Quote:
Originally Posted by willardnigma
From my experience (I've owned the phantom 85 and all of the little 2 strokes.)
for 2 years my main mode of transportation was a motorized bike. It's what I was riding when I got the call about my dad, motivating me to rush over to the next county on hilly backroads.
All of those engines are from the same factory. The phantom 85 I bought was horrible. The head, piston and crankshaft replacement to go from the 66cc to the 85cc creates a ton of problems that ruin any longevity of the bike.
REPLACE ALL BOLTS for mounting the engine and for the intake and exhaust with good ones bought locally. as much as these vibrate I've seen the exhaust and intake bolts shear right off. I've heard of the rear sprocket bolts doing the same, but haven't experienced that myself. You know the typical chinesium quality doesn't pair well with a high vibration 2 stroke.
All of the quality from any of the sellers is hit or miss. The biggest way to get the best performance from my opinion is shorten the intake, get a high compression head. Polish your ports (lots of deburring from the casting on the jug) Windowed piston and reed valve attachment.
Being a china bike rider you know all to well about jetting the carb (hard to find jets for the stock carbs, best finding an aftermarket that fits)
As far as exhaust upgrade go, they're hit or miss. It's all about the rpm range you're running at. The stock one does well if you know how to enlarge the opening just a smidge. The ones referred to as "banana pipes" are just snake oil and sound a bit louder, but aren't truly tuned to give any performance.
All of these kits are way too overpriced vs buying the cheapo kit and finding the aftermarket parts to slap on yourself.
If you want I can link everything that was on my bike that's still in use today since 2018
(the new owner has only had to replace the chain and air filter)
And just like any other china bike
LOTS OF LOC TITE is a must.
Base motor kit
I recommend this High compression head, as the other design are lacking in cooling. You will notice a difference compared to the stock one
Windowed Piston. DO NOT get this upgrade if you don't get the reed valve, or you will lose a lot of performance
Reed Valve (wont get much out of this without having a windowed piston
And the final part, bike wheels with the mounts for brake rotors tend to fit the rear sprocket just fine. This is a must if you want any longevity as pushing the engine harder than stock can rip right through your spokes. Hell even a stock engine can do it if you get one thing out of alignment. |
Oh, believe me I am well aware of all of this information. I don't go into anything without doing epic levels of research. I do thank you for taking the time to say all of that though as it may help others.
Believe me, I planned on doing a LOT to this engine, and replacing most of the hardware, anyway.
As far as the Phantom 85 reliability, it's actually improved some now that they stopped using those stupid bushings. They now use the same connecting rod as the new "110cc" YD100 engines, which use a 12mm needle bearing. In fact, it uses the same needle bearing as the MS460 chainsaw the jug and piston are based off of.
The only real reliability issue they have now is the pistons are breaking apart, and part of that is due to the casing quality, the other part is due to the ring gaps being a bit on the tight side as far as I can tell. One ring was ok at .012" but the other was on the tight side at .006mm. Ideally for the bore size I wouldn't want a gap smaller than .011" when considering they run fairly hot.
I actually purchased a high quality MS460 piston with caber rings for it and gapped them myself. I take no chances. I am also splitting the case and replacing all of the bearings. The crank bearings were damaged during assembly. The crank itself also needs to be trued badly as I can see the runout visibly and it causes binding with the bevel gear. Since I am going to have it apart I am going to balance the crankshaft and try to get my balance factor to 65-70%.
As far as the rear sprocket mount. My idea was actually as you described with the rear hub. Of all the options, that seems the best one in my opinion. I can then run a set of spacers and a 200mm rear disc for clearance.