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Old 02-04-2015, 03:54 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Curious about the engine, :question:

Originally Posted by cannonball2 View Post
Hey Map low transfers aint all bad they give a higher compression ratio. You can ramp the pistons a bit and or stuff the cases.
yeah I have done the piston ramping and it has worked good for me.

thing about some of the jugs I have here is that the ports are very small to start with and then @ BDC they're only half open, I just figured the small ports with only being half open @ BDC was going to really limit the engine for high rpm potential.

The other jug I have that has the larger re tangular ports that are about 90% open @ BDC seem to me is the best choice for a high rpm build that will handle the extra fuel/air mix from a carb like the 20mm Mikuni I recently bought to use in the future.

so far none of the engines I've put the low tranfer port jugs on will rev nearly as high or pull as hard on top end as the larger port jugs with ports that allow a larger fuel/air charge to enter becorw compression.
You may have hit the nail on he head though with case stuffing, that may be the se ret to getting primary case compression up to force a big charge through even the smaller lower ports.

Im in no way an expert on 2 smokers and have a lot to learn, but I just kinda go with what I've already done and what has worked best for me so far.

It is possible though that I could be doing some things that aren't exactly right and robbing myself of some power, but honestly Im not looking to have 60mph bikes, I've hit 52mph on one of them and that was fast enough for me on my lower end bikes, I really just look to get 43-45 mph top speed and a good ruise speed in the mid to upper 30,s that is fairly reliable and Im happy.

Im not one to get super deep into some of it because honestly I just dont have the time or the patience for it, I just want a smooth as possible running cruiser that will allow me to zip with the tracfic in town on the 40-45mph speed zones now and then and also be able to cruise along nicely in the 30-35mph zones and Im a happy camper.

Thanks for the advice though I do appreciate it.

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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