Kawi2strokes.com Forum

Since Yamaha designed and built the DOHC 6 cylinder engine for the 1967 Toyota 2000 GT, how come it took them so long to put inline DOHC engines in their motorcycles like the other guys did?

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1969 H1, 1971 G3SSA, 1974 G5, 1973 H2A, 1975 S3A, 1975 H1F, 1973 Z1, 1988 HD FLTC, Captain America chopper, 2000 Excelsior Henderson, 1965 Bridgestone BS90

As early as the mid to late-1970's, Yamaha made a 4 striker twin, 500cc, DOHC, 4 valve per cylinder, TX500/XS500. They were far better than the TX750 SOHC twins, by far.

I am now driving a 1991 Toyota Camry, Yamaha built 2.5 litre V6, DOHC, 4 valve per cylinder, uses XS750/1100 Yamaha valve shims for valve adjustment, 136,000 original miles, NO problems. I hear these engines run 300K easily, without problems, with only routine maintenance. The car is immaculate, and is a 4 door LX, was given to me by a neighbor. Not complaining, but, I wish it was a 5 speed stick, and station wagon. It drives nice, AC works, much to be admired.

the XS 500 had head big trouble, the head was cracked around the valves (4 by cylinder) after 10.000 miles or less but the whole engine won't burst as did the infamous TX 750 engine

I now have two complete, running TX500's, both well over 25K per. NO PROBLEMS in either bike. I did not put all those miles on these bikes, have put maybe 2K on each over the years, no replacement parts used in either, no problems both run as new. I've never even heard of a valve seat / head cracking issue with any of them.

I also have had 3 TX750's, still have one of them now. The two that have left had engien replacements, per Yamaha warrantee, both below 1,000 miles, both from blown up engines. The one I have, still has the original engine, not the warrantee engine, and I keep it running with early engines and parts I have collected over the decades, not an easy task.

My opinion, taken form decades of experience with both engine designs, the 500's are bullet proof, the 750's were pure disaster and problems.

I love the TX 750,have had 4 of them during from late 70`s till early 90`s ,NEVER had any problem with any of them
I would gladly buy one again,been looking for a while for one in good condition,but here in Norway they are becoming highly collectable now,with prices up to 10-12000 $ for a mint one,and theTX 750 prices are still going up here.

very much third part stories regarding the quality of the TX 750,many of them just as stupid as the weird stories regarding Kawasaki Triples.
But I respect your personal experience H2Rtuner ,and there is no doubt there has been problems with several of the bikes,but I never had that experience with the TX750`s I had.
good to hear your still keeping one going

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72 H2 750 Tracy body
73 H2A 750 the Midnight Train (black and Blue)
69 H1 project
70 H1 project

Well, during the first year of sales, Yamaha here in the U.S. had a factory recall for them, complete engine replacement, don't even open it up, nor try to repair it, we are sending a completely redesigned engine, fix it for free. How many, all of them. I was a service manager at Yamaha of San Jose when this hit, and had one mechanic that did only / all the TX 750 engine changes, he stayed busy for five months doing that.

there was a recall here also,but no new engines, mechanics installed a deeper oilpan,and oilcooler on all TX750 sold in Norway. and I have heard that they on some bikes also broached larger diameter in oilchannel.

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72 H2 750 Tracy body
73 H2A 750 the Midnight Train (black and Blue)
69 H1 project
70 H1 project

Not a Yamaha expert by any means, but the death-knell for the TX750 came very publicly when Yamaha entered several in the "Castrol 6-hour" production bike race in Australia, and they all expired early, and with the same over-heating/under-oiling cause. "The rest is History!". Didn't they completely redesign the cylinder head of the TX500, going to a "2-piece" design? Like I say, not an expert on Yamahas, but I remember the TX750 pretty well! Nice looking bike for it's time, tho!

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"One day, your life will flash before your eyes. Make sure it's worth watching." : anon.

not really fair to compare factory race bikes,with standard road bikes, they are totally different in specs,like the H1 v.H1R, the only thing they share is the two letters TX I am not saying there was no problems with them,of course there was.the recall proves that

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72 H2 750 Tracy body
73 H2A 750 the Midnight Train (black and Blue)
69 H1 project
70 H1 project

They were stock-standard road bikes at the time, Production racing here meant exactly showroom stock - You took off the lights. and wired up the stands, they were street stock! I think Yamaha won a 6-hour race with the RZ 500, one year.

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"One day, your life will flash before your eyes. Make sure it's worth watching." : anon.