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Need help with my 1971 ct1c

23 Mar 2020 17:54
Blukas
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Need help with my 1971 ct1c #11
I replaced the crank seals a while ago. I cant remember if it ran away before or after, but either way i had to close the air screw completely after i replaced them. I think the throttle might not be fully going down as the idle was also high when it was running, i put the motor in the frame but i couldnt put the top end back together cause i had no time. Ill have to check when i get it back together and get it running.

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23 Mar 2020 18:28
trailhand
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Need help with my 1971 ct1c #12
Check routing of throttle cable. I had binding under the tank on one of mine recently....also cable hosing wasn't seating correctly on one end. Cheers!

Toby L
Yamaha CT1 175
Yamaha DT1 250
Yamaha RT1 360
04' Yamah XT 225
05' Honda XL 650
99' Suzuki DR 350

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23 Mar 2020 19:28
MarkT
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Need help with my 1971 ct1c #13
A "runaway" (by my definition) is when the engine revs really high and turning off the ignition won't shut it down.

Stuck throttle/high idle is something else entirely.

If you are turning the air screw in all the way at idle... and the engine doesn't die, it has to be getting air from someplace. Like I said, classic air leak symptom. But you're there and we aren't so without seeing what's happening it's hard to be sure.

Many good suggestions made... good luck and I hope you find the issue quickly! :Buds

P.S. New seals can leak worse than the old ones. Don't ask me how I know. :Ugh

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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24 Mar 2020 15:59
Blukas
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Need help with my 1971 ct1c #14
I found the reason it seemed like there was an air leak, the original crank seals were wood hard so i replaced them, a while ago, and today i put the motor back together and shot some starter fluid down the throat of the carb and it popped a couple of times. What i didnt realize was that the throttle was too high, it wasnt even reached by the idle screw. I am now happy knowing i have probably 0 airleaks and a bulletproof engine. Correct me if im wrong but a motor can run super rich if its idling high and still act normally like a well tuned carb at idle.

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24 Mar 2020 18:20
MarkT
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Need help with my 1971 ct1c #15
The "super rich at high idle" sounds like bad o-ring on jet setter to me.

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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25 Mar 2020 14:22
RT325
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Need help with my 1971 ct1c #16
Not getting the idle speed screw confused with the idle mixture air screw as turning the speed screw in would do just 'that'--speed.

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26 Mar 2020 09:07
Blukas
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Need help with my 1971 ct1c #17
Its odd, the idle is controlled by the air screw because i think its revving high enough to the point that the air screw is adjusting the very high idle, the revometer cable is broke so i cant tell you what rpm its at but id guess its at from 2.5k to 3.5k

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28 Mar 2020 16:19
Blukas
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Need help with my 1971 ct1c #18
Ok its all buttoned up now, but one thing that seems to be missing is the rear brake light toggle wire for when you hit the brakes the light comes on. Does anyone know where this hooks up? I also cant find anything for the rear brake also. Thanks

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28 Mar 2020 16:57
RT325
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Need help with my 1971 ct1c #19
Unless someone has been in there & bored the carb body [like me lol] & overdid it so air is bypassing the slide because it won't cover everything when closed fully shut--then if the slide is hitting the bottom with the speed screw backed out--then the motor should stop no matter where the mixture [air] screw is--& especially if mixture screw is turned in which will richen it up. So [take a breath] if its not shutting down fully, then why not. Do you have the oil pump disconnected & there's an open hole in the inlet where it connects, [sorry just thinking out loud]. Anyway--i 'thought' rear brake light switch for the foot brake was brown & green/yellow. MarkT may know, save me searching. But wires must be tucked away there somewhere.

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29 Mar 2020 01:42
Gr8uncleal
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Need help with my 1971 ct1c #20
Re the rear brake light switch, there's usually a hollow mounting bracket above the rear brake lever. The lever will have a small hole in it for one end of the brake switch spring - on your bike, I think that this is just before the pivot and the mounting bracket should be above this.

For the wires, look for any evidence that they might have been cut off. If they have, you might be able to repair them, but have a check first. I've also known the two wires to be plugged into one another, just to save them hanging loose. As RT325 said, one is likely to be brown and one yellow, or maybe yellow/green.

Good luck with your search!

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