bad news on the 86 kdx...

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Bubbie3737

Member

Feb 28, 2004

50

0

• Apr 9, 2004

• #1

so my friend has a 86 kdx. The headgasket was leaking so i went to fix it. pulled it all out and noticed the front three studs were way up, like somebody had tightened them down real hard and they stripped out the threads inside the block and moved up...Can i re-tap these or what? Has this ever happened to anybody else? I really need to figure this out, i talked him into buying the bike cause it all looked real good and i wanted to get him into riding.

 

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dsndblm

Member

Jul 12, 2003

167

0

• Apr 9, 2004

• #2

You may be able to put heli coils in the engine case to repair the threads. If the stud holes go all the way through into the case the metal shavings will fall into the engine case. Better get some more advice before trying this.

 

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Bubbie3737

Member

Feb 28, 2004

50

0

• Apr 10, 2004

• Thread starter
• #3

anybody else got ideas?!

 

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rethnal

~SPONSOR~

Jul 14, 2002

659

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• Apr 10, 2004

• #4

You could work them back down into position, weld them in place or use a JB Weld type substance and replace the head gasket. As long as the studs don't move it, should be fine. There is not a ton of torque on those studs so it should hold up just fine.

 

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Henk

Member

Apr 15, 2000

63

0

• Apr 10, 2004

• #5

I'm pretty sure the head studs on the KDX don't run all the way down to the cases. I'd try working them back down using a couple of nuts locked against each other to turn them. It will be pretty obvious if they are stripped. If that fails I'd pull the barrel to avoid swarf falling into the bottom end and use helicoils. It's only going to cost you a couple of gaskets more than just pulling off the head. One word of warning if you decide to pull the barrel, on the later model KDXes the nut holding the rack on the powervavle actuator is a left hand thread. Not sure if this applies to the 90.

 

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Bubbie3737

Member

Feb 28, 2004

50

0

• Apr 10, 2004

• Thread starter
• #6

how do helicoils work? I know they are stripped for sure, i looked. and no the holes do not go all the way down to the case, it stops. like i can thread the studs in with my hand, but i can like pull it back it with my hand without spinning it.

 

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dsndblm

Member

Jul 12, 2003

167

0

• Apr 11, 2004

• #7

The helicoils come with a drill bit, insertion, heliciols and tap. You drill the hole to size and use the supplied tap to tap the hole that you drilled. The heliciol insert is threaded into the tapped hole using a tool that comes with the kit. Last thing you break off a small tang that the insertion tool uses to thread the insert. The whole kit costs about 40 bucks. Measure the size and thread pitch of the studs and get the kit. They are easy to use.

 

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CZ511

Member

Mar 2, 2003

91

0

• Apr 11, 2004

• #8

Relax, if the Heli Coil does not do the trick (which it should) maybe you can pick up a used motor on ebay. As of right now, there is a 1987 parts motor (not sure if it's the same) going for just over $100.00. Check it out, maybe that's the way to go. I really hope it all works out for you. The best memories of my "Younger days" was riding with my friends. Don't take it personal that the bike needs some repairs. As a parent, I think trying to get your friend into riding is an absolute great thing. I may be 42 but I still love going out in the garage, turning on the tunes and working on my KDX. Well, to be truthful, for me it's therapy. When I was younger, it was just plain fun! Enjoy the times working on the bike with your buddy and don't be down that the bike needs some help.

Good luck, I wish more kids would try to get their friends into dirt bikes and not into other stuff......

 

S

shr

Uhhh...

Apr 8, 2002

113

0

• Apr 11, 2004

• #9

Heli-coils do work great, BUT! There is some skill in making this repair work. The cylinder should be removed from the engine and secured in a drill press with the hole centered to the drill bit. Note!!!!! DO NOT attempt to use an electric drill as the results will be less that satisfactory! Also be very careful not to over drill the hole, Sometimes when drilling a existing hole a little bigger the drill bit will grab and pull it in deeper than needed.

When installing the Heli-coil, make sure that the end of it's thread wire is 1 to 1-1/2 turns below the top of the deck of the cylinder.

After installation, make sure that you snap off the drive tang of the coil and make sure that you recover the tang.

My biggest suggestion is to let a professional do the repairs. There are a lot of people that try Heli-coils, and do to improper installation it will fail. A proper installed Heli-coil will be as good, and most of the time better that the original threads.

Good luck on your repairs.

 

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Bubbie3737

Member

Feb 28, 2004

50

0

• Apr 12, 2004

• Thread starter
• #10

any idea on what a shop could possibly charge to do this?

 

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Henk

Member

Apr 15, 2000

63

0

• Apr 12, 2004

• #11

Phone your local general engineering workshop. They probably have the helicoil kit already and if you take in the barrel ready to go it shouldn't cost too much. A lot less than a replacement barrel if you bodge the job anyway. Personaly I'd do it myself but I've fitted a few helicoils over the years.