1979 Yamaha XS750SF

JunkyardDog · Posted: Tue Apr 13, 2010 12:37 am Post subject: 1979 Yamaha XS750SF

Hi. I was here a while back with a 1975 Honda CB360T. That didn't work out, I sold it, and now have a '79 Yamaha XS750SF. It looks great and runs great, so far. 17,000 miles on it. Aside from the usual problems with vintage Japanese bikes (lack of parts) is there anything I should watch out for with this bike? I got a real good deal on it, and hope things work out this time. Thanks. Jerry.

MR.CHocko · Posted: Tue Apr 13, 2010 2:30 am Post subject:

You can get parts for those bikes. Just need to know where to look. Trust me the parts are out there.

KirkN · Posted: Tue Apr 13, 2010 4:44 am Post subject:

From one gimpy bike to the next... Very Happy

The Yamaha triples had their share of problems, but none were insurmountable. They had a tendency to jump out of second gear and there was an easy fix if caught early, and a harder fix if it had progressed. I had a '77 and it wouldn't stay in 2nd at all. For a while, I had to 'double-shift' right into third. Sigh.

Do some searching on this forum, we've talked about it once before, I seem to recall. If not, there's a pretty dedicated forum out there for the Yamaha triples. I don't remember the www. because it's been 5 years or so since I owned mine, but Google will get you there.

Good luck, and post some pictures of your cycle if you get the chance.

Kirk

Steve Searles · Posted: Tue Apr 13, 2010 10:29 am Post subject:

JunkYard, It may be a good idea to ask questions about a vintage bike "BEFORE" buying one. In my opinion, those Yamaha triples were a poor design, vibrated too much and second gear transmission problems were very common. Not to mention they are a top heavy cycle for some reason. The Hitachi carbs are somewhat difficult to get parts for but yes, you can get them. Then they went to bore it larger and made an 850 for several years. Come on Yamaha, get with the program! Inline fours are awesome and any Suzuki GS750 will eat that Yammie for lunch as just a snack. Opinion time is over; If there is anything we can do to help you, let us know. I have had several of those triples in the shop and am familiar with them. (Just passed on an 850 a week ago for sale. No thank you.) Maybe I should just give you a list of bikes not to buy. Let's see: Yamaha TX500 or 750, early V4 Hondas, top end oiling problem, etc.

yamasarus · Posted: Tue Apr 13, 2010 1:18 pm Post subject:

Junkyard,
I have to defend the triples here. I have two, a 77D and a 79F. Everything about the bikes is straightforward. They use shims on valve adjustment and seldom require any change. The 750s had Solex type Mikuni carbs similar to the XS650s and they are very reliable. Just keep them clean or ride the bike often. Second gear can be a problem if the bike has been ridden hard. I haven't had any problems myself. I put 40,000 on a 78 that I bought new back then.....and that was in 18 months. Both of the ones I have now have have well over 25,000 miles each and no problems. One serious point. DO NOT EVER RUN LOW ON OIL. Not even a little bit. The crankshaft will not approve. As to vibration, it is better than a twin and worse than a four, but has more torque than a four. And the exhaust note is just plain cool. I have 17 vintage bikes and my 79 is my favorite to ride...anytime, anywhere. If your bike handles funny switch to Bridgestone S11 Spitfires and it will be cured. The Hitachi carbs that Steve referenced were used on the 850s, but even parts for those are easier to find than just a few years ago.

Steve Searles · Posted: Tue Apr 13, 2010 8:06 pm Post subject: Yammie Triple Power!

Very good defense yamasarus. I commend your efforts and actually do agree with you 100%. Interesting the way you put the vibration, more than an inline four but less than a twin. Exactly correct. The sound is like nothing I have ever heard before. Yeah, I tried to fix an 850 about 5 years ago and gave up because you could not get the Hitachi stuff. Have fun with those triple shaft drive machines. COOL!

H2Lou · Posted: Wed Apr 14, 2010 6:53 am Post subject:

tsnapcracklepop · Posted: Wed Apr 14, 2010 2:36 pm Post subject:

I switched my 1980 XS850G to a used set of Mikunis. never looked back. Just about impossible to salvage those fixed jets during carb disassembly. The 850 is quicker than my and more nimble than my lastest acquisition, 1981 CB750F.

try Yamaha-triples.orgv a great buch of riders and mechanics, and volumes of info!!

Russell · Posted: Wed Apr 14, 2010 2:52 pm Post subject:

The impression we were left with over here in our very small market-place is that the issues with the earlier versions of Yamaha's 750 triple, which seemed to suggest rushed development, left a very negative reputation 'out there' so that by the time fixes were available, and later versions improved, almost nobody was willing to to buy one. Perhaps the same happened with certain other Yamaha 4 strokes around that time.There is something intensely evocative about the noise of a 4 stroke triple. A pity that Yamaha didn't, or couldn't, persevere. Look what Triumph have achieved, this time around, with their triples, in spite of some mechanical issues.

yamasarus · Posted: Wed Apr 14, 2010 3:02 pm Post subject:

Russell,
I agree completely with your take on Yamaha quitting on this design. I can't help but wonder where it would be today if they had continued. Lets see. Counterbalanced, fuel injected, chain drive, 1200cc, 6speed. And that awesome sound from that 3 into 1 with an alloy can.
One can only dream..........