Low End Engine Noise

Hey Y'all Im new here!
Ive already found your posts extremely helpful. Thank you.

I own a stock 2021 BS6 Himilayan 411. Evap removed.

It has 3k miles
I recently did a valve adjustment, checked my timing chain tensioner (sits at half, chain stretch ok), changed my oil and greased the swing arm and linkage assembly. I have typical tappet noise and some minor timing chain noise. (My valves were WAY too tight. Less then .08 on BOTH. I set them to spec .08 intake .23 exhaust and the tappet noise got louder but chain noise reduced.) Lastly, my spark plug showed signs of hot and lean (ash deposits, some dicoloration). My piston has some black carbon, not a lot. For low miles, this bike seems to be.... problematic. Rough idle, backfire, louder than I expect mechanically.

I have low engine noise! (I put a towl over the exhaust and listened closely. Noise around oil pump and clutch basket area.)
When I put my head under the bike I can hear it clear. Are these engine generally loud in the top and bottom end, or is it possible I have a bearing issue? Do oil pump chains on these bike have a lot of noise generally?

I have a "chirp" when my clutch is cold. Ive read a lot about this on other bikes, mine has it. My clutch feels nice however.

I have only rode this bike about 100miles since I bought it. I dont trust it for distance or off in the mountains where I want to be yet.

Thank you so much for your feedback.
J.B. Oregon USA

Only 3k miles? has it been sitting a long time without movement in old oil (acid in oil can damage bearings). Any service history available?
In general these engines are tractors. I have seen multiple post 100k km that have been mistreated to the max by short term renters without engine issues. Our own 500cc upgrades run on the same basis but with almost double the power. Still some have hit 60k km and none had any engine troubles.
Of course it could be a lemon - and I regret to inform that I never put myself flat on the ground to listen to the engine sound from that perspective LOL.
with all those specific questions regarding noises and whether they are OK or not I suggest you take your phone, run it slowly around the running engine, possibly with comments from you when a certain suspicious noise is coming up. Then upload to YT and post a link here.
Otherwise we are the kids who hear about chocolate pudding and are expected to love it from the description alone.

sam2019 said:

Only 3k miles? has it been sitting a long time without movement in old oil (acid in oil can damage bearings). Any service history available?
In general these engines are tractors. I have seen multiple post 100k km that have been mistreated to the max by short term renters without engine issues. Our own 500cc upgrades run on the same basis but with almost double the power. Still some have hit 60k km and none had any engine troubles.
Of course it could be a lemon - and I regret to inform that I never put myself flat on the ground to listen to the engine sound from that perspective LOL.
with all those specific questions regarding noises and whether they are OK or not I suggest you take your phone, run it slowly around the running engine, possibly with comments from you when a certain suspicious noise is coming up. Then upload to YT and post a link here.
Otherwise we are the kids who hear about chocolate pudding and are expected to love it from the description alone.

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Only 3k! Im the 3rd owner already.... may be a lemon. I was so excited to buy it I didnt do a great pre inspection before purchase... I love this bike style.

Your reply made me smile. I will make a video.

Also a tip for engine listening in the low end. . . I put a folded towel over the exhaust tip to quiet my exhaust thump and the resonating sound from the pipe, trick I learned from my auto shop teacher many years ago.

Your posts I have read a lot of, I appreciate your work.
Thank you.

Main bearings are huge on this engine.
Oil pump chain is running in oil and doesn't cause problems.
Backfire? Has the exhaust been modified?
Tappets setting has been revised? I would set at 8 and 3 thou tight.

The exhaust is stock as far as I know.

Today, I adjusted the TPS. At closed throttle, the signal was at 0.74v. I backed it down to 0.60v. The idle cleaned up, and the sputter nearly disappeared (not completely). I reset the ECU (battery disconnect) and gave it a 15-minute idle reset period when I reconnected the battery.

It's pouring rain today, so no ride test. No video of the noise.

The bike is different when it's at riding temperature. Noise and function levels change.

I've heard online that the IAC valve can cause backfire. I don't know for sure. On deceleration, it will pop/backfire a little.

I set the valves to 0.08mm intake and 0.23mm exhaust, as this is what I've seen online everywhere. It's a bit tickier now. The timing chain sound was loud with a closer valve gap before I dialed the valves back—the chain is quieter now, valves louder. I think I'll have to find a sweet spot. In the PNW, we get icy cold weather and California-like heat. It's cold now. Might do better closer.

I'll keep hunting and learning. I'm hoping it's dialed perfectly by spring. I have plans for the WA/OR USA BDR (BackCountry Discovery Route).

Dealers with the diagnostic tool can reset IAC.
15mins may not be enough to get to operating temperature, I do 25 to 30mins and use an infra red thermometer.

my Himmi had exhaust pops and stalling after i bought it at 2200 miles
a prowler must have broke into my garage and stole my EVAP and EGR parts
and since then she has not had many pops or stalls

still waiting for the tooth fairy to put a RedBox under my pillow (wishful thinking)
then i will feel good about having the prowler come back and steal my cats!

ohh yeah, it sounds awful
I have learned to ignore most of it

ham said:

still waiting for the tooth fairy to put a RedBox under my pillow

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If the tooth fairy manages to give you a camera or a mobile you could add a pic of your ride as profile pic and we could know if you have a BS4 or BS 6 - just an idea ...

sam2019 said:

just an idea ...

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not that a pic says much, but there we go
its a US spec 2021 so Euro4
and it sounds like a coffee can 1/8 full of assorted gravel
but runs pretty darn good for how lean they are mapped

ham said:

its a US spec 2021 so Euro4

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I'll bet its a BS6. That color scheme was never used on a BS4. Just check visually: is the ECU glued to the Throttle body? if so = BS6 (Euro5)

J.B. said:

Your reply made me smile. I will make a video.

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I also made a video - this is of the 440 but afaik the sound is the same: (warm engine)

sam2019 said:

is the ECU glued to the Throttle body?

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nope its under the seat

J.B. said:

Your reply made me smile. I will make a video.

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Its 2026 now .... will it ever come or is the issue resolved?

Months later... LOL

I'm back with a full report.
Entire rebuild of the motor is required.

I've ordered full crank and balancer. Full top end.
I am upgrading all of the crank case bearings to a much better rated c3 bearing from SKF.

My Crank balancer bearings are the main source of the noise. It sounds like a growling cat/ whirl noise. I have a slight metallic rod knock and piston slap. Seems as the 2021/2022 Euro4 ecu/ Euro5 cat and tripper, build was SUPER low quality parts and nothing on this bike seems to have went well. My cam decompressor had also failed, so that was bad. The stator woodruff key was slightly misshapen, luckily not sheered. The previous owner may have ran it out of oil at one point, I don't know. The only thing I haven't done on this bike yet is split the case. I'm waiting for parts. Otherwise I have pretty much learned and examined all of the components.

I do know that I have now learned so much about this bike I am slightly addicted. For years I was a mechanic and stopped working on things. This bike has got me excited for tuning, wrenching and learning again.

When I am done I will have a much better bike.
I'll be on here more and post and share my videos and photos as I go. I had a busy work season and now I am back into bike season again.

time for a BB upgrade maybe - at least the piston would be forged - quality is certainly better than the stock ones.
I have a new balancer sitting here since years, if you need a cheap spare

I want to do a BB upgrade in the distant future. I will need to get on board with you red box people before that time though and understand the tuning process of maps prior to all of that.

The "update" for the crank is ROYAL ENFIELD considers the crank and balancer as 1 assembly. They are harmonically balanced to each other during manufacturing now. That is the cause of the failures previously. I have a previous version of this crank that doesn't seem to be balanced.

This is all information I've found from hours and hours of digging and research. I am not the export but as far as I know, all cranks and balancer shafts should be harmonized to eachother, so if you replace 1, you should buy the set.

This new balanced set, coupled with my new higher RPM and heat rated bearings, should give my bike a smoother ride and much less noise and issue.

My upgrades so far, Stage 2 Kent cam (Hitchcock), Hitchcock valves, Polished exhaust port in head, Fuel x Pro, K&N filter and Intake snorkel modification.

ham said:

nope its under the seat

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Ham you have the same bike as me. It's a Euro4 Euro5 Mashup. The US bikes in this range have a ton of issues. Your can of gravel is EXACTLY how mine sounded. It drove me crazy. All of the stuff you are experiencing is exactly what supply chain issues looked like in that time era of build. They made our bikes CRAP! completely unbalanced and junk. Overhauling the bearings and bottom end, as well as the AWEFUL camshaft. The stock cam decompressor is probably failed. Thats a source of issue and your crank is probably as unbalanced as mine is.

Check your woodruff key that connects the magneto. If that guy comes loose from all the vibrations (mine did) you will start to experience a real mess. I'm updating my woodruff key to hardened alloy. They may as well have used wood with the one in the bike.

My bike runs good and sounds like it could explode at any minute. LOL

P.s. The thieves stole all my emissions too! Amazing how they do that.

PS Here are the bearings specifics and cross over numbers. I figured I would share to be helpful to the community. I sourced these locally in the US. I used Hitchocks exploded view section on there website to use there numbers as cross reference. I found all of the load data ratings for the stock bearings so I could talk to bearing engineers and understand things better. These tech notes are what I created to send to bearing shops to get heat rated precision bearings to solve my low end gravel and unbalanced feel. My crank/balancer set will be here this Friday. I will also have the bearings. I will begin my entire rebuild next week and video the whole process. Just a couple of US videos on basic stuff, no overhaul videos. I will be one of the only ones showing each step. The project will take me some time and the video will take me at least a month after to edit and upload.

Himalayan 411 Internal Engine Upgrade Specification Sheet
Technical Summary for Industrial Supplier

• Application: Internal combustion, single-cylinder air-oil cooled motorcycle engine (Royal Enfield LS410).
• Rotational Speed: Redline is 6,500 RPM. Main bearings (6306/6307) must handle sustained high-vibration operation.
• Heat Range: High operating temperatures of 200°F–260°F (93°C–127°C). C3 internal clearance is required to prevent shaft binding during thermal expansion.
• Lubrication: Pressurized splash lubrication using 15W-50 semi-synthetic oil. All bearings must be Open Type (no seals/shields) to allow oil flow through the races.
• Hardware Strength: Woodruff Key must be Alloy Steel (Heat Treated) to prevent shear failure during ignition kickback. Head Bolts must be Class 12.9 to ensure consistent clamping force under thermal stress

J.B. said:

Ham you have the same bike as me

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I have put over 5000 miles on her since last July
and once I got the EVAP and EGR stuff off and got all the buzzes and vibes out from the loose
bits and bobs, it really isnt so loud, she still sounds like a can of gravel, but it doesnt get any worse
she starts perfect and pulls hard for a garden tractor
she does still burn a bit of oil, but i tend to keep her pinned alot of the time
look forward to you documentary on the rebuild process