How to make a bigger tank for the Hima

[sam2019]

Finished the manual, if you find mistakes please report here, thanx!

 

[sam2019]

This is a transfer from the old forum where a bit of a discussion was happening - but no relevant information for making it was coming from it except maybe that the size of the tank is not relevant if you also change the bike to "street" without the sideframes. If you keep them then 4.5cm on each side seems the maximum extension without bending those frames at the attaching points.

 

[sam2019]

Lately I have thrown out one of our bigger tanks. the problem was with bits of paint coming loose inside, mixed with fuel created a kind of goo that blocked the fuel flow into the fuel pump (BS6).
I still use it on the carby models with zero problems - possibly because there the fuel tap reaches into the tank and the goo settles on the bottom. We had to extract about half a litre of water though after some heavy rainfall.

 

[Dool]

So, you Discarded the Tank or keep using it on the Carby Bike

 

[thony]

I went through the whole document again and just realized I do not need another tank if I am willing to risk mine.

So, this mod has some major issues and they all take you to the welding right? TIG could be slightly more precise if you are able to source a workshop?

@sam2019:

I will first determine wanted enlargement at the top, say 4 cm (image 1). Or, should determine the total enlargement from the welded strip on the second image? Then the third area to enlarge is the lower extensions which will have to be extended straight down and inwards (kinda 45 dregree) to meet up with the tank's bottom (image 5).

There will be 4 sections of the tank that will have to be welded to the extensions; these are 1. the fuel cap area, 2-3. the sides and 4. the bottom tank. Here is the part I do not have clear: the side panels of the tank are needed to be extended far down or just close the gap made by the overall fattening of the tank unit?

 

[sam2019]

So, you Discarded the Tank or keep using it on the Carby Bike

The tank is different, so I cant use it on a carby. I have not decided yet. There is an option to get the paint off with some heavy duty chemicals. But they are extremely poisonous and may not get all of the paint in which case the effort would be futile.
You can easily avoid this problem by removing the paint prior to welding by mechanical means which should be easy enough. It only becomes a problem once you welded it shut.

 

[sam2019]

One more thing: although the tank was treated with the extra layer of welded on stuff it still developed a few tiny bubbles. These are very small and where not detected with the pressure test.
Also: if I had to do it again I would at least do 3.5cm on each side. 2.5 just does not give you enough extra room to make it worth the while.

The extensions go around the entire tank of course.

I am not sure if TIG is possible with these thin sheets. you may need gas welding.

 

[sam2019]

One reason I stopped selling tanks was the abysimal quality of Indian paint jobs. These guys are so stupid, its not funny any more. They paint a tank with stuff that is not fuel resistant and if you complain they tell you its the fault of the fuel company for "adding new stuff".

 

[Sasa]

A good quality clear coat (2K) was the only thing needed.

Paint could be rubbish as long as substrate preparation is good and clear coat is 2 component urethane or acrilic...

 

[sam2019]

I have now measured the 2.5/5cm wider tank capacity as only 17 liter. The OEM tank has 14.5.
In the light of that I suggest you use 4.5cm widening to get to something like 19 liter. Unless you get rid of the side panels and make it look like a Scram (which I did - its quite nice) that is the maximum. In Scram look you can go wider. I would think even 6.5cm is still not too bad looking.

 

[Dool]

One reason I stopped selling tanks was the abysimal quality of Indian paint jobs. These guys are so stupid, its not funny any more. They paint a tank with stuff that is not fuel resistant and if you complain they tell you its the fault of the fuel company for "adding new stuff".

Ethanol? do they use it in India, that played havoc with a petrol tank for me.

 

[Sasa]

Ethanol? do they use it in India, that played havoc with a petrol tank for me.

As long as percentage is below 10%, ethanol shouldn't do harm to a stock tank, neither inside nor outside.

 

[Dool]

Ruins shitty paintwork but

 

[thony]

Good friend of mine who will possibly make the work here suggests double welding, he says he can do it but has never done so he does not know how much to charge.

 

[thony]

I have now measured the 2.5/5cm wider tank capacity as only 17 liter. The OEM tank has 14.5.
In the light of that I suggest you use 4.5cm widening to get to something like 19 liter. Unless you get rid of the side panels and make it look like a Scram (which I did - its quite nice) that is the maximum. In Scram look you can go wider. I would think even 6.5cm is still not too bad looking.

So @sam2019 I will be sending my tank for the modification this week. Since I removed side rails long ago I can wide. So according to your estimations 5.5cm would be around 20l... I wanted to go for 25 or 30. Any rough thought on the number of cm?

I went through the whole document again and just realized I do not need another tank if I am willing to risk mine.

So, this mod has some major issues and they all take you to the welding right? TIG could be slightly more precise if you are able to source a workshop?

@sam2019:

I will first determine wanted enlargement at the top, say 4 cm (image 1). Or, should determine the total enlargement from the welded strip on the second image? Then the third area to enlarge is the lower extensions which will have to be extended straight down and inwards (kinda 45 dregree) to meet up with the tank's bottom (image 5).

There will be 4 sections of the tank that will have to be welded to the extensions; these are 1. the fuel cap area, 2-3. the sides and 4. the bottom tank. Here is the part I do not have clear: the side panels of the tank are needed to be extended far down or just close the gap made by the overall fattening of the tank unit?

Did you see picture 2? Is that where you are supposed to estimate the whole number of cm and then welding the other steel strips accondingly to maintain the tanks shape?

 

[Dool]

This is going to be good, cant wait to see the finished product.

What sort of Range are you after ?

 

[sam2019]

Any rough thought on the number of cm?

it seems 2.5cm will yield approx 2.5 liter.
so 25 liter would mean 10.5 liter more so 10.5cm on each side - easy

Did you see picture 2? Is that where you are supposed to estimate the whole number of cm and then welding the other steel strips accondingly to maintain the tanks shape?

the widening of 2.5cm refers to ONE SIDE - so a total of 5cm if you look at the middle piece.

you tank will be 20cm wider in total if you go ahead with 25 liter capacity
it will look like the old elephant tanks for the 1950s BMWS

 

[thony]

This is going to be good, cant wait to see the finished product.

What sort of Range are you after ?

It has to be no less than 25 liters to make it worth it. Would be awesome to carry a 30+ liter hump

it seems 2.5cm will yield approx 2.5 liter.
so 25 liter would mean 10.5 liter more so 10.5cm on each side - easy



the widening of 2.5cm refers to ONE SIDE - so a total of 5cm if you look at the middle piece.

you tank will be 20cm wider in total if you go ahead with 25 liter capacity
it will look like the old elephant tanks for the 1950s BMWS

Got it, I will then use the middle as reference and measure with my guy at the shop for the best range.

I'll send photos of the process for sure.