Yup. I made KingJetPack's as well. The following is based on version 3 of my DOHC design. Adapt as required for SOHC. Measure twice, think about it, test fit, measure again, then proceed with drilling or cutting. Post your results when done!
What you will need:
53mm (2") ID PVC tubing (~15cm or 6" total length)
2 or 3x 5/8" 90degree barbed hose fittings
a 5/8" barbed hose T-fitting
5/8" ID hose, oil resistant (~15cm or 6" total length)
2x 5/8" ID rubber grommets
2x UNI filters, Part Number UP-4229 (2 1/4" inlet x 4" length)
UNI filter oil, or UNI Foam Air Filter Service Kit Part Number UFM-400
access to a lathe with 2 1/2"+ chuck or 2" sanding drum and drill press.
- I made the PVC stacks 60mm (2 3/8") long to match the stock DOHC carb inlet pipe length. Adjust length as required for SOHC applications. Longer is better than shorter, especially for SOHC engines.
- Increase the ID of one end of each stack to 55mm x 10mm deep to fit onto carb inlets (or whatever your carb inlet diameter is). You want the stacks to be a snug fit on the carb inlets. A lathe makes this easy and precise. A sanding drum in a drill press will work, but is frustrating and messy. Trying to use a sanding drum on a hand drill will be as much fun as trying to milk a ferret, and probably just as painful!
- Drill a hole in each pipe, close to the filter mount end of stack, to fit rubber grommet. Leave room for the filter to mount (19mm or 3/4") and the grommet.
- Install grommets and mark one stack as Left, the other as Right.
- Install stacks onto carbs temporarily.
- Insert 90 degree barbed fitting into each grommet, pointing towards center, use rubber hose to connect to T-fitting, keeping the T-fitting centered between the stacks with the bottom leg of T pointing straight down.
***NOTE!***: The grommets and 90 degree fittings
MUST be at the 6 o'clock position when mounted on the carbs and viewed from the filter end. The T-fitting should be centered below the stacks for balanced flow. Placing the grommets/fittings at any other position will reduce the efficiency of this design and result in poor crankcase venting! Don't even consider 9 and 3 o'clock to hide everything between the stacks. If at this point you feel the need to ask "why?", keep reading (or just do as you are instructed), a LOT of thought has gone into this design and you haven't fed me enough beer to explain it all!
To further improve the flow through the crankcase vent(s), the 90 degree fittings can be modified. The end of the fitting inserted into the stack can be cut at an angle. Do NOT cut down the entire fitting! The idea is to cause a siphon effect. A 45 degree angle on the side that faces the carb inlet seems to work well. Just be sure that the fitting will fully extend through the grommet once you are done cutting it down.
- Oil the UNI filters and install onto the stacks. They will be a stretch fit, but not that difficult. (Already have pod filters? Are they UNI or K&N? If not, put them on your lawnmower and get UNI filters for your bike!)
- Slip stock clamps onto the stacks and install stacks onto carbs. Make sure the vent tubes are at the 6 o'clock position!
- Don't over tighten the clamps, snug is all that is required. The PVC flexes more than you think.
- Connect crankcase vent tube. If required, use rubber hose to connect remaining 90 degree fitting to T-fitting.
- Check carb sync and go for a ride. Be prepared to spend hours re-jetting carbs to correct for the added/smooth air flow!
I currently don't have pictures. If pics will help you visualize this, grab a pencil and paper and start sketching! I wrote a lot of words to get to this point
Otherwise, it will be a week or so before I get to reassembling mine. Maybe KingJetPack can post some pics of the stacks I made for him.
Good luck! I take full credit for your success, and no blame for your failure! Donations of beer or cash will gladly be accepted, PM me for details!
You can read the story behind their design and operation here:
