Head Specs for use with Nassert Beet Cam

[fordendk]

I am planning to use a Nassert Beet T-1 280 degree duration cam. I have the cam already: http://www.beet.co.jp/english/kawasa...50r/index.html. I am not sure of the complete specs for this cam but have heard it is good.

I already have Yoshimura TMR-MJN 32mm carbs and an Arrow Titanium Street Thunder full exhaust system. I have talked to a couple of mechanics and they seem to recommend port-n-polish. I think this is because they only know how to do this and nothing different (in Indonesia).

I remember RacerX mentioning doing "valve-relieving" in conjunction with this cam to me a while back. What I am looking for is the best specs to modify the head for use with the Nassert Beet T-1 cam.

I have the following questions and would really appreciate RacerX weighing in on this thread as well as anyone else in the know:

1. Is it better to do port-n-polish, valve-relieving or both of these when using this cam?
2. If valve-relieving is the recommended way then what should the specs be for this work (i.e. multiple reducing radii and which radius plus how deep etc... an engineering spec' that I can give to the shop would be best)
3. If port-n-polish is recommended then should the exhaust side of the house also be ported or just the intake side?
4. Will I need to use an exhaust with bigger headers if I get this work done?

BTW bike use is for street

[Racer x]

I have not used anything but stock cams. But I think at least cleaning up the ports of the intake and exhaust would be a good idea. Porting alittle with someone that know how can be good. If they are just grinding away with no flow bench it can be bad.

The main restriction is around the valve seat. So working that area is going to be best. What you are looking for is called deshrouding the valve.

And yes you are limited by the exhaust as to how much you can port. Remember that big ports with out a big pump under them will cause air to slow down. When that happen fuel will fall out of suspension and coat the ports. Hi speed air has inertia and will put in more air and fuel that a big port. But the difference is something you can only find from experience and a flow bench then dyno.
Porting is an art.
http://www.diyporting.com/Shrouding.html
How do you like the carbs?

[fordendk]

Thanks for the quick feedback. What I am actually looking for is the specs for the deshrouding so that I can give it to a workshop here. For example what radius to use around each of the valve seats and how deep to go into the head. Also I want to know whether to do both intake and exhaust sides.

I am fully aware of the hand tools etc. that guys use when porting. The guys here know how to do that and have plenty of experience. Do you think I should have them pnp as well as deshroud or just pnp or vice versa?

The carbs are really good. They completely flattened out my torque curve and gave me a lot more acceleration than the standard carbs with jet kit etc. I run them with dual velocity stacks and no air filter on the street. So far no problems. Have serviced the bike twice since installed and had the carbs cleaned to get rid of any crap. No big deal there either. I have even taken the bike touring outside city in Indonesia with the worst dusty/dirty conditions you can imagine and no issues.

[Bob2010]

Mill the guides for the extra lift and use a higher spring rate maybe?

[Racer x]

The is no spec for the port and polish work. I would say to do the work on both intake and exhaust. And polish the head .
Let us know how it works out. Have you run with out the stacks? Some carbs run better just wide open.

[fordendk]

Originally Posted by Racer x

Have you run with out the stacks? Some carbs run better just wide open.

Never tried without the stacks. Will report back once the cam and porting is done.

[Racer x]

I removed my stacks when on the dyno. I was trying different filters and exhaust systems. There was a clear one hp drop. So I dismissed it. While talking to some very reputable people. People that had the fastest 250 ninja. And still hold the fastest 250 all motor pass at 117 mph they said the same thing. One hp down with out the stacks on the dyno. BUT on the track the bike picked up a couple mph. They did back to back tests and confirmed it. I have not had a chance to conferm it. But that is the story.

[fordendk]

Just in case you are interested this was what my bike dyno'ed today. I changed the Arrow exhaust for a Yoshimura R77 Japan model and installed the Nassert Beet T1 camshafts. The bike is tuned a little lean right now (you can see on AFR) but is running very nicely and the Yoshimura carbs work very well with the Yoshi R77 exhaust. Acceleration is now very good... as you can see on the dyno chart the torque curve is very flat. Max torque is 20.27Nm now (14.95ftlb). It actually accelerates better than an ER6N up to about 140Kmh tested (87mph... ER6 rider was shocked). Max HP was 32.63. The 3 runs on the dyno chart were 3 different ignition maps on my BRT. Interestingly the bike seems to run best on 92 octane fuel:

[mgentz]

Those are some nice curves

[pinnochio]

PnP engine mods..
even the part is quite expensive, but I liked how the beet cam work to improvise engine.
that's why I'm lovin it.