The begining of a dream

[merv]

...How ever after getting marred and having kids this was no longer possibly money wise. Now I'm still marred, ...

Having met your lovely wife we will put this down to bad spelling rather than a Freudian Slip! 

Good luck Merv. Enjoy the journey.
JJ 

Thanks jj, what I should have said was I am still happily marred 

[merv]

Good morning boys and girls, I have a problem, I know, I shouldn't have started  . But I have so hear goes, my engine had fitted to it the zenith carb which has seen better days, it is all seized up in every which way.  I would like to put an SU carb on it, So I have been looking around and  I can find several to buy, I cant find an elbow to fit an SU carb to the manifold can anybody help in this department

[Manky Monkey]

Hi Merv. Zeniths were fitted on the 750cc engines. You sure you've got an 850?

[Olds]

It's an 850. But the manifold is from a 750 (perhaps also the head ?). So you will also need a manifold as well as the swan neck to fit an SU.
Most folk seem to make their own elbow, otherwise the carb sits very high and fouls the fuel tank. If you make your own elbow, you should be able to use the existing manifold. This also allows you to angle the carb forwards to miss your knee.

[Manky Monkey]

I think the manifolds are the same, except for the position of the 2 studs that the carb heated inlet, (the swan neck), bolts to. They're 90 degrees rotated, compared to the 850. If you look at an 850 manifold you can see the original 750 carb mounting position. So a 750 manifold would work with an SU, but the carb would be turned through 90 degrees. On my own trikes I turned the carb to face forwards, which didn't have any effect on air flow, but cleared the tank & looked better.

[Olds]

Yep, that works well and looks good with a skinny tank and manifold extensions. I take it they were built into the 4 branch exhaust.

[merv]

What is the difference between the 750 and 850 engines and is there a difference between the heads and if there is would it matter much

[hunter]

750 motor.                  850 motor.
Bore 62.50mm.             Bore 62.50mm
Stroke 60.96mm.           Stroke 69.09mm
Comp ratio 7.5:1.           Comp ratio 9.5:1

The heads are interchangable.

[merv]

Thanks for that  Hunter, at least I now know I'm alright with the head I got

[andyrennison]

Lucky you. Ive struggled with my head most of my life     

[Manky Monkey]

Yeah, that particular trike had a 4 into 1 exhaust manifold bought from Ebay. I think it came with integral carb manifold extensions, but on previous trikes I've made my own.

[merv]

Would anybody have any suggestions on what would be a good electric fan to buy, also where to position it i.e. in front or behind. I have found one that will push or pull air. these sort of things I need to know so I can work out how to do the frame 

[Olds]

I would suggest a fan with built in shroud. Are  you intending on putting the rad in front of or behind the front down tubes, or somewhere else ? Putting the fan behind the rad (pulling) will mean that road debris such as small stones will not get stuck between the fan and the rad and cause damage.

[hornet6]

Hi merv. As regards to this problem with the elbow for the carb being dog legged .....its been mentioned before on here. I,me sure if we could get the items together, and make a jig so that the angle of the elbow was perfect and mated up to the su carb, everyones a winner. I,me sure there are some photos on here where someone has made their own.
I,me sure it was just an elbow with a flange either end,turned 90 degrees to each other. To be honest...I would be up for making the jig,and making the item in nice shiny stainless if theres any interested parties out there.   

[Olds]

SU elbow. Not pretty but it's covered in insulation. It's two flanges, a cast iron elbow and a short length of tube. This is about as low as you can go and the tube was needed to clear the tank. The flanges could do with being a bit thicker but it works. (The nuts between adaptor and manifold were just to check clearances )