New AMAL setup question - Triumph Forum: Triumph Rat Motorcycle Forums
» Main Menu

Discussion Forums
 » Twins
 » Tiger
 » General
 » RAT

Features
 » Blogs

Motorcycle.com Links

Contribute
 » Photo

Motorcycle Forums
» Insurance
» Sponsors
» Our Partners
»ATV Reviews
»Motorcycle Games

Classic, Vintage & Veteran For Coventry and Meriden Models. Anything pre-Hinckley goes.

Reply
 
LinkBack Thread Tools Display Modes
Old 12-12-2012, 05:31 AM   #1 (permalink)
Senior Member
Supersport 600
Main Motorcycle: X.2007 Triumph Rocket III
 
Join Date: Feb 2009
Location: Melbourne, Australia
Posts: 158
Other Motorcycle: X. 1971 Bonneville T120R
Extra Motorcycle: X. 1996 Yamaha TRX 850
New AMAL setup question

Hello folks,

I have fitted my new AMAL 930's to my t140v 1977 after a top end rebuild, so still running in.

Timing is fixed (thanks to all for the help).

So, back to the Amals. They are brand new, with a main jet 200, needle 106 on the middle clip and pilot bush valve 3. According to the manual, the standard main jet should be smaller at 190.

Here's how she runs.

Start and idle - fine.
1/8 speed, slowtake off - fine
18 - 1/4 speed, hesitate, then slow acceleration
1/4 - 1/2, lumpy and horrible - like its on running on one cylinder
1/2 to full, will not rev to full, lumpy and horrible - like its on running on one cylinder.

Everything gets worse as she warms up/gets hot.

Plugs are sooty.

Will dropping the size of the main jet to 190 or 180 make that much of a difference?

Any other things I should try?

Cheers,

Richo
RICHO is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 12-12-2012, 07:11 AM   #2 (permalink)
Lifetime Premium
Site Supporter
Formula Extreme
Main Motorcycle: T100R Daytona special
 
Join Date: Mar 2010
Location: The Land of Oz
Posts: 713
Other Motorcycle: Ducati 748/853
Extra Motorcycle: Cagiva Mito
Oz ulp makes them run rich, I went down a jet size on my needle jets to 105's on the Daytona to get things crisp

This from my recent build thread:http://www.triumphrat.net/members-re...ml#post2170145

Getting the jetting right with ulp... who else has had the privilege of setting up a pair of non standard carbies with the bloody stuff ?

After the second build I removed the 626 Amals (a mismatched pair) and fitted a brand new set of 900 series 28mm Wassels.
These came setup std with 180 mains, 3 slides, 106 needle jets and needles in the top groove., ran like crap, made black porridge on the piston tops and felt like the cylinders were full of slow burning wool.
I tried different main jets and every needle clip combination to no avail.
2 weeks later and I'm now finally cooking hard brown/grey/black carbon on the piston crowns and can run flat out for an hour in 100 degree temperatures with no issues on BP Ultimate 98 ron unleaded.
I gave up trying to get intelligent plug reads with ulp and started reading direct from the piston crowns with a cheap usb plug in boroscope.
What did I end up with?
Well a phone call to Preston at British Bike Spares in Brisbane to ask did they in fact stock 105 needle jets revealed a well known Norton Commando tuner in Cairns now routinely fits 105 needle jets to all the bikes that came with 106's so he had a good supply of them in stock so that was my first clue.

Further digging told me that BP Ultimate and Shell Vortex, the locally available high octane (98 ron) fuels here will both cause rich running right through the range on carburetter engines due their increased density over the old leaded and lead replacement fuels. (I found details of that on the BP and Shell websites)

Enlarged hi-res photos of the spark plugs also showed slight traces of alloy balls on the insulators caused by detonation, so I knocked the timing back to 37 degrees which completely cured that one.

I ended up with #3 slides, 105 needle jets, needles in the middle position, a 170 jet main on the right cylinder and a 160 main jet on the left cylinder.
Don't ask me why it needs different main jet sizes... I don't know.
Since the initial startup this has been the case with this engine, the valves all seal perfectly, the compressions are dead even, the tappets are set identical the timing is the same on both cylinders with the TriSpark ignition.. So, it is what it is although a half jet size smaller on the right cylinder would make it almost perfect.


Your definitely running rich, but do double check the float levels before making any adjustments or other changes.
Old Cafe Racer is online now   Reply With Quote Quick reply to this message
Old 12-12-2012, 07:35 AM   #3 (permalink)
Senior Member
SuperSport
Main Motorcycle: T110 Triton
 
Triton Thrasher's Avatar
 
Join Date: Nov 2012
Location: Darkest Pulteneytown
Posts: 1,232
Drop the needle and try that for your midrange response, then try a smaller main jet. If that helps full throttle, go down one size at a time until no further improvement.
Triton Thrasher is offline   Reply With Quote Quick reply to this message
Old 12-12-2012, 08:26 AM   #4 (permalink)
Moderator
Moto Grand Prix
Main Motorcycle: T120V
 
Caulky's Avatar
 
Join Date: Jun 2008
Location: Isle of Wight England
Posts: 2,820
Other Motorcycle: 1960 Tiger Cub
Extra Motorcycle: 1971 Bsa A65L
You need to lean out the mixture.
As the plugs get sooted-up it will run crap.
If its very rich at tick-over, its already too late.
Clean the plugs.
Do one thing at a time.
Clear the piot jets, 0.016" guitar string. (file the end to remove burrs)
Set the mixture screws to 1 1/2 turns out to start with.
Check the float levels .080" below the cusp, by pressing on the tang lightly].
MY spares book calls for mainjet 210 for T140V
Does it smoke?
Try a higher octane fuel.
How`s your battery voltage?
Have you strobed the timing?

Caulky is online now   Reply With Quote Quick reply to this message
Old 12-13-2012, 06:04 AM   #5 (permalink)
Member
Grand Prix 250
Main Motorcycle: Vincent
 
Join Date: Feb 2009
Location: Eastern Pennsylvania
Posts: 66
Other Motorcycle: Many
First off, assuming everything else is correct (valve lash, timing, compression, etc...) you can only tune carbs one way. You must start with the main jet. When you get that right you move to the needle, and then finally to the pilot. If you try to do them out of order or more than one change at a time, you will chase your tail forever. Definitely sounds like the main is to big, but you have to do a plug chop at WOT to find out for sure with fresh plugs. Dial in the main jet and then move on the next jet.

Rob
mach1970 is offline   Reply With Quote Quick reply to this message
Old 12-13-2012, 07:13 AM   #6 (permalink)
Moderator
Moto Grand Prix
Main Motorcycle: T120V
 
Caulky's Avatar
 
Join Date: Jun 2008
Location: Isle of Wight England
Posts: 2,820
Other Motorcycle: 1960 Tiger Cub
Extra Motorcycle: 1971 Bsa A65L
Quote:
Originally Posted by mach1970 View Post
First off, assuming everything else is correct (valve lash, timing, compression, etc...) you can only tune carbs one way. You must start with the main jet. When you get that right you move to the needle, and then finally to the pilot. If you try to do them out of order or more than one change at a time, you will chase your tail forever. Definitely sounds like the main is to big, but you have to do a plug chop at WOT to find out for sure with fresh plugs. Dial in the main jet and then move on the next jet.

Rob
Sorry Rob, not according to Amal. (and my experiences).
It`s possible that the main jet is too small.
By the time the engine is warm enough to do a plug chop,
if the low-rev (starting) circuit is very rich,
the plugs will already be fouled with soot, AND the motor will be electrically misfunctioning.
But, given the state of modern fuel, do take note of what Old Cafe Racer says below.

Caulky is online now   Reply With Quote Quick reply to this message
Old 12-13-2012, 07:25 AM   #7 (permalink)
New Member
Minitwins
Main Motorcycle: Triumph
 
jwitt's Avatar
 
Join Date: Oct 2011
Location: Pensacola, FL
Posts: 11
Other Motorcycle: Yamaha Roadstar
Extra Motorcycle: Honda CB750 SOHC
Are the chokes all the way up?
jwitt is offline   Reply With Quote Quick reply to this message
Old 12-13-2012, 08:06 AM   #8 (permalink)
Lifetime Premium
Site Supporter
Formula Extreme
Main Motorcycle: T100R Daytona special
 
Join Date: Mar 2010
Location: The Land of Oz
Posts: 713
Other Motorcycle: Ducati 748/853
Extra Motorcycle: Cagiva Mito
I do feel the OP's dilemma, after a top end rebuild a WOT plug chop isn't really an option till things loosen up a bit so where to start?
(just been through that scenario myself)
.
Old Cafe Racer is online now   Reply With Quote Quick reply to this message
Old 12-13-2012, 03:07 PM   #9 (permalink)
Moderator
Team Owner
Main Motorcycle: Rickman T120
 
Join Date: May 2010
Location: Victoria Australia
Posts: 4,198
Other Motorcycle: T160,TR6
The main jet size won't have any effect below 3/4 throttle.
Make sure the choke slides are pulled fully up by the choke cable,or just remove the choke slides and plug the hole in the carb top.If you plug the hole,make sure whatever you plug it with can't come loose and damage the engine.

If it 8-strokes at full throttle with 200 mains,try 180.2 sizes less than the smallest jet that causes 8-stroking is usually about right;it's a lot easier and quicker than trying to read plugs.
Mr.Pete is online now   Reply With Quote Quick reply to this message
Old 12-13-2012, 06:14 PM   #10 (permalink)
Senior Member
Supersport 600
Main Motorcycle: X.2007 Triumph Rocket III
 
Join Date: Feb 2009
Location: Melbourne, Australia
Posts: 158
Other Motorcycle: X. 1971 Bonneville T120R
Extra Motorcycle: X. 1996 Yamaha TRX 850
Quote:
Originally Posted by Mr.Pete View Post
The main jet size won't have any effect below 3/4 throttle.
Make sure the choke slides are pulled fully up by the choke cable,or just remove the choke slides and plug the hole in the carb top.If you plug the hole,make sure whatever you plug it with can't come loose and damage the engine.

If it 8-strokes at full throttle with 200 mains,try 180.2 sizes less than the smallest jet that causes 8-stroking is usually about right;it's a lot easier and quicker than trying to read plugs.
Ok lads, progress so far. Totally disassembled my carbs, checked the main jet was cleared, removed the chokes and choke cables (do we really need a choke in Australia's climate?) checked the float levels, reassembled the carbs with the clip at the top ring and needles dropped as low as possible.

Checked and reset valve clearance front and back - inlet was tight, possibly incorrectly set by me to the ex setting?

Changed the fuel to BP 98 (had Shell 98 - now a no-no, apparently).

Tuned the carbs for tick over and 1/8th throttle - is now approx 2 and 1/4 turns - not as rich as it was. Seems to idle quite happily now.

Inserted new, hotter plugs NKG B6ES - went for a short run and she revved and pulled as hard as I was prepared to go considering I'm running her in.

Running rich appears to be my perpetual issue, so if this hasn't worked, it's the 180 mains and back to a middle clip on the needle?

I don't want to introduce too many variables into the equation or I'll get lost chasing my tail.

Overall, feeling less frustrated.
RICHO is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Triumph Forum: Triumph Rat Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter your valid email address, that can receive an automated confirmation message. Otherwise, you won't be able to gain full access.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Amal mk2 jet question stevelak1 Classic, Vintage & Veteran 5 05-19-2010 07:16 AM
Carb setup question slam Hinckley Classic Triples 22 02-02-2010 05:24 PM
AMAL Choke setup RICHO Classic, Vintage & Veteran 3 09-27-2009 02:56 AM
Amal setup on Trophy 650 terdah2 Classic, Vintage & Veteran 1 01-17-2009 10:26 AM
New '08: Suspension Setup Question CYNCRZR Speed Triple Forum 9 05-14-2008 04:14 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 10:22 AM.



Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Forum Honda 600RR Kawasaki Forum Yamaha R6 Forum Yamaha FZ-09 Forum
1199 Panigale Forum Roadglide Forum Honda CBR1000 Forum Vulcan Forum Yamaha R1 Forum Yamaha R3 Forum
Ducati Monster Forum Harley Forums Honda CBR250R Forum ZX10R Forum Star Raider Forum Yamaha Viking Forum
Suzuki GSXR Forum V-Rod Forums Honda Shadow Forum Kawasaki Motorcycle Forum Star Warrior Forum KTM Duke 390 Forum
SV650 Forum BMW S1000RR Forum Honda Fury Forum Kawasaki Versys Forum Drag Racing Forum Ducati 899 Panigale Forum
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes BMW NineT Forum
Volusia Forum BMW F800 Forum Triumph 675 Forum MV Agusta Forum HD Street Forum Suzuki GW250 Forum
Yamaha Motorcycles Victory Gunner Forum Honda Vultus Forum HD LiveWire Forum

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

Search Engine Optimization by vBSEO 3.6.0