Modding the engine step by step + trouble shooting

[andybogan]

in campbelltown just down the road from appin track

[numroe]

Originally Posted by Le|Garage

... I chose a lifan 138cc engine and upgraded a few things.
... the chinese bearings were replaced with NACHI bearings.
... The next step was to fit the 56mm Akunar piston.
... To finish off, I decided to take some weight off the crank by fitting an inner rotor and aluminum oil sling. (Standard oil slinger weighs 743g where the aluminum one only weighs 160g)

- Larger 4 prong nut on clutch basket (so that it's the same as the oil sling)
- Magnetic oil drain bolt (Highly recommend these!)

Hi guys, I just bought an MSO 140SR with a Lifan 140 engine (55mm bore, "big valves" and 26mm mikuni carb). Engine questions out of curiosity:

* Are the chinese main bearings a known weakness? Who sells Nachi main bearings? That's a case split to put them in right?
* Who sells Akunar pistons, and how much lighter are they?
* To fit an inner rotor, is that simply a process of removing (pulling) the stock flywheel, and installing the "kit"? How ensure balancing?
* Is the oil slinger under the right side cover? Who sells the alum part? Please explain the larger nut needed on the clutch basket if using an alum oil slinger?
* Has anyone heard of fitting an extern oil filter inline with the cooler?

thanks in advance for any good tips/advice.

[numroe]

Originally Posted by Mack

No, bearing shop, yes, Akunar direct, depends, yes, you can't, yes, ebay, not needed just saves needing 2 dif sockets, yes I have.

Thanks Mack.

Re bearings. Good to hear you think the China bearings are fine.

Re Piston. Via your advice I found HOME Akunar Motorcycle Parts & Accessories. Looks like for a 55mm bore Lifan 140 I can choose between:
* Pro-R, 12.45mm pin to deck, 2.00mm dome. AKRRP002-E
* Pro, 13.00mm pin to deck, 8.5mm dome. AKPRP009-D
Which one will go straight into a stock new Lifan 55mm bore 140cc engine? I sent Akunar a message but they are on holidays for another 2 weeks.

Re IRK and balancing: Is no balancing ever an issue in terms of reliability?

Oil slinger (alum): ebay web link or search keywords? Yeah, I did some searches but came up empty. Saving 700g in rotating mass sounds attractive!

Re extern inline oil filter: Was it effective at screening out particles? Custom job or retail parts?

thanks again.

[Mack]

Start a new thread and I can go into more detail if you want. Don't want to fill these tute threads with ramblings.

[whereja]

nice work on the ports the valve reliefs are a bit rough though