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Ian C
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#849014 05/15/21 2:05 pm
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Cyborg #849296 05/19/21 5:20 am
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Whilst it's a lovely bit of kit the competition for such a construction would be
TZ750 Yamaha's etc as the wheels brakes and chassis place it into a period
post 1980. A very good exercise in spending massive amounts of money to
achieve very little other than boosting someones ego.
An early Biland yamaha outfit would slaughter it.

NickL #849348 05/19/21 3:29 pm
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Originally Posted by NickL
Whilst it's a lovely bit of kit the competition for such a construction would be
TZ750 Yamaha's etc as the wheels brakes and chassis place it into a period
post 1980. A very good exercise in spending massive amounts of money to
achieve very little other than boosting someones ego.
An early Biland yamaha outfit would slaughter it.

I certainly don’t disagree that it’s an exercise in spending massive amounts of money. If you’re saying that primarily based on the Vincent power plant, there likely isn’t much Vincent in there. Probably limited to things like reproduction valve inspection caps. I honestly don’t know much about the bike, but they claim somewhere around 175 hp. I have no idea how far north of 120hp you could get (reliably) from a TZ750. There is a madman lurking somewhere on this forum who would know. With the torque generated from the “Vincent” , my guess would be that it would help level the playing field.....not sure what the current situation is with the bike.
I stand to be corrected, but I think the main issue with that engine is dealing with the heat.

Last edited by Cyborg; 05/19/21 3:32 pm.
Cyborg #849497 05/20/21 10:12 pm
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"There is a madman lurking somewhere on this forum who would know"
Is that someone calling my name, perchance??
A TZ would kill that, better accelleration, lighter, more nimble, less thirsty.
130 BHP every day reliable from a properly built TZ750 (with not many Yamaha made parts in or on it!) - at least that is what mine makes. Possible to get 135, with more time and money that I could ever find.
IMHO The Irving is just an interesting engineering exercise, at over 1300cc (1440??) -don't know if its on methanol, it should produce lots of power, but that engine size excludes it from every (UK based) race class, however I don't know what the Aussie class limits are, so relegating the bike potentially to a 'special special' - so why do it.
The heads are the main problem, but in keeping it looking 'Vincent' like they have just reproduced the heat problem that the originals have when worked hard - its fixable, but not that pretty!
I also fail to understand the 'Irving Vincent' tag, I know they have a beef about PEI's recoqnition, but he was paid to design stuff, you don't see any castings dor Hopwood BSA, or Hele Triumph or Page Ariel, Irving Vellocette.........

Cyborg #849571 05/21/21 3:03 pm
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At 135hp would it still come with a throttle or just an on/off switch? You guys are nuts....maybe not a complete and utter madman, but you gotta be a little different to pilot one of those things.

I vaguely recall (assuming I recall correctly) reading something about the solo version running on alcohol until they were told they couldn’t and the heat became a real issue.

The thing is an interesting exercise and at the same time doesn’t make a lot of sense, but it makes me wish my pockets were deep enough to do something equally as daft.

Cyborg #849608 05/21/21 10:30 pm
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Phil
What the aussie class limits are and what's raced are two different things.
A clown on an 1800cc hardly held the title for some years in pre 62.
The limit is supposed to be 1300 now i think but there were vinnies about at 1400+ as you say.
Methanol is the fuel of choice for 95% of blokes here we are the only ones i know who don't
use it. (I cant't be bothered to start learning about using it at my age!)
Scrutineers are just there to check safety etc so most stuff is highly illegal really.
They just want to get outfits on the grid so anything goes.
I spent my time in pre 72 class competing with 1200cc honda 4's with 13 inch wheels and slicks etc.
Bit of a joke really.

Cyborg #849896 05/24/21 9:46 pm
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Cyborg, "At 135hp would it still come with a throttle or just an on/off switch?" - very much a throttle - 2k RPM power band, you could go shopping on it it is such a tractable pussy cat (for a stinkwheel).
However if you want 'excitement' put the 700 (2 x 350 heads & barrels) top end on it, piston ported razor sharp power band, when that power comes on you better be hanging on real well! Only problem with that wild tuning is getting the thing to actually start up!!
Running TZs in an outfit requires some attention to fuel system and carburation and radiator size and placement, other wise a cheap (relatively) quick race engine.
"but you gotta be a little different to pilot one of those things" - not really, great fun power sliding the bends, you just need to pay attention all the time otherwise it gets to hurt!! - piloting the 16" sitter taught me a lot in readiness for the Yam - BTW those two wheeled thingies will never catch on.....I mean they don't even stand up on their own!

Nick I understand the reason for Methanol with the heat you guys get down there, and it is easy power - don't bother with jets just use drill sizes!!
I understand your frustration with the classes, rules and need for grid population, I used to enjoy the fun of 'stuffing' supposedly superior kit with my old bus - I raced my historic sitter in the CRMC (1980s), it was fun being on the inside line of a kneeler round Gerrards! and the top of Craner curve.
I have a kneeler chassis for the CRMC events or twisty sprints, just need the time to get the motor together, ho ho.

PS rewatching the video again, it is apparent (to me, eventually) that there is precious little flywheel in that motor - it revs (or not) just like a modern Jap race motor.

Last edited by Twin Pot Phil; 05/24/21 9:48 pm.
Cyborg #849931 05/25/21 5:36 am
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PS rewatching the video again, it is apparent (to me, eventually) that there is precious little flywheel in that motor - it revs (or not) just like a modern Jap race motor.

Actually Phill, i had 400+ grams of tungsten put in the cheeks when it got balanced plus it has a standard a65 flywheel.
I don't like light flywheels myself on outfits as they tend to make the bike die in corners. The motor just revs like that,
it is quite lively to say the least........

NickL #850073 05/26/21 8:56 pm
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Nick, So you have heavier flywheels and it revs on a switch like the Irving outfit? how so?? I am obviously missing something here.
My historic has heavy flywheels but does not pick up or die anything like that (positively lazy TBQH)

Cyborg #850339 05/31/21 10:35 am
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Ahhhh, that would be telling eh?

I suspect the cylinder head has a fair bit to do with it. Mark Parker's handiwork,
I just bolted the old heap together and played with timing and carb a bit.

Cyborg #850376 05/31/21 9:34 pm
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Hmmm, now I know what you mean!
Proper timing helps!
I changed the combustion chambers on the historic, but 'retired' it (for the TZ) before really playing with carburation - something I plan to do something about when it gets dragged out again. Hopefully that will also get the best out of the combustion chambers as well.


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