Single carb on a twin.

[brother jake]

I once had a Triumph TR7 750 single carb tiger, it ran good with a dunstall 2 into 1 back out into 2 on it.
Now the Triumph was 360 degree crank which allows longer intake time than a single carb 180 degree engine has.
Honda did some single carb models with 360 cranks and yet went to the trouble of twin carbs on the 180 degree cranked versions of the same basic engines.
Now i do not have a project 180 degree cranked twin i want to fit single carb on, but i would like to hear from anyone who has tried this type of conversion .
I realise such conversions will lose power and the nature physics of the 180 crank will make for fuelling problems in theory. But in reality is this short period in time of the180 degree crank enough to allow practical performance from single carb on a 180 cranked twin.

There are various threads on the www videos on conversions and much debate some of it quite heated all of it inconclusive .
Anybody done it or any thoughts on the matter. ?

[Grumph]

If it's an en500 as per your heading, I wouldn't do it. Smaller capacity 180 twins yes, not a lot of difficulty or power loss.
Bigger capacity, bigger losses. I reckon you're just past the crossover point where it's not worth it.

[FJRider]

If it's an en500 as per your heading, I wouldn't do it. Smaller capacity 180 twins yes, not a lot of difficulty or power loss.
Bigger capacity, bigger losses. I reckon you're just past the crossover point where it's not worth it.

It would be easier to turbo it with the single carb though ...

[brother jake]

Thanks for the reply grumph appreciated, and i had no intentions of single carbing the en500. it is running well on the stock carbs as it is and i do not want to lose any power from that bike if i can avoid it.
I did quite fancy trying a single amal 930 on an old GS500 suzuki at some point , but will shelve that now, i am relieved in a way having a triumph trophy 900 build on the go at the moment
i have plenty to do on that without taking on more work.

[brother jake]

It would be easier to turbo it with the single carb though ...

And just when i had cleared any thoughts of any single carb projects, Now a turbo charged 500 Kawasaki on a single amal, i might just give up the 500 power for project like that.

[FJRider]

And just when i had cleared any thoughts of any single carb projects, Now a turbo charged 500 Kawasaki on a single amal, i might just give up the 500 power for project like that.

Lateral thinking my friend ... or just plain thinking outside the square. Either way ... might be fun ...

[jellywrestler]

Lateral thinking my friend ... or just plain thinking outside the square. Either way ... might be fun ...

there's a book on thinking outside the box, it's for recovering sex addicts i'm told.

[FJRider]

there's a book on thinking outside the box, it's for recovering sex addicts i'm told.

I was going to join a fathers group ... but I pulled out ...

[brother jake]

[brother jake]

Lateral thinking my friend ... or just plain thinking outside the square. Either way ... might be fun ...

Oh it would be fun , no doubt about that.

Google link to just such a turbo conversion. this feels like it could get expensive already.

part 1 gpz 500 turbo

https://youtu.be/H2DbQjASmRE

[Grumph]

Without looking at that link, don't do it....Due to some inherent problems with the EX/EN 500's you're limited to a low boost. Probably more cost effective to put a 650 in the bike...

At 15lb boost the heads walk on the barrel, the barrel walks on the cases and water gets where you don't want it....Been there thanks. Fun when it ran well though.

[BMWST?]

i am not really knowledgeable enough but i dont see why it would not work,after all just about every carbed car was a single carb on a manifold for up to eight cylinders!

[FJRider]

i am not really knowledgeable enough but i dont see why it would not work,after all just about every carbed car was a single carb on a manifold for up to eight cylinders!

Often multi throat though ...

[Grumph]

i am not really knowledgeable enough but i dont see why it would not work,after all just about every carbed car was a single carb on a manifold for up to eight cylinders!

Not to be insulting but you're right - you're not knowledgeable enough. Car engines of four or more cylinders will have a pretty constant draw on a single carb due to the evenly spaced firing intervals.
Twins in cars (fourstroke) have invariably been 360 degree cranks - so even firing intervals which lets you use a single carb.
The staggered firing intervals in a 180 deg twin will inevitably result in one cylinder losing out due to poor distribution of the mixture.
And as I said before - the bigger the cylinders involved, the bigger the problem.

[brother jake]

Without looking at that link, don't do it....Due to some inherent problems with the EX/EN 500's you're limited to a low boost. Probably more cost effective to put a 650 in the bike...

At 15lb boost the heads walk on the barrel, the barrel walks on the cases and water gets where you don't want it....Been there thanks. Fun when it ran well though.

Oh! Well every cloud has a silver lining and all that rhetoric,
At least i wont be getting dragged off my Triumph and in reality that needs all the help it can get.
The En500 based on the old half a ninja 9. 454 motor, is a breathed on for a 500cc, the 650cc is a stronger engine i was once told, And now you have told me so thats twice . .