Hi what is the best triumph pre unit engine to use with Morgo 750 barel and pistons, I also have a twin carb 9 stud head, but I do not think any old pre unit mix match will do, any prefered cam and folowers? also there seems so be a bit of a mess about using composit cranks and 5t big bearing crank cases, I was thinking perhaps a late 6t or triumph t110 engine 59 or 60 era would be the best bet?
Making a triton
- Thread starter malfosse
- Start date
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- Jul 25, 2010
- Messages
- 5,897
3 piece cranks a no-no . Though with titanium bolts ?? Left shift cranks metric bearings , but will turn down to std .
72 Crank is 72 % ballance , Squareish profile X section flywheel & counterweights.Is factory raceing balance factor .
Commando cranks have been fitted to B.S.A.s , 1/4 steel plate centre with bolt on counterweights , 270 deg.set-up.
Gets you a 7mm stroke increase.
Dunno if the 722cc 750s still had the long rods , if your going for a rev'er , a Big Bore Kit on a 650 has a better
length / stroke ratio in the rods. To much angularity limits revs through side thrust on pistons .
A good 650 can be got to rev past 8.000 something like reliably .
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Wide Lne frame ?? RIDGID chain Case gets optimum motor / box positioning , even in slimline .
One in Aus. was 800cc 8 stud , streamlined , dunstall discs , 32 Dellorottos. 159 mph down conrod.But on Methanol .
Used This motor / box spaceing , Dunlor KR raceing tyres .
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Really you need to look at the use it will be put to on decideing spec . Road Bike , Hillclimb ? Raceing ?
Clean , mint , matching big bearing cases mandatory . 5T may machine out for sleeves if base stud pattern matches .
Anything over the 0.5:1 pisrtons mask combustion , and make things awkward .
Close Ratio Triump box or re worked ( re ratioed ) 5 speed is a better place to start .
60s cams were less ' square ' than late ones though two of the right ( int or ex ? ) Left Foot ones are equivilant of 73 ' hot ' cams .
W&S spring set ( for Yam XS 550 - 750 4 valve ) fit Tri & Comm. and are fine for past 8.000, & come with race quality fittings & shims .
Degreeing cams , 3/8 gear wheels , drilled ? & polished . 750 oil pump ( reversed or Hi Capacity job , a decent Magneto ( SR2 ! )
short roadholders & good shocks , Progressive rate springs F & R are better priorities than a irrascible motor .
Frame will break without a head steady .
Most exhausts are trash, Hi Pipe was Std on later Manxes .
Late rods are heavier and slow accelleration .
P.M. for 8 stud tuneing specs .
Were some 8 stud heads about a time ago , early series cracked . 61 cast mark wont unless abused . A good T110 61 or 62 or T120 C or R
if available .
:cry: or build to specs from ground up. LOW TIME parts preferable.Triumph lifed rods @ 60 Hr.
Some ' N.O.S. ' parts COULD be production seconds / cast offs that wernt scrapped .
Left Shift Bing parrallel intake Bonnie Head was only worthwhile part THEY produced ( Co-Operative . Co operating with Wot . Idiot polititions to the tune of 14.000.000 pounds . :shock:
Leave of the Jap Parts . They all fell off the Bonnie inside of a week , usually . :?
72 Crank is 72 % ballance , Squareish profile X section flywheel & counterweights.Is factory raceing balance factor .
Commando cranks have been fitted to B.S.A.s , 1/4 steel plate centre with bolt on counterweights , 270 deg.set-up.
Gets you a 7mm stroke increase.
Dunno if the 722cc 750s still had the long rods , if your going for a rev'er , a Big Bore Kit on a 650 has a better
length / stroke ratio in the rods. To much angularity limits revs through side thrust on pistons .
A good 650 can be got to rev past 8.000 something like reliably .
----------------------------------------------------------------------------
Wide Lne frame ?? RIDGID chain Case gets optimum motor / box positioning , even in slimline .
One in Aus. was 800cc 8 stud , streamlined , dunstall discs , 32 Dellorottos. 159 mph down conrod.But on Methanol .
Used This motor / box spaceing , Dunlor KR raceing tyres .
----------------------------------------------------------------------------
Really you need to look at the use it will be put to on decideing spec . Road Bike , Hillclimb ? Raceing ?
Clean , mint , matching big bearing cases mandatory . 5T may machine out for sleeves if base stud pattern matches .
Anything over the 0.5:1 pisrtons mask combustion , and make things awkward .
Close Ratio Triump box or re worked ( re ratioed ) 5 speed is a better place to start .
60s cams were less ' square ' than late ones though two of the right ( int or ex ? ) Left Foot ones are equivilant of 73 ' hot ' cams .
W&S spring set ( for Yam XS 550 - 750 4 valve ) fit Tri & Comm. and are fine for past 8.000, & come with race quality fittings & shims .
Degreeing cams , 3/8 gear wheels , drilled ? & polished . 750 oil pump ( reversed or Hi Capacity job , a decent Magneto ( SR2 ! )
short roadholders & good shocks , Progressive rate springs F & R are better priorities than a irrascible motor .
Frame will break without a head steady .
Most exhausts are trash, Hi Pipe was Std on later Manxes .
Late rods are heavier and slow accelleration .
P.M. for 8 stud tuneing specs .
Were some 8 stud heads about a time ago , early series cracked . 61 cast mark wont unless abused . A good T110 61 or 62 or T120 C or R
if available .
:cry: or build to specs from ground up. LOW TIME parts preferable.Triumph lifed rods @ 60 Hr.Some ' N.O.S. ' parts COULD be production seconds / cast offs that wernt scrapped .
Left Shift Bing parrallel intake Bonnie Head was only worthwhile part THEY produced ( Co-Operative . Co operating with Wot . Idiot polititions to the tune of 14.000.000 pounds . :shock:
Leave of the Jap Parts . They all fell off the Bonnie inside of a week , usually . :?
SteveMinning
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- Mar 30, 2008
- Messages
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I have a 6T lower with a Morgo kit and 1968 Bonneville head. The trick is getting the right lifter blocks and pushrod tubes. You have to play around until you get the correct 'gap' between the head and cylinder. There are a number of posts about this on Britbike.com. Go to the Triumph section and start searching and you'll see some in-depth discussion on getting the clearance between the head and cylinders right.
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