02 Tuning 1

Tuning 1, Anleitungen / Erklärungen, Auszug ..

There are five individual steps to tuning:

• 1st in sequence- Full Throttle:
At full throttle you are working with the main jet.
If it is a stock bike use the main jet recommended by the manufacturer.
If you have raised the compression start about three jet sizes larger than stock and work back down.
• 2nd in sequence- Idle:
At idle you are working with the pilot jet, pilot air screw.
With most Amal’s you start with the screw out 1 1/2 turns from lightly seated.
• 3rd in sequence- 0 to 1/4 throttle:
At 0 to 1/4 throttle you are working with the slide cutaway, needle jet i.d. and pilot air screw.
Typically a dual carburetor bike I will start with a # 3 and a single carburetor with a # 3 1/2 slide.
• 4th in sequence – 1/4 to 3/4 throttle:
At 1/4 to 3/4 throttle you are working with the needle jet just as the taper starts on the needle,
taper itself and needle clip position.
Without any information to work with start in the middle notch.
• 5th in sequence – Slide Cutaway:
Adjust the slide cutaway for a smooth transition from the idle to the main carburetor.
IT It is not required to ride the motorcycle to adjust the slide.
You should be able to turn the throttle briskly from closed and have the engine respond in kind.

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Recommended starting main jets
based upon Concentric 4 stroke by venturi:

1038   38mm    380

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Tuning The Carburetor:

Too Rich Condition
• White Plastic Float Level Too High — Raise float needle seat in bowl.
• Stay-up Float Level Too High — Carefully bend the float tang.
• Old style white plastic float “Sunk” full of gas — Replace Float.
• Main Jet Too Large— Install lower number main jet.
• Slide Cutaway Too Low— Install slide with higher cutaway (# 2 is Rich while a # 4 is Lean).
• Needle Jet Too Large— Measure needle jet replace if worn, or if not worn, install needle jet with lower number.
• Wrong Needle Jet Type— Install correct needle jet.
• Needle jet cross drilled hole too small.
• Needle Clip Too Low— Raise Needle Clip to higher groove.
• Wrong Needle— Check motorcycle specifications.
• Wrong Spray Tube— Replace spray tube with leaner type – straight cut.
• Pilot Jet Too Large or Missing— Install smaller number jet.
• Pilot Air Screw too far In— Turn pilot air screw out.
• Choke On— Turn choke off.
• Fuel Leaking Past Float Needle— Fine rust in fuel – Clean fuel tank, filter and/or replace float needle.

Too Lean Condition
• Float Level too Low— Lower float needle seat in bowl.  
• Stay-up float used with brass needle (use aluminum).
• Float Bowl Gasket Surface Warped— Replace or flatten surface.
• Main Jet Too Small— Install higher number main jet.
• Slide Cutaway Too High— Install slide with lower number.
• Needle Jet Too Small— Install needle jet with larger number.
• Needle Jet Cross Drilled Hole too Large— It should measure .035″ if larger replace needle jet.
• Wrong Needle jet type— Replace needle jet check spec’s.
• Needle Clip Too High— Lower needle clip to lower groove.
• Wrong Spray Tube— Replace spray tube with richer type: Stepped or slanted.
• Pilot Jet Too Small or Blocked— Clean or replace jet.
• Idle Fuel Circuit Blocked— Clean.
• Idle Transfer Ports Blocked— Clean.
• Pilot Air Screw Too Far Out— Turn screw in.
• Fuel Tank Cap Vent Blocked— Clean.
• Fuel Petcocks Too Small or Blocked— Clean or replace as necessary.
• Float Bowl Vent Blocked or Restricted— Open vent.
• Orifice In Float Needle Brass Seat Too Small— Replace with larger orifice.

TIP: If you have a stock 4 stroke bike kitted with Concentric carburetor of the proper size with a:
• 0.016″ (standard) pilot jet,
• 622/122 0.106″ needle jet,
• standard 622/124 2 ring needle in the #2 (middle) position,
• 3 1/2 slide if a single carburetor model,
• or 3 slide if a dual carburetor model,
• and main jet from the workshop manual.
You will be very close to perfect fuel air mixture in all 4 fuel air circuits. All you should have to do is some fine tuning
like raising or lowering the needle or a slightly leaner or richer main jet.

The new Amal Premier Carburetor.
Tuning the Premier Concentric follows the same procedures as the earlier Concentric.
here are a couple of things that are different. There is a new anodized aluminum slide.
The cutaways match the earlier pot metal slide.
The pressed in pilot jet is replaced with a new screw in jet. This jet allows easy changing, or cleaning.
The standard Premier pilot jet is .017′ (2 annular lines). In spite of information on the internet,
it is mostly Norton 850’s that work better with a .019″ (3 annular lines).
The new carb comes with a new Stay-up float. Because of some dimensional changes from the original white plastic
float they should be used with an aluminum float needle. Also these dimension changes require the top of the float
be aligned with the top edge of the bowl.

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Quelle download

Vintage Bike Magazine » Amal – A comprehensive look Kompletter Artikel als .pdf, 1.1 MB, in Englischer Sprache

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