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|Title: Review: Engine powered air pump for tires|
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Date Posted：02/24/2016 4:47 AMCopy HTML
I always like to have tire repair tools on board my bikes, and since the XL250 is a 6 volt system an electric pump was out. And the compact bicycle pump I carry on the CB125 left my arms aching after testing it on the XL's 4.00-18 rear tire. But I came across the engine air pump below and after a couple of modifications I've decided it's a decent tool. It essentially turns the engine into an air compressor. (CO2 inflaters are another way to go, but I like having more than one option in case of a leaky patch job or second puncture.)
Engine powered air pump from Stop & Go International, web page [url=http://www.stopngo.com/engine-powered-air-pump-for-motorcycles-5-ft-hose-with-quick-release-lever/][color=blue][u]here[/u][/color][/url].
The device comes with adapters for 10, 12, and 14mm spark plugs. To use it, drain the float bowls, then remove a spark plug and screw in the adapter in its place. There are two one-way valves in the body. One lets fresh air into the cylinder on the engine's intake stroke, through the four slots. Then on the compression stroke, the first valve closes and air is pushed past a second valve and through the hose to the tire.
After testing it the first time I noticed several problems. First there was no gasket to seal at the spark plug threads, and also no sealant between any of the three threaded joints in the body. So I added an O-ring at the spark plug end, and sealed all threaded joints. Second, I could hear a burst of air escaping from the slots with each compression stroke. The one-way inlet valve consists of a thin sheet of rubber coiled inside the body, and part of each pumping stroke was wasted before the air pushed the rubber tight against the inside of the slots. The pump worked, but it took 90 kicks of the starter to get 15 psi into the rear tire, and my leg was not happy at the end. I decided that this intake system was redundant since the engine has its own perfectly good intake valve, and with the flat bowl drained there would be no worry about filling the tire with gas fumes. So I sealed up the slots with a few wraps of duct tape and tested again. This time it took only 50 kicks to reach 20 psi, enough to ride on or else rest a few minutes and add another couple dozen kicks. Of course with an electric starter the job would be a breeze, so to speak. (Ground the plug wire to prevent damage to ignition components if turning the key on.)
Another small problem is that the second one-way valve seeps a bit until the tire gets enough pressure built up to force it to seal completely. Now that I see how the device is made, and its slightly sketchy quality, I would probably hunt around for a better made one-way valve, weld or epoxy it to a gutted spark plug base, and make up my own hose. Possibly a small in-line brass valve with steel ball? But with the mods the Stop & Go does the job.
The rest of my tire repair supplies consist of a patch kit, plug kit, and replacement tube for the 21" front. To save carrying two tube sizes I converted the rear to tubeless, using the 3M extreme sealing tape as I did on the GB500, thread [url=http://www.vjmog.com/ftopict-10676-.html][u][color=blue]here[/color][/u].[/url] (By the way, the GB's tubeless conversion has been trouble free after many thousands of miles, and the tires hold their pressure better than my second GB which has tubes.) The XL's front rim is a bit narrow so I decided the sealing tape might not have enough contact area beside the spoke nipples to seal well.
Lastly, I bought a couple of these very nice Motion Pro tire spoon/wrench combination tools, one to fit each axle nut. Actually the big one is only available in 27mm, so I epoxied in a layer of .5mm sheet metal to fit the XL's 26mm rear axle nut. They are very strong T6 aluminum and a light 3.5 oz. each.
Re：Review: Engine powered air pump for tires
Date Posted：02/24/2016 9:50 AMCopy HTML
Well, disregard my tepid recommendation of the Stop & Go pump. After fooling with it a bit more I realized the quality was too low to be trusted, so I ended up making my own setup. I broke the porcelain out of a spark plug and found the inside of the shell has a perfect seat for a 5/16" steel ball. I tapped the plug body to 3/8" pipe thread, then tapped a 3/8" brass fitting to 1/8" pipe thread to accept a 1/8 x 1/4 barbed fitting. Threaded the parts together and fit them to a new hose and now it pumps faster than before. I just need to find a higher quality fitting for the tire end, hopefully one that does not say "Taiwan" on it.
The gutted spark plug, steel ball and fittings -
The assembled parts -