Hi guys I've been spending the day servicing up my zip 70 (setup in sig), heres a list of jobs I carried out today: - Topend removed, cleaned carbon off the piston and head, and exhaust port - Fresh cylinder gasket, fresh head rubber o-ring gasket, fresh spark plug - Fresh piston rings, small end bearing and circlips - Reed block removed and cleaned, paddles cleaned etc.. I didnt bother removing the carb to clean it, because I done this at work a couple weeks ago so it should still be squeeky clean. I put everything back together as always, checking, double checking and checking again that I rebuilt everything correctly, everything lined up perfect etc. Starts and runs fine as normal, perfectly fine bottom end power, mid range power (if not better because the engine is now clean inside), good full throttle too but its when you reach the top of the gears (when the engine starts winding out to full revs), it just starts to bog ever so slightly and wont quite reach top speed. Wont rev quite as high as before, im loosing maybe 500-1000rpm feels like a 50 at full throttle, rappid bottom end though deffinatly a slight improvment (like a brand new kit). Its almost like im running a open filter not jetted correctly. I first thought it could be the fact ive clean the carbon off and its lowerd the compression slightly, So I upjetted slightly and it was worse, so down jetted slightly lower than I had before.. No difference? Down jetted from a 92 to 80 (1 jet at a time), and it just runs the same?? Ive double checked the reeds too, the valves open and snap shut fine, nothings gooped up with oil since Ive just cleaned it all with petrol. Any ideas?
after you did the big clean up, did you oil your air filter back up? if not this will more than likely be the cause of the bogging if nothing else has changed. best way to do it in my experirnce is to wipe oil onto you hands, and then wipe your hands on the filter. works every time for me. the filter will be too dry ie lets too much air through.
Nah I run my filter dry, I cleaned it with petrol and rung it out. Im gonna buy another new plug tomorrow, because I just rode home from a friends house and noticed a bit of miss-fire that wasent there earlier today, so I think the shop gave me a faulty plug. It doesnt seem to be running too rich theres a little extra oil in the cylinder from when I put it back together, got a choco brown dry plug but i think its a bad one.
