31kah sent me his Pilot top end to be hoserized.

Here is the head before and after, looks like the Engine it came from suffered a failure at some time in the past, it is not cleaned up, the squish angle and clearance changed to be closer to what it should be then adjusted to 49cc its a nice pump gas design I have used for years, with just the head mod alone on a all stock Pilot you can feel the difference, easier cold starting, better throttle response, more mid range pull, more top end pull.

He sent me a new cylinder, the new cylinders from Honda are horrible, the casting quality of the old original 89 castings are much higher quality, I removed all the casting and design flaws.

Minor changes were made to enhance performance from bottom to top, I widen and raised the exhaust port to give about 182 degrees on the exhaust duration and 127 degrees for the transfers, some of the transfers tunnels were shorten, or reshaped, some of the transfer roofs were flatten a few degrees.

Moving on to the intake side of things he sent a FMF reed cage, I always liked the FMF cage they always work well, they have a stuffer design that is better than the Honda CR250 cage, other benefits are they have the 4 petal reeds like the Honda and I feel work better than the dual stage reeds on the market.

I use the Honda cage because its much cheaper than the FMF, I would use the FMF reeds on a stock cage if I ever needed replacement reeds (Honda don't sell replacement reeds) before going to the boyseen dual stage reeds.

The FMF cage also is rubber coated like the Honda cage, other after market cages are aluminum or plastic and rely on a layer of oil on the reeds to cushion the reed petal each time they slam close (130 times a second at 7800 RPM) the Honda cage and the FMF have rubber and a layer of oil, the reed patals last much longer, finding split or chipped reed patals on the rubber coated cages don't happen often and when you do the wear on the petals makes it evident that they were run way beyond their intended life.

The FMF cage is not without its own problems, their stuffer is prone to warpage and breakage, I remember long ago a PilotOdyssey.com member had one break (Toyman maybe?) he contacted FMF and they sent him a new stuffer for FREE, if you look at this one its warped.

Their is also a problem I see with alinement of the components that stack up when you assemble the cage, if care is not taken the backing plate, the reed tension bar (blue plastic) and the reed petals end up installed crooked as seen in the pics.

You can see the shadow of the tension bar is on a angle.

On the outside you can see they are all crooked, great care must be taken when you assemble the cage, as you tighten the screws everything wants to to rotate with the head of the screw and end up crooked.

Look at the design and think about whats happening, as the reed petal opens its material (fiber glass) is like a spring it will open so far then it contacts the blue tension bar this makes the reed tension stiffer (dual stage) the further the petal opens, if the blue tension bar and or the backer plate is crooked don't you think this will affect the spring tension on the reed petals? I do so assemble it carefully so they are all square with each other.

Other problems I have found with the FMF cages is the backing plate is made from real super soft aluminum, when you tighten the screws it compresses and you end up actually bending the backer plate, you cant see it well in the pictures until I run a file over it then you see the high and low spots.

After the high spots are removed.

Honda uses steel backing plates they don't do this.

FMF screws don't come with loc washers like Honda, this is why I use loc tite on the threads when I assemble.

The petals were not worn much I flipped the petal over when I reassembled the cage assembly.

Rubber coated cage like Honda.

Anybody that has ever replaced reeds on a reed cage probably knows what a balancing act it is to keep the 3 layers lined up with the holed whilst your fighting to get the first screw in, I use toothpicks at alinement pins so I can get the first screw in place.

Next we look at the stock intake manifold, it does not match up well to the reed cage so I match it up as best I can, their is not a lot of thickness and material to work with on the stock manifold so you have to be careful NOT to remove too MUCH sometimes you cant match it perfectly but you can greatly improve a bad situation.

This manifold rubber is HARD and its weathered I suggest buying a new manifold, not only can a hard rubber manifold separate from the aluminum frame its molded around and cause a huge air leak it also can allow more than normal Engine vibrations be transmitted from the Engine to the carb and upset the fuel level in the carb and cause fuel foaming, the manifold is a heat and vibration isolator/insulator.

Hoser thanks for all the work and documentation. I learned a ton reading over this (as I am sure many will). I never really thought about what was happening with the reeds before and everything you said makes lots of sense.

I will get a new manifold on order and I will see if a stuffer is still available from FMF. I called them to get new reeds about 3 years ago and the tech said they no longer carried them. I ordered them from RockyMountain ATV-- The tech obviously had no idea what he was talking about. Maybe I will have better luck from FMF this time.

Thanks again Hoser, I am excited to get this thing running!

Hey Hoser - My "stock" Pilot could use more mid-range and top-end pull. Does Speechaser's Cool Head incorporate the "nice pump gas design" you mentioned? thanks.

Yes it does, the 49cc is a nice safe design that is a improvement over the stock design, I have even run a 47cc dome on 93 octane with no ill affects.

I just installed my Speedchaser cool head http://pilotodyssey.com/PO/viewtopic.php?t=4232
Stay tuned for testing, it rained today so I will wait for it to dry out a little might be a day or so..