Troubleshooting and Chain Skipping

Let's also talk about this 'fluff' someone mentioned. What exactly do you mean by that? My post was carefully crafted with some time and effort, covering all the necessary details. It took me several hours to put together, so pardon me if I'm not exactly in the mood for jokes right now. Let's aim for something constructive. I ensured clarity and provided every fact, not just for myself but for our collective understanding. Criticism can be valuable, but there's a fine line between something constructive and outright disrespect. Constructive criticism is about growth and improvement, rooted in empathy and respect. It's crystal clear there's a lack of empathy and maturity in your approach. Your criticism definitely inhibits collaboration and fosters pessimism. Let's not sacrifice thoroughness for brevity, shall we?
All wordiness aside looks like Wrench has answered your question. I would add that your sprockets are either machined incorrectly or don't match your chain or vice versa. The roller diameter of the chain could be too large for your sprockets causing it to ride up. See the attached chart.

Chain size chart.png
 
Welcome everyone,

I recently put together another 2 stroking motorized bike (100cc) and had the worst time doing so. Two months ago, I’ve run into a huge problem that I need help with. The chain on my bike wobbles way too much and skips when the engine is idling. It's pretty much annoying because I want the bike to run smoothly at all times.

Here are a few details that might help figure out the issue:

The chain is brand new and well-lubricated.
I’ve checked the alignment multiple times, and it looks and is straight.
The chain tension seems right—not too tight or too loose.
The sprockets are in good shape with no significant wear.
Despite these precautions, the chain still struggles and skips when the engine is idling. It seems to catch and then slip, creating a jerky motion. Once I start moving, the problem becomes less noticeable but still persists to some extent.

I’ve tried a few adjustments to fix the issue:

Rechecking and readjusting the chain tension.
Ensuring the engine mount is secure with no excessive vibration.
Checking the clutch to make sure it’s working properly.
Looking for any obstructions or debris that might be affecting the chain’s path.
So far, none of these efforts have completely solved the problem. The persistent skipping and struggling of the chain makes me worried about long-term damage to both the chain and the sprockets. I’m also concerned about the overall safety and reliability of the bike.

Has anyone else experienced a similar issue with their motorized bike? If so, what steps did you take to resolve it? Are there any specific adjustments or checks that I might have overlooked? Additionally, are there any recommended products or modifications that could help ensure smoother operation at idle?

I’m open to any suggestions or advice. If you need more information about the bike setup or the specific components I’m using, please let me know, and I’ll provide as much detail as possible. Your expertise and experience would be greatly appreciated as I try to get my motorized bike running smoothly.

Another aspect I haven’t thoroughly explored yet is the potential impact of the engine’s RPMs during idle. I suspect that the engine might be idling at an improper speed, which could be contributing to the chain issues. If the engine is idling too high or too low, it might cause the chain to skip due to inconsistent power delivery.

Here are a few more technical details about my setup:

I’m using the default carburetor, which has been tuned to the best of my knowledge.
The clutch is a standard centrifugal clutch, which engages at low RPM.
Given this setup, do you think the problem could be related to the carburetor settings or the clutch engagement? I’ve read that improper carburetor tuning can cause uneven engine performance, which might translate to chain issues. Similarly, if the clutch engages too early or too late, it might cause the chain to struggle.

Another possibility is that the engine’s vibrations at idle are affecting the chain's performance. Even though the engine mounts seem secure, vibrations can sometimes transfer through the frame and cause issues with the chain. I’m considering adding dampening materials or reinforcing the mounts to reduce vibration. Has anyone had success with such modifications?

Additionally, the condition of the clutch might be contributing to the problem. If the clutch is not engaging smoothly or if it is partially engaged at idle, it could cause irregular tension in the chain. Inspecting and possibly replacing the clutch components might be necessary. Does anyone have experience with clutch-related chain issues on motorized bikes?

Another point of investigation is the lubrication of the chain. Although I have lubricated the chain, it’s possible that the type of lubricant I am using is not optimal. I’ve read that certain lubricants can attract dirt and debris, which might exacerbate chain skipping. What lubricants do you recommend for a smooth-running chain that is less prone to skipping?

Furthermore, the rear wheel alignment plays a crucial role in chain performance. Ensuring that the rear wheel is perfectly aligned with the frame and the front wheel can prevent the chain from binding or skipping. I’ve aligned the rear wheel to the best of my ability, but perhaps there are techniques or tools that can help achieve better precision.

Another consideration is the overall quality of the chain and sprockets. Even if they are new, manufacturing defects or subpar materials can lead to issues. Investing in high-quality components might be a worthwhile solution. If anyone has recommendations for reliable brands or specific models of chains and sprockets that have worked well for them, please share your experiences.

Moreover, the tensioner’s effectiveness is something I need to re-evaluate. A spring-loaded tensioner might not provide consistent tension, especially if the spring weakens over time. Upgrading to a mechanical tensioner or one with more robust construction might help maintain proper chain tension. Does anyone have experience with different types of tensioners and their impact on chain performance?

To diagnose the problem, I plan to perform a series of tests to isolate the cause. These include running the engine at different idle speeds, observing the chain behavior under varying loads, and checking the clutch engagement at different RPMs. By systematically testing these variables, I hope to pinpoint the exact cause of the chain skipping.

If anyone has suggestions on specific tests or diagnostic procedures that could help identify the issue, I would greatly appreciate your input. Detailed advice on what to look for during these tests would be very helpful.

Lastly, I am considering the overall balance and weight distribution of the bike. An uneven weight distribution might cause the chain to wear unevenly or skip under certain conditions. Ensuring that the bike is balanced and that the weight is evenly distributed might help alleviate some of these issues. Has anyone found that weight distribution significantly impacts chain performance on their motorized bike?

Another thing I've been thinking about is whether the chain itself might be defective. Even though it's brand new, there's always a chance that there's a manufacturing defect. It might be worth swapping out the chain with a different one to see if that solves the problem. If anyone has had a similar experience where a new chain was faulty, I'd hear about it.

I've also read that the type of chain tensioner used can have a big impact on performance. I'm currently using the default tensioner, but I've heard that these can sometimes fail to maintain consistent tension, especially as the ages. I'm considering switching to another tensioner, which might provide more stable tension. Has anyone made this switch, and did it help with chain skipping issues?

Another aspect to look at is the condition and alignment of the sprockets. If the sprockets are worn or misaligned, they can cause the chain to skip. I’ve checked the sprockets and they appear to be in good condition, but I'm open to the idea that a more precise alignment or even slightly different sprockets might make a difference. Any tips on how to ensure perfect sprocket alignment would be greatly appreciated.

I also wonder if the engine’s idle speed might be contributing to the problem. If the engine idles too high or too low, it could create inconsistent power output that affects the chain. Adjusting the idle speed might help smooth out the power delivery and prevent the chain from skipping. Has anyone found that fine-tuning the idle speed resolved similar issues?

One more thing I plan to investigate is the overall balance of the bike. If the weight is not evenly distributed, it might cause uneven wear or tension on the chain. Balancing the bike properly could help ensure that the chain runs smoothly. If anyone has experience with how weight distribution affects their motorized bike, I'd be interested in hearing about it.

In addition to these mechanical checks, I’m also thinking about the quality of the components I’m using. Sometimes, even new parts can be of low quality and cause problems. Investing in higher-quality chains, sprockets, and tensioners might be a good long-term solution. If anyone has recommendations for reliable brands or specific models that have worked well, please let me know.

I also plan to do some practical tests to get to the bottom of this issue. For instance, I will try running the engine at different speeds to see how the chain reacts, and I’ll observe the chain’s behavior under various loads. By systematically testing different variables, I hope to identify what’s causing the chain to skip. If anyone has suggestions on specific tests or things to watch for during these experiments, I’d appreciate the guidance.

Lastly, it might be worth looking into how the clutch engages. If the clutch is not engaging smoothly or if it partially engages at idle, it could create uneven tension on the chain. Checking and possibly replacing the clutch might be necessary. Has anyone dealt with clutch-related chain problems, and what solutions did you find effective? Given all these potential factors, I think a systematic approach to diagnose and fix the chain skipping issue is essential. Here’s what I plan to do next:

Re-evaluate Chain Tension: I'll start by double-checking the chain tension. While I've adjusted it before, I want to ensure it's within the optimal range. Sometimes, even a slight adjustment can make a significant difference.

Inspect Engine Mounts and Vibration: I'll look into adding dampening materials to the engine mounts to reduce vibrations. Excessive vibration can cause the chain to skip, so minimizing this could help stabilize the chain’s movement.

Fine-tune Carburetor Settings: I'll adjust the carburetor settings to ensure the engine runs smoothly at idle. A properly tuned carburetor can provide consistent power output, reducing the chances of the chain skipping.

Test Different Idle Speeds: Experimenting with various idle speeds might help identify if the problem is related to how the engine is running when not under load. I’ll try setting the idle speed slightly higher or lower to see if there’s an improvement.

Upgrade to a Mechanical Tensioner: If adjusting the current spring-loaded tensioner doesn’t help, I might upgrade to a mechanical tensioner. These typically provide more consistent tension and could help reduce chain skipping.

Check Sprocket Alignment and Condition: I'll use more precise tools to ensure the sprockets are perfectly aligned. Any misalignment, even minor, can cause chain issues. If necessary, I'll consider replacing the sprockets with ones that might be better suited for my setup.

Examine Clutch Engagement: I'll inspect the clutch to see if it’s engaging smoothly. If it’s partially engaging at idle, this could cause inconsistent chain tension. Replacing or adjusting the clutch might be necessary.

Ensure Proper Lubrication: I'll verify that the lubricant I'm using is suitable for the chain and the conditions in which I ride. Switching to a high-quality lubricant designed for motorized bikes might help keep the chain running smoothly.

Test Different Chains: If all else fails, I might try a different chain to rule out any defects with the current one. Sometimes, even new chains can have manufacturing flaws that cause performance issues.

Balance and Weight Distribution: I'll ensure the bike’s weight is evenly distributed. Uneven weight can cause uneven wear on the chain and sprockets, leading to skipping.

Seek Professional Help: If I can’t resolve the issue myself, I’ll consider taking the bike to a professional mechanic who specializes in motorized bikes. They might have insights or tools that I don’t have access to.

Engage with the Community: I’ll continue to engage with the motorized bike community for advice. Forums, social media groups, and local clubs can be invaluable resources for troubleshooting and finding solutions.

Document Everything: Throughout this process, I’ll keep detailed notes on what adjustments I make and the results. This will help track what works and what doesn’t, making it easier to pinpoint the issue.

Review Component Quality: I’ll reassess the quality of all components, including the chain, sprockets, tensioner, and clutch. Sometimes, investing in higher-quality parts can prevent issues and improve overall performance.

Consider Professional Tuning: If adjusting the carburetor and other components doesn’t yield results, I might seek out a professional tuning service. Experts can often fine-tune engines and components to ensure everything works harmoniously.

By following this comprehensive plan, I hope to identify the root cause of the chain skipping issue and implement a lasting solution. It’s disappointing to deal with, but with persistence and the right approach, I’m confident I can get my motorized bike running smoothly. I’m also considering the possibility that the engine's power output at idle might be inconsistent. Even though the engine seems to run fine, small fluctuations in power delivery could be affecting the chain's performance. To address this, I’ll look into the following steps:

Check Fuel Quality and Mixture: Ensuring that the fuel mixture is correct and using high-quality fuel can make a big difference in engine performance. I’ll double-check the fuel mixture ratio and possibly try a higher-octane fuel to see if it helps stabilize the idle.

Inspect Spark Plug and Ignition System: A malfunctioning spark plug or ignition system could cause inconsistent power output. I’ll inspect the spark plug for wear and replace it if necessary. Checking the ignition system to ensure it’s delivering consistent sparks could also help smooth out the engine’s idle.

Evaluate Air Filter and Intake System: A clogged air filter can restrict airflow to the engine, affecting performance. I’ll clean or replace the air filter and inspect the intake system for any obstructions that might be causing uneven air supply to the engine.

Compression Test: Performing a compression test on the engine can help determine if there are any internal issues affecting performance. Low compression can lead to inconsistent power output, which might be causing the chain to skip. If the compression is low, further investigation into the engine’s internals might be necessary.

Examine Exhaust System: A restricted exhaust system can cause back pressure issues, affecting engine performance. I’ll inspect the exhaust system for any blockages or restrictions and ensure it’s functioning properly.

Balance Flywheel: An unbalanced flywheel can cause vibrations that affect engine performance and, subsequently, the chain. I’ll check the flywheel balance and have it professionally balanced if necessary.

Upgrade Components: If the problem persists, I might consider upgrading certain components. High-performance carburetors, spark plugs, and ignition systems can sometimes resolve issues that standard parts cannot. Investing in better components could provide a more stable and reliable setup.

Engine Mounting System: Ensuring the engine is securely mounted with proper vibration dampening can make a significant difference. I’ll explore different mounting options and materials that might reduce vibration and improve overall stability.

Chain Path Inspection: I’ll inspect the entire chain path for any potential points of interference or misalignment. Even a slight obstruction or deviation can cause the chain to skip. Ensuring a clear and straight path for the chain can help maintain consistent tension and smooth operation.

Community Feedback: I’ll actively seek feedback from the community, sharing detailed descriptions and possibly videos of the issue. Sometimes, seeing the problem in action can help experienced individuals diagnose the issue more effectively. Engaging with community members who have faced similar problems can provide valuable insights and potential solutions.

Professional Assessment: If all else fails, I’ll consider taking the bike to a professional mechanic who specializes in motorized bikes. A professional might have the tools and expertise to diagnose and fix the issue more efficiently than I can on my own.

Continuous Learning: I’ll continue to educate myself about motorized bike mechanics and maintenance. Understanding the intricacies of how each component works and interacts with others can help me better diagnose and fix issues in the future.

Preventive Maintenance: Implementing a regular maintenance schedule can help prevent future issues. Regularly checking and adjusting the chain tension, lubricating the chain, inspecting the engine and components, and ensuring everything is in good working order can help maintain the bike’s performance and reliability.

Documentation: Keeping detailed records of all adjustments, tests, and observations will help me track what works and what doesn’t. This documentation can also be valuable if I need to seek further assistance or decide to share my findings with the community.

Optimizing Performance: Beyond just fixing the chain skipping issue, I’ll look for ways to optimize the bike’s overall performance. This might include fine-tuning the carburetor settings, upgrading to more efficient components, and ensuring the bike is balanced and well-maintained.




Through a combination of these steps, I again hope to identify and resolve the root cause of the chain skipping issue on my motorized bike. I’m committed to making this bike run smoothly and efficiently, and I appreciate any advice or suggestions from those who have more experience. Another area of consideration is the overall structural integrity of the bike's frame. If there are any slight bends or imperfections in the frame, it could affect how the chain operates. Even if everything appears to be in good condition at a glance, a thorough inspection might reveal small misalignments or weaknesses that could be contributing to the issue. I plan to closely examine the frame, looking for any signs of wear or misalignment that might be causing the chain to skip. This includes checking the connection points where the engine is mounted to ensure they are solid and secure. I'll also pay special attention to the rear axle. If the rear axle is not perfectly aligned or if it has any slight bends, it could affect the chain’s path and tension. Ensuring that the rear axle is straight and properly aligned with the frame could help reduce the chances of the chain skipping. In addition to this, I'll check the wheel bearings to make sure they are in good condition and not causing any additional drag or resistance that might affect the chain. The quality of the chain itself is another potential factor. Although the chain is new, there could be manufacturing defects or inconsistencies that are not immediately visible. Swapping out the chain for a different one might help determine if the chain itself is the source of the problem. I'll also consider upgrading to a chain known for its durability and performance, especially if it's recommended by others who have experience with motorized bikes. Another potential issue could be the rear sprocket's condition and material. Even if it appears to be in good shape, the material and design of the sprocket could influence how well the chain grips and moves. I'll research different types of sprockets and consider whether switching to a more durable or better-designed sprocket might help solve the issue. Ensuring that the sprocket teeth are not worn down and that they properly match the chain's specifications is crucial. The engine’s performance at idle might also be playing a significant role. Even small fluctuations in engine speed can cause the chain to skip. I'll pay close attention to how the engine behaves at different idle speeds and consider fine-tuning the carburetor and ignition system to achieve a more stable idle. This might involve adjusting the air-fuel mixture, ensuring that the spark plug is firing consistently, and checking the overall timing of the engine. One often overlooked aspect is the lubrication of the chain. While I have been using a specific type of lubricant, it’s possible that it’s not the best choice for my setup. Some lubricants can attract dirt and debris, which can lead to uneven chain performance. I'll experiment with different types of lubricants recommended for motorized bikes, aiming for one that provides a smooth, consistent coating without attracting too much grime. In addition to these mechanical adjustments, I'll also consider the ergonomics of my riding style. If the way I ride is putting undue stress on the chain or any other components, it might be contributing to the issue. I'll pay attention to how I accelerate, decelerate, and handle the bike at different speeds, making adjustments to my riding habits if necessary. Throughout this process, I'll document each change and its effect on the bike's performance. Keeping a detailed log of what I've tried and the outcomes will help me track progress and avoid repeating the same steps unnecessarily. It will also be useful if I need to seek further advice or share my findings with the community. Engaging with others who have more experience with motorized bikes will be invaluable. I'll actively participate in online groups, sharing my detailed descriptions and possibly videos of the issue. Feedback from experienced riders and mechanics could provide new perspectives and solutions that I haven't yet considered. Sometimes, a fresh pair of eyes can spot something that has been overlooked. If these steps do not resolve the issue, I will not hesitate to consult with a pro who specializes in motorized bikes. Their expertise and specialized tools might help diagnose and fix the problem more effectively. Professional mechanics can often identify subtle issues that might be missed by a less experienced person. Preventive maintenance will become a regular part of my routine to avoid future issues. This includes regularly checking and adjusting the chain tension, lubricating the chain, inspecting the engine and components, and ensuring that everything is in good working order. Preventive measures will not only help maintain the bike's performance but also extend its lifespan. Ultimately, the goal is to have a motorized bike that runs smoothly and reliably without the chain skipping at idle. It’s a frustrating issue, but with patience, persistence, and the right approach, I’m confident that I can resolve it. I appreciate any advice or suggestions from those with more experience, as their insights could be crucial in finding a solution. In addition to all the mechanical adjustments and checks, I'll also consider the impact of environmental factors on the bike’s performance. Temperature, humidity, and even altitude can affect how the engine runs and how the chain behaves. I’ll keep track of these conditions when the chain skips to see if there’s a pattern. If I notice that the problem is worse in certain conditions, this could help me narrow down the cause. For example, high humidity might affect the carburetor’s performance or the chain’s lubrication. Moreover, I will evaluate the overall setup of the bike, including any custom modifications I have made. Custom parts and modifications, while often beneficial, can sometimes introduce unforeseen issues. I'll carefully review each modification to ensure that it is not contributing to the chain skipping. This might include aftermarket engine mounts, custom exhaust systems, or non-standard sprockets and chains. Another area to explore is the possibility of external vibrations affecting the bike’s components. Vibrations from the road surface or from the engine itself can cause components to move slightly out of alignment over time. I'll look into ways to dampen these vibrations, such as using rubber mounts or other vibration-absorbing materials. This could help keep the chain in better alignment and reduce the chances of skipping. One of the more advanced steps I'll take is to perform a detailed inspection of the drivetrain under different loads. By testing the bike with varying levels of throttle and observing how the chain behaves, I might be able to identify specific conditions that cause the chain to skip. This can involve using a stationary stand to run the bike at different speeds and loads without actually riding it. Observing the chain and sprockets closely under these conditions might reveal subtle issues that are not apparent during normal riding. I'll also look into the possibility of electronic solutions. Some modern motorized bike systems come with electronic controllers that can help manage engine performance more precisely. If my current setup is compatible, I might consider upgrading to an electronic controller that can provide more consistent power delivery and reduce the chances of the chain skipping. Networking with local bike enthusiasts and mechanics is another strategy I’ll pursue. Sometimes, face-to-face discussions and hands-on help can make a significant difference. Local experts might have experience with the specific conditions and issues common in my area, providing tailored advice that online forums can’t offer. As part of my ongoing maintenance and troubleshooting, I'll ensure that I have all the necessary tools and parts on hand. This includes a complete set of wrenches, screwdrivers, lubricants, spare chains, sprockets. I’m looking forward to hearing your insights and finding a solution soon.

 
Jumpy jerky chain…

1 Out of round sprocket(s)
Either or both machined bad

2 Off center mounted rear sprocket

3 Clutch issue

4 Tune issue

Or a combination of 2 or more things listed.
 
Boy! what a tough crowd we all are. I'm starting to feel like some of my posts are too long now.

I admit I only read 70% but got a pretty good picture. First make sure the chain fits properly in both of the sprockets without binding. If it's "skipping" over the teeth it would be waaay to loose and/or totally out of alignment. If you truely put as much effort into checking this as you did writing about it, I'm sure it's OK. The way I check alignment is to "C" clamp wood yard stick to my rear sprocket and point it at the little one until it just touches. That's straight enough. My gut tells me you have a chain issue.

The big question is ............. why is the chain jumping at idle. The clutch should not be engaged so the chain should not be moving. Idle speed has nothing to do with your problem.
 
I find it quite humorous that we all agree on what OP's problem is, but he thinks he's already got it figured out!

It's also funny that OP says it's a 100cc 2 stroke, and says it has a centrifugal clutch. The only 2 stroke that is stock with a centrifugal clutch is the BT80, which I am very familiar with lol. I wonder if all the issue is is user error (not knowing the clutch is manual lmao).

You should be more open to help buddy, otherwise you're just gonna have to figure things out on your own.
 
OP, pictures from the rear showing chain alignment is needed. Picture from the side showing chain on the sprocket, 3ft away and closeups. Not to pile on, that post hurts to read it. Welcome to the forum OP.
 
Quit being a dick, Dick
Speak like this to any member here again, and you will find yourself taking a vacation. The fact that you spoke like that to a Forum Moderator is the most entertaining part. That's akin to putting your body inside a sharks mouth and saying "bite me."

You have been given a warning. Take it as a sign.
 
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