Drive chain jerky
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Joined: Apr 2012
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From: Lexington, Ky
At 38 - if you think about what's happening, you'll understand why it jumps violently like that.
The countershaft has slowed down considerably. The rear wheel hasn't. Because there's slack on the chain, that rear wheel is pushing the chain forward to the countershaft sprocket and it's not spinning as fast, so the chain jumps because it's "bunched" up effectively.
There's a few videos of that kind of stuff here where people have asked about it before - it's usually normal.
https://cbrforum.com/forum/cbr-954rr...-129442/page2/ (look at moosestang's videos)
I didn't see anything in your video that jumped out at me minus the engine misfire. That doesn't mean there's NOT something wrong with the chain, there very well might be considering what kind of chain it is (no o-ring, volar). What size chain did you get? And are you sure you have the correct sprockets? And most importantly, what does the chain feel like when you spin the rear wheel by hand?
And if it's an exhaust leak, I'm saying it's around the head where it meets the header. Does the bike stall out often? With the engine troubles coupled with the not-in-sync carbs, that bike is going to be all kinds of twitchy and jerky on it's own without anything to do with a chain. If you think about what's happening, the carbs are coming off of the idle circuits at different times even though your engine is spinning at the same speed. And because of that minimal exhaust (I can tell it's loud), you'll need to jet it accordingly. I'm pretty sure the stock jets won't suffice even if you have the mixture screws turned way out. I had a slashcut exhaust on my F3 and I had to use the biggest jets that came with the Dynojet kit plus run 3-3.5 turns out on the mixture screws before I felt like it was running correctly.
The countershaft has slowed down considerably. The rear wheel hasn't. Because there's slack on the chain, that rear wheel is pushing the chain forward to the countershaft sprocket and it's not spinning as fast, so the chain jumps because it's "bunched" up effectively.
There's a few videos of that kind of stuff here where people have asked about it before - it's usually normal.
https://cbrforum.com/forum/cbr-954rr...-129442/page2/ (look at moosestang's videos)
I didn't see anything in your video that jumped out at me minus the engine misfire. That doesn't mean there's NOT something wrong with the chain, there very well might be considering what kind of chain it is (no o-ring, volar). What size chain did you get? And are you sure you have the correct sprockets? And most importantly, what does the chain feel like when you spin the rear wheel by hand?
And if it's an exhaust leak, I'm saying it's around the head where it meets the header. Does the bike stall out often? With the engine troubles coupled with the not-in-sync carbs, that bike is going to be all kinds of twitchy and jerky on it's own without anything to do with a chain. If you think about what's happening, the carbs are coming off of the idle circuits at different times even though your engine is spinning at the same speed. And because of that minimal exhaust (I can tell it's loud), you'll need to jet it accordingly. I'm pretty sure the stock jets won't suffice even if you have the mixture screws turned way out. I had a slashcut exhaust on my F3 and I had to use the biggest jets that came with the Dynojet kit plus run 3-3.5 turns out on the mixture screws before I felt like it was running correctly.
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From: Vääksy, Finland
The chain feels fine when I spin it manually. Im looking into getting the factory pro race kit for the carbs, the chain is NOT 0-ring so I might be looking into getting another chain next season. Hoping this one will last for what little time I have left to ride. I still feel like I need to re-lube the chain. Do you think 1.25in of slack is ok? measuring from the bottom part of the chain to the bottom of the swing arm.
I have to make sure so I understood correctly: measuring from the bottom part of the chain to the bottom of the swing arm, you`re getting 1,25in of slack between when you pull the chain up and down, or between the bottom of the chain and swingarm when tensioned upwards? 1,25 of slack should be good, when measured like firstly mentioned.
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Joined: Apr 2012
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From: Lexington, Ky
If it`s a non o-ring chain I`d recommend properly lubing it with regular motor oil and keeping it clean and well lubed to prolong it`s life. Regular spray on chain greases may not get into the link "hinges" well enough. It will fling and smear your rim but it comes off fairly easy with dish washer spray or similar degreaser.
I have to make sure so I understood correctly: measuring from the bottom part of the chain to the bottom of the swing arm, you`re getting 1,25in of slack between when you pull the chain up and down, or between the bottom of the chain and swingarm when tensioned upwards? 1,25 of slack should be good, when measured like firstly mentioned.
I have to make sure so I understood correctly: measuring from the bottom part of the chain to the bottom of the swing arm, you`re getting 1,25in of slack between when you pull the chain up and down, or between the bottom of the chain and swingarm when tensioned upwards? 1,25 of slack should be good, when measured like firstly mentioned.
AACK!!! looks like its about .5 inches.
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That's very tight. And just for SNG, measure a couple of different spots. It should be the same, but since you're skeptical about the chain, go ahead and do a couple of different spots. And watch what the chain looks like when you're spinning it by hand across the rear sprocket. You want to make sure that all of the rollers are fitting onto the teeth the same. The sprockets should have developed a grease line by now, and it'll help you see if one roller looks raised.
Thread Starter
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Joined: Apr 2012
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From: Lexington, Ky
That's very tight. And just for SNG, measure a couple of different spots. It should be the same, but since you're skeptical about the chain, go ahead and do a couple of different spots. And watch what the chain looks like when you're spinning it by hand across the rear sprocket. You want to make sure that all of the rollers are fitting onto the teeth the same. The sprockets should have developed a grease line by now, and it'll help you see if one roller looks raised.
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Joined: Apr 2012
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From: Lexington, Ky
Got the chain lubed up and I drove it around the block and the jerking is still there but no where near as bad. Nearly gone. I got some motor oil and used that to for lube. Chain is not loud as it rolls either.
thx again for everyone's feedback.My next list of items to work on besides riding skills and not being too scared to ride are getting the carb kit and the carbs in sync, and new front tire.
thx again for everyone's feedback.My next list of items to work on besides riding skills and not being too scared to ride are getting the carb kit and the carbs in sync, and new front tire.
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Joined: Apr 2013
Posts: 85
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From: Vegas
On my old chain i had 1 link that was tight and would do the same jerky thing while riding but on the rear stand rolling it by hand it wouldn't do it.
Once i replaced the chain with a X-ring chain and new sprockets it was smooth again and noise free.
Might check to make sure all links pivot smoothly.
Once i replaced the chain with a X-ring chain and new sprockets it was smooth again and noise free.
Might check to make sure all links pivot smoothly.