Hitchcocks Forum

Some Of You Might remember My Mono Block Post and Hinting a Wall (Complete dead Spot at 60mph)...Sensible advice on here was to raise it a Notch or Two / The Main Needle...SO:.....

: I Dived in to The Amal mono Block to day:..........
And raised The Needle to the Top notch! .............
(Dam for got to note What it was on Original Or Needle Size while it was apart, as Carb was easy But every surrounding Nut & bolt was sized Solid )... So Washed Carb in WD40 Resembled and went for a Blast.......................
She Tick's over Nice, is Relatively fast through the Gears, Hits 60mph and will Still (Just) Accelerate further at 70mph She seemed Ok with a Bit Left.... "So THE WALL, Dead at 61MPH " has Gone & She seems OK......................................................
Will Use it as is and Check again SAT....Slightly More Pipe Bluing..And Air Leaver Fine When Warm, But Play with Luke warm at Lights/Junctions.etc....................
I presume the Next step is if all seems ok Drop a Notch to help blueing or Leave as And Check MPG................
.........Cheers all....Craig......(350 AVL)

Hi Craig, Well that is a strange thing, the needle only affects from around 1/4 to 3/4 throttle and should have no bearing on full throttle which is controlled by the main jet only. ----- I feel it is more likely that it is the cleaning or the carb which may have made a difference. Take a look at our hosts tuning motes for the Amal carb if in doubt as to how to set it up.

Hi Dennis,
Well its all New to Me. I Know a bout the Needle ,But It was Recommend as an Easy thing to try.

You might be right about The Little Bits, as Though the Carb(&Bike) is Low Use ,Every Nut and Bolt & Fixing Is Air Gun Tight & as Dry as a Bone......

All working Ok Now, .......So What is Your sujestion with the main needle then?................Oh its For every day Use & Work...Not the Race track on a 350AVL 20005....
Cheers And thanks For your input................Craig

Hi CRAIG}---- The needle normally has small grooves at its' top and standard convention is to number these grooves from top to bottom ie No1 is the top one down to No5 at the bottom. So, using this method ---- where is your clip currently placed ?? I ask this because you say}---And raised The Needle to the Top notch!... Which would mean it's actually now in its weakest position. And the extra bluing on the pipe would tend to support this.ie engine running hotter....I agree with DENNIS C and think that "wall" was ( and probably still is--)a poor transition to main jet running. What is the recommended main jet for your set-up and what do you actually have fitted ?? ----------- PS}-Any advice is given on the assumption that all else is as standard on the machine. Have there been any other changes ( A Monoblock being not standard on a 2005 350 AVL)??

Hi Craig take a look at this tech info I know its for the Concentric but the way the Monoblock works is identical. http://www.hitchcocksmotorcycles.com/pi ... ettors.pdf

Hello Alan & Dennis,

Yes classic mistake Went up needle Not down,
The 350 AVL Came with The open 91009 SILENCER, REVERSE CONE MEGA On,
and Made a Hell of a Noise, was Slightly faster in top But with air Leaver 1/2 Shut (All the while & Wrong Plug in..Prev Owner) Anyway.................

Right as of to Night its In Notch 2 (one up from Bottom)
No marks On Needle only a 0 on the very Top side (or U)..................

689 Monoblock (I Presume) with AIR FILTER, CONICAL, S&B, Direct on carb,
91045 SILENCER WITH BRACKET AND CLIP, UNIVERSAL Fitted at the moment (light Baffle in).........

Will test in the Morning on Way to work........

She Has Certainly improved since a Rinse Out with the WD40 & Light fettle...
0 to 20mph as Slow as My std 350(Classic) But 20 to 50 Quite fast & 70 top But 60 seems Happy.
Now If after Latest Play it Stays as is With out Blueing and decent MPG.. I will be happy.......

Oh it Has a good (Slow) tick over But Takes a fair Time to Warm up So no Air Leaver at all..
She is to Be My ride to work/Commute Bike So If I give Up I might try a Mickarb...But enjoying The "Problem" at the Moment.....

"Thanks For All th Advice "....Cheers Craig

I was one who suggested lifting the needle but it was in order to establish in a quick and free manner whether his acceleration wall was caused by lean mixture. The needle in a perfect world should be on the middle groove and so it seems clear especially in light of the bluing pipe (a sign of leanness) that the main jet which is contained in the big brass nut under the bowl needs opening out or replacing. If you have a set of drills in increments of 0.1 mm then you could start opening out the jet but if you are a bit new to all this then it is probably wiser to simply buy a bigger jet from our host.

Hi Guys---- might I just clarify something here ?? CRAIG--those numbers I mentioned are NOT actually stamped on the needle as such. They are used as a STANDARD REFERENCE so that we all know what we are talking about when discussing tuning etc. For example }--"I moved the needle from the No3 position to the No5 position"----ie I've richened it.... The different positions can be used to "fine tune" the mid-range response of the carb. Each needle TYPE has a different taper (thus response to fueling) and is registered by a letter or number ( this is what you have seen on yours). Performance tuners will have a "master reference chart" for those letters/numbers and can calculate the exact fuel flow-rate and hence air required etc. That's why serious tuners and racers make full use of the modern Dyno-Tester which can pick-up all those tiny adjustments and display/print-out the full performance facts. We, however are on road machines---and very basic ones at that !! ...But the fundamentals still apply. SIMON was quite right to suggest a quick, practical "test" idea---at least it gives us an insight as to what's happening in your engine.... A simple way of calculating the next MAIN JET size is to go up in 5% increments. Have a look in our hosts catalogue for the recommended jets for your machines' set-up. Be guided by your PLUG-CHOP readings. Just because you intend to "potter round town" doesn't mean we can skimp on a proper job, eh ??

JUST "THANKYOU TO ALL FOR YOUR SUPPORT"

It all seems to be working very well at the Moment so i will Leave it a Full Two weeks (or tank Full) & see whats/What...& Study Needle Charts Just in case...
...So Simon, Dennis, Alan..................Cheers & thanks Craig....(AVL & STD )