Thursday, May 28, 2009

How to use Kreem from a post to the Yamaha 650 email list by Bill Denton 8/30/99
I have used Kreem w/ v good success, but as with most things in life, the preparation is the most important part. Four important fine points to consider:
#1 - Tank preparation: The inside of the tank should be completely free and clear of all loose particulate (i.e rust, dirt and sludge). Even more importantly, it must be totally devoid of any and all hydrophobic (oily) substances, including any and all traces of gasoline, oil and grease. To achieve this, I drop two 8" lengths of medium size linked chain into the tank, then pour a small bottle of liquid degreaser full strength in and slosh vigorously with all the openings capped off. Do this good and long, and don't forget to invert the tank and get all of the surfaces degreased up around the filler neck, as well as the very top of the inside of the tank.Next, add about 1/2 gallon of the hottest water you can get, and add this to the degreaser and the chains still in the tank (don't pour out the degreaser yet... leave it in there) and slosh it around again. The degreaser will emulsify (turn milky white) and hold all of the oils in suspension... this is a good thing. After you are quite certain that you've degreased all surfaces... give it one more slosh just for good luck. Then, pour out the entire mixture and fish out the two chains. After that, pour about a TBSP of hand dishwasher detergent and about a gallon of very hot water into the tank and slosh thoroughly (note: you can use automatic dishwasher detergent here, but as it is formulated to be very low sudsing, it is more difficult to determine when all of the residue has been removed via rinsing.) If you degreased properly in the last step, this wash should produce mongo volumes of suds... also a good thing, as suds are an indication (in this case) that the oily residues (read gasoline) have been successfully removed. Follow by as many cold water rinses as necessary to remove all traces of detergent.
Only now are you ready to phosphate etch the metal in the tank with Kreem kit bottle #1 (Phosphoric acid). Although the directions call for a specific quantity of hot water to be added to the quantity of acid provided, IMO it is better to have a FULL tank of etching solution than to have the exact proportion of acid to water. In the case of an XS650 tank, this amounts to adding perhaps 3.75 gallons of HOT water (3.25 for early tanks) to the acid, as opposed to 2.5 gallons, which (I believe) is the quantity specified in the directions. Again, as in the degreasing step, it is vitally important to have the etching/phosphating solution come in intimate contact with ALL inside surfaces of the tank, including up and around the filler neck. Seal all the tank openings and slosh that bad boy around, but after you're through sloshing, don't forget to slightly crack open the stopper on the filler neck, or the hydrogen gas evolved from the chemical process will blow it out of the hole and across the room, probably splattering phosphoric acid solution on your nice new paint job (don't ask).
#2 - Dewatering: The small bottle of solvent (Kreem kit bottle #2) is MEK (a close cousin to acetone) and is a very good water remover. After you have thoroughly rinsed the phosphate solution out of the tank, it is time to get things dried up and ready for the polymer coating step. Actually, "Dry" may be a bad word to use here, because the intention is NOT to get the inside of the tank dry from all liquid residue, but rather only to get all WATER residue out. The inside of the tank will still be wet when you are done with this step, but it will be wet with MEK, which is perfectly fine, because that is the same solvent which is used in the polymer to keep it dissolved. Caution: do not dawdle after using the dewatering solvent. IMMEDIATELY go on to the polymer coating step. If you wait too long before you go to the next step, you may "flash rust" the inside of the tank, which will require starting over. If the inside surface of the tank begins to physically dry out, you're taking too long and are in danger of forming flash rust. Get you ass movin' boy!
#3 - Coating: Conservatively speaking, there is enough polymer in bottle #3 to do AT LEAST two (probably three) XS650 tanks. What this means is that, unless you have two or three tanks prepped all at once, you are going to not use all of the polymer provided in the kit. You must remove the excess polymer from the tank that you are working on. Follow the instruction very carefully here, rolling the tank around for a few minutes, then letting it set on one side, followed by rolling around again and letting it set on another side, repeating until you are secure in the fact that all interior surfaces have been thoroughly coated. After that, you MUST pour out any remaining polymer, or you will have a puddling problem. Even after you pour out the excess, you must continue the process of rolling the tank and then letting it set on alternating sides, while the remainder of the polymer still in the tank forms a non-moving film.
#4 - Drying/curing time: Probably the one most crucial mistake leading to premature failure of Kreem coatings (after improper degreasing) is insufficient drying or curing time before putting the tank back into service. After you are satisfied that the majority of the polymer in the tank has skinned over, follow this procedure: Remove all stoppers from all openings, both top and bottom (filler & petcock holes). Turn the tank upside down (preferably on a hot surface like your black asphalt driveway at noon in July (January if you're in Oz) and block it in place so the filler neck is facing vertically straight down. Then, rig up a small air pump and hose and stick the hose into the tank from the underside through the filler opening, being careful not to allow the hose to touch the inside surfaces. An air pump from a fish tank fits this bill perfectly. Turn on the pump and let the forced air dispel the vapours from inside the tank, which will aide drying and curing. After a few hours, you will no longer be able to smell vapours coming from the tank. It is then safe to move the tank, but DO NOT use the tank yet. Move the whole rig up into your hot, oven-like attic and allow the air pump to run for another two days minimum, with the hose still in the tank. One day is probably enough, which is why I always do it for about a week just to be sure. It pays to watch the weather and plan to Kreem the tank on a day that is going to be sunny, hot and dry, if at all possible.
If you add the above tips to the (already pretty good) instructions included with the three part Kreem kit, you will end up with a well sealed, carefree fuel tank for many years to come. Good luck!
Bill in Yardley, PA

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