Hot cams for the 610?

While I'm into the top-end for a new cam chain I'd like to bump the ponies up a bit if possible. I've come up short on a aftermarket higher comp piston but seems I've heard about hot cams for the 610. Anybody?

Just go on a diet. You don't need any more HP. Does Denise know about this?

George makes two different exhausts for the 610 and one is, from what I heard, a definite seat of the pants improvement.....over any other pipe.

As I like to say, why make a choice, do both, cam and pipe.....and then eat what you want.

i'd be interested in a cam........

as far as a hi-comp piston, wiseco makes a 13 to 1 available only through fast by ferracci....

http://www.ferracci.com/store/cart.php?m=product_detail&p=169

Not sure if the piston will fit a late model 610?

it fit my 08 fine......still in the process of re-mapping....its not a "drop-in" proposition it seems......

Thanks for all the input, still not sure what all I'm gonna do besides some head work. New piston's for sure too but waiting to see if it'll be OEM or AM. Here's a link to the tear-down over at SMJ.

http://www.supermotojunkie.com/showthread.php?t=93147

Goose you’ve got to put it on a dyno after it’s all said and “done” (<--relatively speaking…)

porting the head is way to go

Is porting the head an art or would any mechanic know what to do?

http://en.wikipedia.org/wiki/Cylinder_head_porting

After some good advise and doing a bit of research I've decided porting and polishing would not be a good thing for a single cylinder thumper like the 610. Yes it would add horses, but at the expense of low end torque which is exactly the desired feature of any 4stroke single. Case in point, the Wikipedia article ASO posted above. Here's the section that discusses this point:

The "Porting and Polishing" myth
It is popularly held that enlarging the ports to the maximum possible size and applying a mirror finish is what porting is. However that is not so. Some ports may be enlarged to their maximum possible size (in keeping with the highest level of aerodynamic efficiency) but those engines are highly developed very high speed units where the actual size of the ports has become a restriction. Larger ports flow more fuel/air at higher RPM's but sacrifice torque at lower RPM's due to lower fuel/air velocity. A mirror finish of the port does not provide the increase that intuition would suggest. In fact, within intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished intake port and a rough textured port is typically less than 1%. The difference between a smooth to the touch port and an optically mirrored surface is not measurable by ordinary means. Exhaust ports may be smooth finished because of the dry gas flow and in the interest of minimizing exhaust by-product build-up. A 300 - 400 Grit finish followed by a light buff is generally accepted to be representative of a near optimal finish for exhaust gas ports.

The reason that polished ports are not advantageous from a flow standpoint is that at the interface between the metal wall and the air, the air speed is ZERO (see boundary layer and laminar flow). This is due to the wetting action of the air and indeed all fluids. The first layer of molecules adheres to the wall and does not move significantly. The rest of the flow field must shear past which develops a velocity profile (or gradient) across the duct. In order for surface roughness to impact flow appreciably, the high spots must be high enough to protrude into the faster moving air toward the center. Only a very rough surface does this.

I will however still be installing new valves and custom cut seats with a 5 bevel grind. A new piston will be going in too, however I've not decided on OEM or a high-comp aftermarket one.

Okay, so completely aside from the debate over porting/polishing a single cylinder dirtbike head and whether it's a good idea or not, I came up with a plan for my 610 after talking to George at Uptite Racing in SoCal. I believe that he probably knows this motor better than anyone on the planet and so I'm gonna trust his opinion. Thanks for the suggestion, Rajobigguy.

First of all let me say you couldn't find a nicer guy to talk with about bikes, he's polite, friendly and will talk to you about your Husky as long as you want. I explained to him that I had gone into the motor for the cam chain swap and wanted to come out picking up any extra ponies I could without compromising the 610's integrity. He says leave the head alone. No altering nessesary what-so-ever because it's one of the best designed he's ever seen on any Husky or even dirtbike for that matter. The intake ports are straight, smooth and simple...don't try and fix what's not broken. As far as going for higher compession by cutting the head down or going with an aftermarket piston, don't do that either. He said he's seen quite a bit of wrist pin failure on the Ferracci piston (and not wanting to diss a product I've never seen), I think I'll still take his advice and leave that stock too.

Next we talked about the valves and what can be done there. My plan was to have KWS regrind and seat them while they were doing the head work and he says go ahead with that, it can hurt and will definitely improve engine efficiency. Side note: my valve guide seals were leaking bad so I knew I was going to be changing them out, so why not do a valve job too. What I thought was oil coming from the valve adjust covers drooling down from the top of the head was in fact leaky valve seals dripping into the exhaust ports and past the header pipes.

The only thing he say's really wakes that bike up is an aftermarket hot cam. And just by chance he makes one. ...or at least he use to. He quit making it when the 610 went to electric start because the starting motor doesn't spin the crank fast to enough to fire the bikes with taller, fatter lobes on his custom cam. But.....just by chance (again), he's developing another one for the modern 610, it will be tested sometime in January 2010, and possibly available by mid Feburary.

So that's my plan. Valve work, new OEM piston (although George said I could stick the original right back in with just new rings), new cam chain (staying with the OEM auto adjuster as per his recomendation too), and a new Uptite hot cam should round out the motorwork I'm planning.