[nickdog]

I am trying to put a 3 valve head on a gpx but the cam gear and gear on the crank are different. the bigger gpx gear does not fit in the 3 valve head so i need to change the gear on the crank. how does it come off? does it need to be pressed off or will it un screw. when you put it back on how do you know it is going to line up with the gear on the head when cam timing is set.

 

[Kurlon]

The crank gear is pressed on. You should be able to use a dremel/etc to open up the cam chain galley in the head so it'll accept the larger sprocket.

 

[nickdog]

Found that i can get the cam gear in through the bottom of the head so that sorts my gear problem out. next problem was cam chain to short so got one made today one link longer and thats that sorted. The problem i have now is i need longer studs. were or what motor has the same thickness but longer studs. Who made stroker motors and needed studs were did you get them.

 

[Z50King]

most stroker motors dont need longer studs. if your careful, you can use cut pieces of all thread that have the right threads. but thats iffy i think



and i found out last night that no one makes an oil plate for an oil cooler for these heads. the bolt pattern for the plate is backwards

 

[Kurlon]

If you're retaining a 79mm tall cylinder, there isn't a matching stud setup in the wild that I'm aware of. If you're de-stroking the GPX mill and running a 69mm tall cylinder, studs out of an SDG 3v mill should work.



How short are the GPX studs with that head? A mm, a couple cm?

 

[nickdog]

The gpx studs need about 1.5-2 cm and the sdg studs need about 5-7mm

 

[Kurlon]

Dunno what to suggest, studs from one of the new Lifan 140's might be long enough?

 

[700'sDAD]

I have been working on this project for awhile. I counter bored the stud holes deap enough to reach the studs and machined some nuts out of hex stock that would reach the studs. I dont know if you have access to a lathe but its not to hard.

 

[Z50King]

yeah thats smart. sounds like a good idea



you could look for 3valve studs from someones old broke ass motor

 

[Kurlon]

you could look for 3valve studs from someones old broke ass motor

They won't work, he's putting this head on a motor running a taller cylinder.

 

[ibmike13]

Just run a BV head with 28/24 valves, the 3 valve heads are total junk so dont waist the time and effort.

 

[Z50King]

i beg to differ. my three valve 107 makes a lot of power up on top, and good torque all around, and it responds to throttle pretty well

 

[nickdog]

and i found out last night that no one makes an oil plate for an oil cooler for these heads. the bolt pattern for the plate is backwards

I found that a oil cooler head plate that i got on a chinese small valve head can work you will just need to make new bolt holes in the head. The oil holes in the plate line up exact with the holes on the head.

 

[Z50King]

oh, and is there enough room on the plate to make the holes? or is it sketchy close to the edge?



i want an oil cooler on mine

 

[nickdog]

oh, and is there enough room on the plate to make the holes? or is it sketchy close to the edge?



i want an oil cooler on mine

Not on the plate you need to drill and make threads in the head.

 

[Z50King]

oh.... can you take pictures of where you drilled them??



you dont have too if you dont have time... its okay

 

[nickdog]

When i do it i will take one for you.

 

[Z50King]

thankyou. i really want an oil cooler on my bike

 

[nickdog]

I just finished putting the motor together will put in bike tomorow to test it. No oil cooler yet just a test to see all is running good.

 

[themountain]

Here is a 3V Monsterengine with 156cc from GERMANY