Rumore motore hymalayan 411 eu4

R

riccardo italy

Active Member
"Good morning everyone,

I purchased a 2018 Himalayan 411 Euro 4 with 19,000 km that has engine issues. I tried changing the oil, filters, and chain tensioner; the bike wasn't well maintained. The bike starts and runs, but it has a very loud lower-end knocking noise that increases with engine RPM, and pulling the clutch lever changes nothing.

I am attaching a video so you can hear what kind of noise it is.

Now I have already removed the engine and I am splitting the crankcases. In your opinion, what could it be? I will be doing a total engine rebuild anyway, but I would like your opinion on what to focus on.

Thanks"
 

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  • VID_20261106_172040.mp4
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Please always write in English. If you do not know English use AI for translation.
I have forwarded your vid to my mechanic, I have an idea but lets see what he says.
 
My mechanic says video not long enough and not specific enough to say for sure but probability 70% seized piston and 30% damaged crank bearings. But if crank then the bike was heavily misused, driven without any oil for long stretch. If piston it can be repaired by changing the cylinder, if crank then full overhaul as you mentioned.
 
IMO I think to take the engine apart is premature. these bikes are built like tractors, the engine lasts over 100k km if not abused.
I would take off the cylinder, check if the head is OK, maybe consider a new valve set with guides (depending on if you see any damage or not). If the piston is seized but not stuck (and it still runs so its not stuck) I can send you an oversized piston 0.75mm oversize and you just bore and hone it to that size - done. costs you 50 bucks for the piston and the work, maybe 150 euros or less. a full remake will run into 500-1000 euros, depending where you source the parts.
 
sam2019 said:
IMO I think to take the engine apart is premature. these bikes are built like tractors, the engine lasts over 100k km if not abused.
I would take off the cylinder, check if the head is OK, maybe consider a new valve set with guides (depending on if you see any damage or not). If the piston is seized but not stuck (and it still runs so its not stuck) I can send you an oversized piston 0.75mm oversize and you just bore and hone it to that size - done. costs you 50 bucks for the piston and the work, maybe 150 euros or less. a full remake will run into 500-1000 euros, depending where you source the parts.
Click to expand...
Thanks; the engine is already disassembled. The cylinder, valves, and piston are all fine, but I suspect the engine was run without oil—there’s a loud knocking coming from the bottom end. I’ve got a tool arriving this week to remove the flywheel; once that’s off, I’ll strip everything down completely and take it to a machine shop for inspection. By the way, do you happen to have a new crankshaft?
 
Before blaming the crank, it’s worth checking:
  • A loose flywheel or rotor. A sheared key or a loose nut knocks heavily and sounds like the bottom end. you are removing it anyway, so check the key and the taper.
  • Balancer shaft gear wear, or balancer timing off after an earlier repair
  • Primary drive gear or clutch basket play
  • Cam chain or tensioner
  • Play in the conrod. With the engine apart, holding the piston (or the rod at TDC) and feeling for up-and-down movement is the quickest check.
Before the machine shop: examine the old oil and filter for metal, and check the sump screen and the oil pump. If the big end failed from oil starvation, the cause has to be found. Otherwise a new crank will fail the same way.

If it had really run dry for any length of time, you’d normally see scuffing on the piston skirt and the cylinder, blued or discoloured parts, or a galled cam. A clean top end makes “low or bad oil over time” or “an oil-flow problem” more likely than “no oil”.
 
"A loose flywheel or rotor. A sheared key or a loose nut knocks heavily and sounds like the bottom end"

I don't think that's likely.
AI hasn't actually had a look inside ;)

The crank has decent sized roller bearings, ( can't say the same for the "J" series)I would suspect the connecting rod bearings if there is a knocking noise.
Be interesting to see what you find.
 
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Dool said:
"A loose flywheel or rotor. A sheared key or a loose nut knocks heavily and sounds like the bottom end"

I don't think that's likely.
AI hasn't actually had a look inside ;)

The crank has decent sized roller bearings, ( can't say the same for the "J" series)I would suspect the connecting rod bearings if there is a knocking noise.
Be interesting to see what you find.
Click to expand...
Thanks for the advice. In the meantime, I’ll open everything up; once it’s disassembled, I’ll be able to see whether I need to order the crankshaft and connecting rod assembly, and we’ll go from there.
 
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