Reading the details, Is it just me, or does the YX 140 - 160 product line inherently offer far more performance potential than the Lifan product line.



My YX140 moved very easily to 160 and when I buy a YX160, (soon I hope) I will make it 180 before I bolt in in a bike.



Doh, why doesn't YX just build a 180?

 

nice job posting info !

im interested in a simple 57mm HC w/ new 30mm/23.5 tb head on the lifan 150

 

Well where do ya start, well thats exactly the problem, yx cant make a 180 because your not gonna be able to start it with out breaking cases and tearing up kickstart gears. Untill those clowns make a decomp mech there is noway there engines are getting bigger than 160cc stock.

 

Reading the details, Is it just me, or does the YX 140 - 160 product line inherently offer far more performance potential than the Lifan product line.



My YX140 moved very easily to 160 and when I buy a YX160, (soon I hope) I will make it 180 before I bolt in in a bike.



Doh, why doesn't YX just build a 180?

to its credit

the lifan 150 is the strongest stock motor going



with your yx160 build you may want to consider a V2 head stock bore piston set up

this a very big improvment over stock with out increasing bore

 

nice job posting info !

im interested in a simple 57mm HC w/ new 30mm/23.5 tb head on the lifan 150

At this point the only piece missing is a piston. The head is available, and the stock cylinder can be bored, or TB's 57mm unit will drop on. Akunar's 57mm bore 15mm wrist pin piston is a lil short, but it's got a happy dome. Valve clearance is a question, although being nearly 2mm in the hole, it may not be an issue even if the pockets are cut small.



Wiseco can make custom pistons, 24 piece minimum order, $125 a unit... Wiseco in the past quoted me $200 a unit for a 4 piece minimum order, still really spendy for an experiment.



Could try making a bushing to go from the rod's 15mm wrist pin to a 13mm unit matching TB's piston, 1mm thick so I don't think reliability would be an issue. The pin height would be low, just like Akunar's offering, just shy of 2mm below the deck.



I want to say I trolled Wiseco's catalog in the past looking for 15mm wrist pin donor bikes, couldn't find any in the right bore range with a 2v head if I remember correctly. I'll take another troll tonight if I get bored. : )

 

Look at wiseco klx125 pistons.

 

Look at wiseco klx125 pistons.

Wiseco is listing a 14mm pin, you thinking bore the wrist pin boss in the piston? Seeing as you've got a lil KLX125 experience... What's the pin height and how's the combustion chamber compare to a Lifan BVH?

 

wiseco is listing a 14mm pin, you thinking bore the wrist pin boss in the piston? Seeing as you've got a lil klx125 experience... what's the pin height and how's the combustion chamber compare to a lifan bvh?

piston to pin heigth is 14.5mm i think, i will conferm this later. The klx uses 30/26 valves so the reliefs are perfect. I want to say if any thing the dome might be a tad high since the combustion is rather large. The wiseco piston are sweet, i will try and post some pics.

 

Here is a pic of the wiseco klx125 piston. DRILL FOR 15MM AND CUT IN KEEPERS.

 

Nice read Kurlon...the only piston I found are from a Kymco Zing 125 and a Yamaha xt 125, they are both 15mm pin and 59+mm bore but the catalog doesen't tell exact specs of them ...bugger

 

Finally decided to crack into my Lifan 150's top end to see what's going on in there.



First, the numbers:



Squish using stock gaskets - 1.31mm

Pin height of stock piston - 14.87mm



Stock cylinder bore - 56mm

Stock cylinder spigot OD - 60.1mm



TB First gen 57mm cylinder spigot - 59.05mm



Lifan 150 case bore - 61mm



So, right off the bat this confirms that there won't be an SCUT style bore kit for this motor any time soon. The piston would clear the cases, but the wrist pin drops past it's mid point when dipping into the cases on it's way to BDC. It wouldn't de-ring itself, but it'd be begging to jam.



The stock Lifan 150's cylinder looks ideal to make 58mm kits out of for Jialing 125s. Plenty of liner material. Or you can go to 58mm with the Lifan 150 bottom end, still no worries. Oh, and yes, the Lifan 150 does use standard Jialing 125 stud spacing, so the rumor that it's different can be put to rest. I've included a pic showing a first gen TB 57mm cylinder slid on, the TB stamp is faded but still barely visible.



The squish is FAR better than the Lifan 120s I've had. For an out of the crate import motor, it's the best I've seen yet. The piston is right up to the top of the deck, as compared to the 120s which are a good 1.5mm in the hole. Cheap upgrade on a Lifan 150? Try a TB 57mm gasket kit. : )



The generous case bore makes it a shame to abandon the idea of a 60mm bore for this motor though... Akunar to the rescue? They are listing bore kits for Jialing 125s/Lifan 120s/Lifan 150s up to 60mm. They've also got 15mm wrist pin pistons, with big fat domes. The downside is the pin heights are all a touch short. Up to 59mm bore, their best is a 13mm pin height, their 60mm offering is slightly better at 13.75mm but still a good mm short compared to the stock unit.



Good thing TB doesn't like using o-rings between the head and cylinder. : ) (Interestingly, neither does Lifan any more...) Just deck that baby as needed.



Lifan's oem piston is a touch fancier now, with three grooves below the rings. No idea what they accomplish.



One disappointing find, obvious discoloration on the rod already... I'm going to have to use some air to verify the oil passage is clear to the big end. Then I've just got to decide WHAT I'm going to do with this thing. : )

Would it be possible to take a Jialing Crank at 57mm and cut it to resemble the Lifan crank? Put the end on it? This is what I don't get. If the Lifan is a 59mm stroke and the Jialing is a 57mm stroke, why won't the scut work. at 59mm it is only dropping into the cases 1mm more right?

 

No 2mm the deck height is the same but in all reality it's actually farther because the lifan need a 14.5mm pin to deck height to get to a 78mm cylinder when the jailing only need a 13.3mm pin to deck heigth to get the 78mm deck heigth.

 

That wiseco piston does look good Hack, although I suspect you're right, it will need the face reworked to match the TB combustion chamber and valve layout... As far as pin retainers, screw 'dem, I can get teflon rod that'll do the trick. : )



Fatcaaaat: Yeah, you can just rework the clutch side crank end to fit a Jialing crank in. If I'm going that route though, I'll rework my SDG 49.5mm crank and make a proper screamer out of this thing.



Vince: I'm really starting to think, other than rebuilds, a 57mm bore kit may not be needed for this mill. I'd bet just going to a TB gasket set to reduce the squish will have a big impact on perf, seeing as it's already a decent runner out of the crate.

 

Can anyone confirm the stock Jialing 125 rod length at 99.95mm? Based on that, I figure a SDG/Lifan 3v 107 should be running a 5mm shorter rod... if the big end dimensions match, a 125 rod on a 107 crank puts the cylinder length at 74mm. The TB 60mm cylinder can easily be decked to match. If I can find a 104.95mm rod, I don't have to touch the cylinder...



Or, use the 107's rod on the Lifan 150 crank, with room for a stroker pin...

 

Piston to deck heigth on the klx125 is 15.1mm

 

Piston to deck heigth on the klx125 is 15.1mm

how much $$ is that piston ??

 

about $80

 

Jialing 125 rod on the Lifan crank, and you've got a 59.5mm stroke setup that takes long rod (12v) pistons. At BDC it's only 1mm more in the hole than a regular Jialing 125, which means the TB 60mm bore kit could be potentially used. On the other hand, the rod is 1mm higher at TDC... but TB's 60mm kit piston only has a 12.25mm pin height from the top of the pin, 18.75mm from the pin center.



http://www.x386.net/TTR/tech/cgi-bi...nheight=18.75&cgiintakemm=30&cgiintakecount=1&cgiintakelift=6.99&cgitranseff=90



That predicts a 16hp motor, and it should never need to wind over 10k RPM if built with TB's new head and a 300a cam. The deck height is only .25mm over, that's easy enough to adapt for with a good head gasket. Seems like a waste of a oil sling-less design though...



Same idea, SDG 49.5mm crank:



http://www.x386.net/TTR/tech/cgi-bi...nheight=18.75&cgiintakemm=30&cgiintakecount=1&cgiintakelift=6.99&cgitranseff=90



Gotta rework the cylinder to loose 4.75mm off the top, or find a longer rod. Again, about 16hp, but this time it's doing it at 12k RPM. And it'd look weird with 5mm worth of extra stud sticking out the top.



http://www.x386.net/TTR/tech/cgi-bi...nheight=18.75&cgiintakemm=19&cgiintakecount=2&cgiintakelift=6.92&cgitranseff=90



3v head... 19hp at 15k RPM, that sounds more like it.

 

Thats SIKKKKK!!!!! Maybe I should do something like that to my 3v 107....and then maybe I should learn how to ride the dang thing as is!!!

 

Anyone wanna make me a 15mm OD 14mm ID sleeve? : )



I wonder if I should just have my existing 15mm pin cut and bored, or if I'd be better off using an alternate base for the sleeve?

 

the jialing rod is 97mm,the sdg107 is 94mm.all dimensions other than length are identical and parts are interchangeable

 

throw the 3v head in the garbage and get the polini 4v head

 

Whew, I just read this and it felt like hearing about astro-physics from my old professor at BSU, i wish I had the know how you guys do. I have the lifan 150 as well but I'm not good enough to need more from it right now.

 

Anyone wanna make me a 15mm OD 14mm ID sleeve? : )



I wonder if I should just have my existing 15mm pin cut and bored, or if I'd be better off using an alternate base for the sleeve?

I hope you're kidding?

 

I hope you're kidding?

Why would I kid? : )



So far I haven't run into anyone with a strong objection to sleeving the rod for a smaller wrist pin. If you've got info to the contrary, post up!