Lifan 150 diffs and pics

[grant878]

thanks numroe very interesting post from someone who knows what they are on about. The 150 sounds great.

 

[crazzy #1]

good work numroe, ill be sure to point some questions your way when i get my SR, your thread is a good read! as are all of them, but 9 times out of 10 i get half way through and start to feel tired (mainly because i am reading them and not long after hitting bed) so half of it has not sunk in! lol, ill have to give them another read...

anyway mate, keep up the good work!

 

[numroe]

You are welcome fellas. As long as it keeps on hauling, it's a great engine. Mated with my carb, and with the A1 cam plus Akunar valves, I just love it. So responsive. I rode it again yesterday. Amazing the usable speed range I can get out of one gear.

My bike is going so well (engine, dampers and handling), that I've decided (again) that one day I am going to put 14+17" wheels on it. I rarely get to ride on small tracks, and I want it to float around a bit smoother over rough terrain. I can put the 12"14" wheels back on it for smoother tracks.

 

[Cactus Jack]

Lifan 150 ignition: Yesterday I tried retarding the ignition. It did start easier, but ran noticeably worse. For sure it did not rev out as nicely under load, but worse was that is was no where near as crisp in response to initial throttle turn coming out of corners. So I rotated the stator plate back (to the middle position). Did not bother trying more advance than the mid position, since cold starting is a problem at times, but otherwise it runs great.

Yes ... numroe most certainly ALWAYS posts interesting info .....

The ignitions are limited because they are fully analogue.... Digital systems sense rpm and crank angle ... then match the timing advance to suit the revs .... whereas analogue is fixed .... some may have a built in stage of advance but they don't match the advance curve anywhere near as closely as a digital system ...

 

[coolmodee01]

we have found that advanceing the timing makes them harder to start causeing kick start problems

i think it has somthing to do with a pre ignition happening is that right

mine runs fine but i havn't touched anything at all but i'm gunna have to throw a bigger carb on it but for now i'm just having fun riding

 

[kaneo]

I have advanced mine and with the pumper 27mm carby i run it starts really well and the extra advance is noticable too, power wise. I also run RF100 avgas in it which probably helps too. I think the initial squirt of fuel from the accelerator pump may be the reason for it not kicking back as it starts first kick hot or cold. Couldnt be happier with my motor. For the money they are excellent.

 

[Cactus Jack]

I ran Avgas 100 (obtained from the aerodrome on the central coast) in my worked XR and lost quite a bit of power (probably needed more ignition advance) ..... LRP with performance Lab Octane Booster (xylene) went heaps better ... I asked at the airport and they said avgas is for slow revving aircraft engines .... I'd say that Avgas needs higher ignition advance and that helps reduce or eliminate kick back with advanced static ignition timing ...

And in a quick web search ... I found this info ....

We are constantly approached by owners who are trying to craft a way that can allow them to get race gas horsepower, without having to run expensive race fuel. Sadly, it just can’t be done.

Normal “octane boosters” are capable of making really poor gas into decent gas, but they cannot make good gas into race gas. That is, normal boosters can make 86 octane to 89. However the same booster can only make 91 into 91.5 or 92. We discourage the use of octane booster except in emergencies.

One alternative used by many is to run aviation fuel (aka “av gas). Av gas is usually around 100 octane, but av gas has other properties that are important. One of the main qualities that makes av gas desirable for aircraft use is that it is actually lighter (per gallon) than conventional gasolines. This reduced weight is important for small underpowered planes that need to be as light as possible to take off.

[Normal gasoline molecules have two “ends”. The “light” end of the molecule ignites easily, and burns with a quick low temperature flame (as a piece of newspaper would burn). The “heavy” end of the molecule is harder to ignite, but burns with a much hotter flame (as a log would burn). To make av gas lighter, the heavy end of the molecule is omitted to reduce the weight of each gallon. Since most aviation engines are low rpm motors, they experience little power loss. However if 100% av gas is used in a high output pwc engine made for race gas, there is a visible loss of power because the “heavy” ends are not there to contribute to the making of power. All that said, we consider it a great idea to mix 50/50 av/91oct fuel for “Hammer 1” kit owners who want a little extra temperature protection during exceptionally hard operation. A 50/50 mix still contains enough “heavy” ends” to allow for good overall power and has a much-improved octane over straight 91-octane] From the below link :

http://www.groupk.com/k800.htm

And :

avgas, any mods needed - ThumperTalk

 

[kaneo]

Very interesting. I have topped up my avgas tank with v power 98 before and did notice it go a bit better up high in the revs. I thought i was imagining it but reading that it seems i was not. Good work as usual cactus.

 

[numroe]

Thanks Cactus. Interesting.

 

[Fiddy@norway]

these pages made for some interesting reading, I'm quite excited about my 150 lying by the foot of my bed as I write this and I've got some questions\thoughts:

1: I'm a real 4-stroker and I crave a strong bottom end and a snappy midrange, I'm not much of a revver and prefer to short-shift and ride the torque-curve instead of going for the red-line, I'll run a VM26 carb mated to a 30mm pipe from Ooracing, don't know how that'll work, but will the engine deliver a power-curve I'll be happy with in stock trim? or should I start looking for a different cam?

2: I love riding super-technical trails deep in the woods, and the very nature of these gearboxes make selecting gears a challenge at times so I'm guessing I'll be riding the clutch a lot, are clutch-slip a weakness on the Lifans? should I get tougher springs before I even ride it?

3: the adjustable ignition, is there anything to gain from playing with the timing? or are the stock setup the best? again I'm thinking about low-end\mid-rang power and throttle response.

the optimal power\torque curve for me would be something similar to my XR's curve (lower numbers of course), bucketloads of low-end and way to much midrange hit

 

[numroe]

1. Torque maximisation: Im doubtful about your choice of the 30mm inlet. I cleaned up and port matched my stock 26mm inlet and it works great for bottom and mid response. The Akunar A1 cam does deliver a substantial boost in bottom end over the stock 150 cam. With the A1 the stock clutch slips - it's that good. Their valves give a little extra response too. I think you are asking for too much to expect a grunty bottom end plus a mid range hit. The "hit" is relative to how the torque feels just below that rev range. According to my rough measurements the A2 cam and stock 150 cam seem very similar in duration, lift and timing.

2. Gears and clutch. You might be surprised. If you get the engine output right (broad torque) then you wont need to slip the clutch all day. Just once in a while because the gear ratios are too wide. I have 2 stock springs + 2 stiffer clutch springs. A good compromise since firm enough to prevent slipping forever if throttle wide open and clutch eased, and soft enough to play the clutch accurately. The gearing just sux. 1st = useless. 234 are about 0.7 apart which is way too wide for my liking.

3. Timing. I played with it, and put it back to stock. I wrote about it on this forum a few months ago. Advance too much and you worsen starting kick back problems - not worth it IMO. Retard it and it starts easier but loses some throttle response.

With my OKO26 I find my bike starts pretty good with a throttle roll on to 1/4 open as I kick - I guess a 2 stroke style carb so a 2 stroke style of starting. Anyway it works well 90% of the time.

I'd ride the 150 in stock form first. Then modify in steps so you learn heaps more about what mods do what.

btw: You might want to get an AUD30 fuelstar TM-VC baby in tank fuel conditioner. One of the cheapest and best mods you can do for low end response and engine reliability.

 

[Cactus Jack]

[Fiddy@norway;185937]these pages made for some interesting reading, I'm quite excited about my 150 lying by the foot of my bed as I write this and I've got some questions\thoughts:

A: Be careful about talking like that ^^^^ ... It's conjures up visions of your sump oil being contaminated with a strange gummy substance ...

(F@N) 1: I'm a real 4-stroker and I crave a strong bottom end and a snappy midrange, I'm not much of a revver and prefer to short-shift and ride the torque-curve instead of going for the red-line, I'll run a VM26 carb mated to a 30mm pipe from Ooracing, don't know how that'll work, but will the engine deliver a power-curve I'll be happy with in stock trim? or should I start looking for a different cam?

A: Run it and see if you like it .... Is your carb a TRUE 26 mm Mikuni (ie 26 mm in diameter thru the venturi = slide area) .... I have a 24 mm Mikuni and the venturi is 24 mm round but the throat cones out to 28 mm out of the rear . I'm assuming that Mikuni cones the throat out so that it acts like the reverse cone of an expansion chamber to reflect and prevent reversion pulse waves from passing back out thru the carbs' venturi ... That would increase throttle response and torque . For those who are going WTF ??? ... Reversion waves flow back to the carb where they pass over the jets picking up extra fuel each time .... ie pure air passes the jets the first time on the way in ... picks up fuel .... goes into engine .... some backs out which pushes charge in reverse back past the jets where fuel is picked up again ... then when it changes direction again and heads back to the cylinder it picks up even more fuel on the third pass of the jets ... At certain points in the rev range as in under load , the intake airflow "oscillates" .... And that causes a momentary rich running condition which in turn causes the engine to run sluggish or bog down until the revs increase and it clears .... In certain cases , reversion can occur right throughout the rev range under acceleration .. (carb too big / ports too big / cam too big for gearing and load) ... So having the intake port bigger than the intake manifold and intake manifold throat bigger than the carb creates "anti-reversion" steps ... which weaken reverse flow signals to the carb .. and therefore make the engine pull better down low and under load ..

Long stroke chinese engines are better off to be torqued and short shifted .... Keeping the engine under load also helps dampen out the transmission of crankshaft harmonics thru the clutch and tranny ...


(F@N) 2: I love riding super-technical trails deep in the woods, and the very nature of these gearboxes make selecting gears a challenge at times so I'm guessing I'll be riding the clutch a lot, are clutch-slip a weakness on the Lifans? should I get tougher springs before I even ride it?

A: Numroe has already sorted that out ... so I'd follow his advice since his clutch appears to be holding up ... A word of caution though ... Most of the knuckleheads with modified GPX and YX motors who are having clutch problems are having those problems due to the fact that they have attempted to totally stop clutch slip ... Clutch slip gives relief from "micro jack hammering" ... As the crank rotates .. it oscillates which puts a buzzing vibration through the clutch basket ... When the vibrations gets to a certain frequency ... it will cause the clutch to slip .... IF the clutch doesn't slip ... something else cops it ... ie the rubbers get mulched to death , the gear teeth break off .. OR the spring posts crack off ... IF you measure the tension of a compressed spring under load ... then vibrate the spring at a high frequency ... it will momentarily lose tension ... In other words .. harmonic buzz turns a strong spring into a weaker spring ... Numroe (and the mountain) have inadvertently found the "right" balance ... I've stated on forums before that whenever you alter the components of an engine ... you upset the factory "balance factor" ... and that can be fatal in regards to a long stroke motor ... The good thing going for the Lifan 150's are that they perform great out of the box ... therefore they don't need too many alterations from stock to make them perform at their best ...


(F@N) 3: the adjustable ignition, is there anything to gain from playing with the timing? or are the stock setup the best? again I'm thinking about low-end\mid-rang power and throttle response.

A: Tread warily here ... Use a proper timing light and degree wheel to know PRECISELY where your engine is firing at and keep it within a known safe range ... You might get away with running an engine with high dynamic advance for a while ... but all it takes is for the engine to run hotter than usual one day ... and you'll pay the price ...


(F@N) The optimal power\torque curve for me would be something similar to my XR's curve (lower numbers of course), bucketloads of low-end and way to much midrange hit[/QUOTE]

A: Well , here's your chance to accomplish your power curve desires ... then pass the info learnt onto others .... Never say NEVER ...

 

[Fiddy@norway]

you both make for interesting reading, just to clear things up, yes my carb is a genuine mikuni VM26mm, and when I said it was mated to a 30mm pipe I meant the exhaust and not the intake manifold, I'm using the manifold delivered with the carb (gonna clean it a bit though),

and it seems like the lifan will deliver enough torque in stock trim, I might be expecting to much of it, but as long as it's not a top-end only machine, I'm all smiles, might look into a cam eventually though....

 

[numroe]

I rode a tricky bush loop yesterday. Just kept thinking to myself while riding how happy I was not NOT have the stock or A2 cam in the engine. As mentioned the Lifan gears are way too spaced out. So often 2nd is too revvy and 3rd is laboring the engine and the ground is so damn bumpy that prolonged clutch fanning is just too damn difficult for my left hand. But with the A1 cam I could slip the clutch in the tightest spots, but otherwise ride in 3rd for the whole loop. I couldn't believe the torque spread.

There's a flip side to the story too. That is when 3rd is too tall and I must use 2nd, then the top end of the rev range (so called "over rev") is not so crazy with the A1 cam, so that gear choice method works too.

If the motor was bottom end weak or top end too peaky there was no way I'd be good enough to lap at my same speeds/times.

 

[pbk]

im picking my lifan 150 up the sarvo anything i should straight away like stiffer clutch springs

 

[allan12]

Hello,

The information you have shared about is quite much helpful thanks for this.hope good from you in future

Thanks!!