Author Topic: throttle spring  (Read 5479 times)

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Offline evinrude7

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throttle spring
« on: February 27, 2017, 07:55:02 PM »
the throttle/carb spring (not sure what it's called) on my 750 k6 is awfully stiff resulting in a hard to twist throttle grip.  has anyone changed this out for a lighter pull spring?  where'd you get it?   
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Offline ekpent

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Re: throttle spring
« Reply #1 on: February 27, 2017, 09:16:26 PM »
 Are you sure the cables are all lubed well and routed correctly and the metal handlebar under the throttle tube is clean and not rusted or gunked up ?  Some of those can contribute to a harder to pull throttle.

Offline Deltarider

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Re: throttle spring
« Reply #2 on: February 28, 2017, 01:14:09 AM »
Quote
Are you sure the cables are all lubed well and routed correctly and the metal handlebar under the throttle tube is clean and not rusted or gunked up ?
I would not recommend to lube the cables if they're OEM Honda. Those are teflon lined and lube does more harm than good. Correct routing is essential however.
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Offline evinrude7

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Re: throttle spring
« Reply #3 on: February 28, 2017, 06:23:43 AM »
yes i believe the cable is routed correctly and moves freely when not connected to carbs.  i read somewhere on this forum that someone changed out the spring and was happier with the lighter spring.  also read that the 750 springs were ultra aggressive springs.  seems that way to me.  i'm a carpenter and work with my hands daily.  have been a guitar player for over 25 years and a lefty so my fingering hand is the one on the throttle.  i'm pretty sure it's not a lack of strength in that hand. 

throttle cable is routed down to the steering lock and back up under the tank and coils to the carbs. 
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Offline evanphi

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Re: throttle spring
« Reply #4 on: February 28, 2017, 07:30:49 AM »
Nope. Not correct.

It should go behind the headlight. It looks like it is longer than stock. It also looks like a pretty wicked downward bend. That would be a big source of friction.

« Last Edit: February 28, 2017, 07:36:15 AM by evanphi »
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline Deltarider

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Re: throttle spring
« Reply #5 on: February 28, 2017, 07:53:26 AM »
Quote
yes i believe the cable is routed correctly and moves freely when not connected to carbs.  i read somewhere on this forum that someone changed out the spring and was happier with the lighter spring.  also read that the 750 springs were ultra aggressive springs.
True, Honda overdid things with that spring. OK, it is very safe but too hard, I agree.
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Offline Phoenix

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Re: throttle spring
« Reply #6 on: February 28, 2017, 08:34:16 AM »
Being a p.... and a right handed guitar player.  I had the same problem.  I took the spring off the carbs and stretched it.  Doesn't need much so don't over-do it.  Makes for a much more comfortable ride.
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Offline Steve_K

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Re: throttle spring
« Reply #7 on: February 28, 2017, 11:03:46 AM »
In the 70's I replaced the spring with one from a 60's era VW on my 550.  It worked well,  but you must have the cables routed correctly. 
Steve
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Offline evinrude7

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Re: throttle spring
« Reply #8 on: February 28, 2017, 04:09:01 PM »
thanks for all the feed back.  yeah evanphi, i think the cable is too long. probably not stock.  i'll see if i can route it how the diagram shows. 

is that diagram on a specific page in the shop manual or owner's manual? 
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Offline evanphi

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Re: throttle spring
« Reply #9 on: February 28, 2017, 04:24:59 PM »
thanks for all the feed back.  yeah evanphi, i think the cable is too long. probably not stock.  i'll see if i can route it how the diagram shows. 

is that diagram on a specific page in the shop manual or owner's manual? 

Shop manual page 119 (116/227 in the link in my signature)
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline evinrude7

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Re: throttle spring
« Reply #10 on: February 28, 2017, 04:27:45 PM »
have the shop manual thanks but that's great you have that in your signature.  i'm looking at the page now.  thanks again. 
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Offline evanphi

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Re: throttle spring
« Reply #11 on: February 28, 2017, 05:02:21 PM »
Any time. We like to help around here. :D
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline riverfever

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Re: throttle spring
« Reply #12 on: February 28, 2017, 05:28:10 PM »
I had the same issue with my 550. I used new cables, made sure they were routed correctly and it still was...robust. I ended up using a new spring. I found springs at an Ace Hardware and grabbed several different rates and just tried them. Th one I have on their now is glorious.
http://forums.sohc4.net/index.php?topic=127186.0

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Offline evinrude7

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Re: throttle spring
« Reply #13 on: February 28, 2017, 05:50:28 PM »
i've noticed evanphi.  this forum is a gold mine not to mention the people on it.  i was able to offer some advice to a begineer the other day and it felt great to share the microscopic bit of knowledge i had on the subject.  good stuff here. 

and thanks riverfever.  i know just the ace down the street. 
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Offline evinrude7

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Re: throttle spring
« Reply #14 on: March 01, 2017, 06:57:29 AM »
evanphi, just realized the bars are not stock thus the stock cable is too long.  planned on getting stock bars but i'll replace the cable as well. 
cb750 k6 - ugly

Offline flybox1

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Re: throttle spring
« Reply #15 on: March 01, 2017, 07:06:48 AM »
Do you have aftermarket cables?   A stock cable will not matter if routed properly, even with shorter bars. 
An aftermarket cable where the sheath is too long/cable too short will introduce the heavy throttle as youve described.
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Offline evinrude7

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Re: throttle spring
« Reply #16 on: March 01, 2017, 07:09:33 AM »
not sure if cable is stock or not.  bars def are not.  cable looks original to bike.  i'll have to take it off and measure it.  do you know what it should be?  total length and exposed cable?
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Offline flybox1

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Re: throttle spring
« Reply #17 on: March 01, 2017, 07:15:08 AM »
Sorry, I dont.
I have had NEW (aftermarket) cables snap on me while out on rides.
Im back to using the 40 year old cables, and without issue.
I will always purchase HONDA cables.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline evinrude7

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Re: throttle spring
« Reply #18 on: March 01, 2017, 07:21:48 AM »
good to know.
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Offline kpier883

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Re: throttle spring
« Reply #19 on: March 01, 2017, 07:33:02 AM »
I have had good success with Motion Pro cables.  Haven't tried any other aftermarket brand.  Nevertheless, I agree that Honda cables would be best when available.
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Offline Stev-o

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Re: throttle spring
« Reply #20 on: March 01, 2017, 07:42:54 AM »
I suggest buying new cables....will be worth it.
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Offline evanphi

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Re: throttle spring
« Reply #21 on: March 01, 2017, 09:54:16 AM »
I suggest buying new cables....will be worth it.

Agreed.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline evinrude7

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Re: throttle spring
« Reply #22 on: March 01, 2017, 11:36:50 AM »
next order.  cables.
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Offline el pachuco

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Re: throttle spring
« Reply #23 on: March 02, 2017, 09:42:42 AM »
I solved my throttle fatigue issue that was a problem on rides lasting more than 20 minutes.

I ditched the fat Tiddy grips, in favor of the smaller diameter OE style grips and I swapped out the very stiff, stock throttle return spring for one that is about 40% lighter. Now the throttle action feels more inline with a modern bike.

Here is a link to the spring I used. I bought mine at a local hardware store.

https://l.facebook.com/l.php?u=https%3A%2F%2Fwww.google.com%2Fsearch%3Fsourceid%3Dnavclient%26aq%26oq%3Dcentury%2520spring%2520C-133%26ie%3DUTF-8%26rlz%3D1T4NDKB_enUS546US693%26q%3Dcentury%2520spring%2520C-133%26gs_l%3Dhp....0.0.0.15125...........0.i0uJ5rAF2cs&h=ATPkVpuO3mMI4o-RyW12UGw1bDT1tOMfdqvvQTVNvyPOPBnH0kA_3BbTQD3Lo65lPFlq_eUJoOZRpLdAff5SA45qtaULLEFgXpdTqviU9Qn-wrWkg3g8R8sfrwTzPPo1r9D5OurHADCA2W-R0V65Jgftp://

Offline Terry in Australia

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Re: throttle spring
« Reply #24 on: October 29, 2017, 04:07:35 AM »
I solved my throttle fatigue issue that was a problem on rides lasting more than 20 minutes.

I ditched the fat Tiddy grips, in favor of the smaller diameter OE style grips and I swapped out the very stiff, stock throttle return spring for one that is about 40% lighter. Now the throttle action feels more inline with a modern bike.

Here is a link to the spring I used. I bought mine at a local hardware store.

https://l.facebook.com/l.php?u=https%3A%2F%2Fwww.google.com%2Fsearch%3Fsourceid%3Dnavclient%26aq%26oq%3Dcentury%2520spring%2520C-133%26ie%3DUTF-8%26rlz%3D1T4NDKB_enUS546US693%26q%3Dcentury%2520spring%2520C-133%26gs_l%3Dhp....0.0.0.15125...........0.i0uJ5rAF2cs&h=ATPkVpuO3mMI4o-RyW12UGw1bDT1tOMfdqvvQTVNvyPOPBnH0kA_3BbTQD3Lo65lPFlq_eUJoOZRpLdAff5SA45qtaULLEFgXpdTqviU9Qn-wrWkg3g8R8sfrwTzPPo1r9D5OurHADCA2W-R0V65Jgftp://

Thanks for posting this mate, I've just ordered a couple of the C133 springs, the only thing that pisses me off about my just completed K2 bitsa build is the ridiculously heavy throttle spring! Cheers, Terry. ;D
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