mdbuehler

Doing things slightly different, hoping to keep that extra capacity

Tank was cheap off ebay, and as I'm painting at the end of my mods, didn't mind some scratches and dings. The red is a really good match, so if you aren't planning on painting, get a good one and you're all set.

With the top of the airbox removed, it will drop right onto the bike, no beating required (obviously more to it then this, but fine for now). The rear tab on the tank that others cut off (but warned of a weld and possible leakage) I bent down to follow the tank contour.

For starters, here's back to back stock tank vs VFR.

Stock:



VFR:



Stock:



VFR:



Most noticeable are the gap under the tank at the rear, and the height at the rear. Aside from that, it looks fairly stock and follows the lines well enough. Looks like a 'roided up Hawk if anything

Next up I'll shim under the front seat catch and seat rest points on the seat, and that should bring the seat up to the tank a bit better (need only .5" or so).

yruyur

great pics so far, I'll be sure to keep an eye on this thread.

Malice

I really like the look of no gap between tank and frame! What's the difference in capacity between the vtr and vfr tanks?
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Weed Vaporizers

mdbuehler

Now that you point that out, I like that quite a bit too! The Hawk is 3.5 if I remember right, and the VFR is 5.8, so a gain of 2.3 gallons. That should be a very noticeable increase in range!

Just finished yoinking out the PAIR system and PCV, much simpler goings on under the tank now. Going to get started on the block-off for the VFR tanks fuel pump hole tomorrow. Sheet steel and a fat gasket should do the trick. Will get pics up as I move along!

joe6pack

So do you have to leave the airbox lid off in order to use the VFR tank? Have you tried running it with the airbox lid off yet?

mdbuehler

To drop it straight on, I'd have to run without the top. I've heard several people say that won't work, but I've yet to hear what happens when you do (minor flat spot, or horribly unrideable, or just no gain?). When the rain goes away, I'll head out with the stock tank sans the airbox cover and see exactly what the story is.

If it runs OK with no top, this is really, really easy. I'm going with the assumption there's a problem if you don't, and will modify the box top (cutting away points of contact with the tank) then put compressable foam insulation on the underside of the tank in those areas so it will seal it back up and become part of the top when its fitted. This will alter the shape of the airbox top a little, but shouldn't be too extreme and I'm guessing the old girl will hardly notice

Tweety

Without the top altogether I imagine it to be close to unrideable... The change in the top of the airbox though with the tank as part of it should be minimal and could work...

yruyur

I agree. Im not sure how much room there is to work with and how much of a mod to the air box would be needed. I guess you could put a thin piece of styrofoam untop the airbox or on the air box without the lid then seat the tank to find where it make impressions until you have it seated all the way.

PUSHrod

Here's a thread I have some real interest in. Please post updates. Thnx.

nuhawk

Where's the link to the thread? If it's Superbling's mod for the Superhawk and if there's any interest: I have the tank and the seat & they are for sale. $550 shipped.

mdbuehler

Like the foam idea for impressions. I was going to use clay but was debating the pain of cleaning it up after. I'll just seat the tank, see where it hits, slice off a few mm from the airbox, and repeat.

The slowest going part is done (for me at least). As aluminum wasn't available at Lowes in sheets of any decent size, I went with steel instead for the fuel pump seal off plate. My cutting wheels don't get through that too quickly! On a side note, I tried the old stick-and-hotglue trick to pull the little dent on the tank (worked great on my old Hayabusa tank) and nearly dislocated my freaking arm pulling on the thing. What thickness of metal does Honda use on tanks?! LOL! Amazed the paint stayed attached too!!

Anyhow, here's the tank all cleaned up and ready to go:



The plan is take the big gas proof gasket on the left on first to cover the hole. The cork one follows (hole is recessed a bit from the level of the retention studs), then the smaller steel plate to apply pressure to the center, and the large metal plate to bolt it all in place and press the whole thing in. Once it works, the petcock will be mounted towards the center of the plate (just drilling a few holes for that).



Here's the air filter with that trimming mod to remove the lip. It made light contact on the outer edges of each side, so its looking like it'll be more the sides then the top of the airbox getting a trip, which is easier for me anyway.



So far I'm into this about $30 for the tank, another $20 in supplies (not counting redundant tank parts bought to keep both usable), and 3 hours of tinkering. I'll seat the gaskets up in a bit and fill the tank with water and we'll see if it holds!

mdbuehler

Looks good! I'll go back with some goof off later and remove all the old foam residue and duct tape slarg on the underside. I imagine a layer or two of enamel may be in order to make rust a non-issue down here.



Off to the auto store for a few filters for the PCV lines. Qatar motogp starts around 6pm, so this may be it for the day

kai ju

Couple of pointers from having done this mod two years ago.
1. The bike will not run with the airbox lid removed, I tried.
2. The 98-01 tank requires very little modification to fit the lid, mainly in the front corners.
I recently had to fit a CB1 tank on top of an F-3 airbox and made the job a whole lot
easier by removing a 10mm wide band of material between the airbox lid frame and the lid.
I taped the lid with masking tape, marked the lid and the used a hack saw blade to
remove 10mm strip of material. Used superglue to glue the lid back on the frame.
If I had thought of this with the VTR/VFR it would have been a lot easier, especially with
the fuel level sender.
3. I left the rear of the tank mount intact but narrowed it down to work with the seat.
4. Reshaped the seat pan and foam to fit the contour of the tank.
5. Raised the seat to match the back of the tank, raised the tail section to match the seat.
6. mdbuehler, nice job with the block off plate, but be carefull where you put the
fuelvalve, mine barely clears the valve cover. ( Spend the money on the stock gasket,
I've never had a leak)
7. Solder or braze the fuel valve bolts into the block of plate and you'll never have to worry
about a leak from that area.
8. Make sure you leave a gap between the tank and the frame. It'll be easier to clear the
airbox and you won't have to worry about the tank damaging the frame and vice versa.

I've added some detail pis of mine that will hopefully help. ( I hope I don't sound like a know it all, sorry if I come across that way)

Kai Ju

mdbuehler

Nice! Thanks for all the info! I didn't realize the fuel valve was going to be so tight, so glad I didn't just aim for the middle and call it good You saved me an attempt at boxless riding too

I was going to weld up something similiar to the stock tank for mounting the rear, but your way looks a lot simpler. With my tab bent down, I bet some angled steel would swing right in there on those two bolts and with two perpendicular holes I can bolt that on solid.

MotoGP is rained out, so back in the garage I may try a variation on that cut a bit out idea, and just lop the corners off as far as needed, then replace the removed material with some sheet plastic or lexan. Hmmm...

Malice

Very interesting project! 4.2 gallons for a stock vtr tank?! I can barely get 3 gallons in my 98 hawk. I must've got screwed
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Iolite Vaporizer Review

mdbuehler

Puttering along! The angle bracket worked great for mounting the rear of the tank. I have an even 1.5 - 2mm all around above the frame, which gives it a little wiggle room.

I pulled the seat cover back, and using a knife and coping saw notched it for the shape of the new tank, then took that extra foam and put it a bit high over the inside of the new cut and pulled everything back together / restapled. I was pleasantly suprised with the result:



I'll go back after that wrinkle later, but it notches in rock solid, and just clears the seam on the mounting tab so looks clean too. I had a bunch of stuff ready to raise the seat, but it looks like theres no need at the moment.

With the seat on, I can finally get clean shots of the 'new lines' of the thing. Really, really liking the taller middle, which makes the front seem lower (dunno why, but that works for me).







Reminds me of the old Suzuki Nuda or the Honda NAS for some reason

About out of things to do, so I guess I'll have to get started on the main problem of airbox fitment.

yruyur

Looking great, don't know if I can get used to the gap at the back of the tank. Really want to see if the airbox mod works

Malice

I definately want to do this mod. I'm tired of only getting 98 miles per tank. I love the no gap on the sides and I can pretty easily take care of the gap at the back. I think the larger tank works nice on this bike.
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Ferrari 575M Maranello Specifications

mdbuehler

For the back gap, something similiar to my old Bandit 400 is the plan. Look under the tank, they have inserts to fill things in. Looks simple enough to whip up a pair (abs or lexan) and mount to fill things in:



I believe SuperBling had a tank bra on his which pretty much covered it all up (so no need for anything at that point).

mdbuehler

Allrighty, not for the faint of heart here! The airbox "trim" turned into airbox snuff film



Must have done several dozen measures and cuts, and believe it or not at the air filter level, the back 2/3 of the airbox follows the contour of the tank within a 1/2" or so. Its tight around the edges, but roomier up top. I'll get some easily deformed insulation strip about 3/4" in depth tomorrow and adhere it all around the exposed perimeter of the airbox, and I'm fairly certain I'll get a pretty good seal.



Got impatient and took apart the old tank for parts, so I'll put the ebay bits on the old tank before selling. Only hold up here is me needing a drill bit for the actual fuel hole.



Least impressive bit of work is this very uninspired rear tank mount With the tab on the tank bent verically, two bolts through the holes lock it in solid.

Hope to have it runnable tomorrow!

steve.g