I love the lifan 150:) but could it get better?

[Fiddy@norway]

alright, so I'm almost done building a new bike, I got the Lifan 150 mated to a genuine Mikuni VM26 and a pretty decent exhaust from OORacing, and DNM suspension all around and man, I'm STOKED!

on my first ride after getting the bike ridable I was actually a little disappointed, the suspension felt way stiff and the engine felt kinda lazy, but after a few hours in the saddle the suspension has settled in and feels better, still not adjusted to my weight and riding styl but what a difference from the generic crap I'm used too...

and the engine have surprised me as well, after some testing I've found out that the gearing is set to around 90kph+ which is WAY to fast for a dirtbike this size, despite tall gearing I can still pull wheelies in 3rd gear with ease, I'm gonna drop 2 teeth in the front sprocket, that should give it a little more punch out of the corners and smooth out the gap between 2nd and 3rd gear.

I do on the other hand have a few issues with jetting, my carb came stock with a #25 pilot and a #190 main, I have since dropped to a #165 main (I think I've read somewhere that a 165 is about close on this engine) but to tell the truth, I really didn't feel much difference. It idles rough and will cough and die from time to time if you ride WOT and then release it (like pulling a wheelie, throttle on, off, on, off, cough and die).

anyone here who can give me a good baseline jetting for this carb on this engine? it's bone stock as I've said, barely broken in, I ride at sea level, summer temperature and 98 octane gas.
pilot is #25, main #165, screw set 1 1/2 out, clip in the middle.

 

[short.y]

sorry to interupt, but have you got any pics of the bike? would really like to see how it turned out..sounds good tho..

 

[Fiddy@norway]

click the link down below to see a vid I've posted on youtube, I'm the guy with the tattoo on the arm. this vid was shot today with the current jetting.
YouTube - Lifan 150 Powerd pitbike preview

 

[short.y]

if its not a rude question, what did you pay for the engine?

where'd u get it from?

cheers.

 

[Fiddy@norway]

I found it on Ebay about a year ago. don't remember the name of the seller, but it was a shop in the USA, and I wouldn't recommend them anyway, they sent the engine in a cardboard box (!) overseas!!

I paid about 400 US$$ for the engine, don't remember how much shipping was, but it wasn't free, I know I overpaid in the end, but considering the prices these things go for here in norway, I't was a bargain...

 

[Cactus Jack]

You need to lose the huge main jet sizes ... they're ridiculously sized for a 4 stroke !!!!!

Being too rich is what's causing your stalling and other problem and rich engines are sluggish and lazy ... especially up top ... You need to do throttle chop runs in top gear going down in main jet size until the engine peak revs crisp and clean ... I normally go down in size until I feel the engine starting to detonate very slightly / hold back ... then go back up a size ... That'll get your jetting "on the edge" where maximum performance is ... but you can go up a further size for safety to deal with all round temperature variations ... Slightly richer keeps the engine a bit cooler ...

If you've got your pilot jet sized right and the air screw set right ... you'll hear a change in the engine note even if you turn the air screw as little as one quarter of a turn either way ... DON'T buy into what some people say about turning the mixture screw out until the engine revs the highest ... They're telling you to set it too lean ... great if you want an engine that overheats when idling , glows the pipe , stalls and is hard to start when hot ... Even that MX FUEL screw article is wrong ... Most of the carbs they're talking about are accelerator pump FCR Keihins and Mikunis and the bikes they're on have throttle position sensors , knock sensors and other computer controlled gadgets to protect the engine from damage ...

If you read how I've explained how to set mixture screws ... your engine will idle all day long without stalling , over heating , coughing , hiccing or farting ... and it'll hold the state of tune for months and months on end being totally unaffected by temperature and humidity changes ... Your engine is tuned properly when it'll start first kick every time without the throttle being touched once it's warmed up ...

Precision50 has some great info in this TT Thread ... except the air screw adjustment procedure ... If your engine won't idle at a slow steady pace without stalling or the idle speed fluctuates (aka flutters) at all ... the mixture screw is set wrong ... It's TOO lean ...

mikuni vm 26(real one) + 140cc lifan jetting HELP !!! - ThumperTalk

Due to the colder climate and increased air density where you live the overall jet sizes may have to be bigger than the sizes that work where we live the ...


Check out the Keihin to Mikuni jet conversion chart ... You're running the equivalent of a #190 Keihin main jet ... Your engine must be running like a fat lazy dog up top ... LOL ... From memory a 175/185 Honda single with a 26 mm Keihin carb on it runs a Keihin #40 pilot and a Keihin #130~135 main ... Powroll race jet kits don't go over a #135 main and they're for all engines up to 175 cc ... worked engines that is ...

Maybe the genuine Mikuni VM26's give crap vacuum and velocity and therefore lousy suction on the jets compared to genuine Keihin carbs ... so they need dope assed big jets to dribble the fuel in ... Just like how a toothless gummy old man needs a big straw to be able to suck up as much hot cocoa as other old timers who still have all the their teeth ?????

Even the Mikuni TM28-1 flatslide carb comes with only a #115 Mikuni main jet ... Now look on the chart and see what that equals in Keihin size ... It all pans out !!!!!!

Allens Performance Mikuni & Keihin Carbs


Width------Keihin # -- DynoJets # -- Mikuni #
0.0350---- 92.5--------- 92----------- 86.3
0.0360---- 95----------- 94----------- 88.1
0.0370---- 97.5--------- 96----------- 90.0
0.0380---- 100---------- 98----------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104---------- 97.5
0.0420---- 110--------- 106---------- 99.4
0.0430---- 112.5------- 108--------- 101.3
0.0440---- 115--------- 110--------- 103.1
0.0450---- 117.5------- 112--------- 105.0
0.0460---- 120--------- 114--------- 106.9
0.0470---- 122.5------- 116--------- 108.8
0.0480---- 125--------- 118--------- 110.6
0.0490---- 127.5------- 120--------- 112.5
0.0500---- 130--------- 122--------- 114.4
0.0510---- 132.5------- 124--------- 116.3
0.0520---- 135--------- 126--------- 118.1
0.0530---- 137.5------- 128--------- 120.0
0.0540---- 140--------- 130--------- 121.9
0.0550---- 142.5------- 132--------- 123.8
0.0560---- 145--------- 134--------- 125.6
0.0570---- 147.5------- 136--------- 127.5
0.0580---- 150--------- 138--------- 129.4
0.0590---- 152.5------- 140--------- 131.3
0.0600---- 155--------- 142--------- 133.1
0.0610---- 157.5------- 144--------- 135.0
0.0620---- 160--------- 146--------- 136.9
0.0630---- 162.5------- 148--------- 138.8
0.0640---- 165--------- 150--------- 140.6
0.0650---- 167.5------- 152--------- 142.5
0.0660---- 170--------- 154--------- 144.4
0.0670---- 172.5------- 156--------- 146.3
0.0680---- 175--------- 158--------- 148.1
0.0690---- 177.5------- 160--------- 150.0
0.0700---- 180--------- 162--------- 151.9
0.0710---- 182.5------- 164--------- 153.8
0.0720---- 185--------- 166--------- 155.6
0.0730---- 187.5------- 168--------- 157.5
0.0740---- 190--------- 170--------- 159.4
0.0750---- 192.5------- 172--------- 161.3
0.0760---- 195--------- 174--------- 163.1
0.0770---- 197.5------- 176--------- 165.0
0.0780---- 200--------- 178--------- 166.9
0.0790---- 202.5------- 180--------- 168.8
0.0800---- 205--------- 182--------- 170.6
0.0810---- 207.5------- 184--------- 172.5
0.0820---- 210--------- 186--------- 174.4
0.0830---- 212.5------- 188--------- 176.3
0.0840---- 215--------- 190--------- 178.1
0.0850---- 217.5------- 192--------- 180.0
0.0860---- 220--------- 194--------- 181.9
0.0870---- 222.5------- 196--------- 183.7
0.0880---- 225--------- 198--------- 185.6
0.0890---- 227.5------- 200--------- 187.5

 

[DvDRip]

If you read how I've explained how to set mixture screws ... your engine will idle all day long without stalling , over heating , coughing , hiccing or farting ... and it'll hold the state of tune for months and months on end being totally unaffected by temperature and humidity changes ... Your engine is tuned properly when it'll start first kick every time without the throttle being touched once it's warmed up ...

where can I read that? did I miss something?

 

[Cactus Jack]

I forgot to add the link to the page showing the Powroll Jetting ... it ALSO shows that a #105 Keihin sized jets suits 125 cc engines ...

POWROLL PRODUCTS FOR THE HONDA VINTAGE 100 & 125

I relate how jets work to a garden hose ... Go out and remove the nozzle off the end of the hose and watch how crap the power of the flow is with the end unrestricted ... Now fit an adjustable nozzle ... When it's opened up too big the liquid won't spray very well with the tap at the same setting ... but as you gradually restrict the outlet size the water flow starts to gain force until it reaches a peak where it has maximum force without losing flow ... Too big a jet will lose power and spray force in exactly the same way ... only fuel is different to water ... the least amount of fuel to the most amount of air gives maximum spray and explosion power / heat generation ... even to the point of damaging the engine ... In a nutshell , you make the most power by using the smallest jet you can safely get away with ... NOT the biggest ...

IF you're going to put in more fuel ... you HAVE to also put in more air to maintain the most efficient air to fuel ratio ... and the only way to put more air in is to either rev the engine a lot higher than stock , bore/stroke to a bigger cc capacity OR supercharge the engine ... In a naturally aspirated engine ... the peak airflow is governed by the port/valve sizes and the cam timing /lift and duration ... As a result ... boring an engine from say 125 to 150 leaving everything else the same requires a minimal of jet size changes ... In some cases the bigger cc capacity actually requires a smaller main jet because it has a stronger vacuum which sucks more fuel thru a given jet size ... ie Honda SL100's run a #38 pilot and a #110 main whereas the same engine bored to 125 uses a #38 pilot and #105 main ... both engines run the exact same carb ...

 

[Cactus Jack]

DvDRip Senior Member " where can I read that? did I miss something?" ...

It's a typo ... I meant to say if you've read ( IE RED not REED) ... as in past tense ... I CBF typing out the procedure all over again for the 10th time ... LOL ...

Tuning carburetors is no different to adjusting a paint spray gun for the best spray that gives the best coverage without runs ... or adjusting an oxy-acetylene welding torch to give the best weld without over heating or oxidising the weld metal OR the flame popping out ... The ONLY difference is that you can't see the jet spray inside a carb or the combustion flame colour inside the engine ... So you have to develop the skills to listen by ear ... much like tuning a guitar ...

 

[DvDRip]

cactus I'm a bit confused about jetting/tuning now..... so do I change the pilot jet up/down till I get the best/crispest throttle response? or how do I know I've got it right, will a plug inspection after idling for a while work?
and if I'm changing pilot jets do I adjust the fuel screw to max RPM with each jet change?

sorry for the hijack fiddy just thought I'd ask while we're on the subject

 

[DvDRip]

DvDRip Senior Member " where can I read that? did I miss something?" ...

It's a typo ... I meant to say if you've read ( IE RED not REED) ... as in past tense ... I CBF typing out the procedure all over again for the 10th time ... LOL ...

Tuning carburetors is no different to adjusting a paint spray gun for the best spray that gives the best coverage without runs ... or adjusting an oxy-acetylene welding torch to give the best weld without over heating or oxidising the weld metal OR the flame popping out ... The ONLY difference is that you can't see the jet spray inside a carb or the combustion flame colour inside the engine ... So you have to develop the skills to listen by ear ... much like tuning a guitar ...

ok thanks mate, I'll have a search through you old posts and see if I can find it,
do you know where I can get a jetting kit for my 30mm mikuni (not sure if real or fake)? like the keihin one you just posted

 

[Cactus Jack]

Here's what Powroll has to say about jetting , fuel etc ...

JETTING SPECS

And note that for their 150 cc 59.5 mm stroker engines they run a "Heavy Duty" rod with a 15 mm pin ... a step up from the stock pin 14 mm ... Makes the 13 mm pin advocates look like dopey assed "engineer's" ... I talked about pin sizes a while back ... and a guy called Bulldog or something like that posted pics of a Daytona engine that had grenaded and put the rod thru the case because the pin bore at the small end of the rod busted off in the middle ... My experience with fully worked XR75's is that the small 13 mm pins wear out and become sloppy in the rod after a while ... they actually wear thru the hard chrome of the rod due to higher PSI on the bearing surface ... Increased power ... bigger gudgeon pin ...

 

[headsmess]

Tuning carburetors is no different to adjusting a paint spray gun for the best spray that gives the best coverage without runs ... or adjusting an oxy-acetylene welding torch to give the best weld without over heating or oxidising the weld metal OR the flame popping out ... The ONLY difference is that you can't see the jet spray inside a carb or the combustion flame colour inside the engine ... So you have to develop the skills to listen by ear ... much like tuning a guitar ...

i remember seein in an old moto tuning book a lil device that was basically a sparkplug with glass instead of ceramic for this.... the ability to see inside an engine while tuning...yeah, apparently now obsolete...what heat range was the "plug" itself... and the slight changes caused by changing back to the proper plug... but im sure you would have seen or at least heard of one before anyway...just an idleeek: a pun) thought i had... but probably woiuld have been handy for rough tuning...

um, what else? oh, my early mode of transport...a husky brushcutter strapped to a bmx.... late one night i noticed the plug was glowing a nice blue colour while running...never seen it since on anything else....
was a very "short ceramic" dj8j plug....

and isnt welding with an oxy torch a bitch when noone tells you to set it ever so slightly rich or carburising...

stoichometric ratios the advantages of efi.... until the puter has a breakdown, at least... and whatever happened to hondas "stratified charge"? too complex perhaps....

 

[Fiddy@norway]

Alright, thanx for pointing me in the right direction again cactus.

I know the basics about jetting, and can solve\diagnose most problems related to bad jetting, but this carb had me scratching my head since I dropped from a #190 to a #165 without any noticable difference, but from what you write I understand why, going from insanely rich to super rich won't make much difference.
I'm guessing my floatlevel might be off to since the bike don't like wheelies, don't like steep uphills or sudden on\off\on chops on the throttle, I need to set a day off and do some testing, and get a kit of jets at the same time.

One thing that got me worried was when I did my second oilchange at about 2hrs (hourmeter), the stock metal-mesh filter was full of shavings, and there seemed to be a substantial amount of shavings that actually got past the mesh too, I threw the mesh filter away and installed a paper one(daytona filters), but I'm now I'm actually worried that the paper one will clog from the shavings, any thoughts about this? I installed a magnetic oil-plug before I even started the bike too, and it was FILLED with shavings...

 

[Cactus Jack]

Here's a really good thread by Numroe ... he talks about metal shavings etc ...

http://www.miniriders.com.au/tech-talk/17334-lifan-150-diffs-pics.html

Cars run paper filters and they take a fair while to block up ... You can try back washing the paper bike filters to clear any gunk out ... I've gotta buy some myself for my Lifan 150 for when I get around to running it ... What price did you pay for your Daytona filter ? ...

Headsmess ... You're referring to the Gunson Colortune kits ... They're still readily available ... I bought one in 10 mm to try ... even though I don't need one ... I got it mainly out of curiosity to check the combustion colour AFTER I've tuned the engine for the best running and performance ... but you could most certainly use one to help tune an engine from scratch ... I bought my set off a guy on ebay in the UK...

gunson colortune - Google Videos

gunson colortune - Google Search

 

[Fiddy@norway]

Here's a really good thread by Numroe ... he talks about metal shavings etc ...

http://www.miniriders.com.au/tech-talk/17334-lifan-150-diffs-pics.html

Cars run paper filters and they take a fair while to block up ... You can try back washing the paper bike filters to clear any gunk out ... I've gotta buy some myself for my Lifan 150 for when I get around to running it ... What price did you pay for your Daytona filter ?

I just remembered I bookmarked that thread by numroe a long time ago, he writes some good stuff there, gonna read through it again.

I bought a 3 pack of these daytona filters from 24moto.se in sweden, paid something like 10 euros, gonna try and source some cheaper ones on Ebay though.

and what conserned me most about the shavings is that a fair amount had gotten past the stock mesh filter, that cant be good no matter what, an oilfilter is a must have on any engine IMO, but the stock lifan one is a cheap and somewhat faulty construction.
the idea about a reusable filter is good, but it should be a 3 stage filter that you could disassemble when you need to clean it, it should consist of a fine inner mesh to catch bigger pieces of junk, an even finer outer mesh to catch the things that slip past the first mesh, and a magnetic insert in the center to catch steel shavings.

 

[headsmess]

hey, thanks cactus just assumed that they wouldnt be around anymore, seeing as the book was early 70's...

 

[Cactus Jack]

YX makes external inline filters but they've STILL got the steel mesh filter ... Putting one of those on the slingerless YX engines will only protect the top end ... the crank (which needs to be protected the most) will STILL cop all the crap unless you block the gallery into the clutch cover off ... then put a fitting after the block off to run a second line in to the crank from the filter ...

OEM YX150 160 engine oil filter dirt bike pit bike:eBay Motors (item 150360092604 end time Jul-24-09 07:46:37 PDT)

NOTHING beats the slingers for thorough filtration ... I've got 35 year old XR75 cranks that are still usable and have never been rebuilt ... Later model '77 and up XR75/80/100's have NO slinger and no filtration whatsoever aside from the pickup screen ... and man ... I've seen some '77 and later cranks with what seems like 1/16 th of an inch up and down play in the rod , ridiculous side to side slop in the cases , and also up and down slop in the crank main bearings ... I won't even bother mentioning the '77 and later heads that the cam has hacked into ... LOL ...

I was looking for a decent XR80 crank (45 mm stroke) but couldn't find any good ones ... I finally got a brand spanking new one off ebay for $120 AUD ...

 

[DvDRip]

hey cactus does that filter go on the oil cooler line? will it work on any oil cooled engine?

 

[Cactus Jack]

Yes it'll work on ANY engine with an oil cooler ... but I'd replace the steel mesh filter with a Daytona / Honda TRX125 type paper filter ... I'm thinking of buying a few remote filters off him ... He's YKJohnson under a new ebay ID ...

They're a copy of the Kitaco oil filters ... at a much lower price ...

Honda TRX90 Performance parts page featuring Kitaco, Takegawa and G-Craft billet aluminium parts.