Why Is My Engine So Hard To Start? Tips From S&S Cycle To Resolve This Issue.

ssengineStreet engines have not only gotten bigger, they’ve also gained compression. Hard starting is an annoying problem that can be resolved either inside or outside the engine. The explanation and tips from S&S Cycle. 

The first step in making these beasts more manageable is to check cranking compression with a good screw-in gauge. S&S recommends 180-190 psi for street use, 200 psi for those who insist on pushing the limits. The easiest way to reduce cranking compression is to install a camshaft that closes the intake valve a little later. An engine with the recommended cranking pressure will deliver good power and throttle response but still be reasonably easy to start. Some engines, however, remain stubborn even with moderate cranking pressures. That’s almost always caused by something outside the engine, a worn or binding starter or starter drive, a weak battery ,cheap or old cables, poor wiring connections, inappropriate ignition timing or overly aggressive advance curve, hydraulic lifter bleed-down, or an improperly spaced alternator rotor scraping on the crankcase, just to name a few of the culprits. Whatever the cause, there are several tricks for making a stubborn engine easier to start. 

A simple wiring change to remove the lights from the starter-ignition circuit will deliver more current to the starter. The draw back, of course, is that the rider must remember to switch the lights on. It is also possible to wire the ignition and starter circuits separately and use the handlebar “Stop-Run” switch to deactivate the ignition. With the ignition switch on and the handlebar switch in the “Stop” position, all battery current will go to the starter. That gives it more power to get the engine turning, at which point the handlebar switch can be flipped on to activate the ignition and fire the engine.

Another trick that can be extremely effective is to run a second ground cable from the negative terminal of the battery to one of the starter mounting bolts. This reduces resistance between the battery and starter, again increasing current to where it is needed. 

One last tip is to leave the throttle closed until the engine fires. Opening the throttle admits more air in to the cylinder and increases cranking compression— the last thing you want. With idle set at 1000 RPM, the engine should start with no throttle. Otherwise, pull the throttle back just far enough to get the engine to fire. Hard starting is a nuisance you shouldn’t have to put up with. If your engine has 180–190 psi of cranking compression but remains hard to start, look outside the engine for the cause. If cranking compression is too high, lower your compression ratio or find a cam that closes the intake valve later.

23 Responses to “Why Is My Engine So Hard To Start? Tips From S&S Cycle To Resolve This Issue.”

  1. 1 Rodent Mar 27th, 2014 at 8:32 am

    Another tip would be replace the electric starter with a kick starter to reduce strain on electric system.

  2. 2 Sharkey Mar 27th, 2014 at 8:57 am

    After hard starting problems and damaging kickback, I’ve just installed the S&S EZ start cams; hope they work…worst scenario is fueling up on a hot day when you have to shut down for only a couple of minutes…worst response is to buy a mammoth starter; make sure everything else is correct before simply using a bigger hammer…had the problem pretty much licked with better cables, compression releases, a 1.4 starter and a lithium battery but the cams were still a bad choice for starting so went the EZ start route…

  3. 3 A 1 MIKE Mar 27th, 2014 at 9:02 am


  4. 4 smithncustom Mar 27th, 2014 at 9:26 am

    Rodent… you took my answer. man up and kick it!!!

  5. 5 takehikes Mar 27th, 2014 at 10:46 am

    or you could buy some thing that is not hard to start……..smart manufacturers put in an automatic compression release to help with starting.

    however the cable tip is huge, factory cables are meant to get through the warranty period if that. Beef them up and make sure they are well connected to the battery, stunning how many are loose.

  6. 6 Fausto Mar 27th, 2014 at 12:12 pm

    Great article Cyril!

  7. 7 Knucklehead on a Panhead Mar 27th, 2014 at 1:17 pm

    This comment goes without saying, but I will. Having lived in South Dakota my whole life, there are days in the winter where 45 degrees is like the typical “90 degree” day in Daytona and I can’t resist getting carharted up and going for a putt. Starting can and will be difficult when your engine oil is cold and thick compared to when it’s 90-100 degrees. It can also cause top end damage as it takes longer for lubricant to reach the top end…. Solution?…. I have a 250,000 BTU diesel forced air salamander that I fire up an hour prior to riding. Another thing I have done is changed the viscosity of my oil making it easier to lubricate my engine. I agree with all the above mentioned idea’s, but hey…Every little bit helps!

  8. 8 fuji Mar 27th, 2014 at 4:54 pm

    Kick start ! Too funny . How common it was [ back when ] to see someone with permanent and temporary leg damage from trying to start their Iron Steed especially when its cold.

  9. 9 Terence Tory Mar 27th, 2014 at 5:47 pm

    Basic maintenance issues aside.This seems a good reason to go find a good professional motor builder and tuner who knows how to build motors for real street riding use.Pay his bill and do exactly what he says.They are out there.They know more than you will ever forget.

    The operator factor is a big one with big twins.I’ve know enough good motor builders who pull their hair out when fools run fresh motors hard from dead cold or expect them to run at high speeds with big throttle openings at very low revs like a tractor so it “feels” right like listening to momma’s heartbeat back in the womb.

  10. 10 fuji Mar 27th, 2014 at 6:11 pm

    Terence Tory. Relax take a deep breath I think your toast is burnning.

  11. 11 Terence Tory Mar 27th, 2014 at 6:17 pm

    Fuji,don’t get me started!

  12. 12 Steve Carr Mar 27th, 2014 at 9:35 pm

    Hey Terence,

    As a bike builder that seems to know everything that has to do with motorcycles , why would you suggest sending something to another builder?
    just asking?

    Steve Carr

  13. 13 Terence Tory Mar 27th, 2014 at 11:48 pm

    Steve Carr,competition is good for business.There is more enough motor building work for competent mechanics.A good rep means work seeks you out and there is no need to worry at all about other guys efforts in the field.I work on theory they will be back when they want to pay real money,for quality work.I never worry what some other guy is doing,I just focus on the job at hand.

  14. 14 HD Rider Mar 28th, 2014 at 6:26 am

    I find that 210-215ccp starts just fine as long as you have compression releases and use them every time.

  15. 15 HD Rider Mar 28th, 2014 at 7:00 am

    I’ll modify my previous post — I’m referring to an EFI bike and it sounds like the S&S tips are more focused on a carbureted bike. I find that with EFI with the right initial fuel pulse and cranking fuel dialed in (I use Thundermax) that you get near instant starts.

  16. 16 JackS Mar 28th, 2014 at 7:46 am

    I know this is a news blog, but I loved the article and would like to see something similar on compensating sprockets. More like it Cyril !

  17. 17 1953 Marlin 39 Mar 28th, 2014 at 9:17 am

    I have found that starting an S&S carburetor equipped Big Twin can be reliably accomplished by getting the starter rolling over as you slowly raise the enrichment lever. About half way to the top of its travel, the motor will find its richness level and fire up. When the motor can be kept running with the throttle lower the enrichener lever back to the bottom and continue warming the motor up.

  18. 18 Smittydog Mar 28th, 2014 at 2:16 pm

    Always park at the top of a hill,and have a lot of freinds around to push.

  19. 19 1550tc Mar 28th, 2014 at 5:07 pm

    Smithy try that with a dead battery on an efi bike…………..good luck 🙂

  20. 20 nicker Mar 28th, 2014 at 5:35 pm


    “…Another tip would be ….. a kick starter …”

    That would either improve the mechanical & tuneup talents of today’s “Bikers” or significantly reduce their numbers…..

    Either option being highly desirable……… 🙂


  21. 21 Terence Tory Mar 28th, 2014 at 6:55 pm

    nicker +.

  22. 22 5toedwillie Mar 31st, 2014 at 12:18 am

    Starting a custom engine has always been a problem. One of the major reasons is that the spark plugs generally fire before the piston reaches top dead center or before TDC this causes the starter to be required to not only spin the engine fast enough to start but to also over come the compression and the cylinder pressure developed by the expanding gases which have begun burning. One of the easiest ways to over come this problem is by firing the spark plugs (ATDC) after top dead center until the engine begins running on its own power and not using the starter. Several ignitions on the market have this feature and the engines never have a starting problem even when running increased compression or camshafts that increase cylinder pressure. One of the easiest ways to determine if the cam, compression, or other issues is the problem is to crank the engine with the plug wires off. If the engine turns over with a fully charged battery it is a very good indication that retarding the the timing during start up to (ATDC) will generally fix the problem. If you would like additional information drop me a email. I have built many high compression engines before the use of auto compression release and this fixed the problem every time.

  23. 23 BCinSoCal Apr 8th, 2014 at 4:14 pm

    Fuji, This issue aside, 40 years later, my knee still bothers me from years of kicking ironhead Sportys back in the day,before Harley wised up and quit offering them. Love to hear people ask “from them kicking back” no, wrong! it’s obvious they never had one and had it “ratchet thru!” Electric start bikes, high performance, quality cables , compression releases, and or cam with overlap. Older kick start bikes, stop twisting the throttle open with every kick, cam with overlap. All of this assumes that the normal maintenance things are right and fresh. Just my two bits worth .

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Cyril Huze