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Hi Guys N Gals,
Finally finished the S&S Sidewinder 100 Build. Bike started right up and all seems well. I decided to gift the old pistons and jugs to another Vet whos bike was in need of a rtop end refresh.
Thats when a mother load of questions and worries started up.. He took the jugs to a machine shop to get then cleaned up etc, and come to find out that the stroke pattern indicated a 4 inch stroke.
I bought the Bike wrecked. the guy I got it from had also purchased it wrecked. No info available on what might have been done to it. needless to say, all of this came to light at about 450 miles into the break in. now the current mileage is 625. I plan on calling S&S in the morning to find out if there is an incoming explosion.
The Bike runs like a runaway freight train, No Dyno yet. from examing all the old parts, it seems there was a stroker crank installed, everything matches TC88 specs and part numbers right down to the cams.and the plate. The Sidewinder 100 kit is a 4 inch bore.
Did I just unknowingly build a 110 and am I gonna end up breaking it down to prevent catastrophic Failure??
Any advice appreciated..
Bike aint pretty, I always do my motors over the winter and the paint the following winter, Cant afford to do both
at the same time on a VA Pension
Pops.
What spare parts makes you think there is a stroker crank? I ask because stroking, without boring a tc88, is very uncommon. I can't imagine any previous owner stroking an 88 and leaving the bore alone.
You mentioned that the old jugs indicate a 4" stroke, that is correct stroke for an 88".
I'm just not sure what parts have lead you to worry that you may have a longer stroke then 4".
Last edited by samsquanch; Jun 12, 2022 at 09:15 PM.
The OEM 88" Twin Cam had a 4" stroke. The OEM 96" Twin Cam and OEM 103" Twin Cam had a 4.38" stroke...
I am unfamiliar with the components of the S&S Sidewinder 100" kit... but the S&S website says it's made to bolt on an OEM 88" Twin Cam engine....Regardless of the year bike you started with, if the Machine shop said the cylinders showed a 4" stroke, and all the components match an 88" twin cam, it would seem the bike started with an OEM 88" twin cam....
So I'm not sure why you think there may be an "incoming explosion" or "catastrophic failure"...? If your Twin Cam was stroked, and the parts aren't compatible, I would suspect something would have "hit" before 625 miles....
For your reference, per spec sheets.... (I hope I copied these correctly.... I tried to proof read my list)
The OEM 88" twin cam has a 3.75" bore with 4" stroke...
The OEM 88" big bore kits: 95" big bore kit has 3.875" bore, and a 98" big bore kit has a bore of 3.937" ... both on the 4" stroke.
The OEM 96" twin cam has a 3.75" bore and a 4.38" stroke.
The OEM 96" big bore kit: 103" big bore kit has 3.875" bore on the same 4.38" stroke.
The OEM 103" twin cam has 3.875" bore and 4.38" stroke...
The OEM 103" twin cam big bore kit: 107" big bore kit has 3.937" bore and 4.38" stroke.
If you haven't dyno tuned it yet, I'd be more concerned about what tune you are using for the break-in, and making sure it's closely matched to a 100" twin cam with your supporting mods...
Last edited by hattitude; Jun 12, 2022 at 09:28 PM.
What spare parts makes you think there is a stroker crank? I ask because stroking, without boring a tc88, is very uncommon. I can't imagine any previous owner stroking an 88 and leaving the bore alone.
You mentioned that the old jugs indicate a 4" stroke, that is correct stroke for an 88".
I'm just not sure what parts have lead you to worry that you may have a longer stroke then 4".
the machinist measured the piston travel in the jugs. Original owner wrecked the bike a week after getting it from the shop. Deceased. Been 2 owners before I got it. It was said he spent a ton of money. The bike ran well after restoration. Didn't need or do any motor work. based on the way it ran we assumed it had a cam upgrade. Couldn't verify that as few marking and no I D. Machine shop told my Veteran friend the stroke wear was 4.378 or something. That's what I know. . My concerns, is the stroke in compatible with the 4in 100 Sidewinder Kit from S&S. Will be calling them as soon as I get to the shop in the morning.
the machinist measured the piston travel in the jugs. Original owner wrecked the bike a week after getting it from the shop. Deceased. Been 2 owners before I got it. It was said he spent a ton of money. The bike ran well after restoration. Didn't need or do any motor work. based on the way it ran we assumed it had a cam upgrade. Couldn't verify that as few marking and no I D. Machine shop told my Veteran friend the stroke wear was 4.378 or something. That's what I know. . My concerns, is the stroke in compatible with the 4in 100 Sidewinder Kit from S&S. Will be calling them as soon as I get to the shop in the morning.
You said in your first post, the machine shop measured the stroke at 4".....???? It doesn't seem you know what the stroke was...??
Short version for an OEM engine:
4" stroke it's an 88" twin cam...
4.38" stroke it's a 96" or 103" twin cam.
If the parts didn't fit, I suspect you would know by 600 miles.... As I said above, I'd be worried about the break-in tune...
Last edited by hattitude; Jun 12, 2022 at 09:37 PM.
The OEM 88" Twin Cam had a 4" stroke. The OEM 96" Twin Cam and OEM 103" Twin Cam had a 4.38" stroke...
I am unfamiliar with the components of the S&S Sidewinder 100" kit... but the S&S website says it's made to bolt on an OEM 88" Twin Cam engine....Regardless of the year bike you started with, if the Machine shop said the cylinders showed a 4" stroke, and all the components match an 88" twin cam, it would seem the bike started with an OEM 88" twin cam....
So I'm not sure why you think there may be an "incoming explosion" or "catastrophic failure"...? If your Twin Cam was stroked, and the parts aren't compatible, I would suspect something would have "hit" before 625 miles....
For your reference, per spec sheets.... (I hope I copied these correctly.... I tried to proof read my list)
The OEM 88" twin cam has a 3.75" bore with 4" stroke...
The OEM 88" big bore kits: 95" big bore kit has 3.875" bore, and a 98" big bore kit has a bore of 3.937" ... both on the 4" stroke.
The OEM 96" twin cam has a 3.75" bore and a 4.38" stroke.
The OEM 96" big bore kit: 103" big bore kit has 3.875" bore on the same 4.38" stroke.
The OEM 103" twin cam has 3.875" bore and 4.38" stroke...
The OEM 103" twin cam big bore kit: 107" big bore kit has 3.937" bore and 4.38" stroke.
If you haven't dyno tuned it yet, I'd be more concerned about what tune you are using for the break-in, and making sure it's closely matched to a 100" twin cam with your supporting mods...
The Pistons Leave a wear Pattern on the jug walls, He is brining them by this Morning. I will measure them myself and take a pic of the calipers when I do.
The tune is a canned tune. still have yet to get a 2 into 1 Pipe or upgrade the injectors. we are Parking it at this point until we know where we are. Ive helped guys wrench Harleys previously but never did an actual ground up restoration/build. also found out last night, bike was wrecked in 2007, it sat until I got it in the Fall of 20. what ever was done was done way long ago...
Thanks for the response and the Data, both are greatly appreciated.
Glad you're going to stop riding it until you get it all straightened out... You should also do a compression check to match against what the kit was supposed to achieve...
I am agreeing with hattitude here, with over 600 miles on it if it hasn't broken yet it probably won't. If the stroke was off like you said by 3/8ths of an inch it would have pushed the piston into the heads by now. I would do as suggested check the tune, and if your concerned about the jugs and stroke run a compression check on it to see where your at. If all that checks out then get it on the dyno and ride on. If you had a stroker crank on that bike you would have seen it when you went to put the second piston on and the first one popped out of the top of the cylinder... Good luck on your project....
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