Pinging problem

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Guido

Guido

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I just got my bike back on the road and after having the head rebuilt and a stud repaired.
They had to surface the head after the stud hole which was welded for the new insert which means this would be the third time in it's lifetime that it has been resurfaced.
I am wondering if the compression is now too high from all the surfacing for the 91 octane fuel that California has.
I checked the timing and it was 28 btdc which I advanced to 30 btdc.
I have a Boyer Mk III ignition, a Norris cam, 160 mains and the needle on the middle groove.
So it pings on acceleration.
Any thing I should check that I haven't mentioned?
The timing chain may need to be adjusted because the mark kind of jumps a little.
Are those degree marks fairly accurate?
 
Guido,

Not sure if this will be your problem, when you set the Boyer as per their instuctions, to I think it is 31 BTDC ( this is a coarse setting of the timing ), you need to then finish the fine adjustment of the timing with a timing light at about 5,000RPM.

If you miss the timing light step, it will ping and kick back at you when try to start the bike.
 
Hey Guido, Yep all of the above.
Have a look at this site for boyer tips.
http://www.nocnsw.com.au.
You might need to bring the timing back a little.
I'm not looking forward to the end of 98 oct., in Oz.
AC.
Plus a great logo.
 
HEHEHEHEHE
Sorry mate, nobody said it YET.
hehehehehehehehehehehehehehehehehehheheheheheheheheheheehheheheeh.
 
Whoa on following instructions as does not apply to Combats or higher CR engines. More than 28' in a hot Combat = back fire starts and detonation prone on much throttle loading. Maybe its a typo but Combat Amals use 240-260 range jets not 160 or lean ping results. Oil leak into chamber can also make it ping prone but I'd vote the timing first thing to diddle back as Norris range of cams lowers effective CR d/t the late intake closing and over lap with open exhaust. Which Norris cam? In decades past learning curves those who tried to 'detune' Combats with just standard cam, got detonation in the 100 octane lead days. Implies its not your CR or cam but spark &/or leaness. Cam degree can mess with ping proneness too. Retarded is less detonation prone than advanced from straight up. Thicker gasket [alters valve rocker geometry] may lower CR but then maybe the cam won't function as desired. Hotter cams require higher CR. Might also consider a cooler plug, which both helps cool chamber by conduction and less a glow plug effect.
 
I've got 112 locally among friendly garden tractor pulling rigs and 110 at a public station and small airport near by but I want to run up to 17:1 on 91 or even 87 octane and spring water or windshield washing fluid. I'm a hayseed now so got to make do.
 
OH yeah, cycle shops sell castrol bean oil for two stroke gasoline and a small dash in your tank leave race track and model airplane odor to please, but just a dash or gets overwhelming. Race shops sell many odor flavors, grape is a best seller and also over whelming when half the dirt tract cars are spewing it.
 
Geez, you had me worried!
I've only just got my old dungas happy with 98.
I don't want any fuel changes for 15 or 20 years,,, then its someone else's problem.

(this is supposed to go straight after AC's post but you all jumped in)
 
Yeah our early dial up party lines were like this too. I don't think its grape oil but some synthetic component of grape smell.
Its possible coke build up is glowing or pilingto ping but do Commando engines ever get run long enough between clean outs to collect enough to matter? Now and then I spray water into carbs till the gray crap blowing out the pipe settles down. 98 ain't the number to bicker over its always 43 or 42.
 
Sounds like compression is too high..........3 options here, either retard ignition timing, reduce compression, or use higher octane fuel.
 
Analog boyers S##K...their production variations have been well documented for decades.
Why do you think they have this brain dead procedure to time them at 5000 RPM?
2000 will work just as well, and if you have to ask why, then you should really have a mechanic work on your bike :twisted:
http://atlanticgreen.com/images/anaboy4.jpg

Read it here because I get tired of explaining the same thing over and over and over ..... :roll:
http://atlanticgreen.com/boyerexposed.htm
http://atlanticgreen.com/boyerevolved.htm
 
I made a mistake, the main jet is 260 and I read the atlantic green article.
I'll try the retarded timing and if that improves it a little then I will add some octane booster and see if that improves it more.
Lowering the compression would be done how? Thicker cylinder base gasket to give it more deck height? Go .080" copper head gasket?
Pulling the head again would have to wait for winter as I have lost too many days already of riding.
It sure is great to have all you guy's out there helping me.
It's been many years since I have had this running and being in the wind on those winding roads is great.
 
Ditto on what DynoDave said.
Things could only be worse if you had an E-Start.
I can't imagine why anyone would substitue this particular item for the standard dual point setup once one has read the info on Dave's site.
Although that may not be your sole problem it is not a desirable product. Mine certainly wasn't.
Go back to points or choose another EI system. An informed customer will choose wisely. Your right foot will thank you.
 
I retarded the ignition and the pining went away.
I am going to degree the timing marks and see how bad off they are.
I am not sure where the degree wheel goes to as the one I printed out is about 6 to 7 inch around.
Where does it go? On the alt stator?
 
The only way to properly check timing with electronic ignition is using a strobe light. You need to get a timing light with an advance feature, so you can degree in the amount of advance required. Then mark accurate TDC marks on the alternator rotor, connect timing light, start bike and then simply use the timing light advance feature to line up the marks at given engine speeds. Make a note of the amount of advance at various speeds, and not only will you have the timing figure, but will also be able to check if the spark is advancing properly.

In general though Brit twins will run an awful lot better if you revert to points ignition over shoddy electronic set ups, but obviously these do need to be maintained, so most people opt for electronic.
 
Degree wheel goes on end of crank which is an issue of how to hold it on. There are special adapters like one Comstock/CNW sell but I stumbled on a down and dirty method using a magnet on front flat washer behind wheel and it worked at treat. Factory dial can be off over 10' its been reported. To get TDC, put on degree wheel any old way, stick straw or screw driver or fancy piston stop in plug hole held stable and turn engine both ways till stops noting degrees at each stop then slit the difference and put wheel to 0 there. Takes a few back and froths to fine tune the final mark. Knife edge mark alternator or dial to know in future. Turn crank backwards to full ignition advanced desired and mark that too for future. When run this 2nd mark is your target, zone. May then diddle a bit more or less for a bit more or less performance and starting ease, but C'do's are real picky with a degree or two off hindering starting. Strobe only aligns marks to read and has no relation to what the bike actually likes best, though should be pretty close if the indexing has been done.
 
I had the points setup for years. Found it to be a PITA due to worn out advance unit. I put the EI on it and what a difference.
I do use a strobe light but it's your std light.
I always wanted a light with the dial in advance feature.
Thanks for giving me another reason to buy a new tool.
I may need a better EI unit. Who knows?
 
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