I assume both have the same direct clamp-on air filter setup with no boot or airbox.

Are you sure the 760 carb is dialed in? Those HSR carbs can be tricky to get right at all throttle positions and keep it right from one day to the next. Accelerator pumps disabled on both? There are different needles that can be used. Assuming the pilot is tuned and the main jet is about right, the needle position can have a large impact on midrange acceleration. Without an accelerator pump, the standard needle would most likely need to be raised nearly all the way to be rich enough.

 

the tm45mm on 760 has no accelorator pump, and 48mm on 720 does... im wondering if the 760 is jetted too lean with 145 main jet in it..last time at dumont i went richer and gained 4-5 bike legths believe it or not..i might be starving it for fuel, but i really dont know yet, both have direct mount air filters..i think the pilots are stock set up..i cut the seat out around K&N on 720 and not on 760, i have another pilot here now to run against so i will try to find out, thanks

 

I know exactly what your problem is, Samcoeds built your 720. He builds some wicked fast DS's. for some reason, just the fact that he lays a finger on them makes them faster. The DS760 is probably fine, the 720 is just faster becasue stacy built it. ask anyone who's seen them run.

 

Sounds about right. My stage 2 jetted at 157.5-160 when ported.

 

three more thoughts...

the rear axle bearing grease can get unbelievably "sticky". i've cleaned out the bad grease on mine and make sure i don't tighten the axle lock nut any tighter than it needs to be to minimize drag at the brake and sprocket hubs.

the nissan brakes can have a lot of drag. they can get sticky. i've worked mine free.

depending on the profile of the tires, you can have a lot of drag (front and rear) when pressure is set too low. if tires are rounded enoughand rim width is narrow enough, higher pressure can reduce drag. with the weight of the DS this can make a difference.

 

The 760 needs more air, put the 48 on the 760 and the 45 on the 720 and see what happens
but I really think duals is the way to go

 

OK- you've got bigger valves, higher compression, .450 lift cams and a Tm48 on the 720 - it'll rev faster and I bet rev out higher than the 763 the way it is right now. What were the tachs reading? I'll bet the 720 was 300 rpms higher. 43 cc's really isn't much, that's about 1 1/2 cubic inches more how much more HP do you realisticly think that'll get ya? The 720 sounds like a very sweet set up to me- I'd like to run against it.
The 763 may be jetted a bit too lean. GEar the bikes the same and start tweaking the 763 you have a great standard to measure it by.

 

Major, the valves are not bigger in 720 [1mm larger than stock stacy said], but i do agree with you about the revs, stacy told me the 720 revs to 12,500 Sam told me the 763 revs to 10,000. you told me before i would feel a good difference with a stroker its all your fault HEHE J/K i only have tack on 720, i think the 763 its tooo lean it gets hotter than normal, i have to go fatter i also know that it is under carbed, the air filter from direct mount is not breathing well i might extend the boot back 8 inches and see if that helps, , i have been very impressed with that samcoeds720, do you want to possibly meet at little sahra utah and run them all?? thanks

 

IF I ever told you you'd feel a difference stroking your motor - YOU WILL once you get it dialed in. The 720 is no slouch and you'll need to be a very good tunner to out run it or mod it the same! There is no replacement for displacement all things being equal ( which there not) it will make a little more power! And yes bring the bikes up to our little ol mole hill and will run em- but we need to do it on a busy weekend when there are 20,000 people there and we'll have some healthy competition.

 

believe me i will get it dialed in, but it always helps to have some other ds owners opinion, i dialed the 720 in ill eventually get this one done before L.S.