Not everyone is comfortable with talking over the phone. Also, emails give you time to do some more research/due diligence as oppose to having to respond on the spot and just saying some mumbo jumbo.
Some people don't understand that posting an ad on Kijiji,for example, doesn't mean you'll instantly have someone respond with "ill buy the bike now". It's a negotiation. Much like when you go to a dealership and you try to negotiate and get some information before you make the purchase. Even when you're getting a brand new bike, you'd still want some more information, right? And that's a brand new bike. Everything is listed on the brochure, yet you still want the salesperson to provide you with whatever information you are looking for. How would you feel if you went into a dealership, asked your questions and the salesperson just handed you a brochure and said "everything is listed there, let me know when you have the money"? It's part of selling. If you didn't want random email responses, don't post your ad in a online public marketplace. Make some signs or post in the newspaper classifieds and put your number and/or address if you think the only way to find out if the buyer is serious is if he gives you a ring or shows up at your doorstep.
I'm not saying you have to call, but if you want a better interaction with the seller it's in your best interest.
I've bought and sold over a 150 cars/bikes/trucks in the last 20 years on kijiji/autotrder/buy&sell(remember that one?). Within the last year I think the spam, ignorant buyers/sellers have gotten exponentially worse.
90% of emails are guys offering offensive offers , ie : comps-$9500,asking-$8500, email offering-$3000!
There is a whole bunch of people that actually make a living scouring kijiji lowballing in mass and then seeing who emails them back, they then sell the item in kijiji for twice what they paid for it, sometimes even using the same pics from the original listing! That's why it can be so frustrating for a seller to deal with emails sometimes.
I promise you that you will have a more pleasant transaction if you muster up the courage to call the seller.
I know it can be a little nerve wracking at first but remember the seller wants you to call them, so don't feel nervous. Be polite when you call and treat the guy like a friend... Heck you both like the same bike, chances are you guys would probably get along anyways!

(I'm friends with at least half the guys I've sold my vehicles too!)
Here are a few tips before you call:
1. Make sure you have the funds ready to close the deal if this turns out to be what you want.
2. Research the model thoroughly before, so you know exactly what to ask the guy and so you know if this is the bike for you. The seller isn't a professional salesman (this is a good thing) so don't expect him to be.
3. Write down all your questions you want to ask on an a pad of paper.
4. When you call write down the sellers name and phone number on top of the questions along with the make an model of the bike.
5. Ask the seller to tell you about the bike. This will let you get a feel for the seller.
6. Ask your questions and see I the seller was withholding any information from his initial description. This is a potential red-flag so just be aware of it.
Call all the bikes of that model that meet your Budget on kijiji and keep all your notes.
From there decide which ones you want to see.
This will make buying the right bike a MUCH quicker painless process, you will be able to negotiate a better deal, and maybe even make a friend in the process.
For the record the kijiji seller in the OP was just ignorant, if he was too frustrated with emailing he shouldn't have replied. There is never a good reason to be rude to someone.
