167FMM mods
 

Picked up a wrecked dirt bike the other day with a good motor. 167FMM (229cc OHV). I'm thinking of replacing the OHC 223cc (Honda 230F clone) motor in my bike for the heck of it, not really gaining much cc or HP but why not.


Question, what's the best mods to make with these 167FMM motors? Is there any other motor that the piston and cylinder can be swapped over to increase the cc's? Like the 171FMM air cooled? I'm probably way off in left field with that but there seems to be so much Honda CG clones and variants.


I saw a motor online that looks identical to the 167FMM but was a 172FMM and used in Russia and Europe??? Same engine bigger bore? I can't find much info in them though.

As a rule I wouldn't trust engine numbers as they relate to displacement. The 171FMM engine in my old quad was actually a 163FML by my own measurement. Years back someone replaced a CG engine with a CB and reported no real power difference, but that was on a Lifan 200.

Agreed. You'd need to pull the head first and measure to see the actual bore, wrist pin diameter and stud spacing. Once you have that, you can search Taobao for a larger cylinder that matches the stud spacing and wrist pin diameter. If you find a match, please let us know.

A ported and shaved head, larger carb (A true 30mm smooth bore), and a good free flowing exhaust will give the most bang for the buck on most of these motors. Instead shaving the head, if you want to get into more advanced motor building you could deck the cylinder to get the quench down to a .035 range for the "best" high compression build, but to achieve this you have to take quite a bit from the top of the jug, which can then result in having a REALLY high compression ratio, so a dished piston would be needed to bring it back down to a reasonable level.

You won't really find a "big bore" kit for these motors anymore as most companies found the gains to be minimal and the cylinder started having trouble with cooling. This is why CCW stopped carrying their big bore kits. In their own words, the gains were minimal and not worth the cost. Spending hundreds of dollars to gain 19cc and no real discernible difference in power or torque. Considering those guys managed to squeeze 23 wheel HP out of a CG250, I will take their word on it.

I'll do some research when I have a minute. I wish the OHC 223 I have was a true 169FMM (230cc) like the tag rather than the 223cc (crf230F clone) that it is. I found a few upgrade size cylinders for the true 69mm bore version. :(



That said, these OHV pushrod 167FMM motors don't have too many options. The big bore kits they used to sell are no long available from any of the distributors I've contacted. Oh well, I'm just having fun tinkering.

Interesting, the Zongshen 170mm/SB250 water/air cooled motor (70mm bore) looks to be a converted 167FMM style motor..... swap the head, use an external pump to pump fluid through it... just thinking out loud. I can get the SB250 cylinder kit cheap.


https://www.alibaba.com/product-deta...5e6830fcrlbSH5

You would be hard pressed to notice any actual measurable difference from that 7cc you wish the engine had.

Like I said, if you really want to go on a quest for power, you could get into actual engine tech and go crazy to get quite an impressive level of power for these little engines. The OHC motors have the advantage of being able to fit camshafts more readily than the OHV CG motor, which would require a cuistom cam grind or sourcing a performance cam from another part of the world.

I wonder if a Hot Cam we used on the Honda 200x for racing would work on these CB engines? :hmm: You can still find them used on Ebay.
BTW Dan, Glad to see you been able to visit more often. :tup:

Well I found a source for the 70mm pistons for dirt cheap. Would it be worth the extra cost to machine the cylinder? Overheating issues? Probably not not worth it unless you have access to a machine shop and want to play. These motors are a dime a dozen but machining costs do add up. Cam grinds could be played with.



Quiet a bit could be taken off the head to up compression and the valves would still not be close to the piston.


Anyway, just playing a thinking out loud.

I am going to make this short. Air cooled=limited power gains on pump gas. Parts=custom very expensive. Believe me i know and anything custom takes forever to get.

I'll make this simple: Inadequate finning on air cooled engines=limited power gains...ARH

This is a reply to add to my post. I said pump gas lol as crappy as that is in most places. Now i will be testing corn oh yes e85 or e50 in my project i feel like its an advantage of sorts. And i think i can still manage 50 mpg×3+ gallon tank so 150 miles of fuel with the benefits of increased cooling and allowing me to run more compression. At a cost of 1.80 a gallon. Win Win

Is this thread still active? I've got a lifan 167fmm that I swapped on to my Honda z50 monkey. I've done a lot of research and mods to my engine. So I have found that it's a 230cc(not a 250) and makes absolutely no power stock. The reason for this is cooling issues, stock the engine oil temp gets up to 250°F

you lose a bit of power when it's hot, but not that much. I can still get up to 70mph in summer here in AZ when its 110+f

I thought I wrote a lot longer letter, but what I meant was that I figured out there's a lot of potential for the lifan. The engine stock has an overheating problem, which can result in the piston heat seizing in the cylinder. I've installed an oil cooler with an electric oil pump. Oil temps went from about 250°f down to 150-180°f.