gary55
Well-Known Member
How do you attach the block to the cylinder?
Time to play. There's no replacement for displacement.
- Thread starter GreasyChris
- Start date
GreasyChris
Well-Known Member
That's a super question, lol. I'm searching for a high temp epoxy and JB weld keeps coming up on my searches. I was going to drill and tap a few holes in the block to give the JB some bite and dimple the jug. There are a couple of small bolts I can drop down thru the top fin, there are 2 on the bottom as well but the intake holes didn't line up well with the bottom fin still on the jug so I took it off as well.
I'll definately be supporting the intake and carb. After it gets attached. If you have any recommendations for what epoxy to use, I'm all ears.
In the early 2000's we used to epoxy strut towers on dodge caravans. Once that epoxy set they were never coming off. Im not sure if it can handle the heat tho.
Mcdonns
Active Member
Chris, your ExtremeTemp JBWeld idea could actually work. They advertise a max working temp of 2400-degrees, and activated adhesives could usually be expected to maintain complete integrity to at least half their temp rating (still leaving you solid at 1200-degrees, or roughly three times what the jug’s hottest area should ever reach). Your block is also intake, not exhaust, so it’s bound to be cooled a good bit by airflow (still maintaining below 400-degrees, even in the worst-case of a seize-up). Yes, increased surface area (or even the dimple-deformation method) will also help. Since your jug is sleeved, you do have a few places with enough meat to get centering pins or even mounting screws tapped in. There’s also the option to solder it in place, but that goes down a completely different rabbit hole filled with opportunities to distort/destroy that jug.
Given the amount of material remaining down the centerline between the sleeve and the block, and given the temperature differentials that are going to be present, I’d be curious about the possibility of eventual fracturing along that centerline or release of the sleeve-to-cylinder fit (possibly allowing sleeve rotation).
Those are just thoughts out loud, for whatever they’re worth. I’m definitely curious about this entire build you got going, and it’ll be awesome to see where you go with it!
{Added} The center/guide pin thing was meaning four-corner drilling through the block and into meat just adjacent to the stud bores (kinda like you were mentioning, by the drill/tap for JBW anchoring) then drifting in rolled pins for stability. That might help with the expansion disparities of the thinned jug, but also maybe serve as a second attachment to give you time to catch everything if the adhesive plane failed (which, if it did fail, would do so in one complete shear). Again.., jus’ thinkin’ out loud (which I ain’t real good at)...
Okay.., back under m’ rock...
Last edited:
GreasyChris
Well-Known Member
I was thinking about that earlier, using a couple of small roll pins to kind of center the block on the jug plus it would prevent any lateral or vertical movement between the block and jug.Chris, your ExtremeTemp JBWeld idea could actually work. They advertise a max working temp of 2400-degrees, and activated adhesives could usually be expected to maintain complete integrity to at least half their temp rating (still leaving you solid at 1200-degrees, or roughly three times what the jug’s hottest area should ever reach). Your block is also intake, not exhaust, so it’s bound to be cooled a good bit by airflow (still maintaining below 400-degrees, even in the worst-case of a seize-up). Yes, increased surface area (or even the dimple-deformation method) will also help. Since your jug is sleeved, you do have a few places with enough meat to get centering pins or even mounting screws tapped in. There’s also the option to solder it in place, but that goes down a completely different rabbit hole filled with opportunities to distort/destroy that jug.
Given the amount of material remaining down the centerline between the sleeve and the block, and given the temperature differentials that are going to be present, I’d be curious about the possibility of eventual fracturing along that centerline or release of the sleeve-to-cylinder fit (possibly allowing sleeve rotation).
Those are just thoughts out loud, for whatever they’re worth. I’m definitely curious about this entire build you got going, and it’ll be awesome to see where you go with it!
{Added} The center/guide pin thing was meaning four-corner drilling through the block and into meat just adjacent to the stud bores (kinda like you were mentioning, by the drill/tap for JBW anchoring) then drifting in rolled pins for stability. That might help with the expansion disparities of the thinned jug, but also maybe serve as a second attachment to give you time to catch everything if the adhesive plane failed (which, if it did fail, would do so in one complete shear). Again.., jus’ thinkin’ out loud (which I ain’t real good at)...
Okay.., back under m’ rock...
Mcdonns
Active Member
Yer already thinkin’ that thru, way in advance!
It amazes me, what y’all come up with, and how well you resolve these. There’s some serious experience and thought behind a lot of these mods, and it’s awesome to watch.I have no doubt there’s some bonehead out there who woulda tried t’ Permatex it on, an’ wired th’ carb up t’ tryda keep it from fallin’ off.
Diggin’ yer progress pics, Chris. This plant gonna go on th’ ‘Goose?
GreasyChris
Well-Known Member
Lmao, ya I bet someone tried white school glue too and couldn't figure out why it didn't work. Lol sounds like Will.Yer already thinkin’ that thru, way in advance!
I have no doubt there’s some bonehead out there who woulda tried t’ Permatex it on, an’ wired th’ carb up t’ tryda keep it from fallin’ off.
Diggin’ yer progress pics, Chris. This plant gonna go on th’ ‘Goose?
Yup, that's the plan for this plant. I have everything I need now to finish building it, just waiting the effffin dremel.
Hopefully I'll get these hoops laced up in the next week or so and then get to tackling the caliper mounts and get into adding some reinforcements to the frame and dropouts
GreasyChris
Well-Known Member
I finally finished the stroker engine this weekend. I attached the reed block to the cylinder using 1/16 roll pins to lock and center it on to the cylinder and a 5 mm bolt threaded down thru the top fin and lots of JB weld.
The final specs on the engine are
Exhaust widened to 29mm
Exhaust raised to 24.9mm (173°)
Transfers 32mm (130°)
Blowdown 21°
The piston has been windowed and polished along with the exhaust port. I removed the bridges in the transfer ports and owned them up leaving the little wing tips at the bottom to direct the charge towards the intake side. And went with a high compression 6cc Puch cylinder head. Squish gap is set at .7mm
The final specs on the engine are
Exhaust widened to 29mm
Exhaust raised to 24.9mm (173°)
Transfers 32mm (130°)
Blowdown 21°
The piston has been windowed and polished along with the exhaust port. I removed the bridges in the transfer ports and owned them up leaving the little wing tips at the bottom to direct the charge towards the intake side. And went with a high compression 6cc Puch cylinder head. Squish gap is set at .7mm
gary55
Well-Known Member
She's a beaut. What did you end up with for squish gap? Did you order the parachute yet?
GreasyChris
Well-Known Member
Lol no parachute yet. Hahaha.
The gap is at .7mm
The squish band is really wide on the Puch head. Not really sure how wide the squish band area is supposed to be but I guess I'm going to find out lol. These heads are only $30.00 from treatland and appear much better quality than the Chinese heads and they're a 6cc chamber. I had to run a 8mm drill bit thru the holes to get it to fit. Any thoughts on how wide the squish should be?
gary55
Well-Known Member
50% of chamber surface area. Page 41Jennings: Two-Stroke Tuner's Handbook - tuners.pdf
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