Suzuki SV650 Riders Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter · #1 · (Edited)
So I thought it was knocking and I started pulling off the engine to rebuild it. Today I drained the oil and there was no metal shavings on the drain plug at all. So I took the spark plugs out and got the pistons moving down and saw if I could push and feel anything and nothing.

I could very clearly hear a knocking noise only while riding it and on the throttle at any rpm. Especially lower rpm, And it had gotten worse over the last week I rode it.

I’m thinking it could be piston slap as I just dealt with that on my dirt bike and the valves were right in the middle of spec when I did the 15k check 4K ago. so I suppose I should still pull the engine. Is there anything in specific I should look for in the top end on these engines or what does it sound like it could be to you all?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
589 Posts
Before going any further I would check very carefully for any exhaust leaks or blowing where the headers meet the cylinder head, or at any of the joints.

What's the history of the bike? How many miles were on it when you got it?
 

·
Super Moderator
Joined
·
9,069 Posts
If the bike has not been wheelied (causes oil starvation) or otherwise abused, the knock is unlikely to be rod bearings.

Piston slap is basically unheard of on modern 4-stroke engines, mostly occurs on 2-strokes, and then is more like a rattle than a knock.

Any chance this bike has, say, 15 to 20k miles and still on the original chain?
 

·
Registered
Joined
·
823 Posts
I would not jump to the engine rebuild solution so quickly, what Tee mentioned is much more likely.
Like my dad's old Zundapp manual said: "before you tear the engine apart; step back, light a cigarette, and think about the simple fix". In other words: put down the tools :)
 

·
Registered
Joined
·
49 Posts
Discussion Starter · #5 ·
Before going any further I would check very carefully for any exhaust leaks or blowing where the headers meet the cylinder head, or at any of the joints.

What's the history of the bike? How many miles were on it when you got it?
It had 14000 on it when I bought it and had been sitting on his porch unregistered for 6 years. It had thick black oil in it when I got it. Much worse than when I changed it again after 3k.

I used a 3/8th hose and put it to my ear and tried to find a leak with it and could not. But I couldn’t check the back cylinder too well. I actually originally thought it was an exhaust leak but as it’s gotten louder it kinda sounds like a metallic ting and not necessarily a thud like a car knock.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
49 Posts
Discussion Starter · #6 ·
If the bike has not been wheelied (causes oil starvation) or otherwise abused, the knock is unlikely to be rod bearings.

Piston slap is basically unheard of on modern 4-stroke engines, mostly occurs on 2-strokes, and then is more like a rattle than a knock.

Any chance this bike has, say, 15 to 20k miles and still on the original chain?
These newer 250 4 strokes eat pistons and cylinders. About 25 hours for a piston or a little longer if you’re easy on it and I’ve had it slap. So I didn’t know if other modern bikes would have the same issue.
Anyway. It has 20k and i have replaced the chain but I’ve done nothing with the timing chain if that’s what you mean. I’ve done no wheelies besides the front wheel hovering a little in 1st gear sometimes.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
9,069 Posts
Sometimes the SV cam chains get noisy between self adjustment clicks.
 

·
Super Moderator
Joined
·
9,069 Posts
Camchain noise is not load-dependent; getting on the throttle will make little difference. The noise will be more pronounced at idle and low rpm. And yes, more like a tap, not a knock.
 

·
Registered
Joined
·
54 Posts
So I thought it was knocking and I started pulling off the engine to rebuild it. Today I drained the oil and there was no metal shavings on the drain plug at all. So I took the spark plugs out and got the pistons moving down and saw if I could push and feel anything and nothing.

I could very clearly hear a knocking noise only while riding it and on the throttle at any rpm. Especially lower rpm, And it had gotten worse over the last week I rode it.

I’m thinking it could be piston slap as I just dealt with that on my dirt bike and the valves were right in the middle of spec when I did the 15k check 4K ago. so I suppose I should still pull the engine. Is there anything in specific I should look for in the top end on these engines or what does it sound like it could be to you all?


Sent from my iPhone using Tapatalk
Check the tightness and fit of the timing chain, that used to cause noises on mine
 

·
Registered
Joined
·
49 Posts
Discussion Starter · #11 ·
Camchain noise is not load-dependent; getting on the throttle will make little difference. The noise will be more pronounced at idle and low rpm. And yes, more like a tap, not a knock.
You really can’t even hear it at idle. It’s pretty much only while on throttle and heavy engine braking. That’s why I assumed it was a bottom end noise but the lack of metal shavings in the oil has me confused. The engine is basically ready to come off because I had a moment and didn’t drain the oil until everything else was removed for some reason.

I really don’t know if I should go ahead and see what I find in the engine or put everything back on and see what I can figure out. The noise definitely got louder every day the last few days I rode it so I decided to park it.

I’d really appreciate any ideas or suggestions as I usually daily my bike it’s killing me and my wallet to drive this truck.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
9,069 Posts
If the rod bearing has actually failed then the most cost-effective solution is to swap in a used engine.

But there is little to lose if you put things back together, ride, see what happens. No shavings in the oil so far is a good sign. It is possible the rods are fine and the noise is something else.

If the rod is truly gone you will find out in short order. A rod knock will become unmistakably loud.

It is also possible to test for rod play as shown in this video. But if the knock is not super loud, the play may be too little to feel.

Good luck. Let us know what you find out.
 

·
Registered
Joined
·
54 Posts
You really can’t even hear it at idle. It’s pretty much only while on throttle and heavy engine braking. That’s why I assumed it was a bottom end noise but the lack of metal shavings in the oil has me confused. The engine is basically ready to come off because I had a moment and didn’t drain the oil until everything else was removed for some reason.

I really don’t know if I should go ahead and see what I find in the engine or put everything back on and see what I can figure out. The noise definitely got louder every day the last few days I rode it so I decided to park it.

I’d really appreciate any ideas or suggestions as I usually daily my bike it’s killing me and my wallet to drive this truck.


Sent from my iPhone using Tapatalk
Well my timing chain used to make different noises depending on the throttle. Rose it 150,000 kms. Before I lost it in a fire. Checked all the timing marks too, still made that noise. Had a big bore high exhaust level, Arrow pipe o it. Titanium. Fast!!!
 
1 - 13 of 13 Posts
Top