Hello is there much f a performance gain by using 750 head on the tr1

Short answer: Yep.  ;D

What's the long answer I understand you get a higher compression and that the cam has a longer duration but has smaller valves so what is the difference in power and in what rev range

With the upp'ed compression it will generally make more power. People CLAIM that there's an ever so slight power loss at the very top starting at around 6000+ RPM due to the smaller valves and in theory there should also better pick-up from down low.I only tried it once with the stock Hitachis and they were in fact strangling down the engine quite noticeably so I can't really tell.

I am currently in the process of overhauling a set of 750 heads that will go on my 1100cc TR1 for road-testing. To have some proper proof together with a good exhaust and Mikuni VM38s it should actually yield some noticeable power.

Cheers,
Greg

Where is the difference?
Is it the shape of the combustion chamber ?
Or is it a small cilinder of extra dead air?
Can you grind off a few mm of the bottom of a TR1 head to get more compression?

The combustion chamber is quite a bit smaller: 47cc vs 55cc of a stock TR1 head vs 64cc of a stock XV1100 head.

Resulting in the following compression ratios (all calculated without a headgasket, so the actual ratios are a tad lower) when used with XV1100 cylinders and crank:

XV1100 heads: 8.3 : 1
XV1000 heads: 8.9 : 1
XV750 heads: 11.9 : 1

Hope this helps
Greg

Only in your bad dreams.........................S.

Care to enlighten me? I based the compression ratios on what I was able to find in the repair manuals...

As I said, the values are approximations. I quickly ran this through a calulator and ended up with some lower values, but still somewhere around 11:1 mark for the 750 heads.

I used this one http://www.csgnetwork.com/compcalc.html

Enter Cylinder Bore Size        95
Enter Piston Stroke Length        75
Enter Head Gasket Bore Diameter 98      
Enter Compressed Head Gasket Thickness 0.75      
Enter Combustion Chamber Volume In CCs      47
Enter Piston Dome Volume In CCs Negative For Dished Pistons (Use '-')      0
Enter Piston Deck Clearance Negative If ABOVE Deck (Use '-') :      0

and it cam back with 11.09:1

I admit I haven't (yet) measured the exact combustion chamber volume of my 750 heads, but I think I am not that far off with the factory's claim of 47cc. The biggest question to me is the thickness of headgasket on an 1100 cylinder as that could easily be twice the thickness and I wouldn't know it... dropping compression to around 10.1:1 straight away.

So weid kimmds no, daß i mid am Ästarreicha auf englisch schreib.....................
Der Kolben ist zu kurz, woaß iaz ned genau, aber ca. 1,5 mm unter OK Zylinder.
Die Kopfdichtung (gepreßt) ca. 0,8 mm.
1100 (XV oder BT) original ausgelitert ca. 7,7 : 1
des andere hob i jetzt ned im Kopf
S.

Ois kloar. Dann übersetz' ich des noch.

For all those who tried to run Sepp's gibberish through google-translate or the like and didn't exactly return anything:

Apparently the 1100 piston can sit up to 1.5mm low resulting in drastically less compression. Using the specs Sepp gave me, I end up with 9.34:1 on that calulator.

are the cams the same duration on 750 and 1000

Yep, same cam.

Just to get this right are using later model 1100 cylinders or bored out  original tr1 cylinders ?

XV1100 cylinders and crank. The latter is mandatory, as the extra cc's come from the longer stroke of the 1100 crank. Bore's the same, but the compression height on the 1100 is different to maintain the same overall height of the cylinders.

Cheers,
Greg

 I´m using the TR cylinders with 1100 crank and new 1100 pistons (95,5mm) , also 750 Heads , no Problems the last 20000 KM,
Ali