Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
Brad Jones
Brad Jones
Mayenne
Posts: 29
Joined: October 2017
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
Page 2 of 3 1 2 3
Joined: Jan 2017
Posts: 1,467
Likes: 51
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,467
Likes: 51
Hi Reverb, The key factor is octane of the fuel you have available.

110 octane leaded race gas is sold for off road use. Our bikes love it! Runs like the early ‘70s.

I ran that for over a year. Could not dilute with normal gas though or it wouldn’t work good.

Problem was not sold in most places so I was on a 100 mile leash. I hated that. Was so freeing when I put in thicker head gasket, .080”. I went on 300 mile ride. Was so happy I nearly wept. I still have to be very careful about ping & detonation though.

I’m not a fan of low compression either. I just want to ride my bike frequently & long distances. So long as I can run continuous speeds of 65-70 mph & 80-85mph for overtaking cars, I’m happy. I just want to go to gas station & get best octane sold here 91. However in very remote areas they only sell 87 & diesel. Ping on 97 is very severe. I had to ride 200 miles over steep roads. All I can say is continuous high rpm & very low throttle openings plus God saved the pistons. The prior day 2 bikes holed pistons. You cannot cheat physics. You have to work with fuel you have. That is the starting point.

Very skilled builders can work with squish band etc to overcome these issues. Still the fuel octane will limit you.

Who knows what the real octane is on fuel we buy? We just have trust number on pump.
Don


1973 Tiger 750
Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: Jul 2020
Posts: 139
Likes: 4
B
Britbike forum member
Offline
Britbike forum member
B
Joined: Jul 2020
Posts: 139
Likes: 4
Don, I believe the Weights and Measures people check on octane ratings etc. on a regular basis. No supplier would want the bad press if they were found cheating. Here is an article;

"The petroleum program run by Weights and Measures in California is unique. Locally, weights & measures officials enforce that portion of the California Business and Professions code relating to petroleum product standards. Periodically, through consumer complaints or routine audits, samples are taken and sent to the lab in Sacramento for analysis. This is done to insure that the product complies with national standards and is in fact the same product as being advertised. Labeling regulations are also strictly enforced to provide product identity and information to the buyer and seller. This includes price sign advertising, making sure no deceptive, false or misleading statements are being advertised, posting the product brand, grade, name, octane ratings to dispensers, ensuring that price advertising signs and pump dispenser prices agree, free air and water to those customers who purchase motor fuel, service to disable drivers and proper labels attached to underground storage tanks to prevent commingling of products."

http://www.buttecounty.net/agriculturalcommissioner/Weights-Measures

Last edited by BAinLA; 12/27/20 12:19 am.

1972 Triumph TR6RV Tiger back from the dead
Joined: Jan 2017
Posts: 1,467
Likes: 51
T
Britbike forum member
Offline
Britbike forum member
T
Joined: Jan 2017
Posts: 1,467
Likes: 51
Interesting. I didn’t know that. I’ve observed bike starts very differently cold or hot on different brands. Shell seems best overall.

Bike pings different on different brands. I find Shell & Chevron a little better. Chevron slightly harder to start cold. Chevron can much harder to start hot. All 91.

At work we found Shell & Chevron a wash for deposits on head, pistons, ports. Of brand fuels gave much more deposits & sometimes would clog air injection ports.

Costco & Safeway were the very worst offenders. Reliably lowered fuel milage 1-2 mpg on my 2000 E320.

Experiments with 87 on my car going east up hwy 4 from Hercules knock sensor pulls timing back 8 deg. Even with slight load on level pulls back advance 1-2 deg. Actually end cost of 87 is more costly in mpg. Reliably 1-3 more mpg out of state with 93.

Want to crack a piston in new Mercedes? Run a few tanks of Safeway 87 through the motor. They run so lean, even the spark plugs must be clocked. Zero room for error. I stared interviewing clients with certain failures. 99% of cars were prefect. Why the odd failures? Fuel 100% was common denominator. Nothing is simple these days.
Don


1973 Tiger 750
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
Originally Posted by TR7RVMan
Want to crack a piston in new Mercedes? Run a few tanks of Safeway 87 through the motor. They run so lean, even the spark plugs must be clocked. Zero room for error. I stared interviewing clients with certain failures. 99% of cars were prefect. Why the odd failures? Fuel 100% was common denominator. Nothing is simple these days.
Don


eek

i'm interested to observe that people with the money to buy a mercedes benz then go to a safeway for fuel to save money. how does that work?

my first job as a petroleum geologist landed me more money than i had ever seen as a starving graduate student. it was hard to adjust. i talked to a geophysicist about it who told me that he would walk through the aisles at the grocery store and agonize over which can of beans was two cents more expensive than any other. then he would go buy a car for XX thousand dollars and not worry about chump change at all

go figure

Last edited by kevin; 12/27/20 11:52 pm.

i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
Originally Posted by The Bonneville Shop
We offer a set of 71mm 7:1 compression ratio pistons (with rings) for the Triumph 650 models. They are available in several oversize conditions. We sell them under part number 70-3610. There seems to be an increase in popularity of the lower compression ratio pistons lately, perhaps due to modern fuels.


bud, you should consider offering a mail-in machine shop service for dual-plugging the cylinder heads. my 9.5 to 1 T120 morgo with four spark plugs runs at any rpm and any load on 87-octane unleaded. there is no detonation anywhere, at any time. i run 30 BTDC spark lead.

the change requires the machine work and twin-tower coils, and it can be done with points although EI is simpler.

the modification is invisible to anybody who isn't peering into the dark space on top of the head where the middle head bolts are.


i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Oct 2006
Posts: 4,007
Likes: 43
I
Britbike forum member
Offline
Britbike forum member
I
Joined: Oct 2006
Posts: 4,007
Likes: 43
Kevin:

His friends neighbors and fellow work associates never saw which beans he bought, but all of them saw which car he drives.
Some people have egos that large that they have to be "poseurs" to satisfy themselves of their "importance."

I have seen some of them living in big houses, with two new cars parked in the driveway, but only a bed, two chairs and a table inside the house.
We called them "nickel millionaires."

Joined: Oct 2012
Posts: 5,531
Likes: 71
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,531
Likes: 71
Kevin, running dual plugs on points is actually simplier...You only need to. replace the two coils and run the plug wires properly.No changes to the original wiring. The hardest part s mountng the dual lead coils but the minature 3 ohm coils from Japanese 4's work nicely.
Don's comment on Mercedes in interesting,...Since the early 2000's the automotive three way cat convertors require a steady stochiometric fuel air mixture of about 14.7 for normal driving, lean mixtures are past history.


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons..
“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
mounting those old 6volt harley coils was a disaster on my commutrr. they kept breaking off anything i used to mount them.. im running dynatek coils now and theyre still awkward.

the little german things from the pazon kits are a much better idea


i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Mar 2005
Posts: 10,597
Likes: 53
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,597
Likes: 53
Kevin those PVL small coils are .7 ohms, I don’t think they are suitable for points.

Joined: Jan 2014
Posts: 3,323
Likes: 16
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,323
Likes: 16
...hello; I do not understand the difference between the 7 ohms and the 3 ohms coils to use it with a EI not points.
Thanks

Joined: Mar 2006
Posts: 4,793
Likes: 41
Britbike forum member
Online Content
Britbike forum member
Joined: Mar 2006
Posts: 4,793
Likes: 41
Originally Posted by reverb
...hello; I do not understand the difference between the 7 ohms and the 3 ohms coils to use it with a EI not points.
Thanks

0.7 not 7.0.

Joined: Oct 2012
Posts: 5,531
Likes: 71
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,531
Likes: 71
Originally Posted by John Healy
Kevin those PVL small coils are .7 ohms, I don’t think they are suitable for points.

No, very short points life, like a minute, lol. The 3 -5 ohm Pazon and some other brand name minature coils look exactly like the inexpensive Asian made coils....But can't say for sure they are the same.
Fernando, The more expensive EI with dwell control generally use a low resistence .7 ohm coil. The less expensive EI generally require a 3 to 5 ohm coil..


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons..
“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
Originally Posted by John Healy
Kevin those PVL small coils are .7 ohms, I don’t think they are suitable for points.


i never measured them because they come as part of the kit. the two dynateks i run with a Boyer are 2.2 ohms each on a twin plugged motor


i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
Originally Posted by Hillbilly bike
Originally Posted by John Healy
Kevin those PVL small coils are .7 ohms, I don’t think they are suitable for points.

No, very short points life, like a minute, lol. The 3 -5 ohm Pazon and some other brand name minature coils look exactly like the inexpensive Asian made coils....But can't say for sure they are the same.
Fernando, The more expensive EI with dwell control generally use a low resistence .7 ohm coil. The less expensive EI generally require a 3 to 5 ohm coil..

here are some cb900 coils

https://www.ebay.com/itm/Ignition-Coils-Caps-and-Wire-For-Honda-CB750-900-1000-1100F-CB1100F-1979-1983/233694502824?fits=Model%3ACB900C&_trkparms=ispr%3D1&hash=item3669471fa8:g:DBAAAOSw6ntfSFzH&amdata=enc%3AAQAFAAACgBaobrjLl8XobRIiIML1V4Imu%252Fn%252BzU5L90Z278x5ickkai8xCwosGKpC0NWj85e%252FBwNVk8%252FHjs5t%252BvDQaBio99JjlfSFxVYp7oSVORw50oVT2cRAa%252BBWhtWHt1Cn23dDjV14w655%252BqaT6KL1ODLtV7spjjjXTZTHT48U0jRdOzUzk5B68YIMN3YvB1np2t4Bocu1Z1ZpFha1fR8gVZblSCOr9gWPIbpFzNwqNJBuEHX2jK07VogwFVK2nV6%252FclApzo0%252BMKyVELKvFEhV6DVeIaby1WLFzwE7POQEkehCtDQs%252FDzPQmbPgbldBVdAh1mK6gNf%252Bb0q3RZPHqbUKOHkBIiNYH6337ZIA7tHW112X9EmH7bZxKVygdEUPNIauLJcLAqdWkbKyyDQXgEt5C6SJGeZGffRs0ptQs5%252BorsLn2j5v7i0GYd00KbXznpPeTcAkYQJyB0pRrFbv1c3pciG9KBTCvwWtCUa867PHQttkNzG8VUQq88ymKpRJCZngja2sEw2TkiN3WdSmVbv43ngD84WkRplCGJH6rQtMwoXayGVpFC3gq5pQqYFpBikJP8uBcB3XhS%252BXrJs4Oas0QsU5ENc2wnKTvJzEazCf2NkeSLzQYFsUKZauTdY3hTZaRfAZwHLMtV1DkF%252F9N2%252B4BpA%252B13xctItOWoNqSgsxcm8qUOofbKcG6MKhlSyA5mLfDX2X84YJ6cpd0WzIOppYQHP0q5OVJwi9wuUjqL9HD4e9HmU2ldJ9GLE6aWkaD80v3G2ASOQgd4wGI3zezVNbjzpm7CnvQKO%252Bio75Win7D7qYXpQ7F39HOq8kS64OkDkHLehFF6hJSbXudmSNALGSnj8fYA%253D%7Ccksum%3A233694502824438a97be61814099b9730111eb3fc5b5%7Campid%3APL_CLK%7Cclp%3A2334524

theyre inexpensive but no resistance is given. how wod i know whether theyd work?

Last edited by kevin; 12/29/20 2:23 pm.

i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Oct 2012
Posts: 5,531
Likes: 71
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,531
Likes: 71
Kevin, I looked at other coils listed for Honda 900, info says 2.5 ohms....Would be ok if wired in series for a waste spark. Otherwise look at Kawasaki and Suzuki 70's and 80's bikes


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons..
“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Joined: Dec 2013
Posts: 5,745
Likes: 114
DOPE
Offline
DOPE
Joined: Dec 2013
Posts: 5,745
Likes: 114
well shoot

that will simplify my future i believe

although i have an ARD for the next scratch built machine


i'm old enough to remember when patriotism meant not trying to overthrow the government.
Joined: Mar 2006
Posts: 316
Likes: 10
S
Britbike forum member
Offline
Britbike forum member
S
Joined: Mar 2006
Posts: 316
Likes: 10
Abt 55,000yrs? You'll need a BIG daily wage increase.

Dammit I just answered your sig line ...it's really late for me, been a long day.

Last edited by slofut; 12/31/20 4:41 am.

'68 Bonnie, '70 TR6r
'74 CL360
trail 70's and minitrails
1 member likes this: kevin
Joined: Jan 2014
Posts: 3,323
Likes: 16
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Jan 2014
Posts: 3,323
Likes: 16
...alright L.A.B; 0.7.

Still I do not understand the difference; I am referring that if one is better than the other regarding performance. Tony, you mention that cheaper EI works with more Ohms; also that use more system electricity? Is harder on the alternator?
Is any better that the coil would be 0.7 or is just like you say, a thing to work properly on expensive EI?


Thanks

Joined: Aug 2001
Posts: 8,534
Likes: 58
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 8,534
Likes: 58
The low impedance coils are the type used in capacitive discharge ignition systems. A pulse of hundreds of volts is sent through the coil by the ignition box. The coil transforms the pulse to thousands of volts in the HT circuit, to make a spark.


Amateur Loctite enthusiast.
Joined: May 2013
Posts: 7,668
Likes: 101
Britbike forum member
Offline
Britbike forum member
Joined: May 2013
Posts: 7,668
Likes: 101
Also if you use a coil less than 3ohms with a standard EI, you’ll fry the box.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

1 member likes this: kommando
Joined: Dec 2004
Posts: 11,054
Likes: 92
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 11,054
Likes: 92
Originally Posted by Allan G
Also if you use a coil less than 3ohms with a standard EI, you’ll fry the box.

I fitted a Green Dyna dual spark coil, green identifies it as 3 ohms but I measured it at 2.9 ohms but thought my multimeter must be out and trusted Dyna more. Every ride in warm weather the Boyer would not provide a spark after 15mins of running, ignition off for 10 mins and I got another 15 mins of ignition. Swapped the Dyna coil out for a pair of 6V PVL's at 1.7 ohms each wired in series to give 3.4 ohms and 100% ignition. The Boyer box is the same and seems untroubled by its overheating events, 3 ohms is a bit too close to 2.9 ohms for comfort, I would use 3.3 ohms as the bottom limit to be sure.

Joined: Oct 2012
Posts: 5,531
Likes: 71
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,531
Likes: 71
Pazon sold me a 3.0 dual lead coil with a Surefire . I first used it on the race bike for a time .The engine would misfire at 7000 rpm when I tried to lean it down a bit . Perhaps the 3 ohm coil was overloading the Surefire. I swapped it out for a Smartfire and no more misfire..Then I put the Surefire and 3 ohm coil on a street bike using a .85 ohm ballast resistor...I did this because of comments like Kommando said....No problems....


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons..
“But I don't want to go among mad people,” Alice remarked. “Oh, you can't help that,” said the Cat: “we're all mad here. I'm mad. You're mad.
Joined: May 2013
Posts: 7,668
Likes: 101
Britbike forum member
Offline
Britbike forum member
Joined: May 2013
Posts: 7,668
Likes: 101
I have the 3 ohm dyna on my A65, but will eventually get around to fitting the 1 ohm ballast resister that I have for it. Mainly for ignition module protection. I think these ignition modules cope for a while with 3 ohms but long term it gives them a beating.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Jan 2014
Posts: 1,268
Likes: 95
N
Britbike forum member
Offline
Britbike forum member
N
Joined: Jan 2014
Posts: 1,268
Likes: 95
A 3 ohm coil is fine, it will get warmer than the 4 or 5 ohm one that's all.
The box will also get a little warmer.
If you actually measure the current drawn and multiply by the typical
output stage volt drop (around 1.5 volts) you will get the watts dissipated
by the box, if running at 100% dwell. So typically.........
system volts = 14.5v when running and with good battery/alternator.

coil =4 ohms @ 25 degs C

Voltage = (14.5 - 1.5) =13 Volts ( system voltage minus drop across output device.)
Current max = 13v/4 ohms = 3.25A

watts dissipated by coil max = 13 x 3.25 = 42.25w
watts dissipated by output device max = 3.25 x 1.5 = 4.875w

NOTE. Switching losses in the output device ie. time to switch on and time to switch off
increase the dissipation, most people would apply a multiplier to the static figure when
this is taken into account. Assume multiplier of min 2 for Fmax of 300HZ.
Dissipation is listed as constant, this is obviously not the case, the dwell duty cycle must
be taken into account for both the output stage and the coil.


If you do the sums for 3 ohms you will see the difference as the I max will change.
Also note that the volt drop across the output device will increase as it warms up.
Plus the dc resistance of the coil will increase as it warms.
It is very important to keep ignition coils as cool as possible for best performance.


A CDI type ignition utilises the coil as a transformer not as an energy storage device
the energy is stored in a capacitor charged to around 250-450v then switched onto
the primary side of the coil, the coil does not store energy as in an inductive setup.
E core type coils tend to work well with these systems as they have more suitable
coupled characteristics, but any standard coil will work to a point.
As i have stated before, there is more to a coils design that just it's static dc resistance,
many qualities make the coil suitable or unsuitable for purpose.

Allan, you can erase this note if you like, it will probably stir up a load of grief with
many people as they all know much more about it.

Last edited by NickL; 01/01/21 2:03 am.
1 member likes this: KevRasen
Joined: Jan 2014
Posts: 1,268
Likes: 95
N
Britbike forum member
Offline
Britbike forum member
N
Joined: Jan 2014
Posts: 1,268
Likes: 95
Some good reading for all you EI users............. Just to prove i'm not lying.

http://gpzweb.s3-website-us-east-1.amazonaws.com/Ignition/IgnitionCoils/IgnitionCoils.html

Page 2 of 3 1 2 3

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