T120 650 cylinder head / two single Dellorto SSI Carbs

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steko

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Hello,

does anyone have experience with two single Dellorto SSI carbs ?
What is about idle adjustment, synchronisation, road performance
and driving behaviour?

Stefan
 
If those are anything like the ones on my '74 Guzzi, they have clever fuel "pumps" inside the needle jet body that give you a nice bit of juice off-idle. I reckon they'd be great with warm or hot cams...
 
The fancy racing 800 8 stud P U Wideline Dunstall Triton where wod Price worked
had 32 Dellortto pumpers on it , way back when .

Even came on B M W s at one stage . were hot sh*t aftermarket conversion in the 70s .
 
T120 650 cylinder head / two single Dellorto SSI Carbs
 
Lack of throttle response is often due to loss of vacuum. I don't think a rapid richening of the mixture is the answer. The quickest acceleration occurs when the mixture is held at a level just before detonation occurs, at all throttle openings. It might be better to adjust to feeding the throttle on in one rapid controlled motion, rather than whacking it open. With road racers, riders of two strokes never have a problem with throttle response because they adjust to the limitations and anticipate. On dirt, things probably don't happen any quicker.
 
acotrel said:
Lack of throttle response is often due to loss of vacuum. I don't think a rapid richening of the mixture is the answer. The quickest acceleration occurs when the mixture is held at a level just before detonation occurs, at all throttle openings. It might be better to adjust to feeding the throttle on in one rapid controlled motion, rather than whacking it open. With road racers, riders of two strokes never have a problem with throttle response because they adjust to the limitations and anticipate. On dirt, things probably don't happen any quicker.
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Re; “With road racers, riders of two strokes never have a problem with throttle response because they adjust to the limitations and anticipate.”. . . . Oh yes they do, particularly if you have a massive pair of 38MM powerjets on a water cooled Yamaha TZ350-that’s 38mm per 175cc cylinder!!! a bigger carb than most car engines have!
 
Some guys have trouble riding bikes which have 'peaky' motors. A four-stroke with a peaky motor can be worse than a two-stroke. Two-strokes usually have less torque when they get nasty. With the older two-strokes, the trouble usually occurs when guys slip the clutch to get them back on song. For anyone accustomed to doing point and squirt, older two-strokes can be very difficult. Later two strokes are designed to be more rideable, so they go faster.
I don't know anything about motor cars, except that they are difficult to high-side.
 
" riders of two strokes never have a problem with throttle response because they adjust to the limitations and anticipate " when its going to sieze ,
allways keeping a finger on the clutch lever .In the 70s anyway .

Actually I rant about this on the Triumph section . Turkeys with C V carbs
were somewhat inept as to the engines requirements when confronted by
a direct action carb.

Incidently , someone who converted a S U to cable / slide reported its
responce too amplified to be rideable .
 
Once you have raced a two-stroke, you tend to always feed the throttle on fairly slowly in a controlled manner. If you whack the throttle open on many two strokes, the motor stops. Some guys ride with no feel for what the motor is doing. What I really like about my Seeley 850, is that it delivers it's best when you feel what it is doing. If you jet and time a four-stroke close enough to the limit, it can behave as badly as a two stroke, however respond to tuning just as well.
 
Re p 10 "if you whack the throttle open on many two strokes, the motor stops.”

Don’t know what you mean, unless you have a gutless two stroke that really is due for the dustbin!
 
Bit late to tell you but the SSi carbs would cost mega money, Don't have a reliable tickover or accelerator pumps and are poorly served with spares now. Well made virtually identical to the Amal TT. As fitted to the Ducati Mach1.
 
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