Phantom 85v3 spark knock and Backfiring

[Wrench]

Air cooled engine
For a more accurate engine temperature, take the temp while your going 30 - 35mph in the wind
Be careful don't crash

 

[Coubob]

How long a period of time are you trying to run it for during breakin at a 20:1 conventional 2 cycle oil mix during your 310 mile breakin period???

I run it fir about 10 minutes each time. I just have it now where it's running 310f. So I'm happy with it now. I found out what ir was causing trouble. I had accidentally got a different needle in it. One that came with the v80 minerelli kit. I put the original bofang needle back in it on the richest notch with the 75 jet. It runs very good and 4 strokes enough now to help cool it but not to much. It revs out nice again. I little rattlely clunky sounding .and it vibrates alot more than my others. But I'm happy with it now. And more confident it might make it without doing a choptop and all that.

 

[DAMIEN1307]

I had accidentally got a different needle in it. One that came with the v80 minerelli kit. I put the original bofang needle back in it

That sounds like quite the "accident" to me that two different needles from two very different kits could get mixed up like that...lol.

 

[Coubob]

Ĥhh

Ok try a colder plug maybe? B8hs? They do run alittle hot but ya gotta get creative. Ask yourself how can I get more air flow? A 32 or 36t sprocket greatly reduces heat AND wear. I've seen guys make Cowells outa 2 peices of plastic oh and like a radiator shroud to a dirtbike and some zipties. To be honest they look rad but I've never needed one and been too busy. Makes it kinda look like a dirt bike. They say it works great directing all that air right at the motor

I put in a new plug I had to get an autolite 4092. And I have a 40 tooth sprocket.

 

[Gordy]

I put in a new plug I had to get an autolite 4092. And I have a 40 tooth sprocket.

I will admit an auto lite is better than the stock Chinese plug, and at least you didn't get champion, but I gotta ask, why not a Bosch or NGK?

 

[Coubob]

..Air cooled engine
For a more accurate engine temperature, take the temp while your going 30 - 35mph in the wind
Be careful don't crash

I had been using a digital meat thermometer and wedge against a fin afterward.

 

[Coubob]

I will admit an auto lite is better than the stock Chinese plug, and at least you didn't get champion, but I gotta ask, why not a Bosch or NGK?

Twice as much I didn't the $

 

[Coubob]

That sounds like quite the "accident" to me that two different needles from two very different kits could get mixed up like that...lol.

I had the new needle on a carb for the minerelli. It kept soft seizing so I put my oko 19 on the minerelli and forgot the one bofang had new needle.

 

[Coubob]

Also I stress this. These are not made to idle. When you check it be as quick as you can. Phantom sitting at a dead stop will surely run pretty hot. Is 340° optimal? No but it's not in the danger zone. Just try to keep her moving and idle as little as possible. It's the rule for all of these motors. I like to put my hand on the magneto cover. If you can't leave your hand on the magneto cover then she's too hot.

I don't let any sit and idle especially this phantom. I can tap the head to gauge temp by feel also to see if the exhaust is hotter than the head.. but I did my phantom to running 310f. So I'm alt happier with it now.

 

[Coubob]