Valve clearances – GT125R
- This topic has 5 replies, 3 voices, and was last updated 1 year, 12 months ago by
.
-
Posts
-
-
-
-
-
-
Just rebuilt the front head, new gaskets, lapped valves, used piston, new rings, and still low compression. 100psi. Checked valve clearances, intake reads 0.08 0.05 exhaust 0.10 0.10. Could this cause the compression issues? Thanks in advance
Did you put new rings on old pistons, then pop them back in to old cylinders?
What did your cylinder walls look like? Do they have deep, vertical scratches?
Did the old pistons have scratches that match the scratches on the cyclinder walls?
Rings are important & relatively easy to swap. Honing the Cylinder walls is pretty darn important to but it’s messy & expensive if you get a pro to do it properly.
I jrecently did it myself but didn’t do my valves yet, Perhaps you could help me with that?
I’ll be doing a photo tutorial of my D.I.Y. rings, pistons & cylinder honing.
My guess is that you’ve got a lack of compression from slightly worn pistons & cylinder walls. It is possible that your timing is out a bit – that makes it seem like low compression when ridiing. Your exhaust valve gaps should be 0.2 – 0.3 for a 250 i think. What bike is it? Bigger shims in there should sort that out. The Intakle Clearances should be 0,1 i think, so you could add some shims to those to open them up a bit more too. As it is i dont think your bike is getting enough Fuel/Air in or exhaust out. It’s not bad but you may notice better power with more open valves, if it is a 250.
PS. I’d buy 2x new pistons, with rings, pins, retaining clips & both head gaskets. Hyosung have them but aftermarket piston kits will save you a few dollars. I highly recomend the Original Equipment Hyosung GASKETS – they are like rubber, not paper. I used a paper gasket on the head and an orignal metal gasket above it. The paper is ok but for stator cover & clutch cover gaskets, the hyosung ones stop oil leaks way better.
-
-
- You cannot reply to this topic.
- This topic has 5 replies, 3 voices, and was last updated 1 year, 12 months ago by .
-
Posts
-
-
-
-
-
-
Just rebuilt the front head, new gaskets, lapped valves, used piston, new rings, and still low compression. 100psi. Checked valve clearances, intake reads 0.08 0.05 exhaust 0.10 0.10. Could this cause the compression issues? Thanks in advance
Did you put new rings on old pistons, then pop them back in to old cylinders?
What did your cylinder walls look like? Do they have deep, vertical scratches?
Did the old pistons have scratches that match the scratches on the cyclinder walls?
Rings are important & relatively easy to swap. Honing the Cylinder walls is pretty darn important to but it’s messy & expensive if you get a pro to do it properly.
I jrecently did it myself but didn’t do my valves yet, Perhaps you could help me with that?
I’ll be doing a photo tutorial of my D.I.Y. rings, pistons & cylinder honing.
My guess is that you’ve got a lack of compression from slightly worn pistons & cylinder walls. It is possible that your timing is out a bit – that makes it seem like low compression when ridiing. Your exhaust valve gaps should be 0.2 – 0.3 for a 250 i think. What bike is it? Bigger shims in there should sort that out. The Intakle Clearances should be 0,1 i think, so you could add some shims to those to open them up a bit more too. As it is i dont think your bike is getting enough Fuel/Air in or exhaust out. It’s not bad but you may notice better power with more open valves, if it is a 250.
PS. I’d buy 2x new pistons, with rings, pins, retaining clips & both head gaskets. Hyosung have them but aftermarket piston kits will save you a few dollars. I highly recomend the Original Equipment Hyosung GASKETS – they are like rubber, not paper. I used a paper gasket on the head and an orignal metal gasket above it. The paper is ok but for stator cover & clutch cover gaskets, the hyosung ones stop oil leaks way better.
-
-
- You cannot reply to this topic.