On September 19th, I purchased a 1980 Yamaha XS850SG off of CraigsList for $550. When I got it, the bike ran but had a few small problems. The electrical starter did not function and the bike would only kick start. The kick start was very, very difficult to operate. The brakes had very little stopping power. The tires were at least three years old. The right side petcock leaked fuel. There was probably gas in the oil (yes, after checking, it was half gas, half oil). The bike seemed to be running a little rich. Both brake master cylinders had seen better days. The tank had been poorly repainted at some point. The original Yamaha and Special badges on the tank and plastic covers were missing. The electrical guts of the bike were in a plastic bag behind the headlight. One good thing that came with the bike is a full set of touring luggage. Nice!
This particular XS850SG can best be summarized as being a fast, dirty, dangerous bike. In other words, the visceral experience every 13 year old gear head dreams of.
Note that posting this was delayed until the title cleared. Now that the title is in my possession, welcome home XS850!
The priority list to repair these defects is as follows:
- Petcock replacement – DONE
- Brake master cylinder replacement (both front and rear) – Postponed. Can be ridden safely as-is.
- Brake line replacement (with stainless steel braided lines) – Postponed. Can be ridden safely as-is.
- Brake caliper rebuild and possibly replace old brake pads – Postponed. Can be ridden safely as-is.
- Electrical system rebuild/repair (including fixing the electric starter, removing strange the 120 volt battery charger, and installing a Battery Tender Jr pigtail plus most likely replacing the fuse block with something modern) – DONE. Fuse block replaced with blade fuses. Battery Tender Jr. installed in place of strange 120 volt battery charger. Electric start works now that petcocks are fixed. Kickstart also works.
- Replace oil (engine, middle, and final drive oil) – DONE. Used 85wt gear oil for middle and final drive. Used 15w40 Shell Rotella for engine. Replaced filter, too.
- Re-badge tank with something interesting (used to say Yamaha on the tank and Special on the plastics) – Still thinking what I want to put on…
- New tires (rubber is at least 3 years old) – Postponed. Can be ridden safely as is.
- Replace spark plugs – DONE. Iridium plugs now installed.
- Voltage meter to monitor what the charging system is up to – Postponed. Can be ridden as is and bump started if needed.
- Replace fork oil and possibly rebuild forks – Fork oil replaced with ATF. No need for rebuild now.
- Fine tune carburetors and verify that the bike is not running too rich – Going to see what the mileage is like first before tinkering with carbs.
- Replace handle bar controls – Okay for now. Looking for a rotary switch to use as engine kill switch.
- Add alarm system (the handlebars do not lock)
- Re-paint fuel tank and plastics
- Polish all chrome and aluminum
- De-baffle muffler and rebuild airbox for more air flow. This will require re-jetting the carbs or replacing with a set from an XS1100. Could also fuel inject if I upgraded the electrical system.
I test rode and purchased the bike at around 10pm. I’m thinking this one might need to take the name of “Midnight Special.”
The chain is for security. Don’t want anyone getting ideas.
Triple exhausts for the triple inline engine. Also dual horns that are pretty loud. Note that the engine is air and oil-cooled. A rather interesting design.
The petcock in the middle top of this photo is leaking gas onto the air box. It will be replaced soon.
Yes! It has shaft drive!
55433.5 miles on the odometer. The speedometer does not go high enough based upon how fast this bike can go. On the test ride, I accidentally took it to 80 mph in 3rd gear (without reaching red-line) and popped a wheelie. This thing is hella fast.
i have some questions you might be able to answer , i left an email address when you get time . thanks.
Hi Frank,
I’ll reply to your email in a while when I get a break in my day.
Cheers!
Douglas
Where did you get the petcocks? thanks.
I ended up making my own. At the time when I needed to replace the petcocks on my XS850 there weren’t any available online. There is another post on this website about how I modified them.
Hi… I just aquired a 1980 Yamaha XS850SG. It jumps in 2nd gear and I’m wondering if its worth the money to have it fixed. What do you think?
Hi David,
I didn’t get too much experience with fixing the transmission on my XS850 before I sold it a few weeks ago. However, I can say that it isn’t THAT hard to work on these engines. If you have rebuilt an engine before, you will have no problem. There is a good chance that you will get lucky and the 2nd gear problem can be fixed from opening up the crank case covers on the bike. You might have a bent shifting fork or worn clutch plate. The best source of advice on this problem will be the Yamaha Triples forum at
Cheers!
Douglas
Thank you my friend…
No worries! Let me know how it goes 🙂
I have recently bought one of these. When I test rode it and drove it home and had it about a week all was good. Now I have a rattle in the case that stops when I pull the clutch lever in. So far it is only when it is semi warmed up but seems to be fine at normal operating temp. No slipping or bad behavior from the clutch that I feel. The only thing wrong is the tach doesn’t work so I haven’t really opened it up. Not sure I want to at the moment. Do you have any ideas? I have a manual but it is a bit confusing. I’m wondering if I am hearing the drive chain or a bad damper or possibly something worse. I could use some advice!
Hi Glen,
I would try to find the source of that noise ASAP. Have you checked the valve tolerances yet? It also is wise to check the timing chain tension and tensioner system. Have you changed all of the fluids? In addition to the engine oil there are also final drive oil (expected on a shaft drive) AND middle drive oil (I hadn’t dealt with a bike with a separate middle drive reservoir before). Can you localize the source of the rattle in the case? There are some covers over the stator/rectifier (generator) and also (if memory serves) the timing magnetic sensors. That could be another place to check before you start tearing into the engine.
It really depends upon how well the bike was maintained over its life whether this is a serious problem or not. Hopefully it’s something simple! One thing you might check is to see if there is a loose bolt or nut floating around on top of the engine cover. Junk can get stuck in there and make an awful racket. Sometimes the exhaust system gets loose and rattles as it heats up, too.
Cheers!
Douglas
How did you repair the electric starter? I’ve had the back for 18 years and looking to sell it but now the electric start won’t turn the bike over, but all electricals work including lights and gauges.
Hi Rich,
In my case it was a weak charging system that was not fully charging the battery. Leaving it on a battery tender between rides made it okay. At some point, a future owner will probably have to rebuild the electrical system but at least for when I had it, that solution (and replacing the fuse block) seemed to solve it for me.
I know that some XS850 bikes have weak or broken electric starters. The only way to fix them is to replace the motor. Try jumpering directly to the electric starter to see if it runs normally first before replacing it. You might find out it’s just an electrical issue.
Cheers!
Douglas
Hi. I left the ignition on after putting my bike in the Garage and now it won’t start. I get nothing when I press the starter button. Fuses are good unless there’s one I’m not aware of. What can it be? Any help would be appreciated
Hi Mike,
All of the fuses should be either under the seat or in the right side panel. If you left the ignition on, I would imagine that the battery has run flat. Recharging it should make the bike start up. If it still doesn’t, you might need to check to make sure the battery is still good.
Cheers!
Douglas
Battery was recharges so that’s good
do you know where to get a new exhaust system for this bike?
Hi Matt,
I’m afraid I don’t. There probably are some used ones on e-bay though.
My xs850sg has a oil leak from the tach cable. Changed the seal twice and still leaks. Any ideas?
Is it leaking through the cable rather than the seal?
You could also check to see if the seal isn’t mating well. The surfaces might have gotten warped.
It may be the cable. Not sure. I’ll swap it out and see. Hard to tell of the surface is warped. Probably going to get rid of it in spring anyway. Tired of the little things that go wrong.
pull the part in the engine where the tach cable atacches.on the engine side it is actually 2 pieces plus an internal seal they r very hard to get apart I took mine to my local dealer who works on my bike (tires,carb clean ,etc.) this part is very easy to damage/break so don’t dealer took it in back said come back were busy came back all fixed no charge
Having an issue get the air box apart any tips need to clean the carbs
There are some kind of hidden screws to do. Have you gotten them all loose? Old rubber and plastic can get pretty hard to break apart, too.
tryig to do the fork oil on my xs850..got these weird slot things under the caps… anybody know how to remove them,? email me at hobosparkes@yahoo.com..thanks
Hi, My xs850 won’t start and backfires when trying. This came on just recently and prior had been running fine (bike has only 10K miles on it). I tried spraying starter fluid in the air filter box with no change. Any ideas?
It sounds like there could be an issue in the carbs. You might try running a solvent like seafoam or techron through the fuel system.
I Just finished Doing A lot of work on an 1880 Yamaha XS 850 triple Special. My name\e is Carl and I have had three (3) of bikes all 1980 Special models. In additon; I have also owned, four XS 1100 Specials. Known own 1982 Yamaha 920 cc Virago ( 1 of several iv’e owned ).
the best advice I have is to get as much info on the bike you’r purchasing.
Short from that , it seems we’er on our own. So just be smart, all of you
Carl
Can anyone tell me the position of the Main and pilot jets in my Hitachi carbs on an XS850L? There are 3 jets in the float bowl held in by a tension plate?