Author Topic: Pulling dents out of expansion chambers.  (Read 397 times)

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Online quocle603

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Pulling dents out of expansion chambers.
« on: September 13, 2020, 11:30:07 AM »
Just got another set of expansion chambers. It had a slight dent on one of them. Decided to see how people pull dents and came across this, *friendly reminder to clean out your oily pipes before proceeding*. I think I will just leave the dents  :eek:

Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Offline oxford

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Re: Pulling dents out of expansion chambers.
« Reply #1 on: September 13, 2020, 12:51:04 PM »
I used that method on a 4 stroke dirt bike header.  I had an expansion plug in the one side that apparently wasn’t in tight enough.  I don’t remember how much psi I had going in but the plug going shooting across the garage was pretty impressive.   :dawg:

Offline rodneya

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Re: Pulling dents out of expansion chambers.
« Reply #2 on: September 13, 2020, 01:09:12 PM »
Dirtbike pipes have a flange on both ends. If you do it properly you use a u bolt or something around the pipe bolted to a plate over the plug.
On an RD pipe I would probably weld something onto the pipe to tie  back to. Or just cut out the damage and weld in a new section.

Offline lawnboy

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Re: Pulling dents out of expansion chambers.
« Reply #3 on: September 13, 2020, 03:20:04 PM »
cobbled these together to fix my pipelines. valve on the end allows some air to escape but still provide enough pressure to expand the the dent. a little nerve racking still but worked like a champ.

Online quocle603

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Re: Pulling dents out of expansion chambers.
« Reply #4 on: September 13, 2020, 03:44:51 PM »
I've seen plenty of people get decent results with a pressure washers. I'm always weary and nervous when a method involves a extreme high and cold temps.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

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Offline m in sc

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Re: Pulling dents out of expansion chambers.
« Reply #6 on: September 13, 2020, 07:06:21 PM »
as long as there is just liquid in there its fine. make sure you bleed all the air out...  when you have air in there its an issue. ive done destructive testing on vessels at over 20k psi (for work). trust me, its not exciting.  liquid doesn't compress. = nothing to expand and go boom when its released.

Online quocle603

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Re: Pulling dents out of expansion chambers.
« Reply #7 on: September 15, 2020, 11:54:00 AM »
I might try things out this winter. I will borrow an electric pressure washer from someone to do this.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Offline rodneya

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Re: Pulling dents out of expansion chambers.
« Reply #8 on: September 15, 2020, 01:34:28 PM »
Be careful with using water. the pressure is applied to the entire pipe and you are often more likely to split the pipe before pushing a dent out.

Offline fyingdg

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Re: Pulling dents out of expansion chambers.
« Reply #9 on: September 16, 2020, 06:07:08 AM »
https://www.hydra-force.co.uk/
I have a hydroforce for my dirt bikes and it works  great. I'm trying to make a new one that will work on older non flange pipes now.

Offline pidjones

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Re: Pulling dents out of expansion chambers.
« Reply #10 on: September 16, 2020, 07:58:24 AM »
I'd go with the manual pump. If you truely fill the entire system, one stroke could either a) bump the dent out or b) split a seam. Don't think the pressure washer can be that closely controlled.
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Offline m in sc

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Re: Pulling dents out of expansion chambers.
« Reply #11 on: September 16, 2020, 08:53:05 AM »
IF you have a diverter valve inline from the pressure washer to the pipe it can be controlled very easily... but the manual one is the way to go.

Online quocle603

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Re: Pulling dents out of expansion chambers.
« Reply #12 on: September 16, 2020, 02:45:30 PM »
thanks for the input on the matter. I might just leave it, I've heard that the small dents do not do too much to the performance...but I might be devil's advocate.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC

Offline m in sc

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Re: Pulling dents out of expansion chambers.
« Reply #13 on: September 16, 2020, 03:23:23 PM »
small dents don't matter. if it really bothers you, drill it from the other side, knock the dent out with a punch, weld the hole back up.

Online quocle603

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Re: Pulling dents out of expansion chambers.
« Reply #14 on: September 16, 2020, 09:16:13 PM »
They don't. If it works,  then it works.
Do not underestimate the power of a two-stroke.

1975 Yamaha RD350 (modified), 1973 Yamaha RD350 (stock), 1971 Suzuki T500, 1981 Yamaha XS650 HS2, 1982 Honda MB5, 1980 Puch Maxi, 1979 Puch Magnum, 1993 Tomos Bullet, 2003 Malaguti Firefox F15 LC