PlanetMinis Forums banner
Cancel
Create thread New Forums

3 Valve Head Tear Down Pictures

Jump to Latest
1 - 20 of 26 Posts

Z50King

· Registered
Joined
·
12,579 Posts
Discussion starter · #1 ·
i personally know that i have never seen a 3 valve head torn down and pictures posted on PM. So i thought i would do it because i am going to clean up the intake and exhaust ports.



This is a Loncin 3 valve engine, not an SDG. The Loncin's have a removable cover on the very front of the head, the big square one like on a stock 50. The SDG does not have a removable cover, it is all one piece



This is the engine out of my Ohalee 107. its a 10/10 bike with right side up forks and big bike swingarm.



well, here they are. ill caption each post with what the picture are of.





This first set is of all four sides of the head, without any covers oops one of them is still sideways, ill fix that later



the oil plate is much different than a stock shaped oil plate. these heads have HUGE upside down oil plates, its weird

i had to take one of the exhaust studs out to get the head off without taking the skid plate off.
 

Attachments

Discussion starter · #4 ·
Here are some pictures of the combustion chamber with the valves removed



there is a steep ridge right in front of half the right intake valve. For these pictures i highlighted it by scraping the carbon off of the ridge.

i mowed it down with a grinder
 

Attachments

Discussion starter · #12 ·
storminnorman07 said:
also will this one drop onto the gpx bottom w/o work?
Click to expand...


im pretty sure you need longer studs and longer cam chain. this head is really long, height wise.



ill go measure them. the exhaust feels bigger than that intake.



i can tell you that the valve retainers fit other import valves
 
#13 ·
The SDG head uses larger diameter dowel pins and it's own tweaked stud spacing. Some Loncin 3v units used Honda 50 stud spacing, some used SDG stud spacing, and it wouldn't surprise me that others use generic GPX/Lifan 125/120 stud spacing. You will need longer studs, or custom long reach nuts to put that head on.
 
Discussion starter · #15 ·
RcWannabe said:
Looks like that head was cast by cave men
Click to expand...


yeah i cleaned it up yesterday. im gonna put it back together today.



thanks kurlon, i want this thread to be informative to people looking into these engines. im gonna go see if the front cover matches the stud spacing on a Honda
 
#18 ·
The exhaust looks like a normal exhaust rocker (I believe it's a direct swap with 70 rockers actually.) while the intake has a fork and two tappet adjusters, one for each valve. On the cam side it's a single rocker just like we're used to.
 
Discussion starter · #19 ·
im gonna post pics in the morning of all the parts. im too tired.



i ported it, smoothed it out and all, and now it only wants to run with the thing at half throttle and choked 2/3s. anyone know why?
 
1 - 20 of 26 Posts
About this Discussion
25 Replies
9 Participants
Last post:
javichu
PlanetMinis Forums
posts
2.1M
members
63K
Since
2003
PlanetMinis forum is the internet's largest mini bike community. View thousands of photos, event coverage, tips, tricks and performance mods.
Full Forum Listing
Explore Our Forums
CRF50 KLX110, DRZ110, TTR90 Chinese/Import Minis - General Discussion Z50, CT70 and JDM Monkeybikes Complete Bikes For Sale - All makes and models