Post by melissascoots on Nov 13, 2012 7:44:05 GMT -5
I have a 150cc Chinese scooter that I seem to be parking wherever it breaks down. The latest problem was the spark plug shooting out of the hole—the threads were stripped. I don’t have the expertise to take the head off and replace that part, so I had to find a different method. I wasted 2 days trying to find a mechanic who would do it for me for less than $500, but no luck. One guy told me I might as well buy a new scooter for what it would cost.. I tried using Blue Magic 18003 ThermoSteel High-Temp (1000 degree) Metal Repair to make up for the stripped threads, but it only held for about a week, before it shot out again. Then I tried a back tap to recreate the threads but the hole was already too big.
Fortunately, my brother recommended a spark plug thread repair kit, so I researched those online. Basically, you drill out the hole and then thread in an insert that has nice new stainless threads that are the size of your spark plug. There wasn’t one site or video that totally prepared a novice like me on how to do it, so I thought I’d combine some of the stuff I learned here so I might save some other newbie from dumping a scooter. (I won’t say a perfectly good scooter – just scooter.) You should probably Google spark plug thread repair videos and watch some before and after you read my story if you don’t have any idea of what they are.
The first problem was finding the right kit. The engine I have is fairly common (GY6). It takes a CR7HS spark plug so I needed a 10mm x 1.0 x .5 kit. (Bad thing is not everyone lists it just like that.) The two most popular brands were Helicoil and Timesert. I didn’t want a Helicoil because from what I could tell, all of Helicoils inserts have a little tang on them which you have to break off after you install the insert. Since I wasn’t taking the head off, and there were big warnings on several sites that you couldn’t let that tang get into the head, I was leaning toward a Timesert kit. They’ll rent you a kit for $125 or you can buy one for $200. But then I found a couple of guys who said they’d tied and glued a string to the tang on a Helicoil and pulled it out by that, or you could use long thin needle nose pliers, so I decided to save some money and go for the Helicoil. They make a Sav-A-Thread Kit that’s cheaper than their regular kit but I couldn’t find one in stores (in Los Angeles) or online in the exact size I needed, so I had to order a kit from O’reilly’s Auto for $82. It arrived in 2 days.
The kit is supposed to come with all you need, but that’s not exactly true. If you are like me, and all the tools you have to draw from will fit in one little girly bag, you’re gonna have to get a handle to turn the drill bit that comes in the kit. (Do all of you have a big tap handle or a ratchet with an 8 sided (not 6 sided, boys and girls) little socket?) Oh and don’t buy a cheap ass $5 ratchet like I did – chances are great that it will break. (We ended up using pliers but that doesn’t exactly make for precision drilling which was supposed to be really important.) Then you need a little packet of anti-seize copper thread lubricant so the insert and the spark plug don’t melt together. Since the insert and the spark plug are the same metal, there’s a greater chance of this than with the original hole which is aluminum. You might want some Blue Magic Thermo Steel to put on the insert and the new hole, but it’s not called for by Helicoil but some sites do recommend it or something like LockTite. Then you need some heavy grease to put on the drill bit to catch the litlle metal shavings so they don’t get in the head. (I substituted what I had--Vick’s Vapor Rub.)
Next, you can pretty much throw away the instructions that come with the kit – worthless. Several of the videos online are for a kit that requires taking the head off and buying a weird size drill bit and using a drill press to drill the hole bigger but that’s not the type of kit I got. You do the drilling with the big tap/drill bit that’s included. At first, we (my darling, wonderful, computer-geek son and I) didn’t screw it in further than the first ½” because that’s all the reach the spark plug has and I had been scared by some site saying you had to be sure not to drill into the valve. But I had also read that if you back the scooter up, it puts the valve in the down position****very important***. So finally we realized that if we didn’t drill further, the hole wasn’t getting big enough for the insert to fit in it. So we drilled on until the ratchet broke and we had to twist it with pliers. We didn’t have a guide as to how far to go so we just guessed at about 1 ¼”. (We should have marked the bit before we started to drill. ****very important**) The Vicks did a great job of catching the shards.
Then I played with a spare insert so that I could see how it fit inside the threading cylinder and where to set the stop. The instructions say to do that according to length but I found that it wasn’t out of the tube by the time it got to the stop so I added a little to the measurement. The next thing that I think the instructions sucked at was telling me to wind it into the tube a couple of turns and then hold it up to the hole and start screwing it into the hole. It made more sense to me to wind it to the end of the tube and then put it up against the hole. We screwed it in until we heard a couple of pops. This worried my son so we made a mistake which I strongly advise against—we unscrewed the threading cylinder. This left a couple of coils above the hole. The instructions say to get it just below the hole.
What to do? I knew that there were listings online for how to remove a faulty Helicoil, so I assumed that it must be something more complicated than ripping it out with needle nose, so we decided to see what would happen if we just left it with a couple coils too high.
Next step was to remove the tang. The thread idea didn’t work—the thread got cut. Maybe I did it wrong. The needle nose wouldn’t fit in the insert now that it was in the hole, although they had fit in before it got wound into the hole. But lucky us – the tang was gone. Well, not so lucky according to all the warnings about not letting it get into the head. But my thought was that it was broken when we started so we couldn’t screw it up any worse than that. And with that in mind, we pressed on to see what would happen once the spark plug was in.
Can you believe that it started and seemed to run quiter and with less vibration than ever? Believe it. I do have less power though, but it runs. Yippie! I can’t go much faster than 45 (or 30 up a hill) but I’m just happy to be going at all.
The next time we do this job (and I feel confidant that we will have to do it again unless something else breaks before this Helicoil comes out), we’ll do better thanks to this less than perfect experience. I hope my saga spares someone else of at least a little crap!
If anyone has any advice on how to improve the power without removing the head (or the carb), please let me know. I want to put my little girly tool bag away and ride before it gets really cold.
Fortunately, my brother recommended a spark plug thread repair kit, so I researched those online. Basically, you drill out the hole and then thread in an insert that has nice new stainless threads that are the size of your spark plug. There wasn’t one site or video that totally prepared a novice like me on how to do it, so I thought I’d combine some of the stuff I learned here so I might save some other newbie from dumping a scooter. (I won’t say a perfectly good scooter – just scooter.) You should probably Google spark plug thread repair videos and watch some before and after you read my story if you don’t have any idea of what they are.
The first problem was finding the right kit. The engine I have is fairly common (GY6). It takes a CR7HS spark plug so I needed a 10mm x 1.0 x .5 kit. (Bad thing is not everyone lists it just like that.) The two most popular brands were Helicoil and Timesert. I didn’t want a Helicoil because from what I could tell, all of Helicoils inserts have a little tang on them which you have to break off after you install the insert. Since I wasn’t taking the head off, and there were big warnings on several sites that you couldn’t let that tang get into the head, I was leaning toward a Timesert kit. They’ll rent you a kit for $125 or you can buy one for $200. But then I found a couple of guys who said they’d tied and glued a string to the tang on a Helicoil and pulled it out by that, or you could use long thin needle nose pliers, so I decided to save some money and go for the Helicoil. They make a Sav-A-Thread Kit that’s cheaper than their regular kit but I couldn’t find one in stores (in Los Angeles) or online in the exact size I needed, so I had to order a kit from O’reilly’s Auto for $82. It arrived in 2 days.
The kit is supposed to come with all you need, but that’s not exactly true. If you are like me, and all the tools you have to draw from will fit in one little girly bag, you’re gonna have to get a handle to turn the drill bit that comes in the kit. (Do all of you have a big tap handle or a ratchet with an 8 sided (not 6 sided, boys and girls) little socket?) Oh and don’t buy a cheap ass $5 ratchet like I did – chances are great that it will break. (We ended up using pliers but that doesn’t exactly make for precision drilling which was supposed to be really important.) Then you need a little packet of anti-seize copper thread lubricant so the insert and the spark plug don’t melt together. Since the insert and the spark plug are the same metal, there’s a greater chance of this than with the original hole which is aluminum. You might want some Blue Magic Thermo Steel to put on the insert and the new hole, but it’s not called for by Helicoil but some sites do recommend it or something like LockTite. Then you need some heavy grease to put on the drill bit to catch the litlle metal shavings so they don’t get in the head. (I substituted what I had--Vick’s Vapor Rub.)
Next, you can pretty much throw away the instructions that come with the kit – worthless. Several of the videos online are for a kit that requires taking the head off and buying a weird size drill bit and using a drill press to drill the hole bigger but that’s not the type of kit I got. You do the drilling with the big tap/drill bit that’s included. At first, we (my darling, wonderful, computer-geek son and I) didn’t screw it in further than the first ½” because that’s all the reach the spark plug has and I had been scared by some site saying you had to be sure not to drill into the valve. But I had also read that if you back the scooter up, it puts the valve in the down position****very important***. So finally we realized that if we didn’t drill further, the hole wasn’t getting big enough for the insert to fit in it. So we drilled on until the ratchet broke and we had to twist it with pliers. We didn’t have a guide as to how far to go so we just guessed at about 1 ¼”. (We should have marked the bit before we started to drill. ****very important**) The Vicks did a great job of catching the shards.
Then I played with a spare insert so that I could see how it fit inside the threading cylinder and where to set the stop. The instructions say to do that according to length but I found that it wasn’t out of the tube by the time it got to the stop so I added a little to the measurement. The next thing that I think the instructions sucked at was telling me to wind it into the tube a couple of turns and then hold it up to the hole and start screwing it into the hole. It made more sense to me to wind it to the end of the tube and then put it up against the hole. We screwed it in until we heard a couple of pops. This worried my son so we made a mistake which I strongly advise against—we unscrewed the threading cylinder. This left a couple of coils above the hole. The instructions say to get it just below the hole.
What to do? I knew that there were listings online for how to remove a faulty Helicoil, so I assumed that it must be something more complicated than ripping it out with needle nose, so we decided to see what would happen if we just left it with a couple coils too high.
Next step was to remove the tang. The thread idea didn’t work—the thread got cut. Maybe I did it wrong. The needle nose wouldn’t fit in the insert now that it was in the hole, although they had fit in before it got wound into the hole. But lucky us – the tang was gone. Well, not so lucky according to all the warnings about not letting it get into the head. But my thought was that it was broken when we started so we couldn’t screw it up any worse than that. And with that in mind, we pressed on to see what would happen once the spark plug was in.
Can you believe that it started and seemed to run quiter and with less vibration than ever? Believe it. I do have less power though, but it runs. Yippie! I can’t go much faster than 45 (or 30 up a hill) but I’m just happy to be going at all.
The next time we do this job (and I feel confidant that we will have to do it again unless something else breaks before this Helicoil comes out), we’ll do better thanks to this less than perfect experience. I hope my saga spares someone else of at least a little crap!
If anyone has any advice on how to improve the power without removing the head (or the carb), please let me know. I want to put my little girly tool bag away and ride before it gets really cold.
