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XR400 gas tank observation

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Well, I finally broke down an installed the replacement Lone Star graphics that XGX sent me several months ago. The first set bubbled in about 2 weeks and after contacting XGX (real nice people by the way), they sent me a replacement set. I've had them for a while, but just been running a bare tank afraid they would bubble too. So, I removed the tank this time, drained the gas, and used a blow dryer on low heat,(outside through an 8' vacum cleaner hose for safety) for about 30 minutes untill the return air had no gas smell. I lightly buffed the outside of the tank with 0000 steel wool and cleaned with touluene and let dry completely. I'm hopeing this time they will stay (going to wait a week or so before putting gas in the tank too). Now, to the observation, I had the tank at about the same angle as on the bike while draining, and after it quit running out (on reserve), I tilted the tank over to get the gas from the off side to the petcock. I was suprised that it was almost a quart that had not drained. If they had put an equalizing tube from one side to the other, it would probably add 20 miles or so to the range of the stock tanks. Wonder why they don't do that??

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YES! Exactly, thats what i was thinking! How does the fuel from the right side of the tank get to the fuel tap! when its spit in 2 like that!

Does anyone know?

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Yep, I always knew there had to be fuel left in there when the petcock side ran out, just never realized how much was there.

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it is not the gas in your tank that makes the decals bubble. polyurethane plastic gives off a gas for it's entire life, which is a hellll of a lot longer then you or i are going to live. the newer gaskets are perferated to help keep this from happening. :cry:

Kaos

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The Acerbis 21 litre tank has two petcocks and an equalisation hose between the two. In answer as to why Honda doesnt do it. MONEY, If it cost 5 bucks and you sell 10000 bikes, well you do the Math! :cry:

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It's just bizare that it would do fine for 2 years, not a hint of a bubble, and thenall of a sudden, big bubbles overnight on the original decals. The first replacement set had the perforations, but it looked like they didn't go all the way through the clear top coat. It was the clear coat that got huge bubbles under it, and when I tried the pin prick trick, it still left wrinkles big time. I think the top coat had actually stretched out, and wouldn't lay back down. The guys at XGX said they were using a new material on the last ones, so maybe it will last. They sure look great now anyway.

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Yes that pissed me off too, that seemed to happen all of a sudden on the standered stickers on my 400, I was always going to get round to get some perfierated sticker set for it, but i never did. I think it looks ok just with the red tank, looks better that stickers with wrinkled bubles all through it anyway.

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The gas tank is high density polyethylene! Not polyurethane.

I am a polymer chemist and have work with this stuff for over 30 years. All gas plastic gas cans tanks etc are HDPE.

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Does the polyethylene really out-gas that much on it's own? The first set of aftermarket decals had bubbles under them approx. 3" in diameter and raised 1/2" just over a couple of days time from when I checked the bike.

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Found this old thread, anyone have the xgx lonestar graphics on a blue YZ450? If so any pics? I would like to put these on my 07 YZ.

I think the bubble issues on the tank detailed in the post are related to the permeability of HDPE (hydrocarbons absorbed into the wall of the PE). I imagine this may affect adhesion. Today's automotive gas tanks, of which a large % are made from HDPE, are multilayer parts. They do this with designed "barrier" layers to prevent (reduce) permeation of the hydrocarbons. I don't think that the tanks on our MX bikes are as robust as the auto designs but I could be wrong.

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YES! Exactly, thats what i was thinking! How does the fuel from the right side of the tank get to the fuel tap! when its spit in 2 like that!

Does anyone know?

It's simple. While your at a stop with about 1/4th of the tank left push the bike waay over fairly quickly on its left side to where the handlebar almost touches and bring it back up. Bingo, problem solved.

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Hey, the trick to keeping graphics on is to KEEP fuel in your tank. Because it's the VAPORS of the empty tank the escape through the sides of the tank and make your graphics peel.

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It's simple. While your at a stop with about 1/4th of the tank left push the bike waay over fairly quickly on its left side to where the handlebar almost touches and bring it back up. Bingo, problem solved.

Hmmm... an extra reserve :lol:

The thing I wanna know, why do stock graphics last for year and years, but aftermarket ones peel so quick?

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