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Discussion Starter #1
I was doing a quick valve job on my motor and noticed one of the valve cover bolts is a little loose ... not quite stripped, but close.

Anyone ever heli-coil the cam caps? Any suggestions? The bolts seem to be 7 mm (definitely are not 6 or 8 mms).

If I understand the heli-coil situation properly, you drill the hole out with a one-size larger bit (8 mm), tap the hole with an 8 mm tap, screw in the insert with red locktite, and voila! Right? Or wrong? I've never done this before (I'm usually a stickler for using the proper torque values.)
 

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That sounds about right, though I've never done it for that exact application, the little packet of heli-coils will/should have recommended drill/tap sizes and bits of how-to.
 

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And, I think you can get a the same or even higher torque value, upto a degree, with a heli-coil because there is more area being grabbed.
 

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A buddy just had the same problem with his Katuna last year had two cam caps strip out..then had the heli-coils pullout. Lots of bad luck. He should have called me first. APE has oversized hold down bolts(8mm)cheap. Just make sure that if you use heli-coils or retap to 8mm that the holes are centered on the orginals.
Bones

http://www.aperaceparts.com/
 

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And, I think you can get a the same or even higher torque value, upto a degree, with a heli-coil because there is more area being grabbed.
<font size="2" face="Verdana, Arial">I'm still thinking of doing the Heli-Coil repair of my drainplug hole. I don't understand how more area is grabbed, but I've been told that a heli-Coil *is* stronger than a tapped aluminum hole. Aluminum race car engines are supposedly intentionally Heli-Coiled for this reason. Has anyone else heard of this?
 

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helicoils are steel, which is stronger than aluminum, so yes, they're stronger than the stock threads.

be careful with cam caps.....i've seen some crack when helicoiled....
 

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I guess it's not that more area is being "grabbed" by the bolt alone, but by the bolt to coil to head. i.e. if you were to count the bolt and coil as the fastener unit, the coil takes up more space in the connection, "grabbing" more area, and probably allowing for more torque.
 

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You guy seem to worry about torque value...That is what stripped the camcaps/drain plug in the first place! Over-Torque combined with steel bolts into a alum. hole is as much to blame. APE also sells stock sized hold down bolts in alum. this helps to prevent the steel bolts from ripping out the alloy threads. I replaced all of the stock steel hold downs with the APE ones. Cheap insurance at 59.95 for the stock replacements and 64.95 for the 1mm oversize plus they are billet so look good too!
Bones
 

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for valve cover bolts, once you've turned them down to the point where they stop, there's no need to turn them any further. if you do, you'll risk stripping the threads or cracking the cam caps....

[ 04-12-2002, 04:53 PM: Message edited by: jeff ]
 

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Heli-coils are nice, but Timeserts are the Sh*t!!

Whatever method you choose make sure you drill the hole on a drill press or mill or something. You want to make sure the hole is straight up and down, otherwise the bolt won't sit flat on the gasket. Don't ask how I know
 

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Discussion Starter #12
Edster,
So what are timeserts? I've never heard of them.

Oh, and thanks for the tip, I'll be sure to use the drill press.
 

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Hey, that makes sense. I bet the new torque value that would hold is for a bolt 1mm bigger. That's kind of what it is after the Heli-coil.
 

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You guy seem to worry about torque value...
<font size="2" face="Verdana, Arial">Nah, just want to understand how they work.
 

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Originally posted by Ragnar:
</font><blockquote><font size="1" face="Verdana, Arial">quote:</font><hr /><font size="2" face="Verdana, Arial"> You guy seem to worry about torque value...
<font size="2" face="Verdana, Arial">Nah, just want to understand how they work.
</font><hr /></blockquote><font size="2" face="Verdana, Arial">I agree, tight enough is probably tight enough, too tight is too tight.
 

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helicoil kit was tough to find. it was around 50 bucks, install was easy but take your time it is easy to go through the cap. i did all my caps because i like to stay on top of my valve lash, and figured that i might as well do all of them at once instead of one or two at a time. finished product is great, bolts go in with your fingers easily.
 

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Here are some pix. Basically you enlarge hole, Cut a relief, Tap hole, Screw in time sert(it bottoms out on the relief), Run the expander through the time sert(the bottom few threads are tight and when you run the expander through it the timesert expands and locks it into place), and that's it!

These are the strongest thread repair kits you can buy, and it's easy to remove them with a bolt extractor if they strip out.
 

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Discussion Starter #18
Can anyone tell me what size tap to use to tap out the 7 mm valve cover bolt?
 

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Discussion Starter #19
Nevermind, it's a 9 mm tap for the 7 mm helicoil insert. Worked like a charm!!!

Got the new motor in today, and it merely lacks electrical connections, the carbs, and an exhaust. Woo hoo ... power wheelies tomorrow!
 
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