Brutal ???
I'm surprised she didn't crush you to death Johnno.
The love of my life..
Started by
_oldjohnno_
, Dec 22 2013 11:34 AM
34 replies to this topic
#27
_oldjohnno_
_oldjohnno_
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Posted 24 December 2013 - 01:10 PM
wtf happed there
Looks like you somehow hit the strikethrough button. No matter, thanks for the pics.
#28
_oldjohnno_
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Posted 24 December 2013 - 01:13 PM
Brutal ???
I'm surprised she didn't crush you to death Johnno.
You're not wrong Mark, it was an epic struggle that left me feeling totally drained...
#29
Bart
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Shit a brick
- Location:Sydney
- Car:LJ Torana
- Joined: 20-November 05
Posted 30 December 2013 - 09:40 PM
Edited by Bart, 30 December 2013 - 09:43 PM.
#30
Bart
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Shit a brick
- Location:Sydney
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Posted 30 December 2013 - 09:43 PM
#31
_BARRY JACKPOT_
_BARRY JACKPOT_
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Posted 03 January 2014 - 05:56 AM
Wow who built that last one
#32
_Lazarus_
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#33
_oldjohnno_
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Posted 06 October 2014 - 10:56 AM
Thought the two-stroke fans might be interested in an update. Chronic detonation problems were eventually traced to excessive head temps, so a 390 Husqvarna head was modified to fit. The Husky head is much heavier and has a better finning arrangement. The chamber was reworked into a modern semi toroidal shape but ironically this seemed to make just a tad less power than the original Bultaco trench design. I'd like to try a trenched Husky head at some stage but the main thing is the knock is gone and I no longer have to compromise the tune just to avoid det.
Porting was updated to with more exhaust and transfer T/A, the transfers also being re-aimed along the lines of current practice. It simply wasn't possible to achieve sufficient intake T/A without the piston falling out of the back of the cylinder, at least not without a reed. So a YZ carbon fibre reed was added, along with a fifth transfer in the rear wall. The longer duration with the reed meant I didn't need so much carburetor now, so the old VM was swapped for a slightly smaller TMX.
The extra exhaust duration required more length in the pipe, plus I wanted to reduce the peak torque rpms a bit anyway, so a total of nearly 100mm was added. The seal at the barrel end isn't so good so it tends to drool a fair bit of castor oil. The conventional stinger was obnoxiously noisy with the extra exhaust duration so it was converted to a side-bleed type and this brought the noise back to a more reasonable level.
I'd done a fair bit of ignition testing and came across a cheap ($12!) universal Chinese CDI that had an almost ideal retard curve built in, so I replaced the programmable unit with one of these. This means the ignition no longer needs an external 12v supply for its processor.
The clutch and primary drive were also at their limit so these were strengthened too. The sprockets were remachined to take a larger precision Iwis chain with nearly 50% more strength. I had some steel clutch plates laser cut from thinner material, and some paper-faced Jap friction plates modified to fit. So far all this seems to be holding up without requiring so much spring tension that it ruptures your forearm.
The seat was replaced with a plush (!) one from the TSS road racer. Performance-wise it's starting to get silly and lifts the front wheel at stupid speeds. Lots of noisy, smelly fun and the exact opposite of the sweet, docile Sherpa T. Here are some more crappy phone photos:
#34
_SLEDGE_
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Posted 06 October 2014 - 01:17 PM
That's a beautiful bike. The new seat really sets it off... doesn't look like the most comfortable thing though! haha
Is the new front brake set-up still in the works?
And just out of interest, did these bikes originally have side covers next to the filter? If so any reason you don't run them? Performance? Looks?
#35
_oldjohnno_
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Posted 06 October 2014 - 03:42 PM
That's a beautiful bike. The new seat really sets it off... doesn't look like the most comfortable thing though! haha
Is the new front brake set-up still in the works?
And just out of interest, did these bikes originally have side covers next to the filter? If so any reason you don't run them? Performance? Looks?
Thank you. Yeah, I wouldn't like to spend hours on end on that seat, but normally you don't even notice it. The foam rubber pad does grip the arse well though, so you don't slide around. The factory used suede for the same reason.
I tried some different front brake pads and what I'm running now is pretty reasonable - one or two fingers is enough. I'll still change it at some stage though.
Yeah they did have side covers. Although they were called a GT they were never as rapid as the older Metrallas, just more refined and a bit more modern looking. I like the minimalist look; a bike you can see through. Thats why it's so stripped-down looking compared to the stocker below. I still have the stock bits but unlike the older Metrallas or the TSS road racers these have never been much of a collectors item so I don't feel bad at all about hacking it.
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