Modding the engine step by step + trouble shooting

[andybogan]

1

hey guys this is my first post.
i build car engines for mates its a hobby... the bigger the cam the more clearance you need because of valves and the cam getting hotter from lifting further and faster so you need lash to make sure the lash doesnt close up and keep the valves open.

how much compression are you running?
i only ask because i am going to start my engine build soon and am planning on running around 16:1 with my own cam grind and head work big valves etc etc.

it will be running on rf 100 fuel so no problems with detonation.
i am planning on making my cam with a bit more duration and alot more overlap to see if i can make it kickstart easier while staying sround the same lift so i dont stuff up the rocker geometry.

this engine is a lifan 140 as above.

have you thrown it on a dyno yet ? im curious how much power it made.

thanks.

p.s has anyone done their own cam in one of these before ?

 

[tubes380]

i dont know as much as some on this topic, ie mack and others, but 16:1 sounds way too high, i have heard of the yank builders reaching numbers around 12:1 which is where they max out, normal comp numbers are around 9 from what i have seen, maybe aim for something around the 11:1 mark.

 

[ducar.r.spec]

say bye bye to kick start gears at 16:1

 

[no_crf50_here]

say bye bye to kick start gears at 16:1

Couldn't clutch it either, but it'd be easy to back it in....

 

[ducar.r.spec]

Couldn't clutch it either, but it'd be easy to back it in....

u could also climg the grand canyon in the bottom of 4th

 

[corey58]

16:1 wound be hard to get my motor is 14:1 and that not some ramdon number that tested buy the daytona factory and as for 12:1 an daytona 125 has it

 

[andybogan]

cheers mack you know about engines i see.
i am beeing given two cams by a friend that works on these bikes and sells them he is giving my a standard cam for me to get re-ground and a takagowa race cam for me to profile and modify timings i want around 225 intake and 228 exhaust @0.50 with a lobe seperation of 100degrees i will measure what the biggest lift is without coil binding.

i need a very high cr because i want to run shell rf100 fuel and it is more efficiant with ultra high comps.

i am leaving the standard bore size because i want more strength and better gasket sealing.

i will have a look at the studs when i pull my engine down and see if there is anything i can do to strengthen them (where they screw in you mean).

my engine only has 2 hours on it and if it doesnt like the big comp i can always take the comp back down till it works.

and if she blows i will just buy a new one and start again

 

[red_demon24]

good work mate sounds like youve put a bit of time and effort into it should go well.

 

[andybogan]

1

hey all just a lil update have got the stock engine running on rf100 fuel now with the new 26mm o.k.o roundslide carb took a few jet changes to get it right but got there, more throttle reponse now.

i am picking up my irk and oil slinger kit this weekend, once that is all working i will start pulling the engine down.

am also having trouble finding anyone who can regrind my cam for me as they all dont have a master profile since there isnt much of a call for custom cams in these engines.

i will keep looking and updating.

cheers.

 

[coolmodee01]

where are you located?

 

[andybogan]

1

in campbelltown just down the road from appin track

 

[numroe]

... 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]

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

 

[robbo23]

u mention in your thread that u use a magnetic oil drain bolt.well im using a computer hard drive magnet attached next to the bolt.LOL never new u could get magnetic oil bolt.

 

[rosie]

how did u take the flywheel off??

 

[rider456]

use a flywheel puller

 

[coolmodee01]

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.

just a quick one

most well all the main bearings i've seen in a lifan motor have been japenese
and have never had an issue with even one

 

[alphabetica]

Just curious. Do you know what the dia of the main journal on the Lifan 150 ( 1P56FMJ ) crank is?

I have access to good mill and lathe at the moment and am thinking of turning up a custom crank to turn it in to a super stroker.

I was thinking something insane like out from the 56.5x59 to 57x70.

Have my motor half down but have not gone as far as splitting the cases yet.