MX tank question

[Gary Roach]

I was wanting to know if anyone knew when the underside of the MX tank got changed. I'm guessing that it was when the frames went to a high breather, but I'm not for sure.

[rob w]

From what I can gather. The tank on the right, was seen around the same time as the earlier Mint 400 MX's. So maybe around 409 - 411xxxxx. (?)

[brian kirby]

I've never seen one like the on the right, both of mine are like the one on the left, but I've only seen those two MX tanks on the underside.

Brian

[Gary Roach]

Rob,
Thanks for the info. When I first saw the tank on the right, I thought it might be for a non-breather frame. The tunnel is narrow, and there wouldn't be much room between the frame and the tank, so I thought that it would restrict the airflow into high-breather frame inlet holes. I took the tank off of a '76 Cross Country, and the tank has the same tunnel shape as the MX tank, and it's a high breather frame.

Brian,
I never knew that there where different MX tanks either until the other day when I went to pick up two tanks up from the sides, and I noticed that one felt thicker than the other. I have another tank that's just like it.
 
I measured the volume of each tank just to see what the difference was. The one on the left is 220oz.(1.71 gal), and the one on the right is 280oz.(2.18 gal). I measured each tank twice just to make sure.

Here are few more photos:

[Paul Danik]

Gary,

   I have a couple of green MX tanks with a felt like covering where the knees would rub, from what I understand this style is pretty much the earliest version of the fiberglass MX tank, the underside is shaped like the tank on the left. The other MX tanks sitting here are also like the tank on the left.

   I have never seen one like the one on the right.

   Always something new to learn:)

Paul

[Larry Perkins]

Way back in "The Day" when we ordered the first MX tanks to replace the toasters that were on low breather bikes they were like the narrow tunnel tank in the picture so that may have been the deal as I know later ones were like the other.  I had a red narrower one not long ago but it seems like it fit high and low breather models.

Larry P

[rob w]

quote:Originally posted by Larry Perkins

Way back in "The Day" when we ordered the first MX tanks to replace the toasters that were on low breather bikes they were like the narrow tunnel tank in the picture so that may have been the deal as I know later ones were like the other.
Larry P

Sorry to hear about your memory Larry.
LH tank = early model
RH tank = late model
You can take that to the bank.
Bob

[Randy Kirkbride]

My '75 (412-xxx) 125 Six Days has the wider model (LH).

[Larry Perkins]

Bob,

And you were in Austin Texas that day and know EVERYTHING!  Congratulations on being God and all knowing.  Too bad you don't remember an approach to NOT piss someone off.  Also, when I try to answer a question I don't look it up in a resource magazine and PRETEND to know the answer.  You are SOOOO smart.  Looks like Randy and you bank at a different bank.  Again Congrats!

Larry P

[linglewn]

My March 1974 Jackpiner has the narrow (RH) model.

Nelson Lingle
73 Jackpiner
74 Jackpiner
71 DKW 125

[firstturn]

My 1973 Penton 100 with the 35mm forks had the narrow channel so I guess they only sent the narrow tunnel to Texas[].  I did realize that I could use the narrow channel tank on hare scrambles and it held a lot of gas.  I could only compare it to the toaster at the time.  Thanks Gary for posting the question and your capacity results.

Ron Carbaugh

[Gary Roach]

Being that there is a ½ gallon difference in capacities, I would think that there should be different part numbers listed in the manuals, but who knows?! I looked in the very few parts manuals that I have, but the only MX tank I can find was in the '74 Hare Scrambler manual, and the only description it gave was that the color was yellow. I have only one brochure that lists a fuel capacity, and that was 6.5 litres, which converts to 1.71 gallons.

[454MRW]

Gary,
My 76 Cross Country manual also lists a MX tank with the same part # as the Hare Scrambler manual # 52.07.001.100 mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR250 & OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R & CR150R

[OUCWBOY]

I have had a few each of these MX tanks and can only say that since the 70's I am so sure that a couple of these tanks have been switched from bike to bike. Having not worked in a Penton shop, I couldn't tell you what came 1st, but logically, it seems to me that the narrow opening tank would have been for the non-high breather frames and the wider one for the high breather. But like Larry said, I do know that the narrow opening tank will fit on the 73 and 74 frames. Just my 2 cents!

Donny Smith
Paragould, AR

[OUCWBOY]

Also, I don't know how true this is on the part numbers, but I'd bet that once the High Breather frames came out, they modified the mold for the tank to ensure it would fit and just kept the same part number.

Donny Smith
Paragould, AR