Constantly adjusting valve clearance
 

I have a 2013 SSR 250. When the valves are in spec it fires up with the first touch of the e-start. But after about 20-30 minutes of riding it starts to feel down in power and eventually won't start at all.

The only thing I've found to help is adjusting the valves. I open the bike up and the valves are out of spec too wide every time. The frustrating part is the set screw is never loose so I have no clue what is causing my valves to constantly get out of spec. Is anyone else having a similar issue?

When I put them back in spec she runs like a dream again.

It's to the point that I don't really take it on rides anymore because I can't trust that I'll make it back to my truck.

You might want to check that your valve seats aren't loose and being hammered into the head.

Does your bike have the Zongshen NC250 engine? Spud Rider had one with a bad head and the intake valves kept receding into the head (or something like that). His bike was still under warranty, so CSC sent him a new head for free. He did a write-up here, about his bike. http://www.chinariders.net/showthread.php?t=18895

It looks like a complete head for an NC250 is about $125 on Aliexpress. They aren't too difficult to install, especially with all the online videos now.

Thats fantastic info thank you! I'll check that write up first. Not sure if they are getting hammered into the head or not. Definitely no issue with ticking noise in the valve area. Not a bad price for a new head either!

Assuming your engine is an NC250 you could also install a 300cc big-bore kit for another $200, while you've got the head off. It made a noticeable improvement on my bike.

Post up a pic of your motor before you buy anything, I suspect that your motor predates the NC 250 by several years.

Also, what's your valve adjustment technique? Are you adjusting them on a cold motor that has sat overnight? What specs are you adjusting them to? I would await your response before you buy anything.

I know the old ktm rfs motors came with "soft" intake valves that needed allot of adjusting, so it's not hard to imagine with the quality control of some of the Chinese bikes that they'd have similar or worse issues. Maybe valves, maybe seats, maybe other valve train parts?

They've been adjusted cold in the past. And I'm doing .04mm - .06mm on both intake and exhaust. However I've seen other people on this form say Intake: 0.05 mm, Exhaust: 0.08 mm. When my valves are in spec it runs great but the gap is far too wide everytime it stops running well. I'll try and get some pics of the engine tonight to make sure of the model. Anything specific to look for on the motor to help indicate the year and model?

There should be a bunch of numbers beside your shifter ,post them up and the Genius Bar boys will tell you what you have . Truck

I didn’t get a chance to check near the shifter but I did get some pics of the cylinder and head from the right side of the motor.

Not the best photo, but that is a water-cooled engine. The numbers are different than on mine, but everything else looks like a Zongshen NC250 to me. I'm sure an expert will chime in and confirm whether it is or not soon.

Did you ever get this sorted out?

I'm wondering if you are adjusting on the wrong piston TDC.
On the wrong one, the exhaust rocker is tight. On the right TDC, both rockers are loose.

Super important to get this right, then re-check it by rotating the engine a couple of times (easier with the spark plug out) to verify your adjustments.