that pipe is easily available in market , i dont think you can fit any other pipe instead of that , beause it has a collar at one end where it goes into the tappet cover ,,,,,,,,,,,,,,,batter instal a desel engine solenoid , search some old one from old spare parts store and kick off that problem for ever ,,,,,,,,,,,,,i dont think there is any thing name tuning for these engines ,,,,,,,,,,they dont need any timing adjustment,,,,,,,,,,,,,carb need littel bit cleaning and can be done at home with carb cleaner ,,,,,,,,,,filter can also be easily washed/changed,,,,,,,,,,,,but you need to adjust the tappets,,,,,,,,,,,,,i have adjusted once in 3 years only,,,,,,,,,,,,,,,and i over haul my generator after 2500 working hours ,,,,,,,,,,,,,tappets are not a thing which need adjustement after every 100 hours,,,,,,,,,,,,,,i see many gen mechanics who claim it need adjustement after every 100 hours,,,,,,,,,,,,,thats all noncence,,,,,,,,,,,,,suzuki mehran catelog says to adjust the tappets after 40,000 Km , and out mechanics open tappet covers on every oil change and adjust it with wornout feeler guages ,,,,,,,,,,,,,again all noncence ,,,,,,,,,,,,,,,,,i think you no need to change the oil after 40hours,,,,,,,,,,in my case i have installed a hour meter on my gen and i change the oil after 100 working hours,,,,,,,,may be you say that it may damage the engine ,,,,,,,,,,but i noticed while overhaulling the engine that there is no metal wear and tear inside the engine,,,,,,,,,it means changing oil after 100 hours is a wise decision ,,,,,,,,,,,,,,,installing a mehran or any other car ac or radiator fan is good ,,,,,,,,,,,,just instal in such a way that the air enters from the recoil starter side and pushes out from the exhaust outlet side,,,,,,,,,,,,power it with a 12V genenerator output instead of installing a adopter