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Old 04-24-2014, 01:09 PM
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mapbike mapbike is offline
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Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Bought bottom end from Boy Go Fast, should I be worried?

Originally Posted by fischer550 View Post
Thanks for the info map bike. Again though, is a 38mm stroke better than a 40mm? What do you mean by "hybrid engine"
By hybrid I meen what I have read about them being a combination between the grube type engine and a typical PK 80 type.

Im no expert on all these things but I read where Fred maker of the Fred heada and other parts including some high end engine builds refers to the bgf engines as hybrids because of the stroke and piston type combination, he actually uses the bgf lowers for one of his moderate performance builds and he says they're good built lowers so I would no be sfraid of them and as far as performance is concerned Im gonna say you will not likely notice a difference between the 38mm stroke engine and the 40mm stroke engine for a typical build, probably a really high end build might show some performance difference but the way most of us build our engines up I dont think a power difference will be noticed at all, I'd build up the bgf engine expecting it to be just fine, and if it just so happens to have a fairly true crankshanft and the balance of the lower is pretty good it will perform better than a 40mm stroke engine that has an untrue crank and bad balance, high amount of vibration is a performance limiting factor on whichever engine we get, a better balanced engine allows it to rev better and higher if it is set up right, as it has been said by many for a long time here on this forum, " all of the china made engines are a crap shoot" it does seem that we are getting some better quality engines here lately but no matter which " brand" or type of china girl engine we buy we can be assured that we may get a good one that runs for a long time or we may get a lemon......
Main thing is just build it right by matching the components and run a quality oil and treat it like what it is, a cheap china made engine for using on a bicycle that was not designed for and engine, build your bike to be safe with good tires , good brakes and make sure everything is greased very good and stays tight and secure, get rid of cheap thin fenders and mounts, use thick thorn resistant tubes in the tires and make sure chain is aligned and stays at a proper tension, all these things will give you a safer bike and a better chance of having a bike that you can usually have fairly good reliability from, just remember you should give it a good visual inspection before each ride and ride it like a motorized bike and not like a motorcycle and avoid. Deep pot holes that can break frames and taco wheels.... use a mirror and watch out for the cars and trucks that dont see you well and realize how fast you are coming their way, people aren't suded to having a bicycle approach them at 25-30+mph and are prone to pull out in front of you, this is where xefensive riding and good brakes can save your hide.....

Best wishes on the build, im looking forward to hearing abour it and seeing it as it comes together.

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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