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Cam install - Upgrade Spring Questions

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DBishop211

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Discussion starter · #1 ·
I have a 52.4 x 55.5 Lifan.



Tearing the motor down to throw in a HC piston, cam and do some minor port/polish work.



1. Anyone have experience with upgrading their cams? Eg. Is it necessary to upgrade the valve springs? If so, anyone have problems with the rockers getting flat spots on them due to the intense lift and springs?



2. Anyone thrown in a HC piston with a similar motor? If so, will it run on 93 or will i be needing more octane?
 
#2 ·
There aren't many good high compression pistons for the Lifan, if it has the big valve head. 2-bolt valve caps tell the tale.



54mm bores in to the stock aluminum jug, 56mm in an iron one. The common 52.4 ones won't have enough squeeze with the big Lifan chamber.



Stock inner springs will bind with a big camshaft, so you'll want to swap them. New rockers are a good idea with a new, aggressive cam.
 
Discussion starter · #3 ·
firepower354 said:
54mm bores in to the stock aluminum jug, 56mm in an iron one. The common 52.4 ones won't have enough squeeze with the big Lifan chamber.
Click to expand...


first: idk if i have a BVH... valves are 27 and 23mm.



second: Huh? i don't see what the bore has to do with anything... who cares if my bore is 54 or 52.4? as long as my piston and jug are matched up i don't see why a little more compression wouldn't help



(oh yeah... i doubt this engine is actually a lifan... its marked as a lifan with 1p54mi or whatever but it is definitely not a 54x54mm setup.. i put the calipers to the bore and stroke)
 
#4 ·
DBishop211 said:
first: idk if i have a BVH... valves are 27 and 23mm.



second: Huh? i don't see what the bore has to do with anything... who cares if my bore is 54 or 52.4? as long as my piston and jug are matched up i don't see why a little more compression wouldn't help



(oh yeah... i doubt this engine is actually a lifan... its marked as a lifan with 1p54mi or whatever but it is definitely not a 54x54mm setup.. i put the calipers to the bore and stroke)
Click to expand...




27/23 is the big valve head. No, the bore doesn't have anything to do with it, except that the 52.4mm pistons won't add much compression to your motor. 14mm pin?

Sure, 9.5: is better than 9:1, but gets thumped by 11:1;)
 
Discussion starter · #5 ·
yeah its the 14mm pin... i saw some AHP spec about their piston bumping the ratio from 9.1:1 to 12.5:1... i mean i doubt i can trust that... but still seems like it should do more than increase by .4.... where you coming up w/ 11:1 ?
 
#7 ·
DBishop211 said:
yeah its the 14mm pin... i saw some AHP spec about their piston bumping the ratio from 9.1:1 to 12.5:1... i mean i doubt i can trust that... but still seems like it should do more than increase by .4.... where you coming up w/ 11:1 ?
Click to expand...


The 12.5:1 is with the small valve/chamber head. It's a great piston for that application and for the 13mm 114 and 125.



The 11+ is a different piston we run. Big, smooth dome, coated skirts.

Final ratio depends on quench distance, of course.



Image
 
Discussion starter · #9 ·
firepower354 said:
The 12.5:1 is with the small valve/chamber head. It's a great piston for that application and for the 13mm 114 and 125.



The 11+ is a different piston we run. Big, smooth dome, coated skirts.

Final ratio depends on quench distance, of course.
Click to expand...


okay firepower where you getting that piston?
 
Discussion starter · #15 ·
TheCRKid said:
as far as the cam we did not run different springs and tbw0300 was the cam of choice in the lifan 120cc heads
Click to expand...


what kind of performance are out getting out of that cam? eg. improved midrange etc...



I am a fan of low-end hit. I don't like the IRK feeling motors and an all top-end power feel.
 
#17 ·
DBishop211 said:
what kind of performance are out getting out of that cam? eg. improved midrange etc...



I am a fan of low-end hit. I don't like the IRK feeling motors and an all top-end power feel.
Click to expand...
this mod goes back to 2006 , when we were putting lifan 120cc heads on jialing 124cc motors ,,,, its a nice bottom to mid boost



i just built one out of parts motors for my personal bike

stupid bottom / mid w/ a 57mm piston



were testing some cylinders now so we can do 57mm pistons on these 14mm wrist pin type motors again

should now more mid week
 
#18 ·
DBishop211 said:
I emailed akunar they said they don't have a 52.4mm HC piston... just the standard version.. said 300$ + for a special order piston.
Click to expand...


Yeah... That's why I said 54mm;)



Just some options:



The TB 60mm jug and a matching 14mm piston is available, if you wanna go big.



We also re-sleeve the stock jug for 57-58mm big bores. This way you get the added ring seal of a steel sleeve.
 
Discussion starter · #19 ·
damnit... lol i paid 160 + shipping for this motor brand new 3 years ago.



since motor is getting a complete tear-down and rebuild I was hoping I could just drop in a cam and piston and be good to go after I cleaned up my head and ports.... maybe mess with some timing... maybe not.... hoping i would get a highly noticeable increase in power.



this is getting overly complicated lol... and what is worse is i will not remember how to re-assemble the tranny... haha



i feel like this POS motor i have is pretty common and someone should have made a damn HC piston with 14mm pin for a BVH.... what happened
 
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