Linhai 260 questions: rear brake caliper, fuel pump, exhaust

[new_bee]

Hello, I picked up a Linhai 260 classic / aoleus, 2006. not running/ "sitting for a year"
Happy to find this forum where there was a lot of discussion of this model at least in the past.

I put in new oil, gas and plug, installed fuel filter, cleaned carb and was able to get it to run at high throttle for around 20-30 seconds. The muffler was shooting sparks (and in bad shape, possibly partially plugged or full of obviously flamible rusty carboned up stuff) after that amount of time so I shut it off.


Questions:
I have now removed the muffler, while I track down a new/ used one, does this engine need back pressure or is it OK to test run it for short periods of time without?

The plug was fouled black after this so I am not sure exactly if the issue is with muffler restriction, carb, or missing fuel pump.

I was able to find a diagram, and the fuel pump is missing/ bypassed. the tank is mounted above the carb level wise and "apparently" the previous owner drove it so maybe gravity feed is ok? Will it even run (right) as-is? I ordered a generic replacement on ebay but one thing I am unsure of is where to hook the vacuum line up to. The diagrams I found are low quality and I can't tell at all. Does it go to the nipple on the intake elbow ( currently that line is capped on my engine), or to somewhere else?


Finally, the rear brake caliper was loose and missing a bolt/pin. The resivoir was dry so I bled it for a long while with a vacuum bleeder, and what came out wasn't too bad. I hit a dead end trying to find a replacement bolt, although it's possible I could try again to order bolts from a Yamaha yp250 source. so I fabricated one using a m10x1.25 thread bolt x50mm long, and grinding down with a angle grinder to match the other bolt. The bolt seems to work as in threading in to the threads, and the pin section lines things up well.

The pads are installed correctly, there is one retainer clip per the diagram, and the pistons do move when handle squeezed & the caliper is detached however once installed I have been squeezing the handle and the caliper does not tighten up really at all. 3 attachment bolts are secure.

I can't tell for sure if some part is missing or if the caliper pistons don't have enough travel, or if the master cylinder handle is not putting out enough pressure.

Another possibility is that the existing bolt that I copied was not the correct bolt and the pins are too long.

Any help VERY greatly appreciated!

Also all the links to majesty 250 (the Yamaha this is a clone of) service manuals I found are dead. If anyone has a link or can send a pdf copy of a Linhai or Yamaha service manual I would really appreciate that as well.

Thank you