A new to me 77 XS 650

Depends on your carb skills or willingness to learn but for stock carbs stick with late model BS38's 78-79 or any year BS34's, the intake manifolds need to match the carbs. Engine intake, bolt up is same for all years. VM34 Mikunis are the most popular aftermarket carbs. You can buy them "jetted for the XS650" which will be at least a place to start from.
Stock "need rebuild" carbs can often be found for $50 or less, rebuilts $2-300 new VM's $300ish
Don't fall for the knock off VM's, while they may be OK there have been issues in the past.
Carbs from a Kawasaki twin are another popular "upgrade" but for a beach, bar hopper the BS34's would be my choice, easy to tune and forgiving of "close enough tuning"
 
The '76-'77 stock carb set, what originally came on that motor, would be a good choice as well. Any 650 carb set '76 or newer will be linked and use one throttle cable, and that's what you want. As Gary mentioned, the BS34's are a good choice because cheap replacement slide/diaphragm assemblies are available, and the intake manifolds can be readily found cheap too.
 
If you don't know the condition of the motor, or the po can't help as well..............before spending any money on carbs, or anything at all, is to give the motor a compression test. and a leak-down test. This will give you an indication of the condition of the rings and valves.......

And use a thin lubricant squirted in through the spark plug hole to lube the bores before turning it over......i say thin, because ordinary engine oil will give a false reading when doing a compression test

before doing a compression test turn the motor over by hand gently. if a valve is stuck open the piston will jam against it.

I guess you need to by a kick start lever. Advertise on the site or ask in this thread, there are a couple of bike wheeler and dealers, (who are quite reputable and honest, shock, horror, gasp), on here and i'm sure they would have one lying around.

On a cold, and on an engine sitting for a length of time, and the compression is within 5-10 ft lbs between each cylinder, and around and above 120 then it should be ok as it may bed in and the compression will rise. 150 or close, on each cylinder wold be perfect
 
Last edited:
Yah I had thought about that. Good point. I have a bore scope as well that I’m going use to look inside the cylinders after I do those tests
 
At this point, I don't know how many "basket case" motorcycles I've bought. Said you've done bikes before. These run on the same premise as wiring goes. You need a charging system. You need an ignition system. You need a reg/rec. what kinda of battery do you want to run? This will dictate whether you need a shunt reg/rec. I'd probably buy a shunt anyway. Shunt means there's a path for excess voltage. You can easily overcharge lithium.You need a fuse box. From there you can run any light, turn signal, switch in between... etc. Google bobber wiring print. There's a guy on here that sells a harness. Are these there, that is charger and ignition. If so run a test (search on here or google). Like everything else, how much you wanna spend. Compression check on the motor? Doesn't matter, I always go thru motors anyway. Rear wheel spacing. You'll almost gauranteed to need spacers. Buy a chain with new sprockets and get this straightened out first. Do you have a chain? These chassis are stretched. 110 link at least. It's likely you'll need a chain tensioner. You'll need to weld bungs for a gas tank. Seat mounting hardware. Coil mounts. Where are the electronics going to go? Fake oil tank? Get all this fabbed. Get all your fab done with the motor in. Also rear fender. Don't forget this. Get the tires you want and fab up the fender situation. Forward controls? Mid controls? Get this all sorted out WITH the motor in. I'm fortunate to have enough spare motor parts around, I do the motor typically last. I fab the rolling chassis, and then remove the motor for rebuild. Take your time. Address one issue at a time. Don't go into this thinking you'll make money. You will not. This is assuming you don't get a lot a free stuff. Lol. This is a fun hobby. Don't plan on this being a daily rider. With vintage bikes like these, I own a few. One breaks, throw it in the corner and ride another for awhile. I adress one issue at a time. Research, solve and on to the next. Another note: bearings. Replace wheel and steering stem bearings. These are easy enough and knowing that bearing even have a shelf life....just change them.

Tc Bros
Hughs Handbuilt
Mikes XS
Pandemonium
LC Fabrication
Lowbrow
There's several more...a lot of these sell each other's parts.

Edit: Seen you in the wanted ads. Left a post. I'd get BS 38 carbs. Easier to jet for straight or custom pipes.
 
Last edited:
Well I picked up a kicker pedal today. Didn’t have one on the bike when I bought it. The engine cycles which is a good thing. Still have no idea what the internals look like but I will get to that soon. Realized that the kicker gears work and turn the engine BUT, there’s no rebound to the pedal and I hear a loud click every time I bring it back up. I’m assuming the return spring is broken but I won’t know for sure until I take the cover off and check.
 

Similar threads

DB90
New projects!
Replies
5
Views
438
DB90
DB90
G
XT500 Project
Replies
4
Views
244
Charles13
C
Repo Man
XS Restomod rolling chassis
Replies
3
Views
958
Speakas
S
toglhot
Heiden tuning sump filter.
2
Replies
27
Views
1K
bosco659
bosco659
Roy
Top end rebuild
Replies
3
Views
159
Vincenthdfan
Vincenthdfan
Back
Top