Mystery Engine

[Ironriot]

Hi new to these forums. I got a Yammie question to ask and who better than you fine folk?

Basically I noticed a bike sitting up against a house in a decrepid state. I checked it out and it appears to be just a custom dual purpose bike. Its frame is a heavily modified Yamaha and the engine is a thumper of the same make. I've been looking for info on it but I can't seem to really find anything on Yamaha thumpers. So far about the only things I know is that its kickstart, and its small. I'm guess its a two stroke because of the oddly designed valvecover(?). Any help in figuring out what it is would be greatly appreciated. Or maybe just any links to the history of Yamaha thumpers or all the thumpers produced by Yamaha. Thanks in advance

[GNEPIG]

Wasn't Thumper a rabbit in a cartoon?

A picture is worth a thousand words (and would be alot more help to you)
Since you are not sure what the term "thumper" means, it makes your description even more vague.
Yamaha made alot of one cylinder bikes, since they arrived here in the late 50s.

[Ironriot]

I know a Thumper's a single cylinder engine. Why would I use that term if I didn't know what it meant? I'd present a pic if I had one. Sorry though my camera took a dirt nap. And I know they produce an ungodly amount but there has to be certain families and certain sizes. There are popular ones like the 125cc. What other popular sizes are there?

[manshack_one]

try to get us a serial number off the engine and frame. will go a lot farther than "an old thumper" even without a pic.

[GNEPIG]

Quote:
I'm guess its a two stroke because of the oddly designed valvecover(?).

The term "thumper" means; a one cylinder, 4 cycle engine. A 2 cycle engine would have a flat head with large cooling fins and 1 or 2 spark plugs clearly sticking out of the top- no valves- no valve cover.
Not trying to dis you here, good luck on your quest

[Ironriot]

Originally posted by GNEPIG
Quote:
I'm guess its a two stroke because of the oddly designed valvecover(?).

The term "thumper" means; a one cylinder, 4 cycle engine. A 2 cycle engine would have a flat head with large cooling fins and 1 or 2 spark plugs clearly sticking out of the top- no valves- no valve cover.
Not trying to dis you here, good luck on your quest

AH thank you. I guess an old dog CAN learn new tricks. I always thought all single cylinder's were thumpers. You've given me a wealth of info in that reply alone thanks

[prometheus578]

'Were you traveling cross country? What state were you in?"

Basically I noticed a bike sitting up against a house in a decrepid state

I note that you're from the state of Texas.
Most Texans take pride in where they live...
Texas may have some poor, rural communities, but it also has bright, modern cities, from what I hear.
Could you have been referring to Kansas?

Obviously, I have nothing better to write about...
Just my way of saying hello.

[GNEPIG]

LOL

LOL

[Ironriot]

Re: 'Were you traveling cross country? What state were you in?"

Originally posted by prometheus578

I note that you're from the state of Texas.
Most Texans take pride in where they live...
Texas may have some poor, rural communities, but it also has bright, modern cities, from what I hear.
Could you have been referring to Kansas?

Obviously, I have nothing better to write about...
Just my way of saying hello.

Lol bad grammer on my part. The bike, NOT the house was in a decrepid state. And I noticed the bike when I was at the said house for a local band's house party/concert. And hello to you too

[planedick]

Thumper

My neighbor has an old Yamaha 500 cc "thumper", kickstart with a sidehack.

[Ironriot]

Hmm interesting. By any chance does the valve cover look wierd? Kinda dome-ish?

[fredintoon]

Hi Ironriot,
Yamaha made lotsa singles, 2-strokes & 4-strokes. Let Google be your friend.
Google "Yamaha single cylinder" for ~228,000 hits and look for pictures that look like what you saw.
And get back to us eh?

[webbcraft2150]

Thumper is a nickname Prom got along time ago. I think is was the noise he made when he bailed on one of his bikes and bounced off the pavement/dirt. Or maybe after the birth of his 6th child? More commonly, thumpers are indeed 4 stroke singles of any brand. The XT series started somwhere around a 125 size and went all the way up to the "bust your kneecap if you kick it with a locked leg" TT600 and 500. If the engine size is missing from the sidecovers or the tank emblems, you can look on the steering neck for a model and serial number. Also the jug size will cast into the bottom of the cylinder at the base. Usually you would round this number up a few cc's to come up with 125, 250, 400 ect ect. (The XS11 is "only" 1098cc).

BTW, from what I understand, Prom's bark is alot worse than his bite, but then again I say this with the saftey of a few hundred miles between us.

[BentRod]

I have nothing to add here, other than haha Ironriot. You Just can't escape the teasing eh?
now.. what are you doing here anyways.. being unfaithful to your 550?

[Ironriot]

Dude you found me but I found you.