750cc pushrod bike build

[oz]

You could stick it under the seat it would lower the centre of gravity.....Nice and stable!
Just a thought

Oz

[Rchop]

Randy, Randy, oh Randy silly boy what are ya doing.?.... why ya putting the fuel tank back there? have ya ever rode a fat chick on the back of a bike?  The fuel load, even considering it is a dissipating weight, should not be that high and especially back that far back... you should mount your light weight electronics back there... and put the tank where it belongs....
love ya
Kent

That tank will hold less than 2 gallons Kent, do ya really think that small amount of weight would make that much difference back there? I could build one that fit right under my chest and belly on the top of the frame if you think it would be better, but it's still high. No other place to put it other than right behind the front wheel on the front of the frame.

[Rchop]

Oz, unfortunately, there is no room under the seat. Bob, you can see the part of the frame I remade here. I pulled in the top frame rails so my knees fit right in beside the oil tank...

[isiahstites]

Randy, Randy, oh Randy silly boy what are ya doing.?.... why ya putting the fuel tank back there? have ya ever rode a fat chick on the back of a bike?  The fuel load, even considering it is a dissipating weight, should not be that high and especially back that far back... you should mount your light weight electronics back there... and put the tank where it belongs....
love ya
Kent

That tank will hold less than 2 gallons Kent, do ya really think that small amount of weight would make that much difference back there? I could build one that fit right under my chest and belly on the top of the frame if you think it would be better, but it's still high. No other place to put it other than right behind the front wheel on the front of the frame.

Randy, I think Kent is saying putting the weight that high and far back can affect you handling.

Scott

[interested bystander]

Just hauled 10 gallons of paint on the rearmost part of my Ranger pickup 2day- from my shop to my home -  3/4 mile.

I could FEEL the difference in balance with four wheels and I'm older than belly button lint.

On yer scooter it's gonna effect the Cg/Cp relationship and the vertical polar moment.

Maybe a re-think is necessary?

[Rchop]

Randy, I think Kent is saying putting the weight that high and far back can affect you handling.

Scott

I understood that part Scott, it's just that I have lost about 20 pounds since I have last raced. If I hadn't lost it, would the bike handle bad? Most of it was near where the tank would be 

I'm concerned about mounting the tank in the front lower part of the frame. Would that be considered some type of streamlining if I run unfaired in the "a" class?

[Rchop]

On yer scooter it's gonna effect the Cg/Cp relationship and the vertical polar moment.

Maybe a re-think is necessary?

I think you and Kent are probably right 

[ol38y]

Randy, guys run oil tanks down low and in front all the time. Ya probably couldn't get away with making it like a chin fairing but you could do it. Myself, I think along the backbone would be better in your case. Also, as long as your bike is gonna be it will save you 30' in fuel line.  Besides, since you've lost all this weight you need to fill that void...

On yer scooter it's gonna effect the Cg/Cp relationship and the vertical polar moment.

Maybe a re-think is necessary?

I definately agree...

[JimL]

Hi fellas....note to add about "rear mounted fuel".  I used to make some long runs on my old Transalp, so I started using a Tour Master "rack bag" to carry a 2 gallon gas can.  After a few trips, it finally dawned on me that... if I put the 2 gallons of fuel in the bike, when my main tank got low, the bike didn't constantly wobble at anything over 70 MPH!!

I could strap solid items on back, and not really notice it, but liquid??  NO WAY!!

The old CHP Kawasaki 1000s had a pivoted, shock dampened, rear service box due to wobble problems with weight behind/above the rear wheel.  I got the whole story from an officer that stopped me, one night, to talk about riding my Buell with both wheels on the ground.  We sure learn some neat stuff, in strange ways!

[Rchop]

It's a good thing I was just in the mock-up stage with the rear mounted fuel tank. That's what I like about this site, there's alot of experience out there that will prevent me from making mistakes during my build. Thanks guys, as always, all comments and suggestions are appreciated

[Stainless1]

Any room under you?  Even if you sit on the tank and it raises you 2 inches you can fair that with the tail.  Also look at under the frame... what will be air space with the fairing on, that is probably where you should put your gas 

[Rchop]

Putting it under the frame might be the best way to go Bob. I made it with about 6 inches of clearance so I could fit a belly pan under there. If I use half of that space with a tank, it would probably work, thanks.

[Rchop]

So, with all the "suggestions" about the tail mounted tank, I have decided to mount the tank under the frame. I will be running without the fairing for most of this year and I have to use a fuel pump anyway, since it's fuel injected. If there's a conflict with the fairing bellypan when I run with the fairing, I can make a couple of side mounted "tube tanks" like I had on my last bike. At least this one will stay out of the windstream when running unfaired. I made a tank that will hold about 2.3 gallons and I will put a couple of baffles in it before I weld the ends up.
Here's what it looks like now...


http://www.frsengineering.com/pp58.jpg


http://www.frsengineering.com/pp59.jpg

[Rchop]

I have fabricated 2 baffle plates and attached them to the inside of the tank using a portable spot welder. Now I can close up the ends and install the petcock bung...


http://www.frsengineering.com/pp60.jpg


http://www.frsengineering.com/pp61.jpg

[Glen]

Hope you have plans to protect it from punctures.