All there is to know about TSCC

[TheCafeKid]

I disagee. The engine was redesigned in '83 because at that time, three years was a pretty long production run for a Japanese model. Remember, this was during the era when the Big Four of Japan accounted for almost 90% of motorcycle sales worldwide. The sky was the limit for R&D, and they kind of lost sight of their business model, producing new designs not so much to increase their profitability, but rather for bragging rights at the tracks and in the magazine reviews. It was the time when a new design was only cutting edge for a year, maybe eighteen months, before it was rendered obsolete by a newer competing design.

Honda had come out with the V-Four Sabre in '82, and it was no secret that the engine was going to be put into a monoshock, full on sportbike for '83 (the Interceptor). Kawasaki was coming out with a monoshock GPZ750 for '83, and Suzuki knew that if they were going to play in the 750 field (the AMA superbike class was 750cc at the time, and the 750 class was the biggest seller in the showroom) and be competitive with the Kaw and Honda, the current GS750 engine and frame designs weren't going to get it done. Going to a monoshock design required a physically smaller engine, and Suzuki was also working on the oil-cooled GSXR design. The '83 GS750 engine was kind of a bridge between the traditional air cooled GS designs of the '70s and early '80s, and the first-gen GSXR designs of the mid '80s.

Remember, for '83, the GS750T and GS750S Katana still used the '80 design GS750 engine. If Suzuki thought it was truly an inferior design by then, I doubt if they would have continued producing it.

That being said, I agree that there can be some top end oiling issues with the '80 GS750 engine (and the 1100 as well). Premature exhaust cam wear seems prevalent, but can also be minimized by ensuring correct valve clearances, more frequent oil changes, and the use of modern synthetic oils. I plan on making my '81 GS750E my daily rider, which means that unless I get another bike next year (there's always the chance...), within two years the mileage should be increased from about 16,000 where it is now, to about 35,000 miles. I am documenting cam lobe diameters, and will do so at every valve adjustment to track cam wear.

Brett, you're a friend, and know your stuff, but I simply couldnt disagree more as far as the design goes. The 83 T was a "Economy" bike. Drum brake, old tech, used leftovers from the 80-82 era designs. The Honda CB used the same tech in the SOHC for a near decade. The first itterations of the DOHC Honda failed miserably from eating cranks and oiling problems. Hence the F2 design. Zook hit a home run with the TSCC, moreso in the 1100, but IMO the 80-82 design was a flop. Why would they have not used the same set up in the 750 they did in the 1100? I have been looking over a toarched 750 TSCC i have on the bench downstairs. The one massive difference i have noticed so far, and I am stupid for not having seen it earlier: The gallery, at the BOTTOM of the motor, vs mid hight like the TSCC 1100 and all of the 8v bikes. Huge difference? I dont know untill i look at the insides. And yes, I will agree that the exhaust cam is the first to go, as evidenced in the motor i have here. But again, it is common knowlege that they didnt retool unless they had to. The early TSCC variants are not THAT much shorter than the 83 and up models. Yes I will agree that the monoshock was part of the need for change, as the 550 also went thru the same redesign, and again, i have seen problems crop up in those. But you will also note that the 550 design had top end oil feeders built into the head. The early TSCC 750 didnt. I havent yet cracked open the 83 750 i have on the slate to be worked on, but i would chance to guess it has the same set up. IMO the 80-82 was a bastard of tech. They went with the shell bearing crank, and rockerarm 16v top end, and simply didnt have the mapping for the oil ports designed properly for what they were attempting to do. The 1100 TSCC design moved the oil gallery back to mid block, roller bearing low pressure crank and allowed for more oil to be fed to the top end without the danger of too low volume in the crank area because of the roller bearings. Im not saying at all that the 80/82 motors arent decent motors, they are just not the standard "bulletproof" design that IMO Suzuki accelled with in the 8v and the creme of the crop 1100 motors. So I will admit your argument is at least 50% of the reason, while mine, I feel is the other 50%.

 

[Griffin]

Brett, you're a friend, and know your stuff, but I simply couldnt disagree more as far as the design goes. The 83 T was a "Economy" bike. Drum brake, old tech, used leftovers from the 80-82 era designs. The Honda CB used the same tech in the SOHC for a near decade. The first itterations of the DOHC Honda failed miserably from eating cranks and oiling problems. Hence the F2 design. Zook hit a home run with the TSCC, moreso in the 1100, but IMO the 80-82 design was a flop. Why would they have not used the same set up in the 750 they did in the 1100? I have been looking over a toarched 750 TSCC i have on the bench downstairs. The one massive difference i have noticed so far, and I am stupid for not having seen it earlier: The gallery, at the BOTTOM of the motor, vs mid hight like the TSCC 1100 and all of the 8v bikes. Huge difference? I dont know untill i look at the insides. And yes, I will agree that the exhaust cam is the first to go, as evidenced in the motor i have here. But again, it is common knowlege that they didnt retool unless they had to. The early TSCC variants are not THAT much shorter than the 83 and up models. Yes I will agree that the monoshock was part of the need for change, as the 550 also went thru the same redesign, and again, i have seen problems crop up in those. But you will also note that the 550 design had top end oil feeders built into the head. The early TSCC 750 didnt. I havent yet cracked open the 83 750 i have on the slate to be worked on, but i would chance to guess it has the same set up. IMO the 80-82 was a bastard of tech. They went with the shell bearing crank, and rockerarm 16v top end, and simply didnt have the mapping for the oil ports designed properly for what they were attempting to do. The 1100 TSCC design moved the oil gallery back to mid block, roller bearing low pressure crank and allowed for more oil to be fed to the top end without the danger of too low volume in the crank area because of the roller bearings. Im not saying at all that the 80/82 motors arent decent motors, they are just not the standard "bulletproof" design that IMO Suzuki accelled with in the 8v and the creme of the crop 1100 motors. So I will admit your argument is at least 50% of the reason, while mine, I feel is the other 50%.

The '83 750 engine does have the top end oil feeders. It also has oil jets spraying the undersides of the pistons (ala GSXR), a mounted oil cooler from the factory, and a higher capacity oil pump. The engine is 30 lbs lighter, 2" narrower, 3" shorter, and makes 8 more horsepower (although peakier in the powerband) than the old engine.

The '83 was considered by many in the motorcycle rags to be the best handling 750 of the time, but it lost the sales wars to the Interceptor, primarily due to the Interceptor's hype in the magazines about it being the "new wave of the future" V-four, which was supposed to supplant inline four technology as the new UJM engine design.

Retooling wouldn't have been a consideration. Like I said, two to four years was a common production run of any model at the time. In 1982, the original GS550, splendid though the design was, was five years old, and possibly the slowest four cylinder Japanese bike in production by that time.

I won't argue that the '80 GS750 is the most "bulletproof" GS engine design, maybe the least (although the various 250-450cc twins, both four and eight valve designs, also have that reputation). But I do know that there are quite a few of them out there that have oodles of miles on them with few issues in regards to engine failure. My guess would be that the oil starvation issue is primarily a problem at high rpm, and properly maintained bikes that have lived their lives rarely if ever seeing 8,000 rpm burble along pretty well year in and year out for the most part.

 

[Billy Ricks]

The '83 was considered by many in the motorcycle rags to be the best handling 750 of the time, but it lost the sales wars to the Interceptor, primarily due to the Interceptor's hype in the magazines about it being the "new wave of the future" V-four, which was supposed to supplant inline four technology as the new UJM engine design.

Back when my bike was fairly new I'd run across 750 Intercptors fairly regularly. I'd outrun them on a regular basis as well. You don't see many of the Interceptors still running these days. On the other hand you see plenty of '83 and up GS700/750s still running, and running quite well. Mine runs stronger now than the day it came off the showroom floor.

As you stated, it was a stepping stone for the yet to come GSX-R and shared many things in common with the GSX-R. Probably the biggest change engine-wise was moving the alternator from the end of the crank to the rear of the cylinders to make the engine narrower and the light weight of the GSX-R. Compression got bumped up a little and hotter cams were used in the GSX-R. Massive amounts of oil flowed across the combustion chambers to aid in cooling.

 

[duaneage]

If I remember correctly in the early 80's Porsche was the first to use a variable valve timing - vtec to Honda people.

Nope

Rhodes lifters were available years before. The lifter has internal leakdown at idle to lower the cam lift 20 thou and the duration 10-15 degrees. Above 2500 rpm the lift and duration are restored.

Had a set in my small block ford, excellent product.