Topic: Tank, Frame, Harness-- Something's Not Right? photo

[Toxic]

Go back to my photo with the 3 rulers and compare your measurements to mine.

I think your looking at picking up a used tank either way.  At least they are plentiful and not too expensive.

[xenoscr]

Looks like the tank has expanded for some reason. Maybe from setting in the sun.

Maybe someone tried to use compressed air to pop out a dent? I read about that when trying to determine the best way to repair dents in my tank.

XenosCR

[Popwood]

This tank is definitely misshapen; splayed out like the legs on a saw horse. Check out the new photos below. Compared to Toxic's photos and measurements, where his tank is 6" wide in two places along the "tunnel" mine is nearly 8 1/2". And where he was getting an overall width measurement of 11 1/4" I'm getting 12 1/2". You can see how the tunnel walls are splayed outward. This, in turn, causes the very bottom of the tank to be at an angle and not parallel to the ground, which is why my petcock angles out instead of being straight down.

There were other questions raised about the placement of the coils. New photo showing they have been improperly attached to the frame. Ah, PO's, don't we just love 'em.

So what to do about the tank? First, It came this way to me and I've clocked a couple thousand miles since I got the bike last June. So it works and it's pretty clean inside. We're talking appearances here mostly and overall, mine just looks like in needs to loose a few pounds-- it looks fat.

Is there a chance in hell the sides could be brought back together removing the splay? Here's what I'd propose to do: trace the bottom exterior shape of the tank on 3/4" plywood. Bandsaw to that line. Pad the plywood edges a bit where they meet the tank. So now you have two bandsawn edges and two other edges of the plywood that are straight. Use probably 4 clamps across the outside plywood edges and slowly tighten the clamps drawing the tank sides together. Because the plywood edges match the shape of the tank, clamp pressure will be equally distributed along the entire edge of both sides. I've done a lot of pretty sophisticated woodworking, including bending plywood to curved shapes using specifically shaped cauls as I describe here. But, of course, wood is far more forgiving than metal.

Seems to me the question here is: Live with the tank as is since it works. Try bending it back to approximate shape-- at best a 50/50 chance of success. Just forget it find a replacement tank. If I try bending and it gets screwed up, I'll buy a replacement anyway. If I don't bend and buy a new tank I'd have usable back up or could sell it to some unsuspecting fool.

Thoughts on my dilemma?

[HondaMan]

It's definitely splayed: the clue (to me) is the non-parallel curl brackets. Hard to imagine what could have done that! The K5-6 tanks were the same width and overall proportions as the earlier ones, but just had brackets that were changed a little. The cross-mixing symptoms are then as I described earlier, but nothing this severe! 

(Another example, for the curious: K0 diecast through K2 were the same, then the petcock moved forward a little on the K3-K4 tanks, and the tank donuts got bigger to push it back and raise it slightly. Changes in the carb brackets occurred to fit the new petcock: if you install K1 or K2 carbs on a K3-4 tank with original tank, the synch bracket hits the petcock just before fully closing the throttle, making it want to hang at 1500 RPM...installing K1-K2 tank on a K3-4 setup usually requires obtaining or trimming to smaller donuts, and the tank sits a bit lower, making a gap at the seat-tank interface. So, then you need the K1-K2 seat from the "new" factory, with the longer overhang on the front of the seat and the naroower sides near the driver's legs. And so it goes...    )

[Toxic]

I'm all for the experiment, try to squeeze it back into shape.  If you mess up, get a used one.
No offence but the tank just looks odd sitting on your bike. Personally I couldn't live with it like that.  But that's just me, I'm like that.

Thanks HondaMan for that info on earlier carbs and tanks and their changes.
I checked my pile of bike parts and I have no idea if my carbs are K0 to K2 or what year my freshly painted tank is.

I just I'll find out if there are any fitment issues when final assembly happens.

[Soos]

perhaps the tank has had compressed  air in it???

[Popwood]

I made the bending form and squeezed the tank so it's closer to the original dimensions but a new problem was created and some of the original ones remain. The squeezing put a crease in the metal near the neck because one side of the tank was bending more than the other. That's the new problem. It's not terrible but it is disappointing. The tank still sets high and doesn't align properly, still bottoms out on the frame as before.

Other than ebay and the "for sale" section of this site, where do I look for a replacement tank and what might I expect to pay? This all started because I plan to do a repaint of the tank and the new side covers I have from LPM. Not looking for a perfect tank or the right color, just the correct fit for a '75 750K that's in reasonable condition. Or, failing that, I can live with what I have but would prefer a tank with a better fit. Anybody have one out there? Suggestions?

[MickeyX]

As far as I know, you can still buy them NOS from Honda. There are some on ebay but they aren't very nice at all. Rust is pushing through the paint. Maybe someone on here has one to sell. 

[Toxic]

The green primer one I posted pics of above, I paid $60 for on ebay. It's primed and ready for paint.

Take your time and the tank you presently have does work.

I would rather buy from a forum member but ebay can be a good source if you are careful.

[Popwood]

Hey, Toxic,

I've sent you a PM about your tank. From your post you imply it may be for sale? I'm interested if so.

[xenoscr]

www.yamiya750e.com sells brand new tanks. Expensive as hell though. $550 for a primered tank. They are also K0-K4 style (left side petcock)

I notice you're in OH. Cycle Re-cycle is a shop her in Indianapolis that usually has a good selection of used tanks for sale. I'd be a road trip to pick one out. The guy Rob that runs the place can get a bit short with you and can be a bit of an @$$ but he knows his stuff and his prices are right. I bought a tank from him with a couple fixable dents and a spotless near rust free inside for $50. Well worth it considering I spend almost triple that for the purple tank I posted pictures of on eBay. I'll sell you the purple one if you want it. There are no dents, the rust isn't too bad on the inside but someone bondod the badge mounts on the sides.

XenosCR

[HondaMan]

Thanks HondaMan for that info on earlier carbs and tanks and their changes.
I checked my pile of bike parts and I have no idea if my carbs are K0 to K2 or what year my freshly painted tank is.

If the carbs are all moving with two throttle cables, you can rule out the K0 type. They had 4 cables. 

[Popwood]

Here's and update, some progress and a tip on interior tank cleaning I tried successfully.

Thanks to the warm (50 degree) weather here today I was able to re-route the wire harness to where it belongs and mounted the coils properly. So that's good to go.

I'm on the lookout for a replacement tank, but decided to continue work on the I have. In the end, I may decide to just use it. It looks far less misshapen now with the sides now in a near vertical mode as opposed to slanting outward.

Right now, I'm doing the electrolysis thing on the tank interior. Just started so nothing to report. But I did some cleaning first. Here's the tip: bought a couple small wire brushes that have the wires projecting down, not like on the edge of a disc. Picked up at local hardware store. These have a short shaft (arbor) that I mounted into a 12" long extension normally used for extending "spade" or "speed-bore" wood drill bits. Chucked this into a drill and wired brushed many of the deep recesses where the varnish, some rust and other crud collect. Worked really well and a heck of a lot easier than than throwing a bunch of nuts, bolts, screws and chain in the tank and sloshing around for hours with muscle power. I had sprayed the inside with WD40 and added some paint thinner while wire brushing. After that, I added some acetone and lacquer thinner to dissolve some varnish the brush couldn't reach and let that soak for an hour or so. That was followed by a warm water rinse, which was followed by a simple green and water soak for a couple hours. Another thorough warm water flush and then started my electrolysis.

A bit of trouble, but good experience I figure.

Lastly, thanks for those offering all the help and suggestions of where to find a replacement tank should I go that route.   

[Steve_K]

I have a 76 550K that has a BCR tank.  I want to raise the rear of my tank.  I brought a new rear tank rubber for a 76 550K, so I could get the tank mounted.  I want the tank higher in the back so I can mount the seat.  Could the K1 thru K4(for 750K) do it for my problem?  I thought all the rubbers were the same.  BTW the search function worked for me.
Thanks Steve