Ghetto Bobber

Tonkaman

Well-Known Member
Location
West Jordan
Last week I picked up a 1978 Yamaha xS750 that @Herzog generously donated.

All I know about the bike is that aproximately 5 years ago it was a running bike. It got sidelined to become a cafe racer project and has sat outside since that time. The build progress didn’t get further than cutting off the back of the frame, and removing most of the body panels.

Here’s how it looked once it got home
 

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Tonkaman

Well-Known Member
Location
West Jordan
Awesome, thanks!

I’ve done lots of different dirt bike projects over the years, but modifying a road bike is all new to me.
 

N-Smooth

Smooth Gang Founding Member
Location
UT
Looks like a fun project. My bro had a ‘8x Yamaha Seca which looked pretty similar to that and I had a ‘83 Virago 750. I miss the days of the old ghetto bikes.
 

Tonkaman

Well-Known Member
Location
West Jordan
I pulled the carbs and tore them down for cleaning. They are in terrible condition! I’ve seen worse as far as old fuel and ethanol, but never seen so much internal damage to the parts. 961BDC28-1BDB-432D-B2E4-EB7C275ECCDD.jpeg171C135E-9C85-4D8F-B7C6-3672BA3B1A18.jpeg0C6394FC-4B4C-4BB4-B21D-817ACA499814.jpegE4C730B9-1B7D-4053-85CA-A3236F57F3A3.jpeg

2 of the 3 air screws have the tips broken off inside the carb. I ended up having to drill out the carbs to get them out. Unfortunately I can’t get those screws from Yamaha anymore so I’ll have to find an aftermarket solution 1C09FFEF-14C1-4BF1-88F1-79C4C4CAAE45.jpeg8D8725E4-73D0-4965-88B4-6B52ED7A9586.jpeg94A99025-46DB-4739-9D75-5C57DCA9BF33.jpeg


1 of the diaphragms looks like it got hot enough to melt somehow. Considering it’s $200 to replace I think I’ll try to reuse it. 6C975DA6-B8F1-4946-9599-927723086376.jpeg

One of the towers that holds the float pin is broken off. The float was also bent out of shape, but easily bent back. I’m hoping I can use it even the the float won’t have a stopper when open. EDF6C1F3-A9A6-46F5-8381-DF60358543F4.jpeg

I’ve never seen a needle that has gouges and dents all over it either. 75C4957B-55A4-49B4-9C5D-D3CBC8339DE0.jpeg
 

Tonkaman

Well-Known Member
Location
West Jordan
I have no idea how a float pin gets bent, but here’s proof that it can happen. A1476AC7-F2E0-4934-A645-E38F269968CD.jpeg

The plastic tees for fuel between carbs are all cracked. These are on a long back order, so I’m hoping they will hold long enough to verify the engine will run. D78AEF49-CD5B-4D90-9C37-31C280FDA9C7.jpeg

The intake boots arr made out of radiator hose pieces that are all rotting away. 34EE9601-8E8B-4048-A37D-45E1C6DFCA65.jpegD8C8A082-F369-493C-9CAC-FA54CB5E71D3.jpeg

The air filters are Chinese Cheepies that have a lip on the inside blocking air from the ports on the intake side of the carb. I can’t imagine the bike ever ran with them installed. 02975F4D-5157-4CAC-8F43-144E9271DC06.jpeg

The fuel tank had 1/4 tank of a fuel/water mixture inside. It’s heavily corroded on the inside, like growing stalagmites kinda corroded… 8DF8278D-6606-43B4-957C-3D0BAFC55E5C.jpegA1CEB82D-44DD-4D6C-BFD4-EB959F724DC8.jpeg
 

Tonkaman

Well-Known Member
Location
West Jordan
Good news! She runs!

I changed the oil, turned the engine over by hand. Since everything rotated smoothly I decided to try rotating the engine with the starter. I hooked up a new battery, drilled out the ignition lock cylinder, and made a start button out of a screwdriver lol 😆.

It turned over very smooth, so I did a compression check. Each cylinder had good numbers! I put new spark plugs in, squirted some starting fluid into the intake and SHE RUNS!


I rebuilt the carbs with all the old parts since OEM parts are all backordered. I’ll reinstall them with the rotted radiator boots, and rig up a temporary fuel source. If I can get it to stay running, I’ll go ahead and invest more time and money to this ghetto bike 😎
 
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