Does size really matter....Carbs that is?

[Darrell Taylor]

the inlet size/reed size dictates the answers really,,
on a piston port large inlet manifolds/tracts like large carbs to deliver the required quantitys in the limited inlet time available
on ts1,s with old school big reed valves / inlets big carbs help but dont perform as well as a smaller carb and reed combo
on modded ts1,s with smaller reedblocks or venturised systems small carbs match the performance of bigger carbs ,the bigger carbs show better midrange power on the dyno but display poorer throttle response in use so less power with faster response times can often mean a faster machine i find this the case too often in mx and quad tuning
small reed conversions like the lth reed block like any size carb from 24 to 35 and create good throttle response but power and response and economy is not really bettered than the smallest 24mm carb
the big rb reed /inlet combo likes the bigger carbs plus the crankcase reed intake likes to take the extra full duration intake available

[speedy]

the inlet size/reed size dictates the answers really,,
on a piston port large inlet manifolds/tracts like large carbs to deliver the required quantitys in the limited inlet time available
on ts1,s with old school big reed valves / inlets big carbs help but dont perform as well as a smaller carb and reed combo
on modded ts1,s with smaller reedblocks or venturised systems small carbs match the performance of bigger carbs ,the bigger carbs show better midrange power on the dyno but display poorer throttle response in use so less power with faster response times can often mean a faster machine i find this the case too often in mx and quad tuning
small reed conversions like the lth reed block like any size carb from 24 to 35 and create good throttle response but power and response and economy is not really bettered than the smallest 24mm carb
the big rb reed /inlet combo likes the bigger carbs plus the crankcase reed intake likes to take the extra full duration intake available

Thankyou Darrell, a very informative answer, that has cleared up one or two of my niggling thoughts. With this in mind, I think I shall stay on me 30mm Delly and keep me Amal for a later date. Since you have mentioned the RB, I have a question for a friend over here. He is having a second engine built at present and is going to be putting his RB 225, 58x107,with Franspeed race into another scoot. It currently runs a 35mm tmx mikuni. He was thinking, as he has a spare unused mikuni tm 30mm carb that he thinks will fit under his panel without cutting the SX panel, would it work as good as the 35mm that's on currently on that particular engine. Cheers for the advice, Speedy.

[simonwwfc]

I've got a 30mm flat side mikuni on my Muggelo 200 small block I'd like if poss to change this for a dellorto carb

[tonydevon]

Simon, my muggy 198 smallblock kit was on a 26 dellorto, really worked well, and I eventually managed the 10 miles per litre, far better than my initial attempt at jetting LOL was doing about 5 miles per litre, dyno session paid for itself in petrol just on the ride home LOL

[simonwwfc]

Thanks tony for advice . I just think a 30mm is a juice guzzler plus the amount of fuel spit out of carb onto runners I hate .....il look at a 26 dellorto

[stokky]

I seem to remember that the inlet spigot diameter on all following carbs is exactly the same :-

DellOrto 32
DellOrto 34
Mikuni TM 38
Mikuni TMX35

In which case surely they can only allow the same amount of volume of charge to go through ?????

For my sins am running a Mikuni TM 38 with power jet on one of my bikes !!!!!!!

[simonwwfc]

Just after a bit of advice please if I change my mikuni 30 flat side with power jet 50 on my Muggelo 200 small block kit to a 26mm dellorto will I need to change my carb manifold to suit . Thanks simon

[Darrell Taylor]

the inlet size/reed size dictates the answers really,,
on a piston port large inlet manifolds/tracts like large carbs to deliver the required quantitys in the limited inlet time available
on ts1,s with old school big reed valves / inlets big carbs help but dont perform as well as a smaller carb and reed combo
on modded ts1,s with smaller reedblocks or venturised systems small carbs match the performance of bigger carbs ,the bigger carbs show better midrange power on the dyno but display poorer throttle response in use so less power with faster response times can often mean a faster machine i find this the case too often in mx and quad tuning
small reed conversions like the lth reed block like any size carb from 24 to 35 and create good throttle response but power and response and economy is not really bettered than the smallest 24mm carb
the big rb reed /inlet combo likes the bigger carbs plus the crankcase reed intake likes to take the extra full duration intake available

Thankyou Darrell, a very informative answer, that has cleared up one or two of my niggling thoughts. With this in mind, I think I shall stay on me 30mm Delly and keep me Amal for a later date. Since you have mentioned the RB, I have a question for a friend over here. He is having a second engine built at present and is going to be putting his RB 225, 58x107,with Franspeed race into another scoot. It currently runs a 35mm tmx mikuni. He was thinking, as he has a spare unused mikuni tm 30mm carb that he thinks will fit under his panel without cutting the SX panel, would it work as good as the 35mm that's on currently on that particular engine. Cheers for the advice, Speedy.

speedy

the 35mm and 30 perform the similar but the 35 has much better panel clearance so best to keep 35 on ,theres lots of mods to do to the 30mm mikuni to get it to work well too so i doubt he,ll set it up without major problems occurring

[Lambretta500]

We used to run a 38mm Delorto on the group 7 sidecar 240cc with 220 or 230 main jet, 8petal reeds an water cooled , it run like a dream, well when it ran it ran like a dream if you know what i mean, there's a pic of the engine on here somewhere in a road bike

[Lambretta500]

just found pic its under LC230 ant shows carb