Need Help Low Cost Valve Job on a Linhai 257 cc  By  bob123456789 (Read 4,271 times)

First who ever told you you should get 200 psi ? my 300 cc new get 260 tops. I'm thinking you have a couple of issues fuel, and spark you say after you ride it it drops off sounds like you first after it happen see if it starts with a spray of starter fluid just to see if it will go. If not check spark yes you should have a few tools with you. This way your aren't guessing when you ask questions here.

I have been kinda busy with a similar issue. Blew a bargain drive belt (purchased locally and it turned out that even though it was OEM the vendor had it sitting on the shelf facing a window for years so even though it looked new it was not) and finally got around to dealing with it and found the valve gaps off when I went through things. When I took the variator off to clean up behind it I found the Aramid fibers had gone through the oil seal on the timing cover and up into the head. After I cleaned it all up I found the valve gaps a bit large on the intake side and cringed at the implications along with the low compression when I keyed it over. Bottom line belt fibers jumped valve timing enough to hit and damage the intake valves so I had to pull the head and am in the middle of doing a valve job.

Yours looks like something was injested through the intake or a valve cracked on the rim and the broken bit bounced around in the cylinder unless you caused the scratches when first inserting the camera. Myself I did not bother with a camera inspection since it was obvious to me when I saw the intake valves with such a wide gap on an engine that rarely ever needs the intake valves adjusted that the head needed to be pulled.

Did you take pictures of the cylinder walls with the piston at the bottom of the stroke?

Those seem to be a very odd-ball size as most are 8mm, 10mm, 12mm or 14mm OD with the ID 1.5mm to 2.5mm smaller with a wall thickness of 0.75mm to 1.25mm. A 0.375mm wall thickness seems a little thin for a 257cc engine. As long as you can match up the OD and Length you should be good. Standard for the 260 variants should be 16mm long, 14mm OD and 11.5mm ID.

According to all the fastener web sites I have checked so far there is no such thing as a 8.75 mm dowel pin. Are you sure its not 9mm or 3/8 inch? Standard appear to be 8mm, 10mm, 5/16" or 3/8". You may have to get a 10mm and have it turned down and cut to length.

Parts for Scooters $3.99 for a package of 4:

www.partsforscooters.com/Dowel_50cc-2

They are 0.05mm shorter which should be fine.

On an item that small they will usually put then in an envelope and send them in the mail. They are right across town from me so if I get my order in before noontime I will receive it the next day or I have the option of just paying over the phone and picking up my order from the receptionist at the front desk.