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Jul 1st 2019, 09:30 PM   #1
 Nevari's Avatar
 
  Jul 2019
  Indianapolis

  1977 Yamaha XS750 Special
1st time owner 1977 Yamaha XS750 Special

So I just purchased my first bike and yes it is a restore project in a way. The original owner told me that the rear brake needed to be hooked up and that the coils needed replaced as the bike will turn over but will not actually start so I am starting there tomorrow since I just picked him/her (haven't decided yet). But I am wondering if there could be any other minuscule issues that could be causing it not to actually start as I am going to the part shop tmw to get what is needed.
Jul 1st 2019, 11:40 PM   #2
 Ralgha's Avatar
 
  Jan 2016
  Portland

  2012 Ninja 250, Tiger 800
Many possible causes for it not starting. Has it been sitting for a while? Gummed up carbs is what I would lean toward.
Jul 2nd 2019, 05:33 AM   #3
 Nevari's Avatar
 
  Jul 2019
  Indianapolis

  1977 Yamaha XS750 Special
Quote:
Originally Posted by Ralgha
Many possible causes for it not starting. Has it been sitting for a while? Gummed up carbs is what I would lean toward.
It sat in a garage fully flushed gas and oil tank for 2 years while it was diagnosed to a coil issue that they never got around to fixing. I will check the Carbs today before I grab some parts for her to see if that may be a thing!

I would like to try and do all the work myself but it's my first and so correct me if I am wrong but I assume it's very similar to working on a car just smaller parts/area.
Jul 2nd 2019, 05:39 AM   #4
 Akdawg's Avatar
 
  Dec 2018
  Goldendale WA

  Classic Sportsters, Triumph & BSA
Do yourself a favor and find a factory service manual. Clymers, Chilton kinda OK but factory is the most accurate. Whilst you're searching see if you can locate a parts manual as well, the exploded parts views will be helpful especially if a PO has been mucking about. Once you get it running and qualify oil pressure and engine condition think about upgrading to electronic ignition. Get rid of the points and condenser set up, will add many smiles to your riding.
Jul 2nd 2019, 06:26 AM   #5
rob
 rob's Avatar
 
  Sep 2018
  Maple falls

  2003 sv1000s
NICE! My 1st bike was a 1979 xs750 special.
Put thousands of miles on. Only issue I had was the
The rubber between carb and head cracked. But at that time
The bike was 20 years old.
Jul 2nd 2019, 08:01 AM   #6
 Nevari's Avatar
 
  Jul 2019
  Indianapolis

  1977 Yamaha XS750 Special
[QUOTE=rob;57037]NICE! My 1st bike was a 1979 xs750 special.
Put thousands of miles on. Only issue I had was the
The rubber between carb and head cracked. But at that time
The bike was 20 years old.[/QUOTE

I always wanted a Cafe Racer style bike so when someone was selling this one (especially for the price) I had to have it. I will have to lower it some as I am a 5'2 woman and the previous owner was 6'4 male; but I was able to get it on the trailer and off into my garage with no issue lifting it so there is hope for me yet. Just going to be a learning adventure as I have only ever worked on cars really....

I took the Carb and Cyl off and checked both for needing to be cleaned and any wear or tear and those all seem to be fine. I did find a hose that has been cut but I am assuming that is the brake that I was told would need to be replaced and hooked up. I'll take a picture later and see if I can attach it here!
Jul 2nd 2019, 10:27 AM   #7
 Brassneck's Avatar
 
  Apr 2016
  Seattle, WA

  '79 XS650; '01 FZ1
Congrats! Post up pics, would love to see it.

Most classic bikes are fairly simple to work on...not quite the same as working on a car...but the principles are similar: Combustion engine, manual transmission, charging/electrical, running gear, etc.

For the most part, they can be easier to work on because there's not much there, and relatively easy to access...but at the same time, they can be harder to work on because things are technical/intricate and parts aren't always readily available.

I'm very familiar with XS650's...not so much on the 750's, but I do know a lot about classic/vintage bikes and getting them running/riding reliably...so happy to help where I can.

The XS750 is a tripple, if I recall...so 3 carbs (Definitely will need to be cleaned/inspected, synced and tuned...I'd bet $ on it). Electrical is old technology...will need to go through it to ensure connections aren't corroded, etc. If the coil is bad, that's an easy fix...but it's not often that coils go bad. Not saying that's not an issue for you...but coils are fairly stout so there might be other issues going on...in addition to/or instead of the coils.

I'd second the recommendation to get a manual and see if there's an XS750 forum to join....which may be a HUGE help in learning from "experts" as you go.

Good luck!
Jul 2nd 2019, 01:34 PM   #8
 
  Jan 2016
  Sandy, OR

  2009 VFR, 1990 GSX-R750, 1983 CB1000c
Before buying parts.

Drain the tank and pull out the old petcocks, blast the tank the petcocks out with carb cleaner to get any debris, sedament old fuel out. These are usually vacuum activated so you can test they are working once reinstalled by using a vacuum pump(attached to vac port) to see if fuel flows out the fuel line while in "on" and "res" positions.

These old bikes have a tendency to get weak connections over time so going through the plugs cleaning tightening connectors where needed can make a huge difference in how much power there is at the ignition switch etc. Check all of the electrical connections. Pay close attention to the ignition unit connections/blades if there is a loose one the unit can be opened and the solder connections heated to re-solder them.

After that you can check power to the coils there is usually more than enough spark plug wire on those coils to pull the boot back trim the end and check the resistance. I have found the spark plug wire to be bad on otherwise good coils. It takes some patience but you can have success using new wire with an old coil that is still in spec.

Have fun, I bet you will have it on the road in no time.
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