FYI emgo steel roadster tank issue

bought an emgo steel roadster tank from a local vendor, now that i've had a chance to check it out and get ready for the leak testing, the 1/4"bspp blanking plug i bought doesn't fit. called the vendor, and hes now having the same problem with the other one he has on the shelf. the thread is suppose to be a 1/4" BSPP which is 19tpi, we can only get the fuel tap in 3 turns before they jam up. looks like they were taped to 18tpi or possibly the bstp thread.... crap

850commando said:

bought an emgo steel roadster tank from a local vendor, now that i've had a chance to check it out and get ready for the leak testing, the 1/4"bspp blanking plug i bought doesn't fit. called the vendor, and hes now having the same problem with the other one he has on the shelf. the thread is suppose to be a 1/4" BSPP which is 19tpi, we can only get the fuel tap in 3 turns before they jam up. looks like they were taped to 18tpi or possibly the bstp thread.... crap

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I wonder if it's really EMGO. I've bought four of them and none had a problem. The EMGO tanks are baffled just like the originals and they are heavier metal than the originals.

Have had mine several years. No problem with BSPP threaded stock type petcocks.

BSPT is a taper thread, which of course, a tank wouldn‘t / shouldn’t have. But if that’s the case, a BSPP male thread should go in quite a way IIRC.

The good news is that IF it’s BSPT, then it’s a very straightforward job to tap it out to BSPP.

But I’d check first, I think it more likely to be NPT or a metric thread...

Its an Emgo tank ! taking it to the machine shop tomorrow and we'll see what a 1/4" bsp tap says.

850commando said:

or possibly the bstp thread....

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There is no such thing as a BSPT female thread. All female threads are BSPP, only the male half is tapered. It is possible that it was tapped with a worn out or undersize tap. As long as the thread pitch is not too messed up, you should be able to tap it out okay.

I also have an Emgo roadster tank sitting in my garage waiting to go on the '70. My biggest issue with it is the finish of the weld seam around the bottom of the tank - very rough and jagged.

I have been subduing the urge to take a sanding wheel to it, and have only hand filed it so far. It is cleaning up, but there are a couple of spots that I am worried about how deep I had to go. Definitely will be leak testing it.

It also had a dent in the seam area in the LH corner by the seat. I have been able to dolly most of it out thankfully.

I have not checked the port threads yet, but I will. I have a 1/4" BSPP tap in my tool box.

Derek Wilson said:

There is no such thing as a BSPT female thread. All female threads are BSPP, only the male half is tapered. It is possible that it was tapped with a worn out or undersize tap. As long as the thread pitch is not too messed up, you should be able to tap it out okay...

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good to know about the female thread being bspp, i'm wondering if they used threaded bungs which distorted upon welding...

AFAIK, most American bikes use NPT threads for fuel taps. European and Japanese use metric. I imagine it quite possible that in the tank fabrication shop / factory someone fitted the wrong ones.

I’d check carefully before sticking a tap up there.

Okay so, after running the BSPP tap through the bung, it cleaned up and the std British style fuel tap screws in properly. It looks like it distorted during welding.

Fast ED, the Emgo tank is as close a copy to the factory original tank as possible, and in this regard the original fuel taps were 1/4" BSP, and my current fuel taps now fit perfectly to that spec.