Fuel Tank Question

[Randy Lamp]

About a year ago, I restored a plastic mx tank for my 250 Penton. After removing the old decals ,glue and dirt,I was able to wet sand and buff out the original finsih. I then added some new stickers and it looked good as new.  I only rode the bike a few times this past year,but it did sit for awhile with fuel in it. Maybe a month or two.

What I have noticed is the once smooth as glass finish is now rough and riddled with small imperfections. Its almost like the original finsih has shrunk, exposing the texture of the fiberglass matt under it. Has anyone else had this problem?  Is the cause of it modern day fuel? Should I be draining the tanks when the bikes are not in use?

Thanks,
Randy Lamp

[Dwight Rudder]

It must not have been plastic but fiberglass.  Pentons didn't have plastic tanks stock. Be sure that the fuel you are using doesn't have alcohol in it as this will eat up the tank.  Draining between uses is surely a good idea any way.
Dwight

[Randy Lamp]

Yes,the tank is fiberglass. I will start draining my tanks when the bikes are not being used. Kind of a pain in the neck,but well worth it compared to messing up a perfectly good original tank like that.

Thanks, Randy

[crash carden]

Hello Randy, I had a fiberglass Penton tank do the same thing and this tank was in excellent original condition. I have always drained the fuel out after I ride, but I was using this bike as my rider at the time and I was riding a lot so I left the fuel in the tank for a few weeks during the spring riding season. I kept a close eye on the tank as I knew this could be a problem with modern day fuel in the old fiberglass tanks. Sure enought it happened the finish on the tank was bubbling up and looking rough and I thought I had destroyed it:(. Of course like you I drained out the fuel,and was mad at myself for not taking the time to drain the fuel out after each ride like I usually do. However I then took the tank removed the cap and opened both fuel cocks and set it outside in the sun everyday and allowed the gas to evaporate for a week or so. Then I let it set in the shop with it opened up as well for a few more weeks. I my case all the the fuel evaporated and the fiberglass dryed out and the gel coat smoothed backed out as if it had never been damaged:D. I have used the tank many times since with no problems and the tank still looks great:D! Of course I never leave the fuel in the tank more than a day even on my riders. Try it it might work for you as well,good luck!  Crash Carden.    Go Team Penton!

[Ernie Phillips]

I have used Caswell Fuel Tank Sealer on my fiberglass tanks with good results.  It seems that the original polyester resin does not hold up to modern fuel blends.

  http://www.caswellplating.com/aids/epoxygas.htm

Caswell says that the one pint kit can do 2 - 5 gal tanks.  I did 3 tanks, 2 Penton & 1 Rickman tank with one kit.  I prep'd all the tanks and did them in one shot - I mixed the whole kit, dumped 1/2 in into 1st tank and 1/2 in 2nd tank and sloshed around for about 10 minutes, then dumped remainder in tank #3.  I had enough product to do tank 4 but sealer started to go off so I quit.

Tank prep is the key to success.  I started with purple degreaser found at auto parts stores - put in full strenth & flushed & flushed.  Put in more purple stuff & flushed & flushed - rinse water must come out clear.  If not, do more degreasing.  Final cleaning with acetone.  As aways, read and understand the manf. insutructions.


Ernie P.
Chattanooga, TN

[454MRW]

I was worried about my stock KTM MX6 fiberglass desert tank having problems since I was running 93 octane pump gas in it. I had added some fuel fresh in the premix gas because of the wet conditions of the ISDTRR in 2006, and left the gas in the tank for a YEAR with no problems. The gas was from a local Marathon station and the bike was only ridden 3 or 4 times after the RR before I removed the engine. I checked the tank very closely after draining the gas last October, and saw no evidence of softening or damage. Not sure if it was because of the gas its self or the addition of fuel fresh, but I am continuing the use of fuel fresh as a precautionary measure. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S

[Young Ted]

It appears there could be different fiberglass tanks, if that is possible. The fiberglass tanks I have used were not drained and premix never damaged the finish. As far as I know they weren't sealed either. The only problem these tanks gave me were leaking after being clobered. Not being able to keep decals on a plastic tank is a different situation.

Young Ted