Re: noob from the bay area lookin for a good time
the links up and down the sides of this forums (as best i can tell) are all good places to start.
i hesitate to send you to someone I haven't bought from but i can tell you that i nearly pulled the trigger on one of Dax' entry level motors (it was the shipping that stopped me, i live in canada) guys website is a mess, but my communication with him was confidence inspiring.
that said you can probably get a motor from bikeberry or gasbike or another dealer with a similar catalogue (most are very comparable or the same motors) just keep in mind what you are buying Vs. what you need. several of the kits out there have some small upgrade in them (a billet head, or an upgrade carb, or somesuch) but unless you see something in the kit that you think is a really good deal dont pay an extra 50-100 bucks for them to drop a few bolts and bits of metal in the box and call it a 'premium motor mount'
some things to keep in mind:
a lot of the hardware (nuts and bolts) in these kits are of sub-par quality, you may want to go to the hardware store to replace all that stuff regardless of what motor you get (watch out for the studs; exhaust, intake, and mounting) these regularly strip out and need to be replaced (most people will just replace them out of the box, a couple of dealers include upgraded hardware)
the carburetors that come with these kits (air filter looks like vaders mask, mandarin characters on choke) are serviceable at best. there is a specific carb (dellorto SHA or clone) that is universally regarded as better, most other carbs you can get with the kits are at best a marginal upgrade.
as far as i can tell none of these kits come with an inline fuel filter, you will most likely want to get one (available at hardware/auto parts stores) there is a very small filter built into the gas shutoff valve in the kit, this filter is not quite adequate. while you are doing this there is no harm whatsoever in replacing the fuel line with higher quality.
the throttle twist grip that comes in the kits barely qualifies as a toy, you will almost immediately want to replace that. I had to cut plastic casting errors out from inside mine to even get it to work at all! there are plenty of replacements available out there, i have seen some thumb operated throttles like on a weed whacker that would work perfectly if you are okay with that. as far as upgraded twist grips I am currently looking into using an OEM replacement from a Harley Davidson.
word on the street is that the ignition coil that comes with the kit is sub-par as well, several replacements exist though i cannot attest to the quality of them (yet)
and finally like any motor vehicle there are a few parts that work fine, but an upgrade would be better (i am mostly talking about the spark plug, every engine likes a better spark plug) two strokes in general like higher quality oil in the gas mix, and dislike ethanol additive. the instructions in the kit say to use an obscene amount of oil, just go by what the instructions on the oil bottle say.
the final piece of advice I have is not to rush.
when you are building be prepared to waste time re-doing things. if you are unsure about something, feel free to hesitate. having the bike sit for another day is more than worth it compared to cracking your head because you rushed it.
break it in slow, be gentle with it.
take it apart if you think there's a problem, be okay with carrying most of your toolbox with you when you ride.
before and after every ride take the time to look at your engine, learn to listen to the machine.
on the road you might be able to get up to 45 MPH but 25 will get you there just as well. take it slow and enjoy the ride.
welcome to the gang, and good luck!