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Makotosun

Fork measurement needed 71 CT1

  • Dennis D
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Fork measurement needed 71 CT1 was created by Dennis D

Could someone measure their CT fork tube from the bottom of the lower
tree to the centerline of the axle and let me know what you come up with?
I think the bike I am working on has had longer fork tubes installed on it.
Speedo cable and brake cable are short. Thanks, Dennis
 
01 Oct 2022 13:59 #1

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Replied by Tom P on topic Fork measurement needed 71 CT1

20.5"
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01 Oct 2022 14:23 #2

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Replied by MarkT on topic Fork measurement needed 71 CT1

I'm not near a CT1 right now... but mod was DT forks on CT and Yamaha even listed parts needed for conversion in manuals.

I believe CT forks were 30mm OD upper fork tubes and DT was 34mm. So that would be a quick check too.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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01 Oct 2022 14:32 #3

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Replied by Ht1kid on topic Fork measurement needed 71 CT1

My Ct1c is 19.5 in
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01 Oct 2022 15:32 #4

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Replied by Swoop56 on topic Fork measurement needed 71 CT1

Over the decades , these bikes can have had fork modifications  .
Booster springs , different aftermarket fork springs , aftermarket damper rods , or shorter or longer
preload spacers . Any of these mods can  affect the measurement you're looking for , let alone
sacking out of original fork springs , as did happen .
You've already had reported variations , albeit in the same ball park , but hopefully an average figure will emerge .
 
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01 Oct 2022 16:34 #5

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Replied by Ht1kid on topic Fork measurement needed 71 CT1

Swoop yes my Ct1c was bought used a couple of years ago had a chamber and different carb had been rode hard but well  maintained I rebuilt the forks and used KDI cables the best way is diameter as MarkT said mine is 30 mm
01 Oct 2022 17:04 #6

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Replied by Dennis D on topic Fork measurement needed 71 CT1

These measure 21 3/4 from the bottom of the tree to the axle centerline.
30mm on the diameter. I had some cables from a 250 that worked out.
This also explains why the kickstand seemed so short on this bike. The longer
forks with the bigger tires really had it leaning over. Extending the kickstand
took care of that. Thanks for taking the time to get the measurements for me.
D
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01 Oct 2022 20:33 #7

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Replied by Dennis D on topic Fork measurement needed 71 CT1

Agree on the measurement variations. I took this with the forks
fully extended. The clip on the lower tree for the cables was broken
also. Stock brake cable couldn't be routed behind the keyswitch
as it was in a bind. Tried moving the lever on the splines and 
couldn't find a happy spot for adjustment. 
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01 Oct 2022 20:41 #8

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Replied by Tom P on topic Fork measurement needed 71 CT1

Just for the record, my measurement of 20.5" was with the forks fully extended, and I'm absolutely sure that this front fork is stock with no modifications.
01 Oct 2022 20:55 #9

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Replied by Dennis D on topic Fork measurement needed 71 CT1

I had a response of 20 1/4 from a guy with an original low mileage bike
so the responses are in the ball park. The longer forks work alright for
the guy that owns it, and he is tall so I wanted to keep them for him if
I could. Thanks again, D
01 Oct 2022 21:05 #10

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