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Ash Small

Wed Mar 05 2014, 10:25PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Aluminium fuel tank arrived today

I'll post another photo after it's polished and fitted with a fuel cap.

paris

Fri Apr 04 2014, 01:57AM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
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Posts: 121

I keep a keen eye on this thread
(.... PENDINE SANDS is up soon , this weekend me thinks , not sure)

Ash Small

Fri Apr 04 2014, 04:11AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

paris wrote ...

I keep a keen eye on this thread
(.... PENDINE SANDS is up soon , this weekend me thinks , not sure)

I looked into it a couple of weeks ago, and apparently it's not happening this year, although there is a car event around the last weekend in June.

EDIT: The thing that's holding up progress on this thread at the moment is a lack of affordable high speed mosfets (around 10nS switching time, not including delay, around 1200V and around 30A continuous (60A to 80A pulsed). There is some room for manouvre, but the 5nS switching time mosfets used in the pulse generator linked to above are Â£40 each from Farnell, and the only other ones I've found that come close are very reasonably priced, but are in California and the postage costs are ridiculous, so if anyone has any suggestions I'd be grateful.

EDIT: RS is now stocking these:

which aren't too far off the mark. I'll have to see what others are in the ST range. These have 78A pulse rating, but switching times are a little slow, nearly 15nS and only 800V. Price is good though, Â£2.33 each if I order 50. They should certainly be good enough to run some initial tests, but I'll keep looking for a while longer.

Link to the ST range of SuperMESHâ„¢ 5 power MOSFETs

Ash Small

Tue Aug 19 2014, 10:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

If anyone is still following this thread, the twin disc WP upsidedownies arrived a couple of days ago, and I fitted them to a set of yokes (triple tree) today;

paris

Thu Aug 28 2014, 09:08PM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

your money . and the MOSFETs ?

Ash Small

Tue Sept 02 2014, 08:45PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

paris wrote ...

your money . and the MOSFETs ?

Not quite sure what your point is, but as new MOSFET's are becoming available all the time, and the fast ones are getting cheaper, I'm in no immediate hurry to order MOSFET's while I still need to get other parts etc.

I am planning to build some test circuits using slower, cheaper MOSFET's, but again, the technology is developing, so I feel I'm better off getting other parts as they become available on Ebay, etc.

I'm also considering some of the points Sulaiman mentioned above, such as insulation for ~100nS pulses @ ~50kV.

The yokes I had (pictured above) turned out to be 30mm too close together to get the hub and discs I have into, but I managed to get some suitable ones (from two different sellers) on Ebay, which arrived this weekend:

The bottom yoke will need 3mm sleeves machined, though

paris

Sat Sept 06 2014, 06:08AM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

no not smart mouthing .
been reading article on XS650 crank rephasing from 360 to 270 hmm lot to it

Ash Small

Sat Sept 06 2014, 01:59PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

paris wrote ...

been reading article on XS650 crank rephasing from 360 to 270 hmm lot to it

Is the XS650 crank one piece, or does it bolt together? I can't remember offhand.

It's basically just crank and cams. Some of the early Japanese camshafts were bolt together too, if I remember correctly.

Obviously ignition timing needs sorting too, but that's usually pretty straight forward. You can also have issues with single carburettors, but if I remember correctly, all the XS's were twin carb.

Obviously, a one piece crank machined from something like EN21 ( I can't remember offhand what the Weslake cranks are machined from, it may be EN24, but I can check) would be a lot stronger. I'd love to have space for a bigger lathe

paris

Sat Sept 06 2014, 08:18PM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

Ok , so weve established ,you havent got XS650

phil irving was all for rephasing triumph but they disagreed!! (with irving, thats just wrong)

the XS crank is all pressed together.

Im keen to see how ign will turn out . 2 strokes are so fast reving surely they must be reliable for 4 strokes at half the speed ??

Ash Small

Sat Sept 06 2014, 09:44PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

paris wrote ...

phil irving was all for rephasing triumph but they disagreed!! (with irving, thats just wrong)

I think Triumph tried it with some of the unit 350's, at least a mate of mine had a 90 degree 3TA when I was a teenager, I assumed it was a standard 'factory job'. Most of the talk on Brit Bike Forum regarding 90 degree and 76 degree cranks relates to Triumph based stuff. Weslake has been producing them for years. I've also come across some 90 degree Weslake cranks for Nortons (The Norton crank can be squeezed into Triumph cases as well, and there are loads of Norton based diaphragm clutch kits that will fit other engines.)

paris wrote ...

the XS crank is all pressed together.

Can you unbolt it and turn one side through 90 degrees, then bolt it back together? (You'd still be better off with a one piece crank though, as I mentioned above. This would also facilitate a longer stroke. I've come across a few long stroke XS's, I think the biggest worked out at ~1,000cc's, maybe even bigger.)

paris wrote ...

Im keen to see how ign will turn out . 2 strokes are so fast reving surely they must be reliable for 4 strokes at half the speed ??

As I mentioned earlier in this thread, I'm only aiming for around 5000 RPM with this project, with separate coils for each cylinder, although the same principle, with sufficiently fast (read 'expensive') MOSFET's, should be able to be adapted for higher RPM.

As an aside, when Jaguar developed the V12 engine, they had to have special coils developed, as the existing V8 coils weren't up to the job (I think I touched on this earlier in the thread as well).

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