Honda cg125 engine noise

[Otreed]

I have restored an old Honda cg125 that has not been used for about 3 years. Everything on it has been cleaned, powder coated and replaced where necessary and it looks a treat. I have got it running but it is very load, way loader than normal and it almost sounds dry or tinny. Engine has not been apart as it was running ok when it was parked up.I have checked oil pressure and it’s all good with fresh oil. It also misfires a bit and I’m wondering if it’s the replacement exhaust I have fitted. It has been tightened up and gasket replaced but it still doesn’t sound right. Pushrod engine so can’t be a cam chain noise. Any ideas?

[skyrider]

take it it isnt the standard exhaust then

[Otreed]

It’s not a genuine Honda one, but it’s the standard shape/size nothing fancy. Maybe cheap metal making a difference? Although would that make it misfire if it’s a cheaper exhaust?

[skyrider]

fastbob would probably know he is your cg man

[fastbob]

I have restored an old Honda cg125 that has not been used for about 3 years. Everything on it has been cleaned, powder coated and replaced where necessary and it looks a treat. I have got it running but it is very load, way loader than normal and it almost sounds dry or tinny. Engine has not been apart as it was running ok when it was parked up.I have checked oil pressure and it’s all good with fresh oil. It also misfires a bit and I’m wondering if it’s the replacement exhaust I have fitted. It has been tightened up and gasket replaced but it still doesn’t sound right. Pushrod engine so can’t be a cam chain noise. Any ideas?

 

Hello . First thought is that the baffle is loose inside the exhaust . I used to fit cheap and cheerful pattern exhausts to CG,s that I had done up . If memory serves I did have one with a loose baffle rattling around that had to go back to the supplier. Try whacking it with a rubber mallet and see if anything sounds loose. Another thing well worth checking is whether the rotor is a firm fit on the crank shaft . If the Woodruff Key or the keyway are damaged you will get a knocking noise and the timing will be erratic . Apart from that I can't think of anything else that would make a noise . As you say , it's such a simple engine. Might be worth popping the barrel off for a look . Hopefully it isn't top or bottom end bearings or piston slap but it's worth investigating . Good luck , keep us informed .

Edited September 15, 2019 by fastbob

[Otreed]

Possibly. Would it make the engine sound “dry”? I was worried about low oil pressure but it’s all good. I have a video but it’s not letting my upload it. Its an aftermarket replacement exhaust, ever had this issue with these?

[fastbob]

Possibly. Would it make the engine sound “dry”? I was worried about low oil pressure but it’s all good. I have a video but it’s not letting my upload it. Its an aftermarket replacement exhaust, ever had this issue with these?

 

Nice job . I'm a little surprised that you have gone to all this trouble without opening up the engine for a poke around .

[Otreed]

You’re right. It is my first build so a big learning curve. I suppose it was running fine before it was parked up and left so didn’t want to open that can of worms with dismantling engine. Easy enough to get it apart though just want to see if I can avoid that.

[Mr Fro]

Possibly. Would it make the engine sound “dry”? I was worried about low oil pressure but it’s all good. I have a video but it’s not letting my upload it. Its an aftermarket replacement exhaust, ever had this issue with these?

 

I'm not a fan of cafe racers but that looks pretty bloody smart!

[julianl]

That is a good looking bike, well done!

You can upload the video to YouTube and then post the link here.

[Ian Frog]

May I ask if you do know the reason it was parked up and left?

My worry is the previous owner had engine issues so left it to one side.

As was said before have you opened her up and had a look?

Hope you get it sorted.

Cheers

Ian