Topic: Can anyone explain this throttle spring?

[Bigmant]

Hey gang!

Just curious if anyone has any idea how this may make the throttle on a Cb750K feel as easy as a modern bike? My spring is SO heavy that my forearm is burning after about 20min. Wondering if this guy somehow figured out something clever!

[bryanj]

No idea but what is going on below?

[denward17]

No idea but what is going on below?

Air pods?

[Bigmant]

No idea but what is going on below?

Yea AirPods

[PeWe]

Stock spring is very hard on these carbs.
I found a weaker spring at Webike. Not cheap but painless throttling without the throttle grip rubber twist on its tube. Important that cables are routed so return will work by let go off the grip.

My Mikuni TMR32 carbs need very little to lift. Despite that a quick return.
I think my old Mikuni Smoothbore VM29 was easy to handle too.

[pjlogue]

I replaced my throttle spring with a similar length spring with lighter coils.  The throttle is much easier on the wrist now but will still return to a closed position if I let go of the grip.  I found the springs at Lowes.

-P.

[rotortiller]

There are also thicker grips available offering a better leverage however the wrist travel is longer with the larger circumference. And then there are those throttle brake thingies. Not a problem for some, as wankers do have a very strong wrist lol! 

[Phoenix]

I just stretched mine and it works fine.

[Bigmant]

I also found a similar length spring with a lighter compression at ACE hardware. Works like a charm. The bike in the picture though looks to have two springs, and the rubber is covering where the two hooks join. I’m amazed it worked so well despite looking somewhat janky.

[Oddjob]

Fit a small split ring, like a key ring, I fit some around 8mm and that reduces the amount of strength needed to pull it by around 20%.

I fit the ring around the lower peg when I have carbs apart, then just hook the spring onto the ring. If you haven't got carbs apart I suppose you could try and thread it on.

[Bigmant]

I’m wondering why someone would split the throttle springs into two springs and then tie it back with a spring. Why not just use a lighter spring?

[Bigmant]

Here it is again, I’ve brightened the picture up a bit.

[PeWe]

Spring is attached too high?
Here a set when I assembled them.
See green arrow where the pin is for spring upper attachment.
And yes, the seen holes in chromed parts have not yet got the bolts when photo was taken

[Steve_K]

Back in the 70s I had VWs and noticed the spring from the VW carb would fit,  Needed careful cable routing and it worked fine on my 74 CB550.  It might work on the 750s
Steve

[dave500]

also have clean bar end and throttle tube,use graphite powder not any wet type lube like grease or oil,be sure the grip end isnt fouling on the bar end or its flange at the cable housing,with a lighter spring it should feel much better and snappier.

[newday777]

also have clean bar end and throttle tube,use graphite powder not any wet type lube like grease or oil,be sure the grip end isnt fouling on the bar end or its flange at the cable housing,with a lighter spring it should feel much better and snappier.

Good point Dave.
I had a goldwing that I brought back to life that had a gummed up throttle tube and handlebar. I had to clean them out to get the throttle to operate correctly. Dry graphite powder is the best lube in there so you don't get dirt contamination gum.

[dave500]

light grease or oil might be ok at first but it will gum up dry out or collect fine #$%* and go sticky,polish the bar where the throttle tube rolls and graphite,itll last for years.

[Deltarider]

Graphite powder is often overlooked. Years ago I had to replace my key switch, after I had mishandled it for consecutive years with WD-40 (a typical case of overnursing). Locks like these don't need any fluids. In winter season car locks etc. are best served with a little graphite powder. Also great for sparkplugthreads.

[HondaMan]

This might be a clever way to stick with "the letter of the law" while solving the 2-handed throttle grip OEM spring problem. Just take 2 of them, tie them together, put them back in: if the cop mentions it looks like "it was modified" (a ticket-able offense where I lived in Illinois during the 1970s) he could still say, "No it is using OEM parts" - and no one could say any different!

In Illinois back in those days, cops were always after bikers. I remember the funniest 750 chopper ever that came in one day for some sparkplugs while being ridden all the way across the USA one summer: it had not one, but TWO dental mirrors attached with nicely-made (machinist-grade) handlebar clamps holding them up, a taillight that was EXACTLY 2" x 2" size (an old Alabama "minimum allowed" law), some Huffy bicycle front brakes (the ones that squeeze onto the edges of the wheel rim) on the 12"-extended springer front end that had 2 tiny shocks about 3" long (looked like toys, so small) on the moving-arm side of the springer axle, locked-solid KONI rear shocks with springs cut to match to lower the rear, and a 3"-wide plexiglass curved windshield in between the instruments. The front wheel was a 1.75"x15" size, the diameter being the minimum allowed in 2 States (and I'd never seen the tire brand before). The bike had a license plate from California, back when they used to make up dream bikes, but it was 50-State legal to ride! The tank was excellently painted, with topless women sporting a cop-like badge on their shoulders on both sides...it looked airbrushed!
Oh, yeah: on each of the side covers (also custom-made) there was a 2"x4" side reflector (Ohio State requirement) and they were carved like 2 eyes looking back at you.

[Deltarider]

In Holland we still live in the Wild West. We don't have TÜV, nor MOT, no ruling on emission either. Cars yes, bikes no. It's all to the owner which modifications, which parts he wants to use and he is free to change his carb settings. The main reasoning is that riding a motorcycle is relatively dangerous and that the rider will be aware of this. I seem to remember mortality riding a bike is 7 times higher driving a car.
If you're stopped by the police, they will check your documents and maybe they will kneel to inspect the thread of your tyres. You will not be allowed to continue your ride when your tyres thread is worse than what is law. For the rest, I don't know what they'd inspect. O, yeah at night you may be pulled over when your taillight, brakelight or blinkers are not working. If you have spare, you're good. 
Recently in some cities there may be one or two poles with camera's on it, that can photograph your license plate, when you produce excessive loud noise, but it's still experimental.

[HondaMan]

In Holland we still live in the Wild West. We don't have TÜV, nor MOT, no ruling on emission either. Cars yes, bikes no. It's all to the owner which modifications, which parts he wants to use and he is free to change his carb settings. The main reasoning is that riding a motorcycle is relatively dangerous and that the rider will be aware of this. I seem to remember mortality riding a bike is 7 times higher driving a car.
If you're stopped by the police, they will check your documents and maybe they will kneel to inspect the thread of your tyres. You will not be allowed to continue your ride when your tyres thread is worse than what is law. For the rest, I don't know what they'd inspect. O, yeah at night you may be pulled over when your taillight, brakelight or blinkers are not working. If you have spare, you're good. 
Recently in some cities there may be one or two poles with camera's on it, that can photograph your license plate, when you produce excessive loud noise, but it's still experimental.

Boy, that's the Wild West for sure! Here in Colorado there are some intersections with 16 cameras giant strobe lights, and sensors on every post: if you "stretch" a red light according to their sensors, it takes 12 photos of you and mails you the ticket. The courts threw them out: they got permission from the State to ding your Driver's License if you didn't pay up, so it's still valid, but no points against your license, now. My wife got one from one of those. In the mountains the interstate (I-70) has every inch covered with cameras now, so I don't ride it anymore.

[PeWe]

No more vehicle inspections for my bikes!
Classic vehicle.
My CB750 K6 visited its last inspection 2018.
The CB750 K2 2019.

My CB750 no 3 not yet assembled.
It will get the stock engine from my K2.
The running and inspected K2 a bored and louder setup.
A stocker will pass inspection by flying colors without adding extra sound muffling.

Then no more inspections for the 3rd bike. K2 1975 as my other K2.

The inspections on me

[Deltarider]

Allow me an anecdote. Coming down the slope of a bridge I jumped a red light. The very moment I did this, I noticed from the corner of my eye a motorcycle cop posting at the side of that T-junction. I applied the brakes but ofcourse I ended meters further than where I should have stopped. It was a useless and stupid reaction ofcourse and I anxiously awaited the cop's reaction. Lazily he mounted his bike, crossed slowly the T-junction and pulled over beside me.
"Please follow me", I heard from under his helmet. "I find you a kind of interesting", he added. I knew I was in trouble and that it would cost me. I followed him to a parking lot, where collegues of him were checking several cars: documents like drivers licenses etc.
We parked, he raised his helmet and kneeled beside my CB500.
"Wow... original?"
I happily explained him the minor mods I had done, like the horns, the rear shocks and my homebuilt EI. He nodded admiringly, got up and tapped me on the shoulder.
"Take good care of it." And off he went. He had not even asked me to present my documents.
Whenever I am in the US, I train myself to be on guard. Cops talk like robots, you can't use humour or irony to soften the conversation and above all: you can't walk the streets! They even have a word for it: jay walking. 
In Holland it is ofcourse illegal to walk the motorways. For the rest, you are free to do what you want.
Where I live, most pedestrians and cyclists ignore or should I say 'navigate' red lights, even within distance of a patrol car. Just avoid eye contact, so that they would not feel obliged to act.
But when camera's are involved, it's different. Within a week of me riding at 121 km/h where the speed limit had been 80, I had an envelope in my mailbox: € 340,-! Uche uche!
 

[The Lone Builder]

In Holland we still live in the Wild West. We don't have TÜV, nor MOT, no ruling on emission either. Cars yes, bikes no. It's all to the owner which modifications, which parts he wants to use and he is free to change his carb settings. The main reasoning is that riding a motorcycle is relatively dangerous and that the rider will be aware of this. I seem to remember mortality riding a bike is 7 times higher driving a car.
If you're stopped by the police, they will check your documents and maybe they will kneel to inspect the thread of your tyres. You will not be allowed to continue your ride when your tyres thread is worse than what is law. For the rest, I don't know what they'd inspect. O, yeah at night you may be pulled over when your taillight, brakelight or blinkers are not working. If you have spare, you're good. 
Recently in some cities there may be one or two poles with camera's on it, that can photograph your license plate, when you produce excessive loud noise, but it's still experimental.

That's interesting, as is PeWe's comment. France has recently introduced Control Technique inspections – the equivalent of TUV/MOT  - for bikes; cars had been inspected fro a long time. The story is that this is an EU requirement, which was resisted for as long as possible, but finally te Govt had to comply.

Now if Holland and Sweden don't have these tests, is the French Govt telling porkies?

[HondaMan]

Allow me an anecdote. Coming down the slope of a bridge I jumped a red light. The very moment I did this, I noticed from the corner of my eye a motorcycle cop posting at the side of that T-junction. I applied the brakes but ofcourse I ended meters further than where I should have stopped. It was a useless and stupid reaction ofcourse and I anxiously awaited the cop's reaction. Lazily he mounted his bike, crossed slowly the T-junction and pulled over beside me.
"Please follow me", I heard from under his helmet. "I find you a kind of interesting", he added. I knew I was in trouble and that it would cost me. I followed him to a parking lot, where collegues of him were checking several cars: documents like drivers licenses etc.
We parked, he raised his helmet and kneeled beside my CB500.
"Wow... original?"
I happily explained him the minor mods I had done, like the horns, the rear shocks and my homebuilt EI. He nodded admiringly, got up and tapped me on the shoulder.
"Take good care of it." And off he went. He had not even asked me to present my documents.
Whenever I am in the US, I train myself to be on guard. Cops talk like robots, you can't use humour or irony to soften the conversation and above all: you can't walk the streets! They even have a word for it: jay walking. 
In Holland it is ofcourse illegal to walk the motorways. For the rest, you are free to do what you want.
Where I live, most pedestrians and cyclists ignore or should I say 'navigate' red lights, even within distance of a patrol car. Just avoid eye contact, so that they would not feel obliged to act.
But when camera's are involved, it's different. Within a week of me riding at 121 km/h where the speed limit had been 80, I had an envelope in my mailbox: € 340,-! Uche uche!
 

I love it, Delta!
In the mid-1980s one morning I was hustling to work via an alternate route (about 15 miles from home) because of an urgent call I had to answer. When I reached the road that runs right at the foot of the Rocky Mountain's Front Range I entered it at a tight hairpin (25 MPH tops) into the sun where it turned out to have the speed limit sign 40 MPH I didn't see for the glare, after which it runs a wiggly line along the mountains to my [then] office, all to avoid freeway traffic jams from an accident. I put it to it to get up the road. Well, as it turned out, the morning sun behind me also kept me from watching my mirrors much, and a pair of motorcycle cops had pulled onto the hairpin not far behind me: they ran at the speed limit (40 MPH) and, as he later told me, they "wondered what the heck I was riding" because I covered the 4 miles to the STOP sign so fast they had to go to lights-on to catch up in the next leg of the road and catch me. I was heading north then and caught the red lights in my mirrors, so at the next STOP sign I just waited until they caught up - on their CX500 Police bikes. When he got off his bike to talk to me, he just asked me if I knew the speed limit, which I had not seen, so I just said, "it's not 55?" (then it was national speed limit law), to which he almost laughed and shook his head. I said, "Well, you got me then." He looked at my bike and fairing and asked, "Is that stock?" and I said, "Mostly". Then he smiled and said, "Look, I know how easy it is to get rolling on a bike, I'm not going to cite you, but you need to slow down." I asked him what the limit was there and he told me 40 MPH, sign back at the hairpin. I explained that I didn't even see it: the sun was right in my face there, and he replied, "yeah, us, too."

I had been close to 100 MPH in that first stretch.

Heck, it was an urgent morning!

And, after I found the traffic jam and took the "long way" around I had already touched 7600+ RPM in top gear on the straighter stretch before the hairpin...