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Discussion Starter #1
Hello,

I rebuilt the carbs twice to find out the points had a pinched wire so that's taken care of however, whenever I'm in gear, clutch in, the bike will start to rev high on its own and almost redlines when I give it the tiniest amount of gas. I was riding down the street and it just kept going with zero throttle and then stops accelerating after a second or two. It's extremely scary not being able to control the bike when your need to decelerate. I also recently changed the bars and am thinking it's the throttle cable or control but not exactly sure.

Lastly, the bike rides really rough and slips out of 2nd gear. should i start with value adjustment and cam chain?

Any recommendations on where I should start would be greatly appreciated!

Thank you!
 

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First, you should post an introduction so we can get to know you (mechanical background/skills/aptitude, bike experience in general) and your bike. Since you changed the bars, cable routing could easily be a factor and pictures always help. Cam chain and valve adjustments are always helpful on an older bike, but that is not going to help your 2nd gear problem... and I can tell you with certainty that if you continue to ride it and let it jump out of second gear, you'll be doing further damage to things that might just be okay right now - shift forks - and that will require a bottom end teardown and repair. Right now, it's probably the shift detent mechanism and related worn parts at fault, it's a pretty typical issue with 450s as the parts age. Trying to answer questions like this without any visual aid is the reason introductions with pictures are helpful
 

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What exactly did you do on the carbs when you stated you rebuilt them. What did you replace exactly?
Here's a quick check list based on what you told us so far.

1. Take the tank off and see if the revving issue continues. If not then you have a throttle cable routing issue and something is caught up somewhere. What bar did you change to? Again more details and pics would help
2. If the Revving continues then likely you have a vacuum leak somewhere either on the carbs or the boots. Check by spraying some carb cleaner around the boots and carb bodies to see if the idle suddenly picks up.
3. If there is no vacuum leak as checked from above then check your ignition advance and see if something there is stuck.
4. Regarding the gear slipping, what oil are you using? You cannot just use regular automotive oil in these bikes since they have wet clutches. You need to use oil rated for JASO MA
Rotella T4 is a cheap good choice for this.
If everything else checks out then it's probably the shift detent mechanism like Tom stated above.
 

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Discussion Starter #4
Thank you so much guys! I'm going to try my best to get to all of your questions asap however I just noticed the throttle linkage is hanging up and gets stuck when playing with the throttle. I can push it back down easily but every time it hangs up mid way and won't go back down.

Still trying to figure out how to post pictures through replys
 

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Discussion Starter #7
Hi 76 Twin. So the guy who was working on it rebuilt the carbs so I honestly do not know if he replaced anything. I had no issue with this previously, so I definitely know it happened in his hands.

Took the tank off and the cables seem to be perfectly fine and synced. At first I thought it was fixed when I removed the tank but then link got stuck again. I can feel tension once its raised above the halfway mark (image attached). I believe this is why I had no control and kept accelerating

I just got some regular bars from Common Motors - https://www.common-motor.com/honda-superbike-bars

Thanks for the oil recommendation! I really appreciate it! I use Rotella for my old diesel and is some good stuff!
IMG_20190721_183239.jpg
IMG_20190721_183406.jpg
 

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Call him up and ask for for original carb parts if he still has them. The reason why I say that most aftermarket carb rebuild kits do not have the properly sized jets and needles and will cause all kinds of problems.
Unless they are damaged, I have never found a reason to replace any brass parts (jets, needles, etc...) on the carbs. The only things needed to be replace were gaskets and o-rings.

Take your throttle cable off and check to see if it is moving freely. It maybe partially broken or kinked inside and causing the hang up. Replace as needed.
 

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Also see if the throttle cable has curled at the ends where it connects to the carbs, this can also hold the carbs open.
 

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Discussion Starter #10
Removed the cable and it still sticks. Do you have any recommendations on a good carb rebuild kit? Im worried its the spring.
 

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Check alignment of the butterflies in the bores, you might just need to loosen them and realign them if they are dragging on the bore wall.
 

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Take a look at the clutch cable in the upper picture in post #7 - it looks like the inside throttle arm is hanging on the clutch cable, which is curved backward

View attachment 286824
I was wondering how long it would take someone to notice that...........
 

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So you were torturing everyone while knowing all along?? :lol: :lol: :lol:

It's a close juxtaposition the cable has with the left carb (Mikunis solve that problem, but certainly not worth doing on a stock bike just for that)
 

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Discussion Starter #15
False alarm, it was the cable. One is crimped while the other is straight. Going to order a new one today. Thanks guys! Also, I noticed the boot was cracked so I will get that as well.
 

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Discussion Starter #16 (Edited)
Will the detent mechanism be an easy fix or does that require a full teardown? What should I be looking for when I find the detent mech, loose, chipped, etc.. Just want to be prepared for when I do get to this part of the project.

Are parts readily available and if so where is the best place to go?

Right now I'm at 25,000K miles and am considering a full teardown if necessary.
 

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Yeah, the detent mechanism parts are pretty much unobtanium at this point. The prime suspects are the larger detent roller of the two (commonly referred to by some as a pizza cutter) and the star-shaped part on the end of the shift drum, which gets worn on the tips of the star causing sloppy location of the shift drum (which moves the shift forks to the exact spot for positioning the gears for the proper speed you select). It can all be accessed under the clutch inside the right crankcase cover without a full teardown, but my warning previously was in case you (or the PO) had ridden the bike long enough that the shift forks had already suffered wear or being bent by the trans kicking out of second. Sometimes you can buy the "pizza cutter" on eBay, but no point in doing so unless you find someone selling a NOS part

450shift drum.jpg
 

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