Spark plug insulator around electrode broke off in the motor

[Doc Brown]

Originally Posted by Gasser Nate

I have seen them fracture the porcelain all the way through. To be honest I didn?t even watch the video yet, just a quick comment before I went to sleep! 😆

Yeah, this can happen, I just have never seen that to be honest.

If it were my bike I'd get rid of the RK head and use the OEM head. Then I'd use the OEM needle, jets and slide plus the exhaust (if available) and the OEM spark plug. During rebuild I'd check:

reeds
rubber flange the carb sits in
flywheel and especially the woodruff key
ignition pick up and if it sits tight
power valve (ease of movement)

Then go for a test ride and see if the engine sounds normal. For me the engine sounds strange in all your videos. You may remember that I asked you on Thumper Talk which camera you use because all other vids I have seen the 300 GG's sound way different. I really admire you for being so patient and not giving up.

Sorry for bending your ears and writing so much, but I need to mention that I don't like it if a needle is used in its lowest or top position. You mentioned that you have your NECH in fifth(!) position and the AS only open 1 turn. For me that indicates that something isn't right. I have jetted quite a few 300 Gasser's and at standard temperature (18 C or 65F) and with either a 40 or 42 pilot jet I never had it at less than 1.5 turns out, most of the time between 1.75 and 2 turns.

Maybe someone can borrow you an identical carb for testing. Unfortunately the US is so far away otherwise I had sent you mine. I can't ride anyway, we are all under quarantine due to Covid virus.

If all the things mentioned above are good and there are no air leaks you can start to play with the carb. Maybe a JD kit (worked for me very well on 3 Gassers) would be worth a try.

Good luck!

Doc

[Jakobi]

Even at 44 seconds on the downhill she sounds likes shes lean with erratic idle. Like others said.. check your engine for air leaks.

Also take the time to cc the trapped volume.. especially if you've had a failure. Double check timing.. and I wouldn't bother with iridium plugs in a 2 banger.

[TGM_OFFROAD]

I got my cylinder and piston today so I am going to start the rebuild process and then pressure test.

I pulled the flywheel and everything looks good visually.

I think part of my problem is I don't know what it is "supposed to sound like" other than what I hear on videos and that is always hard to judge. This is my first 300 and first 2 stroke since my rm125 in 1999.

Should have pressure test done in about 2 hours or so.

[Anders]

Originally Posted by TGM_OFFROAD

I got my cylinder and piston today so I am going to start the rebuild process and then pressure test.

...

Should have pressure test done in about 2 hours or so.

We will watch this space...

[swazi_matt]

Originally Posted by TGM_OFFROAD

Yes I was just riding it back to my truck. I carry tools with me but nothing to take the springs off my expansion chamber

not going to add to the sparkplug issues, but an easy way to remove the springs is to use a zip tie, just make a big loop and use it as a pull

[gg3]

Originally Posted by swazi_matt

not going to add to the sparkplug issues, but an easy way to remove the springs is to use a zip tie, just make a big loop and use it as a pull

So you don't need to take the skin off your knuckles,scratch your pipe or hit yourself in the face with pliers to remove them?

[TGM_OFFROAD]

Put it back together and it dropped from 7 psi to 5psi in 3 minutes. I found bubbles at the base gasket which is weird because it is brand new. Its a paper gasket, would you recommend using a sealant on it?

[TGM_OFFROAD]

I used some ultra copper sealant on the base gasket and now it is holding 6 psi for 16 min now.

[Zman]

Originally Posted by SS109

Yeah, the engine doesn't sound right in that video. Sounds lean to me. I would definitely be checking for air leaks. Make sure the exhaust pipe is sealed up well to the cylinder as air can be introduced there as well.

It sounds lean to me as well at high rpms. That can be a problem even with 100 octane fuel.

Sorry I responded to page one of this thread.

[TGM_OFFROAD]

Originally Posted by Zman

It sounds lean to me as well at high rpms. That can be a problem even with 100 octane fuel.

Sorry I responded to page one of this thread.

The weird thing was with a 170 it would get on the pipe. A 172 would cause it to sputter like it was too rich. I think my base gasket was the air leak, I have it sealed up now it would seem. I am going to test it again in the morning and hopefully take it out to the local park to do a test ride.