Britbike forum

Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesThe Bonneville ShopLowbrow CustomsSRM EngineeringGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership: Premium Membership Gold Membership


New Sponsor post
Cyber Monday Sale - 10% off at The Bonneville Shop
by The Bonneville Shop - 11/29/21 5:34 pm
New FAQ post
How to find my own threads?
by reverb - 11/20/21 3:55 pm
Manuals on DVD - Buy 4 for 3
All 4 DVD Manual
Member Spotlight
MikeJ
MikeJ
San Mateo, CA USA
Posts: 33
Joined: March 2017
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
NickL 79
Rohan 73
Top Likes Received (30 Days)
Newest Members
old ion limey, muzz750, Motorcycles and Art, SteveDee, Gus_Carrero
11,924 Registered Users
Who's Online Now
11 members (KevRasen, desco, D.Bachtel, wilksville, John Harvey, Spitfire Ken, Magnetoman, triton thrasher, konon, M.Gunderson, Stuart Kirk), 44 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
#860810 10/15/21 3:06 pm
Joined: Jul 2021
Posts: 3
P
Paul C. Offline OP
Novice poster
OP Offline
Novice poster
P
Joined: Jul 2021
Posts: 3
I rebuilt the original carbs on my 71 Bonneville. No matter how much adjustment, I simply can't get the bike to idle smoothly. I have checked the pilot jets and nothing seems to be constricting flow. I'm noticing I'm not getting any fuel to come out when I tickle the right carb. The carbs have the original floats still in them. Is this a float issue with the right carb? Will a new float help the idle circuit?

Triumphs on eBay
Joined: Aug 2001
Posts: 8,809
Likes: 101
T
Britbike forum member
Online Content
Britbike forum member
T
Joined: Aug 2001
Posts: 8,809
Likes: 101
Tickler not flooding is usually the roll pin in the bottom of the tickler button needing to be pulled out a little bit.

Or a float level that is too low, but why would that happen?

How do you know the pilot jets are not blocked?

Last edited by triton thrasher; 10/15/21 4:49 pm.

Amateur Loctite enthusiast.
Joined: Aug 2016
Posts: 384
Likes: 37
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Aug 2016
Posts: 384
Likes: 37
The pilot jets are just part of the story, those tiny holes fore and aft of the trailing edge of the slide must be clear too.

Joined: Nov 2005
Posts: 7,888
Likes: 57
Born To Run
Offline
Born To Run
Joined: Nov 2005
Posts: 7,888
Likes: 57
To adjust the roll pin on the tickler I use a pair of side cutters. Push down on the tickler button and grasp the roll pin tight to the carb body with the side cutters. Using the bottom of the carb body as a fulcrum point, gently lever the roll pin out enough so the roll pin can contact the float, lift the float needle and flood the bowl.

Steve


'77 T140J Silver Jubilee
'82 T140ES TMA Royal
‘69 BSA Rocket 3 (patiently awaiting it's turn)
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Joined: Jan 2017
Posts: 1,831
Likes: 91
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,831
Likes: 91
Hi Paul, First off, original plastic floats are a disaster with modern USA fuels. Any Ethanol at all in fuel will soften float, the tangs will skew & float level will go too high. Float level has direct effect on mixture across the board. Correct float level & proper sealing float needle are imperative.

No tickle is clue something is amiss. Did it used to tickle?

All that aside. Does mixture screw change the way runs at idle. Meaning screwing in/out you should hear mixture change. Does rpm change with idle screw.

Looking a little deeper. For good idle the rest of the motor must be in good condition. Meaning valve adjustment. Point gap, if points are fitted. Timing. Spark plugs & plug wires, coils, etc. meaning good spark. Proper battery voltage to ignition system is critical. Finally compression must be good. Cold compression test doesn't mean much. Warm motor best you can before testing. A little low due to ring/bore wear you can often live with. Leaking compression by valves will almost always result in poor idle.

Tuning motor, including getting good spark is first step. You may have already that. Then move to carbs.

Also sync of carb slides is important. One slide too high that cyl does most the work even though rpm is ok. This results in poor idle as well. Lots to think about.
Don


1973 Tiger 750
Joined: Nov 2005
Posts: 7,888
Likes: 57
Born To Run
Offline
Born To Run
Joined: Nov 2005
Posts: 7,888
Likes: 57
Some good reading and info here:

http://vintagebikemagazine.com/technical-articles/AMAL/

Cheers,

Steve


'77 T140J Silver Jubilee
'82 T140ES TMA Royal
‘69 BSA Rocket 3 (patiently awaiting it's turn)
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
Joined: Oct 2012
Posts: 6,036
Likes: 181
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 6,036
Likes: 181
This is what AMAL had to say in 2017....More or less they are saying E10 is ok in their carbs....
http://amalcarb.co.uk/ethanol-fuels


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jan 2017
Posts: 1,831
Likes: 91
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,831
Likes: 91
Hi, Funny they say effects plastics. I can say with 3 different bikes using California E10 with in 2 months the original plastic floats go soft. Putting float on bench a few weeks it rehardens, but retains the new distorted shape. Yet banjo screen is in effected. These bikes were in long term storage before E10 was sold.

Absolutely ethanol has more octane, thus Indy cars & other racers burn 100%. It takes about twice as much 100% ethanol as gas. On the Harley hill climb bikes we started by doubling all jets. For our motors, they like high octane. No matter how they put it in fuel they want it. Generally speaking in California going about 5% larger on jets across the board, lowering needle a notch gives improvement. Modern motors have oxygen sensors which automatically compensated. FFV are interesting. The very sensitive oxygen sensor picks up on very different O2 in fuel burning. Computer sees this & has internal map that compensates. Normal motor O2 sensor goes out of range. Defaults to fixed parameters map & turns on check engine light.

They incorrectly say USA introduction of E10 didn’t cause many problems. Not the case in our Dealership. We ran 100-125 cars a day through shop. We replaced fuel hoses, fuel pumps. Tank strainer orings, injector orings by the hundreds. Plus rubber diaphragms in fuel accumulators tire like mad.

AMAL developed the stay up float & viton tip needed specifically for ethanol blend fuels.

Once you compensate for modern fuel AMAL carbs work great. They really do.
Don


1973 Tiger 750
Joined: Oct 2012
Posts: 6,036
Likes: 181
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 6,036
Likes: 181
The Jalopy Journal is the largest hot rod car forum on the internet..US pushrod V8's mostly with the usual multiple carb etc. The cut off is 1965 so there's plenty of vintage stuff. The ethanol fuel debate comes up from time to time and it's always the same, about half the replies are trouble,the other half is no trouble. Some replies are just blaming ethanol for an engine in bad tune. Some places in the upper midwest have had E10 since the late 1970's and no one complained until years later when they found out...
The nature of the internet is you never know who is being honest...I have seen E10 leave deposits in carbs and so on but nothing much more than that... I use non ethanol in the bikes and small engines. I did use E10 in the many vintage trucks I had with no problems even after winter storage .....
Don ,you worked primarily on imported cars? My fleet of Jeep's never had problems

IMG_0636.jpg

79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jan 2017
Posts: 1,831
Likes: 91
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,831
Likes: 91
Hi Truckedup, Nice collection!!
One thing is certain. Stay up float & viton tipped aluminum needle works really well. Plus easy to set float level.

The manufacturers were on the ball for the most part updating rubber parts & plastics. What is bad about California fuel is the low octane putting to drive oh diagnostic cable on my car & looking at laptop readings for timing. Even small grade backs off timing 5-6 degrees. Steeper hill it backed off 10-14 degrees. Using 87 octane it will back off 5-10 degrees on the level if you accelerate at all, even gently. Fuel mileage is decreased so much 20 cents a gallon increase for 91 makes it cheaper overall.

Leaded 110 race gas bikes run so good you can’t believe it. A few stations & Sonoma Raceway sells unleaded 101 octane race gas. Bikes run really well with that also. This is California street legal. I used both for a year. No bad side effects. Even 1 qt. of 91 blended in tank full the race gas looses lots of its good performance.

Back to the AMAL our E10 is very poor starting heat soaked. All the carburetored cars does same. On the British bikes cure is tickle hot, hold full throttle, kick hard. We do this all summer. Later AMAL MKII close enrichment lever as if motor was cold. Keep it reving fo a minute or so, then it will idle & run slowly again. We usually don’t turn tank tap off hot motor when parking like for lunch. If you do bowl evaporates in about 5 minutes or less. Then carb gets smoking hot from heat coming up intake port. Even the thickest heat insulator doesn’t help. Very hot city riding I’ve see gas bubbles coming out carb up fuel lines back when I used clear hose. E10 just kills clear fuel hose. We gave up on that long ago.

I’d really like to see what your special built motor would do hear.
I go east I reliably get 2-3 more mpg in my car.
Don


1973 Tiger 750
Joined: Oct 2012
Posts: 6,036
Likes: 181
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 6,036
Likes: 181
Don, as you know , fuel octane is rated on a single cylinder test engine with variable compression... In theory 91 octane in NY is 91 octane in California regardless of the additive package. A few stations here sell unleaded 100 street legal gas but most are content with the E10 93. Most stations sell the 90-91 octane non ethanol gas.I know a few Triumph riders using it with no problems...Typically this is a humid climate with average summer temps of 80f

Plugging a scanner into my 2010 Chevy I can access the the engine management, fuel trims, timing and so on. It also shows the ethanol content of the fuel, 8-9 % around here on the E10 fuel. If you have a comprehensive scanner and a late model vehicle see if it shows ethanol content...
That Jeep photo was taken about 10 years ago...The are all sold. This photo was my vintage Chevy trucks circa 2000. All of them are now gone. Just became to much for me to deal with...And a few motorcycles...

8119728629_dcb4d3c278_z.jpg 26934438422_654f051d1f_c.jpg IMG_0635.jpg

79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Jan 2014
Posts: 3,587
Likes: 34
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,587
Likes: 34
Hi Tony; the red one in the right looks very nice. Circa ´40s?
I see many there have asphalted entries. Here is way expensive; like thousands of Dollars. Is that cheap there?

Joined: Oct 2012
Posts: 6,036
Likes: 181
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 6,036
Likes: 181
The red one is a 1937 Chevy...As shown it has a much modified 1955 5.0 GMC inline 6 cylinder engine.....I built the truck around 1995 and it was my first experiments with tight piston to head clearance to improve combustion in vintage engines with the first engine, 1958 4.3 Chevy inline 6...
Asphalt entries or driveways are about $20 to $40 USD per square meter in this area


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Oct 2008
Posts: 7,409
Likes: 182
Britbike forum member
Offline
Britbike forum member
Joined: Oct 2008
Posts: 7,409
Likes: 182
Nice trucks!
The prevalence of similar vintage cars and trucks in my neck of the woods is why we are blessed with many stations with ethanol free petrol in all grades.
Usually in the boonies they only have premium, bootleggers and bikers. laugh


Santa Claus wears a red suit, he's a Communist

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
92 BMW K100rs "Gustav"
Joined: Jan 2017
Posts: 1,831
Likes: 91
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,831
Likes: 91
Hi Hillbilly, I don't have a fancy scanner at home, just code reader. I used the genuine MB one from work. I don't know of a menu in it that can tell Ethanol content. Actually I've not heard of a scanner that does that. I've been retired 5 years. So I'm left behind. After 1-1/2 years I let my smog license & all my ASE certs expire. Our retirement plan worked out so I determined I'd never have to work again, except for fun on bikes & a few selected cars. Certainly don't make a profit. Just for fun. It usually is fun for me.

I've pondered this octane thought for some years. There has to be more than just the simple octane numbers that effects fuel & our bikes. Higher compression vintage cars (before EGR) have a propensity to ping bad on 91 also. The only additive that actually makes any difference at all for ping is Torco fuel accelerator. It turns 91 into 100. It really does & California legal. However.... You basically must use it full strength. Makes fuel cost about $15 gallon. Just this week Shell station up the street raised price on 91 to $5.039 per gallon cash. Credit card add 10 cents.
Don


1973 Tiger 750
Joined: Oct 2012
Posts: 6,036
Likes: 181
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 6,036
Likes: 181
Don , my scanner is a Blu Driver, a small wireless device plugged into the ecu port under the dashboard and displays on a iPhone or Droid device.. I believe most better scanners have this feature. Our car is a 11 year old Chevy FlexFuel so the Ecu needs to make adjustments for fuel type. I believe it measures specific gravity to determine ethanol content....
With electronic engine controls and variable cam timing ,modern sport bikes have up to 13.5 compression and 200 hp per liter off the showroom floor...
Many with older V8 performance engines use new aftermarket heads with fast burn combustion chambers so the engine can use up to 10 to one compression and make more power than the old design heads.And cam timing is important here..


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"

Moderated by  John Healy 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5