I'm planning of tearing down my 68 T120 top end and changing to a 750 big bore this winter. As long as I'm rooting around in there, what do I need to do to let me run unleaded gas? I figure on the seals having enough lead ground into the seals that it'll work without additive, but I mine as well change it. Also, does someone make bigger valves for more power? Of course a port job would be needed too. But the main thing is, what is needed to safely and fully convert to unleaded? Thanks, Kyle

I'm planning of tearing down my 68 T120 top end and changing to a 750 big bore this winter. As long as I'm rooting around in there, what do I need to do to let me run unleaded gas? I figure on the seals having enough lead ground into the seals that it'll work without additive, but I mine as well change it. Also, does someone make bigger valves for more power? Of course a port job would be needed too. But the main thing is, what is needed to safely and fully convert to unleaded? Thanks, Kyle

The simple answer is you need to replace the valve seats. Back in the olden days they used lead to lubricate the seats- newer ones are harder.

I am not sure about where to find bigger valves, if you did fit them you would need new valve seats for sure, and some expensive machining of the head.

Another option is an 8 valve head (if you could find one). They were fitted as stock to some of the later T140s, prior to that there were some made by aftermarket suppliers.

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"You can't fly with the eagles if you keep scratching with the turkeys."

The simple answer is you need to replace the valve seats. Back in the olden days they used lead to lubricate the seats- newer ones are harder.

I am not sure about where to find bigger valves, if you did fit them you would need new valve seats for sure, and some expensive machining of the head.

Another option is an 8 valve head (if you could find one). They were fitted as stock to some of the later T140s, prior to that there were some made by aftermarket suppliers.

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"You can't fly with the eagles if you keep scratching with the turkeys."

Would the 8 valve need new cams, too? Or would the rockers just be different? I was planning on the re-grind of the seats for bigger valves, but I'd still need stainless inserts to put in there. Kyle

Would the 8 valve need new cams, too? Or would the rockers just be different? I was planning on the re-grind of the seats for bigger valves, but I'd still need stainless inserts to put in there. Kyle

I am pretty sure that the cams followers and pushrods would be the same regardless of the head. Far as I know the difference would be in the rockers.

Check out http://www.normanhyde.co.uk/ there is plenty of hop-up stuff available there to tempt you. If anyone has big valves he would be the man.

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"You can't fly with the eagles if you keep scratching with the turkeys."

I am pretty sure that the cams followers and pushrods would be the same regardless of the head. Far as I know the difference would be in the rockers.

Check out http://www.normanhyde.co.uk/ there is plenty of hop-up stuff available there to tempt you. If anyone has big valves he would be the man.

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"You can't fly with the eagles if you keep scratching with the turkeys."

Sweet thanks for the link. How hard is it really to tune a dula carb head, like the Bonneville? Kyle

Quote:

On 2004-12-16 16:27, Thats_my_Ride wrote: How hard is it really to tune a dula carb head, like the Bonneville?

You mean like porting etc? I have no direct experience but there was a lot of development work done on theses bikes for racing etc so there is plenty of potential.

Do a search for a book called Triumph tuning, written by Stan Shenton. It has a whole load of good information in it.

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"You can't fly with the eagles if you keep scratching with the turkeys."