NGK plug cap problem

45u

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The inside of the NGK plug cap is made of brass where it hold is to the plug. Every gallon of fuel I have to replace it as the part that holds the cap on the plug wares out and will not stay on. Has any one else had this problem? I am sure it has to do with vibration.
Thanks
Jeff
 
I'm assuming you DID take the terminal nut off the plug - are you sure it is real NGK, as I've replaced many of the chinese caps with real NGKs and never had a problem
 
Yes as they say NGK on them come in a NGK box and where left over from when I had my motorcycle shop for 0ver 13 years. Been working on and much of the time make a living working on motorcycles including but not limited to machine work for 45 plus years. I still have all my own machines. The plug cap will not even begin to go on with the plug thread on top.
Thanks
Jeff
 
I avoid the NGKs with resistors, but if you're firing OK that won't cause failure of the cap. I get NGK LZFH caps that are short, zero resistance, & look just like the chinese caps that come with kits - I've seen a lot of NGKs with very long bodies that may not allow the top of plug to get all the way up inside, and I've also seen caps with a rubber seal at bottom that was so tight that I had to put that on plug by itself to get cap on, then pull the rubber back up over the plastic.

Other than that, there is no reason the steel spring inside would fail to hold the steel threads on the plug.
 
I avoid the NGKs with resistors, but if you're firing OK that won't cause failure of the cap. I get NGK LZFH caps that are short, zero resistance, & look just like the chinese caps that come with kits - I've seen a lot of NGKs with very long bodies that may not allow the top of plug to get all the way up inside, and I've also seen caps with a rubber seal at bottom that was so tight that I had to put that on plug by itself to get cap on, then pull the rubber back up over the plastic.

Other than that, there is no reason the steel spring inside would fail to hold the steel threads on the plug.

I assure you after 45 plus years of working on motorcycles much of the time as a living it is installed properly but the sprinting does wear out in about half a gallon just like the stock plug caps. Motor runs just fine till the spring wares out and the cap pops off. I am going to try a standard cap where you have to thread on the piece on the plug. I had several CDI s come with this set up.
Thanks
Jeff
 
CDI's come with 2 different plug caps.
One has a little tension clip, which can only be used on a plug with top cap off where the threads are, the other is fatter to accommodate the plug with the cap on.
They don't play nice together.

Cap On.. Cap Off.. Cap On.. Cap Off..
 
CDI's come with 2 different plug caps.
One has a little tension clip, which can only be used on a plug with top cap off where the threads are, the other is fatter to accommodate the plug with the cap on.
They don't play nice together.

Cap On.. Cap Off.. Cap On.. Cap Off..

Yes this is what I was saying in my above post.
 
going to a rubber cap and replacing the terminal nut on the plug should fix your problem, but there is nothing about the HT motor that would cause this - you need to look at your cap and plug and try to figure out how they differ from the thousands you've probably seen on motorcycles - I've worked on motorcycles for 57 years and owned a shop for many years, I now am only full time repair for these chinese POSs in my area (cause they're about all I can lift at my age)
 
going to a rubber cap and replacing the terminal nut on the plug should fix your problem, but there is nothing about the HT motor that would cause this - you need to look at your cap and plug and try to figure out how they differ from the thousands you've probably seen on motorcycles - I've worked on motorcycles for 57 years and owned a shop for many years, I now am only full time repair for these chinese POSs in my area (cause they're about all I can lift at my age)

I am so called retried but past customers after trying others will not let anyone touch their motorcycles but I. Some have been customers for over 30 plus years. My only transportation is my motor bike and my rig (motorcycle with sidecar) as in 45 plus years of none stop riding I have only owned a cage when the children where small because I hate a cage! Only the good Lord can keep me off motorcycles.

I have some wanting me to build them motor bikes but with the poor quality I do not see how to make money on them and still do customers they way I have always done them. I know what is causing the plug cap problem it has to do with vibration.

Just a FEW of my toys I use often.







 
With a drill press you can drill a couple holes in the crank wheels to balance out that vibration
 
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