OK I had several requests regarding my comments made in another thread about using Wintergreen to soften rubber, specifically - and most importantly for me - the rubber carburetor hoses, and I took several pictures during the process.
The Basics - '75, CB750F hoses seem to be hard as rock. Purchased a quart of Wintergreen (horse liniment) from Amazon for $12.95 plus $6.50 shipping (does not appear to be synthetic). Decided against the Xylene as its flammable and the process works best when the mix is heated using either Xylene or water.
False Starts - I purchased a used Crockpot as some on the forum had mentioned for $6, it had the highest wattage rating of the 6 or so they had there (250W). It got the solution really hot (186 degrees) but never to a boil. I left the hoses in for an hour, no change, two hours, no change, finally went to bed and let them simmer all night, no change.
Final Setup - Got out my old Coleman stove and used gasoline as fuel, and an old metal pail. Had no problem getting it up to a rolling boil in 5 mins. or so. I used enough water to cover the hoses and then some in the pail, lets say less than a gallon and 4 ounces of Wintergreen.
My wife happened to have this nice little metal rack that went into the bottom of the pail to keep the hoses off the bottom.
Once she starts boiling the oil kinda comes up to the surface and goes back down, I guess you could say emulsifies.
Here you can kinda see the oil droplets up at the surface
These were my original hoses and I am trying to squeeze them together in the picture.
Here is the after - I am able to squeeze them easily, more so on the carb side, less so on the head side.
Results - It worked, took about 45 mins. at rolling boil to start seeing an impact, ended up running it for 1.5 hours by the time I finished.
I also ended up throwing in a few other pieces from time-to-time and watched each piece carefully like the small rubber spacers in the battery box, maybe 10 mins., the heavy rubber bottom of the battery box, 15 mins. In the case of the rubber from the battery box it was rock hard when I started and nice and soft when I finished.
The hose on the back of my air cleaner was rock hard and it took maybe 10 mins. It did flare the ends but they did go back to normal shape after about an hour, probably should have left the clamps in place instead of pulling them back. This was just a test on the hose I was going to be replacing them with new.
Rock hard
After process
Flared Ends
Lessons Learned - Probably should keep it at a rolling boil rather then a high boil as I think the Wintergreen boils off quicker at a high boil. I mean you get going and it looks like its going to work so you think OK more heat gets the Wintergreen further into the rubber.
I should have added more water initially, as it boiled I was loosing water and had to add some which slowed down the process. But - maybe I should have not had it at such a high temperature?
I do not have a brand new pair of hoses to compare as far as the ability to squeeze but it seems the head side of the hose is harder to compress then the carb side and its maybe a little thicker in this area. Sooooo maybe its harder to get the Wintergreen deeper into the rubber. I think you would have to experiment a little with coming up with the "best" temperature to keep the rolling boil at, which get the best effect. Maybe a higher concentration of Wintergreen would penetrate deeper?
