Merc super 10 hurricane KG7 won't spark

[camccardell]

Found an old mercury KG7, and it turns over well when I pull on the cord, really dang hard when the spark plugs are in it.<br /><br />I can't get a spark from the plugs, and I pulled the flywheel off and the points are openin and closing just fine and are making contact. I scuffed em a little bit to make sure they had good contacts.<br />I doubt both coils are bad, bust is there any way to check em?<br />Any help would be greatly appreciated

 

[Laddies]

Re: Merc super 10 hurricane KG7 won't spark

No problem to test them with a merc-o-tronic tester or a magneto tester any small engine shop or marina should have one

 

[Chinewalker]

Re: Merc super 10 hurricane KG7 won't spark

Hi Cam,<br /> In general, if the coils don't look bad, they're probably okay. For starters, let's find out what magneto you've got... The KG7 used two different mags. One was the Bendix Scintilla, which had a Bakelite cover and magnet on the crankshaft. The other (and preferable) magneto was by R.E. Phelon and had the magnets on the rim of the flywheel.<br /> The weak spot on the Bendix mags was the low relative speed of the magnet in relation to the coil laminates. The weak spot on the Phelon mags was the tiny condensers which weren't very robust. For either mag, make sure the points are SPOTLESS. You can dress them with 600 grit Wet Dry sandpaper, then run an index card dipped in acetone, carb cleaner or laquer thinner through them. If you still don't get spark, particularly with the Phelon mag, replace the condensers. I believe you can order them right here at Iboats.<br /> Run it with Champion J6C plugs on a diet of 24:1 mixed fuel. 87 or 89 is fine.<br /> The combination of the recoil pulling on the flywheel nut and the aggressive compression ratio will make your motor pull over hard. They're a real beast! I can turn around 30mph with mine on my 12-footer, and in racing trim my KG7H will push my 10-foot hydro close to 50mph. <br /> Have fun!<br />- Scott

 

[camccardell]

Re: Merc super 10 hurricane KG7 won't spark

I'll give it a shot, but I have a question on the mixture.<br /><br />According to the tank label it says that it needs 11:1 ratio... 3/4 pint to every gallon of gas, or 12oz.<br /><br />does it make a diffirence?<br /><br />and the magnet are on the crank, not on the flywheel<br /><br />Chris

 

[Chinewalker]

Re: Merc super 10 hurricane KG7 won't spark

Hi Chris,<br /> Go with the 24:1 mixture. The Mercs of the 1950s are primarily steel roller and needle bearings and do well with the leaner mix. I know of some folks who run theirs 50:1, but I consider that too lean, as there is still a major bronze bearing at the center main that likes extra oil. One consideration - If you were to run the motor on a small hydro or something where it would be spending 99% of it's run time at wide open throttle, I might bump it to 16:1, but that's only if you're running the tar out of it it.<br /> Magnet on the crankshaft means you've got the B-S mag. They've been known to work, but I've had mixed results with them, particularly at idle speeds. Make sure the points have good contact with the armature plate and invest in some new condensers. If you can't find original style condensers, I've found that Evinrude/Johnson condensers for most of the 2-cylinder models from the 1950s/1960s will work fine. Might have to lengthen the primary wire on the condenser to do it. New coils are available, but they're not cheap. Try Grubb's marine at oldmercs.com. <br /> Did yours come with the lower cowls? Nice to have if it did...<br /><br />- Scott

 

[clove]

Re: Merc super 10 hurricane KG7 won't spark

We have ran KG-7's for over 40 years and they run extremely well. run them on a 10" wooden hydro in SW Michigan. We have always ran them 24:1 with no issues what so ever. We even have the lower cowls but since we have had the motor, actually my dad did, when knew, we never used them. They are still in great shape. Good luck with the spark issue, and as previously suggested, go to Grubbs Marine. He has been the best source for the older Merc parts. <br /><br />Just a note: If you get hooked on the KG-7, try and find a Yamato 102. Have one of these as well on a 10' Tunnel--turns 65MPH! It's a blast!

 

[Chinewalker]

Re: Merc super 10 hurricane KG7 won't spark

Just a side note - the Yamato 102 mentioned by Clove is a racing motor - not suitable for service use...<br /><br />- Scott

 

[Tyty]

Re: Merc super 10 hurricane KG7 won't spark

I bought condensers for my KG7 off oldmercs.com it would be worth it since they arent extreamly expensive...