I am a new member and I am trying to find out about putting in spark plugs in a yamaha 650 classic- v-star. Has anyone had any trouble with this. I am sure that it doesn't really matter which bike i'm on. I tried to replace the spark plugs yesterday, they both came out fine, and one went in just fine, but the other is nearly impossible to get in. Is there anything I can buy to clean the threads with out getting any debris in my engine? Or am I just doing something wrong? Please respond ASAP.

 

Check the plugs you pulled out to see if there was any thread damage on the plug or if there are any aluminum shavings in the plug threads. Next check the plug you tried to install against the old plugs as it is not unheard of to have bad threads / damaged threads on new plugs. You might try to insert the old plug and see if it will go in or not. You might have a cross thread problem and if the threads are too badly damaged (unable to get the plug to go in and straighten out the threads) you are looking at putting in a spark plug Heli-Coil at the least... If it is a very slight cross thread then you can try running a tap with grease on the flutes to try to catch the shavings and run it in and out a few threads at a time. I have known guys who have tried to stuff a red rag (part of one - cut up) into the sparkplug hole, tap the hole for the Heli-Coil, fish out the red rag with shavings and then stick an air hose down the spark plug hole and slowly turn the engine over with the flywheel / clutch / etc. without apparent damage, but I wouldn't....
Hopefully it is a bad plug or the begining of a cross thread and you get it straightened up...

 

I have looked at the old plugs and they match exactly. There is nothing wrong with the threads. I have also tried to reinsert the old one and it didn't go in either. Just like the new one. Is there some kind of cleaner that I could use to clean the threads in the engine? Where can I get a tap for cleaning it? Thanks, Adam

 

You reckon a battery cleaner brush would work? If it will fit OK, then spray some WD-40 down in the hole whilst twisting the brush. I would think if you have to tap out the threads, you could hold your shop vac nozzle down by the tap to suck out any shavings but work the tap very slowly. Good luck!

 

Maybe you just ain't holding it right. Try going back and forth with it maybe you just not catching the thread right. Like said before if you have to run anything in there to clean up the threads hold a shop vac hose up there and it should pull anything up. If you get it started turn it some and then back off keep doing this over and over and it might clean up a thread if thats the problem might have to put a little grease or oil on the threads to lube them some.

 

Plugs are sometimes a real pain. If you HAVE to chase threads, try a cotton ball coated with Vasoline in the hole (the Vasoline will catch and hold any debris) and run the plug in, then pull the cotton with a needle nose plier or some sort of forcep.

If this still is a problem, you may be looking at a tow/trailer to the dealer. Don't force the plug.

 

thanks for the info. I got some insight from a dealer. they said I should get a tap and do it that way. coated with grease to catch the shavings.

 

Interesting discussion - I'm sure there are those of us out there who have had experience with cross threaded spark plugs, me included. I have always attempted to do most of my car and bike service. My first car was a '67 VW bug which I cherished - $1590 brand new!! Anyway, the plugs were at a bad angle and I did cross thread one - it blew out on my way to my parent's home and I thought I had been shot - chugga chugga chugga - LOL - the mechanic dropped the engine and heli-coiled it - I asked about the shavings and he said - "aw crap - they never hurt anything!" Put it all back together and, when it started, lotsa sparks out the exhaust - (kinda purty) - I assume the sparks were the burning aluminum head material.

 

that was a priceless story!! remind me not to buy a volkswagen!!

 

Put some lubricant on the threads.