... (over a year)

Names Matt...
I come here with a problem...

Now my V-One S is dead standard...
its on its 4th Litre of fuel (and yeah its a fair bit old, over 2 y/o and only young engine)
Anyway...
The tune is like YUCK...
On a full tank, she is rough and rich, really bogs, wont rev up...

But i hit 1/4tank of fuel left... i hit the throttle and you can actually hear it break traction and it really pulls out to red line really quick...

Its beautiful thing when running at its peak performance...

Now if i tune the first part of the tank as optimum, i run into a lean engine run by the end of the tank...

How can i fix this?

Im thinking it is the pressure from the exhaust giving less force at lower tank levels...

(same amount of exhaust gases, but more room to fill, allowing less pressure on the tank of fuel...)
(same exhaust gas volume, less area in the tank, giving high pressure...)

Is there anysort of device i can put between the exhaust and tank on the pressure line that will hold pressure equal?
(pressure in tank rises, valve closes, pressure drops, valve opens?)
Sorta like a Wastegate on a Turbo, but from pressure not electronic controlled...


Thanks Guys...

Will be back a bit more often hopefully...

(Looking at porting my GS15-R when it blows up... I'm too stingy to buy a good motor, so i rebuild and work it... )

Check and see if your fuel tank has the baffle in it in the pickup in the bottom off the tank. THe orginal V1S when it first came out didn't and Kyosho revised the tank with the extra baffle.. Nothing like trying to tune a motor on air bubbles.

BB

I know it has 2 pieces of plastic coming upwards from the bottom, i thought they were for stopping fuel slosh...

Is that what im looking at?

From memory, there was two running length ways down the tank. Then on the revised tamk a small baffle was placed in front off the pickup at the end off the tank.... hope this helps.

BB

So the baffle was put there to remove air from the fuel line?
Where would i get one from?
Because i only have 2 plastic things running length ways, thats it...
its one of the original styles (version 1)
It was the one before the V-One RR style rear suspension set up... forget its name... but was a common V-One S conversion, and then they bought it out as a stock set up on the Lola style V-One S

Are you tuning the motor on the 1st tank out? Try getting the motor decent for 1st tank then refill and put the race tune on it while running 2nd tank, not heated up enough. With on-road it takes longer to warm up I think, 2-speed doesn't shift right if at all for a little bit, then after more time might seem like bogs right when it shifts. If your tank had a tube from pressure line going to bottom of tank that's definately problem and I'd fix that first, can get a new tank or just put pressure fitting on the lid and close off stock pressure hole in tank.

You'd have to buy a new fuel tank...

If the tuning is being changed that much durring the tank, I think the problem is a cracked tank. Many times, a hairline crack will develop along the seam of the tank. Ones the tank get more then half empty, the pressure from the exhaust will leak out, leaning your engine out.

If your tank has a tube for pressure that goes to the bottom that is your problem, either get new tank that doesn't have tub to the bottom or put fitting on the lid. For precaution you can take a soldering iron and melt the seam in the tank where's the 2 parts are put together.

The fuel pressure line goes in at the top of the tank, beside the filler spot...


I'll take the tank out soon, and do an air/pressure check with it...
And Ill check the fuel lines at the same time

Alright, here i present the problem again...

After pulling the car completely apart today, and cleaning and servicing everything, i pressure tested the tank... NOT A SINGLE LEAK... GAH...

Now i had a look in the tank, and it has a little piece of plastic running across it to stop it sloshing at this point, but it is the tank from the S1, not S2...
But i think i found my problem anyway...
I havent tested yet, as i ran outta batterys on the last time i ran it...
But when i put in some o-rings to stop it getting any vibrations, i put an o-ring on the top of the top deck, and one between the top deck and fuel tank... no i did a look today when i put it back in, and if the tank isnt screwed nearly fully in, it touches the metal chassis...
So i now only have 1 o-ring in (one on top of top deck...) and it doesnot touch the chassis, but is slightly loose, so that the vibrations through the top deck, are dissipated,
Once i get new batterys, i'll let you know of any further progress...

Also, BROKEN bearings SUCK majorly...


And i hate grease packing bearings...