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News › Punch out the King. Boring out the King Quad

I bought my King Quad in 1995. Right in the showroom I was leery of the 300 CC engine (Which of course I found later to be 280 CC) "Won't that be a little short on power" asked I. The dealer assured me that, "Oh no, it has LOTS of power." Right. Anyway, I was sold by the tranny and IRS etc., all the neat features this ATV had. It proved to be everything I wanted and was a great and versatile machine....BUT.. I quickly became displeased with the experience of being left behind on hills by my riding buddies. In high school I'd made my own big bore conversions for a couple of motorcycles and had good success, so I reasoned I could do it with this thing too. First, though I started looking around in the ATV magazines to see if someone had already done the research and made a kit for this bike, as I reasoned if I was less than thrilled by the power output then others must be too with this long manufactured design. Sure enough, there was one. I sent for the Mickey Dunlap's Four Stroke Tech overbore kit. This has made all the difference.
I was now able to keep neck and neck with buddies 350 Big Bear, and after doing a proper carb setup and the K+N air cleaner, forget about it.
It doesn't pull your arms off with wild acceleration mind you, but for a King Quad it takes no guff from most other utes. Reliability? It's been running seven years now. Wheelies too. I have it in mind that this is the way the factory should have made this machine. Here's how it goes.

It seems to me that the kit was a couple of hundred dollars, but what it might be today...
FST supplies the cylinder liner and the piston and pin. The job requires lathe work and boring and honing to the right finish. If you are paying a shop to do all that I have no idea what the labor would amount to. I am a pretty fair machinist and have access to these tools.

Four Stroke Tech does the whole job,(at least at the time they advertised that the conversion could be done in their shop) though I have no idea what they'd want for this, nor how handy Pennsylvania is to where you are. You could perhaps ship them your cylinder...

Mickey Dunlap's
Four Stroke Tech
460 Hogback Road
Hyndman, PA 15545
Phone: 814-842-6159
Fax: 814-842-9221
www.fourstroketech.com

The web site link doesn't seem to work for me...
If you are going to do this mod, then here's what you have to do.
You must strip the motor to the point that you have the cylinder off. The shop manual says you have to take the motor/trany out of the frame, but you don't. Just get yourself a 4 1/2 foot piece of 2x4, lock the back brake, lift up the front of the bike until the back carrier is on the floor and pop the wood under a front A arm and there it is. Major wheelie. Everything is at a handy height to do the work from a seated position. (Have the gas tank nearly empty or the air box gets gas in it)
Slack off the bolt for the exhaust pipe clamp under the seat. Take off the pipe guard and 12 mm pipe head nuts and slide the pipe off, remove the carb plenum's Phillips screws, and take out the 10 MM rocker cover bolts, except the top ones with the rubber gaskets. Pop the rocker cap off. Take off the cam sprocket and and snake the chain off it, use some haywire to keep the cam chain from getting lost in the crankcase. Lift the cam off and store it. Attack the head nuts. Two are cap nuts with copper washers, remember where they go! They are to hard to get at 10 MM nuts under the cam side of the head. Spin 'em off. Lift the head off a bit and slide something like a super skinny long screwdriver through the cam chain under the head so you can take the haywire off and then remove the head. Careful of the depending cam chain guide. There�s just enough room to snake the head out. Look at the studs and see which one has the little rubber O ring on it. Get a new one of these from the Suzuki shop when you buy your new head gasket. Despite that you must replace this O-ring every time you have the head off, they will have been too stupid to have it in stock so order early. One from an O ring kit won't do, too skinny. Get the Suzuki ring. If you don't replace this ring each time you strip down the motor you will be ticked off by an irritating mystery slow oil leak that drips right onto the exhaust pipe and stinks like, like burning oil. Anyway now you take the two 10 MM nuts off the cylinder base and slide the cylinder off, jam rags in the crank hole and take the piston off.
To modify the cylinder to take the new sleeve you must bore it out. I used a friend's 14 inch lathe as my nine was a bit small for this. I glued two 6" square 3/4" plywood scraps together and used a hole saw (I think it was 3") to center bore it. Then I set the protruding cylinder base through this hole and clamped the cylinder to the face plate and roughly centered it. Mounted on the lathe, I finished centering it with a dial indicator and set up the boring bar. The point is, of course, that the cylinder must be centered axially and the head surface must be parallel to the face plate.
The cylinder sleeve supplied by FST is cleaned and vernier callipered to find out exactly what outside diameter it is and the cylinder is carefully bored to an interference fit of .004" Take very fine cuts as you approach the finished size, as a boring bar has a tendency to chatter and the smoother your surface that will be the contact between the sleeve and the outer cylinder, the better will be the heat transfer from the liner to the finned cylinder block. A rough inner surface will result in the liner effectively sitting on the high spots and being effectively insulated from the cooling fins.
You must measure the land on the top of the sleeve and carefully turn the cylinder block to accommodate it. This is a critical step, too deep and you'll fail to seal compression, too shallow and you'll have oil leaks from the stud gallery that carries pressurized oil to the head. (If you want to play it safe you can leave it a smidgen proud and later lap the whole new top cylinder surface on a piece of oiled medium emery paper taped to a pane of glass)
When you are done the machining of the cylinder block then take the bored plywood you used on the lathe work and set it in a vise with the hole facing upwards. Maybe you'll need to use a wood vise or a workmate. This is where you are going to put the cylinder. Make sure you have at least two inches clear under the 3" hole. Clear a path. You've got one chance at this...
You clean off the new liner really well and put it in the freezer for at least half an hour, preferrably on a piece of wax paper, you don't want anything sticking to it. You put the cylinder in the oven and bake it to 400 degrees. Give it time to get up to heat, maybe 20 minutes.
Now in quick succession you get the cylinder out of the oven and set it upright over the hole in the wood, you fetch the liner from the fridge and carefully drop it down the machined hole and it goes in like a slipper. Thunk.
The hot block has expanded and the cold liner has shrunk, (Honey I shrunk...) so they go together like magic. As they reach a common temperature they tighten up and they are together!
The cylinder now needs to be bored to size and honed to the proper finish. This job might best be farmed out to a shop that has a boring machine, because if you are using anything other than a very stout boring bar a small amount of chatter near the finishing cut could be too deep to hone out, ruining the liner and send you back to square one. They don't want a whole lot for this, a local bike shop did mine for $40.00 CDN. Give them the cylinder and piston and ask for a .002-.003 fit.
Or maybe chicken out and have them do everything...
Gap the rings.
I recommend making a new base gasket from .030 gasket paper. You will be using a stock head gasket and you don't want the piston whacking it now that its edge is going to lap over the edge of the head/cylinder face.
Take the allen bolts out of the chain tensioner and take it off. Take it apart and reset it to the bottom.
Put 'er on TDC, point the new piston the right way, slide the cylinder on. If you have no ring compressor I found that a plastic scraper is handy to poke the ring ends into place. Put the new O ring and head gasket on, put the head on and torque it down. 15-18 ft. lbs. Of course you've been fishing that cam chain through and have it hanging on its haywire. You can put the cam on two ways but who in their right mind would want to bolt the rocker cap on and open the valves at the same time? Set the cam in place with the lobes down and put the chain on the sprocket so the lines scribed on the camshaft end are flat to the gasket surface, and bolt it up. As long as the piston is right at TDC and the lines on the cam are flat, it�s timed. The camshaft should lay flat on its ways and not spring up on the far end, or something�s not right down below (Not on bottom sprocket right, tensioner left in and not reset...). A little grease on the lobes for that first dry bit of running and bolt on the tappet cover. Put the tensioner in the right way up, slide the spring into the hole and put the nut on. I didn't say this was easy, just said to do it.
Screw the carb and nut the pipe back on. I wouldn't put that heat guard back on the exhaust pipe. It just keeps Suzuki from getting sued by idiots burning themselves turning the fuel tap blind, and it holds a lot of heat in to the head.
Now take out the board and let the bike drop.
The stock idle jet is OK but you'll have to put the slide needle on the lowest (Richest) setting. I use a #134 main jet at my 150-3000 Ft. riding area. I don't know what the later KQ's smaller carb would want.
Normal break-in procedures (Just avoid prolonged full throttle ops.) and away you go! No more following the group at a respectful distance, or being denied the lead for being too slow. Now the King has some authority.

Posted by glenlivet on Thursday, May 13, 2004 (00:50:12) (4772 reads)

"Punch out the King. Boring out the King Quad" | Login/Create an Account | 2 comments

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Re: Punch out the King. Boring out the King Quad (Score: 1 )
by Weasel on Thursday, May 13, 2004 (00:54:45)

Great article glenlivet! Thanks for taking the time to write up your article for the ATVF membership.

Thanks again!

| Parent

Re: Punch out the King. Boring out the King Quad by Mud on Thursday, March 02

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