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Discussion Starter · #1 ·
Hey all, I’m having a couple of issues with an 03 rebel I just purchased recently :confused:
On a shorter ride, one of about 40 minutes, my bike stopped accelerating how it should (loss of power)? In first gear, it no longer stalls when I let go of the clutch, and it inches forward. And when I try to throttle to get up to speed, it stops at around 5 mph and sounds like it’s struggling to go any further. I’ve taken apart the carb and cleaned it, replaced spark plugs, changed oil, and a new air filter is on its way (the old one is scrap at this point). Could my issues be coming from the clutch assembly itself? Is my idle too high? I’ve tried adjusting the clutch lever as well. I’m starting to get at a loss of what to check next. Any help is appreciated, cheers!
 

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Welcome to the forum.

If the lack of acceleration first began in the higher gears, I would suspect the clutch is slipping. Using oil containing friction modifiers can cause that. All 30 weight oils in North America, that are not motorcycle specific, contain friction modifiers. I'm not plugging motorcycle specific oils as I believe they are over priced and no better than many other oils. Currently, all 40 and 50 weight conventional oils do not contain friction modifiers, and that is what the majority of members here use.

A more likely explanation would be the carb wasn't completely clean, or debris in the tank got into the carb. If the tank is rusty, it should be cleaned. Tank Cleaning | Page 5 | Honda Rebel Forum Installing an inline fuel filter helps guarantee a carb remains clean. How To Install a Fuel Filter | Honda Rebel Forum

How was the carb cleaned? Carb spray isn't sufficient to clean a dirty carb. Disassembling it and soaking only the metal parts in Berryman Chem Dip for 2-7 days, then thoroughly rinsing it with water and blowing out all the orifices with high pressure compressed air should get it clean.
 

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Discussion Starter · #3 ·
Previous owner isn’t sure what kind of oil was in the bike, but I’ve replaced it with Valvoline 10W-40 motorcycle 4-stroke. I haven’t soaked the carb, but I will just for the extra assurance. The power loss started in a higher gear, and it translated to first gear now as well, so I’d think the clutch is still slipping. I’ll check the tank to see if it’s rusty. What would be the second most likely explanation other than the carb and fuel tank?
 

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Once an oil with friction modifiers is used, the fiber clutch discs are ruined and have to be replaced. It wasn't clear to me from your description if the engine is running normally or if it's a clutch issue. Are you using the fuel enrichment (choke) lever when starting and gradually pushing it off as the engine warms? Can you rev the engine once it is warm? If yes, and since the "power loss" began in a higher gear, I would say it's a clutch issue. Clutch slippage due to improper oil usually manifests itself in the higher gears and becomes progressively worse in each gear. There should be about 3/8" - 3/4" of free play at the end of the clutch lever before resistance is felt. Hopefully, yours is just a clutch lever that needs to be adjusted. Rather than take a shotgun approach to mechanical issues, eliminate the simple things first, and then progress to the more involved (clutch lever adjustment, clutch repair, carb cleaning, tank rust removal, etc.).

What service manual do you have? Following the Clymer manual on how to replace damaged clutch discs can ruin your transmission. Don't ask me how I know this.
 

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Discussion Starter · #5 ·
Once an oil with friction modifiers is used, the fiber clutch discs are ruined and have to be replaced. It wasn't clear to me from your description if the engine is running normally or if it's a clutch issue. Are you using the fuel enrichment (choke) lever when starting and gradually pushing it off as the engine warms? Can you rev the engine once it is warm? If yes, and since the "power loss" began in a higher gear, I would say it's a clutch issue. Clutch slippage due to improper oil usually manifests itself in the higher gears and becomes progressively worse in each gear. There should be about 3/8" - 3/4" of free play at the end of the clutch lever before resistance is felt. Hopefully, yours is just a clutch lever that needs to be adjusted. Rather than take a shotgun approach to mechanical issues, eliminate the simple things first, and then progress to the more involved (clutch lever adjustment, clutch repair, carb cleaning, tank rust removal, etc.).

What service manual do you have? Following the Clymer manual on how to replace damaged clutch discs can ruin your transmission. Don't ask me how I know this.
I don’t have any service manual as far as I’m aware, and I’ll have to make sure I’m adjusting the clutch correctly before assuming it’s a clutch part gone bad. I went ahead and threw the carb in some berrymans to soak, since I’m waiting on an air filter anyways. The engine seems to run fine, I’m able to use choke t get it started and slowly close it as it warms, and I can rev the engine, it just doesn’t accelerate like it should. For some reason If I dump the clutch on first gear, the bike doesn’t stall either. It was working fine for the first half of the ride, but it felt like it could have been shifting weird.
 

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Discussion Starter · #6 ·
Also, when I took apart the carb, I was following a guide. Didn’t say to count the revolutions of the jets until the very end, after everything was taken apart. Am I SOL here? Or is there a baseline that I can set the jets to?
 

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If the engine runs well, but the bike doesn't accelerate properly, it sounds like the clutch may be slipping. The classic symptoms of a slipping clutch are the bike speed will not increase when engine rpms increase. It begins in the upper gears, and then over time progresses to lower ones. Eventually, maintaining speed and acceleration in the upper gears becomes impossible, followed by the lower gears over time. If you need to replace the clutch plates, you will definitely need a manual. The Honda service manual is best IMO.

The slow and main jets are not adjustable. Simply tighten them until snug. Only the pilot screw (#5 in this diagram), and the idle adjustment (#10) are adjustable. The initial adjustment of the pilot screw is 2 3/4 turns out from lightly seated. Do this before mounting the bowl, which has a projection to limit how much the pilot screw can be turned, to the rest of the carb. The idle should be set to 1,400 rpm, plus or minus 100 rpm. Do this when the engine is thoroughly warm. 2009 Honda CMX250C A CARBURETOR | Cheap Cycle Parts The carb is essentially the same for all 1996-2016 250 Rebels, so don't worry that the diagram says it's for a 2009.
 

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Discussion Starter · #8 ·
I’m looking into replacing the clutch discs and such, but is there a manual that’s superior? Does the manualslib website have an up-to-date manual compatible with my 2003? If it doesn’t, would you be able to share the clutch section with me? And finally, what are the torque specs for everything I’d be messing with on the clutch? Will I need to replace the center lock nut? And do I need a special tool to hold the clutch together?
 

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You can't go wrong with a Honda service manual. It will have all the info you need.
 

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Discussion Starter · #10 ·
Thanks! I’ll look into grabbing one of those :)
But what are the torque values for the screws and nuts when reassembling the clutch? I could only find the values for the 4 plate screws I believe.
 

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Maybe someone can share that section of the manual; it's a little more than I want to transcribe. Plus you're going to need the manual before diving into the clutch. There are work arounds for the special tools the manual may specify. Suggest you get a new lock nut as well.
 

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Discussion Starter · #12 ·
Yep! I have a new locknut on the way already, no clutch plates yet. Been having trouble deciding which brand to get! I’ve heard kg clutch factory Kevlar are good, but I couldn’t find a solid website to buy a kit from. Also, a new issue has come up. I ran the bike last night, and it can slowly get up to speed. I got it up to 25 mph, and tried to shift it into 2nd. It shifted but It didn’t seem like there was much change in speed, and the engine was running hard. Sounded like it was running harder than it should. After coming back from the test ride, I noticed a thin amount of smoke coming out of the right exhaust only. Lighter in color, as if it was a white, slightly grey smoke. Any idea why it would only be in the right side? I’m going to open up the side tonight and take a look at the clutch.
 

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Maybe someone can share that section of the manual; it's a little more than I want to transcribe. Plus you're going to need the manual before diving into the clutch. There are work arounds for the special tools the manual may specify. Suggest you get a new lock nut as well.

Excuse me for butting in here. What are friction modifiers? I think I used a straight 30W when I changed mine. Should I change again?
 

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Friction modifiers are the additives that make energy conserving oil energy conserving. My understanding is they make the oil more "slippery", reducing friction, and improving fuel economy.

If the oil you used in the Rebel contained friction modifiers (see below), it's probably already too late. I did this with my first Rebel and it didn't take much time at all before the clutch started slipping.

The circular logo on the back of oil containers used to say "energy conserving" or "resource conserving" if they contained modifiers. I'm not sure if all energy conserving oils still do. The letter designation SN on the back of the container indicates that the oil contains friction modifiers.
 

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SM and older API spec oil had the "energy conserving" or other warning tag in the bottom half of the doughnut, SN (and up) it's a given they have them.
"Them" being molybdenum
Motorcycle wet clutch safe oils are usually the quite old spec SJ, but more important is you want to see JASO MA on the label, meaning it's certified for wet clutches.
 

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