Dual Plugs or conpression releases

All ignition related articles
Posts: 1263
Joined: Fri Jul 03, 2009 8:23 pm
Bikes: 65 FLH 82 FLH
Location: Michigan
Been thanked: 54 times

Re: Dual Plugs or conpression releases


Post by Bosheff » Tue Feb 23, 2010 8:52 pm

As I remember, yer Pan and Shovel FLH's were 8.5:1 c.r. When gas turned to shit 30 years ago, the easiest and cheapest way around the detonation issue was to drop down to 7.5:1 c.r. pistons when it came time for a top end job. Simple, cheap, and no real loss of power to speak of considering the pump fuel that was available. Oh ya, don't put a bunch of fat girls on the back on hot days if yer mill is preignitin....bosheff

Posts: 285
Joined: Sun Nov 01, 2009 10:10 am
Bikes: '37 UL, '79 Frankenstein, '88 Sporty
Location: Oahu Hawaii
Has thanked: 5 times
Been thanked: 5 times

Re: Dual Plugs or conpression releases


Post by Sir_Rat » Sun Feb 28, 2010 2:03 am

I may be wrong here, some of you "old timers" :D should know. Wasn't the gas back in the 30's n 40's n early 50's not all that good either? Wasn't it not until the middle 50's to late 60's early 70's that the "good stuff" became available? All this talk about hard starting, high compression, dual plugged, piston burnin, strokin, smokin motors makes me appreciate a good stock Harley Davidson all that much more. A good healthy Harley is not hard to start. It only gets hard to start when somethings wrong or when the person starting it screws up. My 59 FLH always started with any where from 1-3 kicks. 1 kick (spark retarded) when hot. When cold she took 1 primeing kick and then 1 -2 kicks starting kicks. The only times this wouldn't work meant either one of two things. Either something was wrong and needed fixing or I had drank too many beers, in which case she would absolutley refuse to start until long after I had kicked myself sober. Kicking a bike should'nt be a violent knee bustin experience if you keep your bike in good shape. I ride with slippers on around here and have no problem kicking "my" bikes. Hell I kick em bare foot sometimes. I've seen some guys kick their bikes with their hands even. It all boils down to how well your bike is tuned. Knowing what your doing factors in as well. I'll take a stock setup any day.
Just my opinion....aloha peeps

Posts: 3337
Joined: Sat Jun 26, 2010 1:54 pm
Bikes: 1958flh 1969sporty,had a knuckle but sold back to original owner
Location: NEW JERSEY
Has thanked: 195 times
Been thanked: 259 times

Re: Dual Plugs or conpression releases


Post by 58flh » Tue Mar 01, 2016 3:12 pm

Gents---I realise this post is old//Just wanted to add my 2 to it.Compresion Release???//WHY??/Even at 10.5 to 1 comp.-ratio/I just dont see using one!Also im not saying that AGE or WEIGHT has a hand in it.To me Compresion releases were NEEDED on the Flatracker/Bord tracker bikes of the time!/& still are.HD realized this among other companies that closed shop long ago like before 1917 NEEDED them.Remember back then women were jumping on shwinns with motors & pedling the crap out of them to build-up enuff comp. to fire the mix.IF you ever started one of these great bikes ,you can appreciate why a release was needed IF IT DIDNT FIRE WHEN IG. SWITCH was hit to fire & IT DIDNT.NOW try pedling that bike with it on its rear stand & full of comp.!/That leather belt would just SLIP if you could even get to peddling the motor under comp..IN using the comp.-release you now can build comp. again like your suppose to & Fire the single-up & go.In later yrs. when there were 2-lungs to fill-up with comp. of air & fuel,Became even more of a challenge.FAST FORWARD to today//if your Ratio is 12 to 1 or greater,The hell with Releases you fire by Rollpins or a briggs/stratton 3hp that locks into the hub & off you go for a 1/4-mile full of fun./If a man truly has problems kicking his bike & its comp.-Ratio is high/A 1-inch longer arm Will help with the grief!.But ba STOCK Ratio of 8.5 to 1 for FLH or 7 to 1/Can litteraly be fired by hand!!!/A stock runner just needs not to be kicked until the bushings leak/just let your body weight onto the kick pedal & they FIRE-UP that easy!.-(This is why Bubbletesting is important)-Have bubbles /no starting,unless dropped in 2nd down a hill!)--Riding with an airleak means HEAT! FIX it properly & there the simplest machines to start in thier purest form.-----Respectfully----Richie

Post Reply

Return to “Ignition”