Honda Twins banner
1 - 20 of 21 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
I'm new here. I have an 86 Rebel 250cc Limited Edition. The lady I bought it from said it's always sounded this way. I have had it for 8 months and nothing has broken on it.

It sounds like a Diesel. I've pulled the cylinders, checked the timing chain for tension while running, took the starter chain off and push started it. A mechanic told me it can't be the Crank end bearing as that's a Growling sound. It can't be piston slap because it will go away after it warms up and the piston expands.
It's not the transmission. When it's in gear and the clutch pulled in, nothing in the trans is moving until I release the clutch so that eliminates the trans.
The noise it there whether Idling, riding 60 MPH, etc. All other Rebels I have listened to are quiet with no engine rattle. I"m out of ideas.
Here is a link to my Youtube showing the sound. Some of the background noise is a truck going past.

I sure hope someone can help me.

Thanks
 

·
Registered
Joined
·
3,926 Posts
It's super hard to tell from a video like that but I'd have to take a wild guess and say it's a loose cam chain. BUT, when you shut it down I didn't hear the typical "clack". So as I say it's just a guess...

Could be any (internal) chain on it as I'm not familiar with that model really..


GB :mrgreen:
 

·
Sensei
Joined
·
27,180 Posts
That "rattley" sound is likely the tappets and cam chain.... Adjust the chain first, then see if it persists.......
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #4 ·
It only has one chain. No matter where I put a stethescope, it sounds the same everywhere. I ran it with the valve cover off and pressed a screwdriver against the cam chain tensioner in hopes I could tighten it up more but it was already tight. There isn't anyway to adjust the chain tension. They automatically adjust.

Loose tappets is usually a clicking sound. I can put my hand on the side cover and feel it making the noise unlike other Rebels.

I used to be an Auto Mechanic and I could tear the engine down and know what I was looking for but on a bike, I'd be tearing it down BLIND not knowing where to look.

Stupid Honda dealer looked at it and said "hmmm we don't have problems with Rebels" then walked away. Guess he wanted a Blank Check before he would give me any idea what it could be.
I'll try to get a better sounding video.

thanks guys.
 

·
Premium Member
Joined
·
5,610 Posts
Rustybux said:
Stupid Honda dealer looked at it and said "hmmm we don't have problems with Rebels" then walked away. Guess he wanted a Blank Check before he would give me any idea what it could be.
That's unbelievable :shock:

Yeah, maybe a better video would help everyone hear it better.
 

·
Premium Member
Joined
·
771 Posts
Hmmm..... well, I had a CM185T a few years back and that motor is the daddy of your Rebel. You're right, normally, they don't make ANY noise.

You've checked timing chain and starter chain. Valves out of adjustment is ticking not rattling as you mentioned (I didn't listen to your video). I'm thinking piston slap (which will NOT go away as it warms up if the clearance is bad enough) or something loose in the primary / clutch side. Pull that clutch cover off and have a look, it ain't rocket science. :D


Ah, I just had a quick look at some old pictures of that Twinstar, and there are quite a few things under that clutch cover - the primary gear drives the clutch AND the oil pump, either of which could be rattling / loose. Also in there is the clutch lever mechanism. Also in there is the kickstarter shaft and return spring arrangement. Also in there is the shifter star-wheel and return spring mechanism. Any of those things could be loose and rattling.

And, I can't imagine this is it, but maybe it's something loose on the OUTSIDE rattling against the motor - footpegs, motor mounts, exhaust, etc.

Good luck with it.

Kirk
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #8 ·

·
Registered
Joined
·
10 Posts
Discussion Starter · #9 ·
kirkn said:
Hmmm..... well, I had a CM185T a few years back and that motor is the daddy of your Rebel. You're right, normally, they don't make ANY noise.

You've checked timing chain and starter chain. Valves out of adjustment is ticking not rattling as you mentioned (I didn't listen to your video). I'm thinking piston slap (which will NOT go away as it warms up if the clearance is bad enough) or something loose in the primary / clutch side. Pull that clutch cover off and have a look, it ain't rocket science. :D


Ah, I just had a quick look at some old pictures of that Twinstar, and there are quite a few things under that clutch cover - the primary gear drives the clutch AND the oil pump, either of which could be rattling / loose. Also in there is the clutch lever mechanism. Also in there is the kickstarter shaft and return spring arrangement. Also in there is the shifter star-wheel and return spring mechanism. Any of those things could be loose and rattling.

And, I can't imagine this is it, but maybe it's something loose on the OUTSIDE rattling against the motor - footpegs, motor mounts, exhaust, etc.

Good luck with it.

Kirk
I know Rebel does not have a kick starter. I did take the side cover off and took all the clutch plates off and checked them. The oil pump runs off the gear also. Removed the pump and cleaned it and reinstalled.
I guess I can take the clutch basket off and put the side cover back on and run it and see what happens. I have checked everything on the outside and they are all tight.

I looked behind the alternator, didn't see any marks on the inside of either cover in hopes something was rubbing. Maybe this bike was a Fluke from the factory.... I would split the case if I knew what to look for. Not sure quite how to check for piston slap and measure the pistons and cylinders.

Thank you for all your input... anything will help.
 

·
Premium Member
Joined
·
771 Posts
Well, moving away from the right side, and into the left - the starter clutch fits behind the alternator rotor. I think it's the kind that has the rollers held in place by small springs that engage when the starter motor spins but disengage when the motor spins faster than the starter. And I think that the starter gear is bolted onto the back of the alternator rotor. Maybe something in THAT system is rattling. This wouldn't go away just by removing the starter chain.

Piston slap occurs when there's too much clearance between piston and cylinder. It's a straigtforward measurement and compare to specs. Go or no go. You'll need a micrometer large enough to measure piston outside diameter and an inside micrometer suitable for measuring the bore. Compare to specs.

That's all I can think of that you haven't already checked. If that doesn't pan out, then one or more of your checks must've missed something... :oops:
 

·
Sensei
Joined
·
27,180 Posts
Did you use a new o-ring and gasket on the "replaced" oil pump?...A "seep" there could reduce oil flow volume to everywhere..............
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #12 ·
66Sprint said:
Did you use a new o-ring and gasket on the "replaced" oil pump?...A "seep" there could reduce oil flow volume to everywhere..............
The noise was there long before I pulled the oil pump to clean the screen. I'll check it again
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #13 ·
kirkn said:
Well, moving away from the right side, and into the left - the starter clutch fits behind the alternator rotor. I think it's the kind that has the rollers held in place by small springs that engage when the starter motor spins but disengage when the motor spins faster than the starter. And I think that the starter gear is bolted onto the back of the alternator rotor. Maybe something in THAT system is rattling. This wouldn't go away just by removing the starter chain.

Piston slap occurs when there's too much clearance between piston and cylinder. It's a straigtforward measurement and compare to specs. Go or no go. You'll need a micrometer large enough to measure piston outside diameter and an inside micrometer suitable for measuring the bore. Compare to specs.

That's all I can think of that you haven't already checked. If that doesn't pan out, then one or more of your checks must've missed something... :oops:
I'll try to pull the rotor somehow. don't have the Puller that's needed. when i had that side cover off, the sprocket felt very tight that's behind the rotor. I think I need to jack up the air cleaner and put another bike underneath it..
 

·
Sensei
Joined
·
27,180 Posts
No need if you're sure it's correct....Just investigating some alternative possibilities for your noises.....
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #15 ·
I found another rebel engine that runs great for 80 dollars. Going to pick it up this Monday.
I'll go over it and double check everything and swap my chrome side covers, valve cover etc over to this other one and see how it goes.

I'll let everyone know.
Thank you everyone for all your input.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #17 ·
Picked up the other engine. The guy had it laying around. I swapped my head as his valves were leaking. put my Clutch plates in, swapped out my alternator rotor, installed all my chrome side covers etc. Started up the engine and it sounds WONDERFUL. No Diesel sound, rattling sound or anything. sounds like a normal bike.

Now i need to tear into my old one and hope to see something. I checked the pistons and cylinders, I don't see any marks of any kind that would show Piston Slap, Timing chain is tight etc. Now to just find time to split the case. I NEED to know what was rattling.

Now I have a rebel 250 engine that I can sell parts off of.
 

·
Registered
Joined
·
104 Posts
I'm bringing this back from the dead, but did you ever find what was causing the noise?
I have a CM250C and I also am very curious, also how you found the removal of the oil pump. I am in the process of stripping my engine. Wife bought the bike last Nov for me as an advanced Xmas present and I promptly thanked her by parking it up and then building a shed in which to do a complete resto. Finished the shed last week, and the bike is now pretty well in bits. Waiting for a flywheel puller. Now to the bitter bit. I know from the other forums that the oil pump screws are a right PITA to remove. I have a brand new #3 Philips bit, and with care and my manual impact driver I couldn't budge any of them. I then tried a t-bar on the driver end and got great grip, which on all three screws is just chewing the heads up. So my plan is as follows. Once I have the flywheel off, I will split the cases. I can see that the primary gear is loose on the crank, so I assume that the right case complete with oil pump should lift off of the crank. Then I hope to undo the two pump casing screws, lift off the casing and take out the rotor to reduce the chance of damage, and drill the three screw heads off. After removing the body of the pump, I should then be able to apply some heat and remove the screw stems with moles.
What does the panel think? I can see no other way.
Apologies for the length of post!
Pete
 

·
Registered
Joined
·
104 Posts
Answered one of my questions - having managed to get the screws undone, beneath the oil pump there is one of the crankcase screws so the pump HAS to come off anyway. In the end, I drilled into each screw 4mm dia about 4 mm deep, and whacked a #2 bit in there, followed by a good belt with the impact driver. Each screw immediately released so I reckon they were, as much as anything, gripping on the head taper, and probably the heat from drilling gave them some help. So I have ordered some allen headed countersunk replacements.
Hope all that was of some use to others!
Pete
 
1 - 20 of 21 Posts
Top