Bought the Bullet Train 80cc (70cc in UK) petrol 2 stroke electric start bicycle conversion kit. The engine is a lot better quality than the cheap Chinese ones from ebay ect. The Bolts are quality strong Alan key heads that don't snap & strip their threads all the time the 8 studs (4 front & 4 rear) clamp the engine to the bike frame so much more securely and safely than the cheaper 2 bolt sort on the cheaper "china doll" 80cc (66cc UK) ching chong cheaper Kit. Not to take anything away from them as for the price they function ok. I got 3600 miles on mine before the piston wrist bearing disentergrated and ripped into the piston, piston rings & cylinder walls. It's hard to get the correct EXACT type replacement as the cheaper Chinese sites and ebays ect all just copy or download the same generic pictures so don't go by the pictures unfortunately it seems that the only clearly defined spares for the "80cc"china doll seem to come from online stores in the USA but the postal & custom or other fees make it impotent as a UK supplier with the insane cost of the postage is often maybe 2 or 3 or more! times the cost of the goods your purchasing!? The BT 80 is much less demanding in servicing. You really have to check & tighten or replace snapped bolts or parts constantly on sometimes a daily basis other wise you end up pedalling home as yet again somthing has gone. Only complaint so far is on my Bullet Train Kit the Pull start was so weak from the start and failed after pulling starting it off just a handful of times. Also the replacement wide crank set's pedal arms although intentionally are bent to clear the engine were both not completely straight along the vertical access thus making the pedals both point in slightly a few degrees making them not completely horizontal when view from the front of the bike or rear with the pedals in their uppermost & downward position meaning that when you pedal the bike it causes your feet to rock from left to right in a wobble.