Hawk250 Port & Polished Head

[ben2go]

I usually find them as soon as I finish placing the order.

[timcosby]

Originally Posted by JerryHawk250

Thanks guys. I just ordered them from CSC. Laws of the universe. If something can go wrong it will.

just as soon as the package arrives it will be laying right on top of the bench in the way!

[Cheapo_ChiRi]

Originally Posted by Megadan

Silva, Jerry, and myself are all jumping off the deep end in terms of engine performance.

Silva did a great basic PnP with a .7mm head mill. His results, while not quantified, required 1 1/2 steps up in main jet size, which is the same step that is required for an intake and exhaust, and a 5mph increase in top speed (while also being at 6500ft). Roughly this equates to a 2-3hp increase, which is nothing to sneeze at. His results are easily repeated by anybody with a rotary tool and basic sanding rolls and grinding stones. http://www.chinariders.net/showthread.php?t=20362

My own thread, with more aggressive port work as well as some chamber work. (port work begins on page 5 post 71): http://www.chinariders.net/showthrea...984#post270984

I am also going a step further with a VM30-83 carb, but even the stock sized PZ30/VM26 can support these engines with head work.

I am sure Jerry will take lots of pictures, and even entertained doing a video. I know his plans are to go a bit more aggressive like myself.

Head porting and milling has been proven to gain at least 3 and upwards of 6hp in some cases, depending on how aggressive the port work and how high the compression is increased.

Nice!!! Those horsepower numbers are a very decent power increase to the Hawk.

If you guys get really good with Hawk cylinder head porting, you guys should consider buying a bunch of stock heads and sell them to the rest of us with your ported & polished work done to them. I'd buy one for sure.

[HILL]

Has anyone put one of these heads on a flow bench, ever? Kinda' hard for me to imagine that anyone equipped for it has bothered with a Chinabike, especially one designed for what these are, but I'd love to hear of someone doing it and be able to see their results.

Porting is a nice way to gains but done wrong it can result in less power than an engine's original output. Many times less material removal is more productive.

Can't hurt to match ports up wherever possible though.

[Cheapo_ChiRi]

Originally Posted by HILL

Has anyone put one of these heads on a flow bench, ever? Kinda' hard for me to imagine that anyone equipped for it has bothered with a Chinabike, especially one designed for what these are, but I'd love to hear of someone doing it and be able to see their results.

Porting is a nice way to gains but done wrong it can result in less power than an engine's original output. Many times less material removal is more productive.

Can't hurt to match ports up wherever possible though.

Agree, but a few of the members here have demonstrated beyond belief that they are incredibly talented and dedicated to Hawk performance (like Megadan, JerryHawk250, etc) and I certainly have total faith in them, their work, and their words!

[Megadan]

Originally Posted by HILL

Has anyone put one of these heads on a flow bench, ever? Kinda' hard for me to imagine that anyone equipped for it has bothered with a Chinabike, especially one designed for what these are, but I'd love to hear of someone doing it and be able to see their results.

Porting is a nice way to gains but done wrong it can result in less power than an engine's original output. Many times less material removal is more productive.

Can't hurt to match ports up wherever possible though.

No flow bench at my disposal anymore, but this is far from my first rodeo with port work.

First, the intake port is already rather large given the engine displacement, so outside of blending transitions and reducing the pinch point fron the ramp up to the valve guide is all that is needed. Minor opening up around the sides of the guide also helps reduce this pinch point and also helps increase flow at higher lift by reducing the low pressure zone at the top of the bowl, and actually increases velocity. There was minimal material removal.

If you go to my post you will see the exhuast port had a lot of material removed drom the valve guide area along the roof of the port, which is where it matters the most on the exhaust side.

Not even my port work is super aggressive, compared to how I could have gone.

As far as port matching. There really isn't any to do on the intake side. The exhaist side needs a little work, but compared to the other parts of the port, it is a very minor concern.

As far as selling ported heads. I doubt anybody would want to pay the price of labor to do this work. Even being generous you would be looking at 300 bucks easy.

[ben2go]

Even the guys that do P&P jobson the daily take a while to get it done. I have a very mild P&P done on two engines, one a Furd 2.8 V6 and the other being an AMC 304 V8 I built to a 307. The heads were rebuilt at the same time. It took two weeks per set to get them back. The V6 heads were $650US when done. The V8 heads were $900US. All I had done to the heads was port smoothing and polished exhaust ports.

[david3921]

Originally Posted by JerryHawk250

Today I decided to port, polish and deck the head. In the process of reinstalling the valves my valve spring compressor slipped and things went flying. I lost one of the valve spring retainer keeper and have spent the pass couple of hours looking for it with no luck. If anyone has a spare just laying around I would be happy to take it off your hands.l haven't had a chance to see if I can find online yet. I'm sure it will be on a slow boat from China. The pour girl is all apart in the shed just waiting for the ported head.

One of the reasons I bought a magnetic sweeper. I love hearing that tell-tape "clack" when it picks up a lost part. Also, it's great for cleaning the driveway of tire piercing screws and nails.

[JerryHawk250]

Originally Posted by timcosby

just as soon as the package arrives it will be laying right on top of the bench in the way!

Yes , that's usually how it works. Lol

[JerryHawk250]

Originally Posted by Cheapo_ChiRi

Nice!!! Those horsepower numbers are a very decent power increase to the Hawk.

If you guys get really good with Hawk cylinder head porting, you guys should consider buying a bunch of stock heads and sell them to the rest of us with your ported & polished work done to them. I'd buy one for sure.

It's real time consuming. You don't want to know what I would charge. Like Megadan said. $300 would be generous

[JerryHawk250]

Intake side on these heads aren't that bad. Just need a little cleaning up. The exhaust side is the worst. Lots of material was removed to open it up. Here are a few pictures. I shot a video and will post when I get a chance to edit it.

[JerryHawk250]

I took .040" off the head. Now waiting on keepers from CSC so I can put it back together. I have more pictures on my camera these are just a few I took with my phone.

[Megadan]

Took a whole millimeter off the head eh? I was considering doing the same thing lol.

[JerryHawk250]

Yep, after reading that article you posted I figured why not? Its all your fault if I gain a little extra power. Lol

[Megadan]

I am good at inspiring "Bad" ideas.