CRF450R Fuel in frame Mod

[Red 450]

The frame rails of your CRF can easily be converted into a 1.8 liter fuel tank for about $20. The frame rails already have holes drilled into the bottom of the spars just before they join the forged castings that the foorpegs mount to. The first step is to drill these existings holes to the correct size then thread them to accept pipe fittings. Plug one of the holes then install an air fitting to the other hole so you can air test your frame to see if you have any pinhole leaks in the welds. Using soapy water it is easy to see if you have any leaks that need to be sealed. A drop of JB Weld will seal the pinholes permanently or you can get fancy and tig weld them closed. Once your frame is tight you connect the two frame rails together with hose and fittings then connect the line to your carb. Some people install a petcock on the line and others don't. The next step is to install a vent at the top of the frame rails where they come together at the steering head. This can be done by drilling in a small fitting or if you have the ability drilling out the bolt that holds your top tank mount in place. Thats it you now have increased your fuel by 1.8 liters without going to a larger tank. The first person to do this mod and post photos on the web was RideRed from Michigan. I've had mine in place now for about 150 hrs. without any problems at all.

[Ranger_450F]

Thats cool,

I would have been real nervous when I stated drilling holes in my $6000 dollar bike

[Live2ride]

good idea, but i wouldnt feel comfortable enough with gas alway sitting in my frame just sitting, and corroding. even though i know its almost impossible, i wouldnt run the risk of gas corroding through the frame, specially an aluminum one. very clever!

[Woody_393]

Here are the pictures. Red 450 Will explain each of these later.

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[Woody_393]

Here are some more. I believe Ride Red from TT is the owner of these. The idea is the same, but the tubing and routing are a little different. Works the same though.

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[Red 450]

Thanks Woody CRF for posting the pictures. The idea of using the aluminum frame rails for a fuel tank has already been done by a factory. The Buell Firebolt holds it's fuel in the frame or so I have been told. If anyone thinks that they would like to do the frame rail conversion I will help by answering any questions that you might have. It actually works really well, much better than putting a container in your fanny pack.

[Woody_393]

Not a problem. Always happy to help.

[MoTo202]

could this work on gen 2 (2000-2001) cr frames, this could be a good idea for a radiator over flow.

[Red 450]

This will work on the older generation frames but if your looking to build a coolant recovery tank you are much better off using the front downtube that runs infront of the cylinder. It is much closer to the radiator vent tube and is really easy to convert. Cost for the coolant recovery tank is about $4.00 in parts. The July issue of DirtBike will have an article on the modification.

[Florida 393]

Check our thread in the 4-stroke knowledge base forum for the directions and pictures of the coolant tank modification.

As to the aluminum corriding from the gas, the aluminum should be okay if your fuel is not a methanol blend. The remaining heavier oils present should minimize any problems. The alloy used is pretty good stuff and we ran aluminum tanks in the 70's (yeas I am that old) without any problems. BBR now makes and sells several aluminum tanks for one off applications or people with money to burn.

Bill

[DAC45]

How do you get the fuel into the frame? This sound like a mod I'd like to do, but have not figured that part out yet?

[Red 450]

The fuel gets into the frame thru the connection made at the carburator. The gas just fills up he frame until it reaches the level of the fuel tank. It takes a couple of minutes to completely fill as your pouring it into the tank at a high volume then it has to fill the frame thru a 1/4 inch hose. Just finished my second season with this mod and there has been no problems at all. Sure beats packing an extra fuel container. If you have any questions just ask.

[davecampbell]

i was wanting to buy a 3 gal tank but this mod looks better
question is where do i buy that little fitting for the carb that has two hose connections?

[Florida 393]

Dave,
Any hardware store that carries gas and plumbing fittings will have them. You can also find them at auto parts outlets that carry fuel system repair parts. Hope this helps out.

Bill

[AKColby]

Would this mod be doable on a 2 stroke?I mean with the oil an everything?

[Keetoman393]

I was asked by a member to see if this would work on a 2-stroke considering it has premix. He can't post to this Knowledge Base Forum so could someone PM me or another mod so we can asnwer this?

[Florida 393]

Keith,
As far as the pre-mix fuel and the aluminum I stand by what I said years ago. We used aluminum tanks on many bikes in the 70's and the factories still have one off aluminum tanks.

If the spars on the 2 stroke Hondas are assembled like the 4 strokes the modification should work just fine. I don't remember how John's '02 CR 125R was built but I will find out and put something in the 2 stroke KB for them. Give me a few days to scope this one out. I will try to see what the different generation frames changed also.

Bill

[AKColby]

Yes, I'm talking about an 03' CR125

[bikepilot]

I'll be trying this on my CR250R this winter - will let you all know how it goes.

[pdmoyes]

Okay, I have a couple of questions:

1.) Does the fuel go all the way down the frame to the footpeg level? If so, how is it pumped back up to the carb.

2.) I would think this could affect handling in a good way for racing mx. I only put in enough gas to finish a moto to keep things light. By have the fuel in the frame rails, I would think it lowers the center of gravity and would help the bike turn better. Any opinions?