DT 250/400 tank

[Leslie]

Hi I am fitting a 76 DT 250/400 tank to my tracker, The tunnel of the tank is too narrow, has anyone got around this problem, as i have seen plenty on the forums with the DT tank conversion, I thought about spreading the tank, but the fear of creasing the steel is putting me off.

 

[Downeaster]

As far as I know, it requires major surgery: cutting out, widening and re-welding the tunnel. That's the only thing that stopped me from doing it as I think the result is GORGEOUS!

 

[Leslie]

As far as I know, it requires major surgery: cutting out, widening and re-welding the tunnel. That's the only thing that stopped me from doing it as I think the result is GORGEOUS!

Downeaster you are correct, the tank is with my local fabricator, he is cutting and i will try it before it is welded up and painted. I will only be riding it in the summer with short trips into Derbyshire & Lincolnshire.

 

[willis]

Would the tunnel fit over the backbone if the cup mounting style wasn’t on the tank or frame? Thinking along the lines of mounting tabs welded on the tank to bolt to top of the backbone perhaps.

 

[Leslie]

Would the tunnel fit over the backbone if the cup mounting style wasn’t on the tank or frame? Thinking along the lines of mounting tabs welded on the tank to bolt to top of the backbone perhaps.

Willis, Keep an eye on this post as i am altering the tank as we speak.

 

[Raymond]

Downeaster you are correct, the tank is with my local fabricator, he is cutting and i will try it before it is welded up and painted. I will only be riding it in the summer with short trips into Derbyshire & Lincolnshire.

I expect it will be short trips. My DT400 used to run onto reserve before 60 miles. Mind you, that was a thirsty stinkwheel and petrol was cheap in the '70s.

And your tank will have a reduced volume; will look luvverly but bike will be a bit of a forecourt Queen?

 

[Leslie]

Would the tunnel fit over the backbone if the cup mounting style wasn’t on the tank or frame? Thinking along the lines of mounting tabs welded on the tank to bolt to top of the backbone perhaps.

Willis I have had to cut the tank, 12mm/1/2" app each side of the bottom of the tank, also I am going to have to get a smaller petcock

 

[Leslie]

it fits perfect now and the position doesn't effect the steering, just the DT petrol tap is too long, I will be looking for a shorter petcock.

 

[Raymond]

British bikes often have smaller, simpler taps. I bought a petcock for the RE Bullet from Feked - and they have a few styles.

 

[Downeaster]

Nice!

 

[Leslie]

Got my petrol tank back from the paint shop (Vale Paints Meden Vale) info@vale-paints.co.uk

 

[Leslie]

I expect it will be short trips. My DT400 used to run onto reserve before 60 miles. Mind you, that was a thirsty stinkwheel and petrol was cheap in the '70s.

And your tank will have a reduced volume; will look luvverly but bike will be a bit of a forecourt Queen?

Raymond I live central to several bike meets, plus Donnington Cadwell & Mallory, not to mention Matlock possibly the best bike meet in the UK.

 

[Leslie]

I am getting there with the bike, slowly, just minor works around the tank/seat

 

[Leslie]

Lads i need smaller coils as I have changed my tank and the old ones are just too big, any suggestions

 

[Signal]

Without seeing the size you have to work with its hard to offer anything other than generalisations.
Here are my ideas:
If your bike is not rephased is one dual output coil easier to fit under the tank.
I cant think of any small 3ohm coils of the top of my head but have a look at electrex world they have smaller sized coils just make sure the resistance is correct. IE not a CDI coil.
Can you remount the coils you have differently to suit the space you have. I did this on my tracker with an Omars tank.
I have used after market car coils on my road XS 650 using custom brackets . Not the big ali can type coils that Grandads Zephyr had much more compact.
Last alternative: massage the tight spots out of the tank with a hammer. I Did this to a CB900f tank to get it on a XS 850 frame

 

[Leslie]

Without seeing the size you have to work with its hard to offer anything other than generalisations.
Here are my ideas:
If your bike is not rephased is one dual output coil easier to fit under the tank.
I cant think of any small 3ohm coils of the top of my head but have a look at electrex world they have smaller sized coils just make sure the resistance is correct. IE not a CDI coil.
Can you remount the coils you have differently to suit the space you have. I did this on my tracker with an Omars tank.
I have used after market car coils on my road XS 650 using custom brackets . Not the big ali can type coils that Grandads Zephyr had much more compact.
Last alternative: massage the tight spots out of the tank with a hammer. I Did this to a CB900f tank to get it on a XS 850 frame

Without seeing the size you have to work with its hard to offer anything other than generalisations.
Here are my ideas:
If your bike is not rephased is one dual output coil easier to fit under the tank.
I cant think of any small 3ohm coils of the top of my head but have a look at electrex world they have smaller sized coils just make sure the resistance is correct. IE not a CDI coil.
Can you remount the coils you have differently to suit the space you have. I did this on my tracker with an Omars tank.
I have used after market car coils on my road XS 650 using custom brackets . Not the big ali can type coils that Grandads Zephyr had much more compact.
Last alternative: massage the tight spots out of the tank with a hammer. I Did this to a CB900f tank to get it on a XS 850 frame

My engine spec, so a twin coil set up is required

Bored out to 750cc (80mm) with new pistons, rings.

Rebuilt and rephased 277-degree Crank and Cam

Larger Valves with uprated Springs

Uprated 4 brush starter motor.

Sump filter conversion to cartridge filter kit

Hi-Performance Oil Pump

New bearings and seals throughout

New solid-state ignition Newtronic with twin coils

All casings were vapour blasted and refinished.

 

[Signal]

You need 2 coils. The tunnel in the photos looks pretty narrow and I am guessing that the Newtronic ignition being an older design wont be able to drive a coil with resistance too much lower than stock. I think you will be hard pushed to find suitable coils much smaller than the ones you have.I had a similar problem when I changed from a Probe ignition to a Power Dynamo on my rephased tracker.
As an idea can you mount the coils on top of each other in line with the main frame tube. It will need some nutting out but I did a quick check with some old coils and I think it can be done.
Attached are some photos of the power dynamo gear fitted to the tracker.

 

[Jim]

Jus' to throw another option out there....

No law says the coil(s) have to go under the tank. Since I'm running pod filters (OEM airbox removed), I mounted the MP08 coil on the front of the battery box. Should be enough room there for dual stock (or whatever you decide) coils.
Has the added benefit of being rubber mounted since the battery box is.

 

[Leslie]

Has anyone got a dyna Dynatek Dyna Mini Ignition Coil i can loan and see if i can use it on my build doesn't need to be working I just want to use it as a jig, I will return and pay for postage to NG229QA United Kingdom

Jus' to throw another option out there....

No law says the coil(s) have to go under the tank. Since I'm running pod filters (OEM airbox removed), I mounted the MP08 coil on the front of the battery box. Should be enough room there for dual stock (or whatever you decide) coils.
Has the added benefit of being rubber mounted since the battery box is.


View attachment 325850

View attachment 325851

Thanks I will investigate this option cheers mate

 

[Signal]

Leslie the coil pictured is 0.5 Ohm have you checked that the Newtronics ignition can safely power it. It may draw to much current for the switching circuit.