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Twin Cam
Transplant
Part One of Two
Text and Photos By Oz
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High in the Hills Above Ventura, we find a great burrito and a better set of tools...
Well, now that you've got that new twin-cam scooter you're probably sitting around thinking about just what to do next; beef up the power plant, or try to find the finest burrito in the area? With your last bike a cam was the simplest way to get a significant horsepower boost, but now your engine has two of them, and a whole new technology besides, what'll you do? Well, since you're reading this, and you know our crew can find the best burritos in any town, your problems are over. With the help of the fine folks at JIMS, and our super tech department, we'll make those cam changes a breeze and get you to chips and salsa heaven, quick.
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We met up with two of the lynchpins of JIMS, Paul Platt and Fuzzy Quaranto, at the secret JIMS workshop in the hills of Ventura. The plan, install a set of Andrews' new twin cams in Paul's twin-cam Dyna. (Photo 1) The challenge, get it done in time for lunch at the Fuzzy's favorite Mexican Restaurant on the corner. This seems reasonable, except for the fact that we'd never done it before, a fact made unimportant by the presents of a set of JIMS twin-cam tools.
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Photo 1
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Photo 2
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Photo 3
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After securing the bike on whatever kind of lift you have, blow off all the road crap that's accumulated on the pipe side of the engine. Remove the spark plugs. Pull out the push rod tube spring cap retainer and collapse the tube toward the head. You can hold the tube in place with a small bungee cord or a long spring. Raise the rear wheel off the lift, and, with the transmission in 4th gear, use the rear wheel to rotate the engine until the lifters on the rear cylinder are in their lowest position. Using a pair of bolt cutters, cut the stock push rods, remove the pieces and discard. (Photo 2) Rotate the engine to bring the front cylinder lifters to their lowest point and remove the push rods in the same manner. Remove the lifter covers, lifters and lifter dowels and set aside in a clean spot.
Photo 4
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Photo 5
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The cam cover is the next to come off. Remove the Allen head bolts securing the cover to the engine case. The cover can be suspended by a small bungee and hung in front of the brake pedal. You must be careful with the cover bolts, however, because they are slightly longer than the camshafts support plate bolts, you must be sure to keep them separated. The primary cam sprocket and crank sprocket bolts are now removed, using JIMS crankshaft/cam shaft locking tool. (Photo 3) Using JIMS twin-cam tensioner tool, (Photo 4) relieve the spring tension on the primary chain tensioner and insert one of JIMS retention pins (Photo 5) through the tensioner arm and into the support plate. This will relieve the tension on the chain and allow the sprockets and chain to be gently worked off the shafts.
Photo 6
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Photo 7
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Immediately set the chain and sprockets down and mark the outside of the chain, with a colored marker, (Photo 6) to make sure the direction of travel is maintained. Now remove the four Allen bolts holding the oil pump to the support plate, and next remove the six Allen bolts holding the support plate to the engine case. (Photo 7) In order to reach the last support plate bolt you must also remove the front chain guide by squeezing the two tabs and pushing it rearward through the two cast blocks in the support plate. The support plate and the cams can now be removed by applying a gentle prying pressure between the side of the support plate (Photo 8) and lightly working the plate back and forth until it comes free.
Photo 8
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Photo 9
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Photo 10
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Photo 11
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The support plate is now placed in a soft-jawed vice, (Photo 9) or other holding fixture, and using the same technique as with the primary chain tensioner, relieve the pressure on the secondary cam chain tensioner and install the other JIMS retention pin through the front of the support plate. (Photo 10)
Photo 8
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Photo 9
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Photo 10
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Photo 11
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The cam bearing retaining plate is now removed (Photo 11) along with the slave cam retaining snap ring, (Photo 12) and the cams are ready to be pressed out. Using JIMS camshaft, and camshaft bearing remover/installer (Photo 13) carefully press the cams and bearings out of the support plate. At this time it is necessary to mark the cam chain, with a colored marker, (Photo 14) to assure that the chain is reassembled with the proper direction or travel. At this time, if you plan to re-use the bearings, or if this is a bearing change, the bearings can be removed using JIMS Twin-cam camshaft bearing remover tool. (Photo 15) The plate can now be cleaned and the new cams can be installed.
Photo 12
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Photo 13
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Photo 14
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Photo 15
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Ride Safe, --Oz
Onward to Part Two...
Back to JIMS Page on Bikernet...
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