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Discussion Starter #1 (Edited)
I'm new to the ATC/TRX dragster scene so I have a few questions.
I have been around auto drag racing where a common way when increasing hp and durability is to fill the water jackets with a filler that hardens, one brand is Hard Blok water jacket filler. The trick is after pouring the filler there is time to install torque plates before it hardens.

Are you guys doing the same with the 250R drag motors?
I hear about expoxy filled water jackets in some TRX250R drag motors but is not allowed in the stock class drags.
Would the concrete and iron mix formula such as Hard Blok work?
I just need some education on the subject.
Thanks.
 

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I thought you're into Hotsaw's, now "ATC/TRX dragracer"...? LOL

You can fill ATC/TRX250R water jackets with an epoxy, or compound as long as the 'coefficiency of expansion' of the filler material is similar to Aluminum. Not sure "Hard Block" is made for Aluminum, might be designed for Iron Blocks. Their are epoxies filled with Aluminum with similar 'expansion' characteristics to cast Aluminum cylinders.

Better yet would be to build a one piece Billet Drag specific cylinder with NO water jackets; I think I will do just that on one of my next Drag projects.

Carlos
 

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what drag products no one has ever seen 1 ???? you have a drag bike ? funny its never been talked about. i konw there are standing challenges for you to attend drag races but you never did.
 

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And your attack once again provides an answer to the OP in what way? It only derails a conversation, makes no usable contribution, and provides ZERO assistance to.

You are a price...!

Carlos
 

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Discussion Starter #5 (Edited)
I thought you're into Hotsaw's, now "ATC/TRX dragracer"...? LOL

You can fill ATC/TRX250R water jackets with an epoxy, or compound as long as the 'coefficiency of expansion' of the filler material is similar to Aluminum. Not sure "Hard Block" is made for Aluminum, might be designed for Iron Blocks. Their are epoxies filled with Aluminum with similar 'expansion' characteristics to cast Aluminum cylinders.

Better yet would be to build a one piece Billet Drag specific cylinder with NO water jackets; I think I will do just that on one of my next Drag projects.

Carlos
Carlos,
Yup I'm still into a Honda CR250 hotsaw, Lol. I thought with a ATC/TRX 250R drag narrative to this thread may draw more replys
In all comparison a CR250R hotsaw is in the same engine category as a ATC/TRX250R dragster.

I have some friends who are into auto drag racing and when they get serious with their engine builds they half fill or full fill their water jackets.
Back in the 1970's Devcon aluminium based epoxy was poplar and worked well to make more durabilty and rigidity when making big horse power.

The cement grout with added iron media got popular in the mid to late 1980's with the introduction of Hard Blok. It's compatible with cast iron sleeved aluminum block race engines.
Fill the waterjackets and then install torque plates on the top decks before it hardens.
Guys have gone for years and hundreds of runs on these cylinder walls with only minor maintenance.

So I know guys out there are filling their 2 stroke jackets. Mostly for covering up leaks on over porting.
But I'm sure controlling cylinder bore roundness and shifting is another reason.

I see JB Weld high heat extreme is rated for constant 2400F which is way over the melting point of aluminum.
But it would be very expensive to fill up a CR250R water jacket.
Hard Blok filler would be alot cheaper and probably more stable with better heat transfer.
 

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I wouldn't fill the water jackets with anything that did not expand similar to the Aluminum casting...while relatively expensive; Aluminum Filled Epoxies are the Best IMO.

Carlos
 

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Discussion Starter #7 (Edited)
I wouldn't fill the water jackets with anything that did not expand similar to the Aluminum casting...while relatively expensive; Aluminum Filled Epoxies are the Best IMO.

Carlos
Thanks Carlos,
Yes Devcon liquid aluminum 10710 in 1 lb. package seems to be the best product to buy.
 

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Discussion Starter #8
Thanks Carlos,
Yes Devcon liquid aluminum 10710 in 1 lb. package seems to be the best product to buy.
I'd put about a half inch minimum layer of JB Weld High extreme heat on top of the exhaust port in the water jacket just to be safe.
Put the Devcon liquid aluminum on top all the way around and up the open deck cylinder.
 

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I'd put about a half inch minimum layer of JB Weld High extreme heat on top of the exhaust port in the water jacket just to be safe.
Put the Devcon liquid aluminum on top all the way around and up the open deck cylinder.
That will do the job. Not really sure the benefit to doing all this on a 2 stroke small single cylinder, obviously I understand the theory, and how it works on large multi cylinder Drag engines. Just saying I have never really seen a measurable gain or performance increase on the Dyno or Track.

Carlos
 

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Discussion Starter #10 (Edited)
That will do the job. Not really sure the benefit to doing all this on a 2 stroke small single cylinder, obviously I understand the theory, and how it works on large multi cylinder Drag engines. Just saying I have never really seen a measurable gain or performance increase on the Dyno or Track.

Carlos
Some say when the cylinder has solid support there is less out of round , less distortion,.less maintenance .
A good idea to torque the head and base nuts before the epoxy dries. Then do a bore and hone after with a torque plate.
I hear the Devcon is lighter then water and in a drag motor better heat dissipation. If only half to 3/4 jacket fill the head can still be cooled with water in the cooling system.

But the most important situation with my 1983 CR250R cylinder is it has an open deck . My spare 1983 cylinder must have had an upgrade later that year as it has a semi closed deck. This was a experimental year as it appears. 1982 and 1984 and on have closed decks.
I thought about drilling and tapping four 6mm set screws through 4 corners of the upper part of the outer cylinder wall to support the cylinder bore like what the upgraded cylinder has with its 4 cast in lugs.
Still may be an option...
63784
63785
 
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