TSCC????

[Wingnut]

Just picked up a sweet 80 GS750L. Did not hear it run. It's been sitting for two years but has only 10K miles and is in exellent restorable condition.

My first question is the Engine says TSCC on the crank cover. A friend was over to look at it and he told me what that means, but I can't remember what he said. Something.......combustion chamber. What ever! But then I was reading in the clymers manual I got wth the bike and the tune up specs for the TSCC engines are different than the others. Valve clearance, timing etc. Then I noticed the front fork oil and crankcase oil quantity's are different if you have a TSCC engine. Front fork oil??????NOW I'm CURIOUS!

Does anyone know what the TSCC thing is all about?????

Thanks

Bob

[earlfor]

Re: TSCC????

TSCC is twin swirl combusion chamber. All TSCC engines are 4 valves per cylinder and have valve tappet adjusters. All other GS engines are 2 valves per cylinder and the valves are adjusted with shims which sit in recesses called "pots". The valve clearances between the two engine designs are different. Maximum ignition advance I believe is the same for the two configurations, but the rpm that max advance is reached is different. Total advance is the same, but the curve is different.
Tune up specs for 8 valve and 16 valve engines are different as are carb adjustments. 8 valve engines use Mikuni VM mechaincal slide carbs. 16 valve engines use Mikuni BS series CV carbs.

Earl

Just picked up a sweet 80 GS750L. Did not hear it run. It's been sitting for two years but has only 10K miles and is in exellent restorable condition.

My first question is the Engine says TSCC on the crank cover. A friend was over to look at it and he told me what that means, but I can't remember what he said. Something.......combustion chamber. What ever! But then I was reading in the clymers manual I got wth the bike and the tune up specs for the TSCC engines are different than the others. Valve clearance, timing etc. Then I noticed the front fork oil and crankcase oil quantity's are different if you have a TSCC engine. Front fork oil??????NOW I'm CURIOUS!

Does anyone know what the TSCC thing is all about?????

Thanks

Bob

[Wingnut]

Thanks earl,

So can I asume the four valve 750 has more power than the two valve? And I noticed, in the impecable maintenance records the head gasket was changed due to an external oil leak when the bike was 8 years old and had 2k miles. It now has 10k. Are these a cronic problem? Should I change it while the engine is out of the bike? Also, are these engines as good as the two valve engines for reliability? I had a 750 F honda that had 4 valves and the head was a cronic nightmare.

Thanks for sharing

Bob

[saaz]

The reliability of the 750 4 valve is great. It also has a plain bearing (high oil pressure) lubrication system, whereas the 2 valve has a low pressure roller bearing system. The 4 valve 1000 and 1100s continued with the low pressure oil system. Does anyone know why the 750 diverged????

The 2 valves did come with CVs in the larger engine sizes in their later model years. Ironically in some markets the last of the S model 1000s had big slide carbs...while in other markets they did not..very confusing!!

[Wingnut]

Thanks for the input. Great bit of knowledge.

This site is the best!

bob

[earlfor]

I believe the 2 valve 750 is spec'd at 67 hp and the 4 valve is 72 hp.
Head gaskets and leakage are not a problem on any of the GS engines.
I suspect that any bike with only 2k miles of use in 8 years would have a problem with dried out seals and need the same maintenance. My rule of thumb is, if it isnt broken, dont fix it. I have a 4 valve 750 and a 16 valve 1150. Both are perfectly reliable and I ride about 30k miles a year, so they dont sit around to be looked at. :-)

Earl

Thanks earl,

So can I asume the four valve 750 has more power than the two valve? And I noticed, in the impecable maintenance records the head gasket was changed due to an external oil leak when the bike was 8 years old and had 2k miles. It now has 10k. Are these a cronic problem? Should I change it while the engine is out of the bike? Also, are these engines as good as the two valve engines for reliability? I had a 750 F honda that had 4 valves and the head was a cronic nightmare.

Thanks for sharing

Bob

[Hap Call]

The reliability of the 750 4 valve is great. It also has a plain bearing (high oil pressure) lubrication system, whereas the 2 valve has a low pressure roller bearing system. The 4 valve 1000 and 1100s continued with the low pressure oil system. Does anyone know why the 750 diverged????

For economics...the high pressure 750 uses plain bearings and a single piece forged crank which is a lot less expensive than the roller bearing multi-piece crank on the 1100 and 1150.

One other note on the TSCC. It is considered the first modern application of narrow valve angle technology in motorcycles...basically the grandfather of all of today's modern high performance motorcycle engines.

Hap