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.: XT660.com - The #1 XT660 Resource :. ( https://www.xt660.com/index.php)

- Engine & Gearbox ( https://www.xt660.com/forumdisplay.php?f=206)

- - XT660X to Raptor 700 conversion ( https://www.xt660.com/showthread.php?t=5895)

Very very good Kev,at first I�m going to the stg1 mod+Pc3 as i�ve already bought.I thing the loss at bottom rev range doesn�t bother too much as you only fell at city commuting,I use my bike more often for traveling at the twisties near my city and most of the time the bike is reving at mid and sometimes at top end so I thing it will be OK for me.First I will try the maps you�ve send me,thanks for that.and if the the bike doesn�t feel good I will try a custom map at this guys www.spiga.com.br he is is the only one in Brazil that is Dynojet Certified Center can you believe Brazil is so far behind in these things he will charge me R$400 Reais for a custom map almost $230,00 Dolars, too much I thing but I don�t have a choice .Can�t wait for these stuff to arrive here for me.Thanks for these usefull information....:notworthy::notworthy::notworthy:

All fuel maps are in the map section. Once you have your custom fuel map please send it to me & I will list it with all the other maps.

http://www.xt660.com/showthread.php?t=2887

Another XT700 dyno result

http://www.xt660.com/showthread.php?t=6689

I have to agree, it looks nice, but I would personally not port the head like that.

I never remove the valve guides like that. The valve guide does two things. It aligns the valve to seat correctly and shortening it can cause the valve to vibrate or not align and not seat correctly each time. Then, the guide also helps with the cooling of the valve. The shorter it is, the hotter the valve will run, especially on the exhaust side. So, leaving it stock length also helps to keep the valve to run cooler.

Also, not sure how much you gain by removing the guide form a air flow point of view. I don't think to much, but if the valve does not seat well, you will loose more than what you gained with the little extra flow.

Then there are a few other things I would change, but that is my own opinion and might not be worth the effort.

Kev, that looks shiney and new!

I do agree, the removal of the guides is a bit radical. I would also look into blocking the AIS hole in the exhaust port.

What other things did you have in mind Freez?

I see the Raptor boys are into 3D porting with flow bench testing, high tec stuff if you have the funds.

Kev, I have a slightly different view to these guys.

I believe that a flow bench is a great tool to have, but flowing by numbers is not the way to go.

It is a fact that the heads that make excellent flow numbers on the flow bench do not always make the best HP on a physical engine.

A flow bench for one cannot simulate actual engine conditions and it flows at a constant vacuum. A real engine flow in pulses so there is a vast difference in how air flows under these conditions. Air accelerates, slows down and even builds up in pressure inside a port. None of which can be simulated on a flow bench.

I see that more and more new generation heads are using smaller and smaller ports and when you put these heads on a flow bench, they produce bad numbers, yet out there on the track, they eat the hi flowing heads for breakfast when it comes to acceleration and power output.

I prefer to flow with mathematical formulas and ratios. I would calculate port choke point based on valve diameters and open or close the port to get the ratio I need. Yes, it might cost you flow numbers on the flow bench, but we don't ride flow benches, we ride engines and the air behavior inside and engine is a lot more complex than just flow numbers.

How to correctly gasflow or port is head is not easy and there is only a handful of places where you can learn to do this correctly. It took me years and years to collect information about this subject and I am actually also not sure if my info is correct. You get so many different views. I picked one view and stuck with it, right or wrong, who knows.

he who dares hopefully wins.what a thread

Lost me long ago :tongue3:

For me I know a fair bit about four stroke heads but do not have the actual experience of porting many of them. This is where experience come in, trial & testing over time. I have done many two stroke cylinders & heads over the years.

I do agree making ports bigger does not always produce more power, to gain torque you need velocity as well as volume, altering or adding bridges or ramps in ports will add velocity which will produce more power.

It's all about delivering the correct volume of air at the fasters speed to the engines demand at all rev ranges. Very hard to get right.

When I had my XT head off it was know where as bad around the seat area as the Raptor heads that I have seen.