The start of a new build...

#1
Decide to start a build thread of what I am doing. Will start with the head work, followed by the motor it is going on. Not sure of its going on the 208 or the 212 clone yet. No these are not predator motors either. Both getting clone rods, cams and flywheels.

So I have posted this or something similar in the past but thought a few people might like this. I have a GX160 head that's the UT1 NOT UT2. It has an 18cc chamber and 26mm intake and 23mm exhaust valves. It dose not use lash cap on the exhaust. Neat looking head but have yet to install one on a running motor. The intake and exhaust ports are a little smaller than the 196 clone heads.

My hopes are that the larger intake valve and smaller runner will make better torque than a 196 clone head. I'm hoping that the staggered valve size should help create a better torque curve than a normal GX200 style head would in the 2,000-5,500 RPM power band I intend to use it in. This head is just going to get the short side radius rounded and the port edges knocked down with some 80 grit. I am hoping to get a valve job done by a shop if possible but might just end up lapping some valves in and running it that way for a while.

Some people think that larger valves are only for high RPM motors but they can also be good for low RPM torque too. At low lift as valve is close to seat the valve is the restriction not the port so increasing the valve flow area creates more flow at low lifts and should help with torque. My thoughts are smaller port, larger intake valve 18cc chamber and smaller exhaust valve should all = more low and mid range torque on a stock motor. Going to put pictures below in a few posts so its not one long running post...
 
#3
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Don't trust the caliper reading in the picture. I just have it to show the difference in port size between the heads. You can see in the second picture that the port is larger. Its about 1mm larger in all directions. The top valves are the UT1 GX 160 valves 26/23 and the bottom are the normal 25/24 set up.

To clear this up the UT1 head with the 26/23 valve combo I am using has the small ports. The large port head is the normal 196 JT casting from a stock BSP motor.
 
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#4
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I posted these pictures in another post for some one earlier but this is how I am doing the port clean up. I am rolling up some 80 grit emery cloth so its stiff enough and long enough to reach the port sides and around the valve guide. The short side is being shaped with a thin, long piece of also 80 grit. just pulling it through the port and moving from side to side so I am not sanding in one spot too long. Also changing the angle I pull it at as pulling the emery tight and straight seams to cut faster but having the emery looser and pulling vertical to the valve seat seams to cover more area and round more than pulling parallel to port.
 
#5
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Probably dose not look like it but I have a few hours in to sanding. My last head I removed most the metal I wanted gone with the dremel and cleaned up with the emery but I want to modify this head to have as much bottom end torque as I can and am trying to keep velocity as high as I can. I am afraid if I open it up around the guides it might loose a little in the bottom end. I could not fit my finger past the valve guide before I started on the exhaust port. I can now fit my finger tip just about flush with the combustion chamber. Dose not look like I did much but I increased that area of the port a good amount.

Now I have to wait on other parts to show up in the mail.
 
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#6
I don't show it well but I spent a lot of time around the guides on the roof of the port. I also knocked the cast finish off with the 80 grit. Should have taken some pictures of around the guides.
 
#7
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Here is my arsenal of parts so far. The Mikuni intake is a little larger than the intake port of the head. Going to port match. My plan is to match a gasket to the intake manifold and use it as my template. Not sure if its worth doing but its getting done. Might clean up the intake too cuz as you can see it is not uniform were it mates to the head.

So not decided on cam yet. Probably a CL1 high torque but have not got the cam for this build. Have 22LB springs and ratio rockers, aftermarket guide plate, 22mm Chikuni, +.020 rod. Still waiting on my block and crank. Running a dished piston. Need to file down a stock timing key about .020 because the flywheel I am using has 25* timing. My other thought was to use regular rockers and a black mamba JR cam. Also need to order crank shims.
 
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#8
Think I might have found a good shop to do my valve job. DMD performance. Still chatting with them about it. Would much rather have a good performance valve job done then just lap my valves in. On any performance motor the power is in the head. So far they have killer customer service. It's 10pm on a weekend and there still quick to respond.
 
#9
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OK build has changed directions due to what I have on hand right now. The GX160 heads not getting sent out for a while. Going to build the 212 clone. This is my JT head with the predator hemi valves. I lapped with 600 grit and checked the seal using penetrating spray. It's pretty much WD40. After 5 minutes no leaks. No port work on this head. It's a clone head with stock predator hemi valves and clone 22lb springs as of now. Head is a new part from ACR. Was $14 plus $6 a piece for the valves.

Hope to work on short block tomorrow or the next day. Might get a BSP4 Cam for now as I have 2 new ones laying around. Not sure yet.
 
#10
Well sent back a ducar block I got from NR Racing and long story short I am having it replaced with a hemi predator block. Might use it instead of the ACR for this build. I think there pretty much the same thing. Will see what it looks like when I get it. NR has great customer service. Things are on hold tell spring though. My son decided to show up early so we now have a new mini in the family
 
#13
Thanks guys. I am using the GX160 aluminium flywheel. It's a factory flywheel. There only $40 and hold together just fine for removing governor. Not as nice as billet but lot cheaper. Timing is only 25* but that's a simple fix if a person wants more timing. I am going to try it at 25*
 
#16
Well go-powersports is very clear that there header dose not fit with the stock air box on. I want to use it that way anyways. I cut 1.5" out and welded it back together. My billet rod, GX160 flywheel are installed. I also installed an aftermarket guide plate so I can swap to ratio rockers and swapped the stock carb for a .650. I want to see if it's worth doing with the governor still in. If it works with governor "adds power but still limits RPMs like it should" than I will try the rockers and maybe a ported head.
 
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