Phantom 85

[skiles Whitney]

So I purchased a new phantom 85 engine it came to me on Friday I have the first V3 version from November of 2022 this is the most recent version of the V3 and the windows in the piston are about the size of a dime or smaller and the bike falls on its face from quarter throttle as soon as I hit quarter throttle and not even quarter throttle it just falls on its face are the windows supposed to be the same size as any other window piston on the market or do you know if they've changed them and made them smaller because I compared them to my replacement piston that I bought with my first phantom 85 which is still in the box I still have the cylinder and piston brand new in the box in the windows in that piston are normal size I've been playing with the carburetor but I'm about to take my old phantom 85 carburetor and put it on this bike cuz it ran perfect out of the box except for the tiny hole in the bottom of the crankcase that carburetor and engine runs perfect because I took it put it on another bike and it runs like a beast on a California motorbikes racing engine and it runs like a champ and I'm not kidding with that reed and that carburetor setup for some reason it likes it so I'm taking that carburetor and putting it on my phantom if it does the same thing I know what's wrong it's those windows anybody have any thoughts thank you

 

[neodymium]

My phantom piston also came with the smaller windows. I believe they did this because the older larger windows were causing the piston to fall apart due to them being too big and causing weak points. I can't tell you how mine runs since my head needs to be replaced unfortunately. Id look into your carburetor tuning though as any time I've had this symptom it was usually too rich or fuel supply related

Spark plug for scale in photo

 

[skiles Whitney]

Well it's good to know that it wasn't just quality control and they're making the Piston Windows smaller but the carburetor problem it is just that it is a carburetor problem because when I found a hole in the bottom of my crankcase on my first phantom 85 engine I bought I took the Reed and the carburetor off and I put it on a engine I got from California bicycle engines which was a racing engine and that engine runs like I would never imagined it could so yesterday when I got home I took the new carburetor and put it on that bike and it falls flat on its face that I've checked the float and I've checked the needle and I've checked needle jet I can see light in customer service asked me if I checked everything to be sure before I got a hold of them unfortunately this is not my first rodeo LOL I told him yes I took it all apart and checked

 

[ImpulseRocket]

Checked for vacuum leaks yet? The flanges of my cylinder were pretty uneven and damn near "as cast." The carb O ring can be a pain to get seated properly against the inlet for the oz reed too. My stator for the ignition was also installed like crap. Double check the magnet isn't installed backwards either.

 

[neodymium]

Checked for vacuum leaks yet? The flanges of my cylinder were pretty uneven and damn near "as cast." The carb O ring can be a pain to get seated properly against the inlet for the oz reed too. My stator for the ignition was also installed like crap. Double check the magnet isn't installed backwards either.

I did need to adjust my magneto as it was hitting the magnet.

How does one verify that the magnet isn't backwards?
Nevermind found a video with a quick search through the forums that explains this a bit better. This isn't an issue I've ever had as I take photos before I disassemble.

Any suggestions for something I can wrap the oz reed inlet with that would help seal it. Maybe something like Teflon tape? I've got a bit of that on hand already. I dislike this speed card design with the oring seated far back and nothing around the actual mouth making contact with the reed. Seems like leaks waiting to happen..

 

[DAMIEN1307]

Any suggestions for something I can wrap the oz reed inlet with that would help seal it. Maybe something like Teflon tape? I've got a bit of that on hand already. I dislike this speed card design with the oring seated far back and nothing around the actual mouth making contact with the reed. Seems like leaks waiting to happen..

Mine does not leak whatsoever, I built the entire motor on my kitchen table before ever putting it on the bike which made it quite easy to seat that carby O ring nice and tight where the reed valve inserts itself into the carby.

 

[DAMIEN1307]

I did need to adjust my magneto as it was hitting the magnet.

My magneto was off center as well when I got it and even the main hold down nut was totally loose on the stator.

When I finally was able to get help from a buddy who didn't have arthritis in his hands like I do to remove those four hold down screws, even he exclaimed thay were waaay too tight and suggested we do not reuse them because removing them stressed the threading, but buy some good American hardware to put it back together again which we immediately went to Lowes hardware and did just so...lol.

 

[neodymium]

My magneto was off center as well when I got it and even the main hold down nut was totally loose on the stator.

When I finally was able to get help from a buddy who didn't have arthritis in his hands like I do to remove those four hold down screws, even he exclaimed thay were waaay too tight and suggested we do not reuse them because removing them stressed the threading, but buy some good American hardware to put it back together again which we immediately went to Lowes hardware and did just so...lol.

Do you remember what size bolts you needed for the magneto? I wanted to replace those as well. I have a caliper but I don't know the thread pitch

 

[DAMIEN1307]

Do you remember what size bolts you needed for the magneto? I wanted to replace those as well. I have a caliper but I don't know the thread pitch

I couldn't tell ya, what I do is bring the screws etc, with you to the hardware store and just simply match them up, they all have the different little test thingys that you can screw into so you can test your existing hardware to tell ya what size your gonna need.

 

[Deleted member 33388]

I'm getting a phantom 85 soon and was wondering if putting the cylinder on is a pain.