ST13Fred
Active Member
The valves on all Honda engines hold clearances very well. These engines are so smooth and quiet the auto owners manual say to adjust if they 'sound' noisy.
Valve adjustment tips and advice please
- Thread starter kumatae
- Start date
summitx
Site Supporter
This sounds like very bad advice. Valves mostly need adjusting due to the valve seat wearing (mainly exhaust) which causes the clearance to decrease. They get quiet not noisy. If this continues to where the valve no longer seals at the valve seat you will get a loss of compression, If not corrected the hot gasses will burn out the seat or cause the valve to fail at the neck.
If you have an experienced ear and you don't hear them a bit you should adjust asap.
If they are getting noisy the adjuster could have come loose (never seen this happen) or you have bigger problems associated with not frequent enough oil changes or poor quality oil and you are wearing the cam lobe or rocker face. This is uncommon and not why valve adjustments are part of regular maintenance.
Always adjust the exhaust valves to the loose end of the spec. A little ticking is a comforting sound.
dduelin
Site Supporter
If the comments are limited to Honda cars the advice is 100% accurate. I've owned a handful of Honda cars in 30 years and the maintenance schedules did say to adjust valves at 105,000 miles 'if they are noisy'. Limited to motorcycles however this is bad advice. I generally follow the manual's recommendation which sets the schedule by mileage not decibels.
summitx
Site Supporter
Hmm wonder if they had hydraulic lifters, only thing that makes sense along with the adjust interval. Certainly not the B2000 engine used widely by Honda in older Civics and crv's. Biggest issue with blown motors on that engine is taking out an exhaust valve.
summitx
Site Supporter
I agree follow the recommended interval in the service manual but to be on the safe side. and if you understand or have experienced how they wear it makes sense to set your nc exhaust valves on the loose side of the specification.
dduelin
Site Supporter
I don't think Honda has built a production engine with hydraulic lifters. Honda has been putzing around with chain-driven ohc engines since the late 50s. We've had two CRVs with the B20Z engine, the 2000 was at 260,000 when it met an untimely end against a concrete median, the 1999 is knocking on 200,000 as I type this. It has rocker arms with screw and locknut adjusters not that different from the NC700 engine. Our 1995 Civic coupe had a D series VTEC and was wrecked around 190,000 and the Accord that replaced it was traded at 238,000 still running well. Both of these had similar valve train mechanisms.
summitx
Site Supporter
Yes, similar experience. Still have a crv with 280,000km. Have never changed the intake valves and only minor adjustments throughout its life on the exhaust. Has a bunch to do with how you operate it. Heat is the enemy. If you look at the crv forums you will see a number of threads on folks that have taken the heads out from not adjusting the valves. I think the forum recommendation for adjust interval is 30,000 miles regardless of what the manual says.
Back to the op's question. Don't wait for them to get noisy. Adjust at the intervals in the service manual. Set the exhaust at the loose side of the spec. Use good oil and don't get the thing too hot. IMHO
rippin209
Well-Known Member
I'm going to agree check at intervals according to the manual, my valves got tighter not looser, but only once did one valve get out of spec. I got my NC with 5,000 miles on the odometer and checked them at 8 and again at 16, the first time almost all were slightly off, the next it was the center four (across from the catalytic converter) so 2 intake and 2 exhaust needed adjustment only one was actually out of spec, after that I've only had to adjust one or two valves that were just slightly off (well within spec but I was already there so) I checked at 30k and 50k and nothing has moved a hair, but that's me and it could be different for others
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Ferndiego12
New Member
Hello to all.... I have to totally agree with the earlier post by summitx . Indeed valve clearences usually tighten up (valve noise gets quieter) as the engine is run due to valve seat wear. This is especially true in motorcycle engines due to the increased RPM operating range as compared to let's say a passenger car. These days, cars (due to transmission shift points tuned for fuel economy) seldom see more than 3500 RPM at any given moment. So for my recently purchased NC700X with about 9500 miles on it , I will be inspecting/adjusting the valve lash ASAP. It sounds a bit "too quiet" for my taste. I would bet a 6 pack and a pizza pie that there will be some tight clearances found on my NC700X. I again agree with a an earlier comment that a "slight" tick from the valves is a sound of comfort, at least for me it is for sure. Just my 2 cents for what ever it's worth. Thanks to all
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I don't disagree with your thoughts on valve clearances tightening up. But, red line on my NC700 is the same as on all my cars and trucks, give or take a few hundred rpm. It's not stressed or rev'd any more than my car and truck engines.
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dduelin
Site Supporter
Yes however the NC700X is an exception to the general rule of motorcycle engines which normally produce more horsepower per liter than car or truck engines. At 76 hp/liter the NC engine still produces more power per displacement than many car or truck engines. My Miata has 10 hp less per liter. They [motorcycle engines] are also smaller and more lightly built with bearings and bushing surfaces under more load per surface area and the operators often are shifting up and down through the rev range far more often than a car or truck. All aluminum blocks and heads came into common MC engine use over 50 years ago while a relatively new development in car engines and still relatively rare in large truck engines.
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Interesting. That got me thinking, so I did some math. As for hp/liter, my pickup truck (80), my minivan (81), and my subcompact car (75) all have a comparable rated hp/liter to the 76 that you stated for the NC700.
Yep, the minivan wins the performance war. They are so under appreciated.
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dduelin
Site Supporter
Well, the NC engine isn't a very good example of motorcycle power/displacement as it is designed primarily for efficiency. A Honda 600 sport bike makes about 135 hp or 225 hp/liter. The CB500X makes 118 hp/liter. Anyway, the point is that generally speaking motorcycle engines are more stressed than car and truck engines.
D
Deleted member 5383
And hey, look at some of the examples of two-stroke snowmobile engines -- incredible power to weight for machines that are not specifically designed for racing.
Yes, but this is a valve thread. Adding rotary valves, reed valves, and guillotine power valves to the discussion.
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D
Deleted member 5383
Thread drift catches me again! Drat!
True, but since this is an NC700/750 forum and we're talking about NC700 valve adjustments, I guess it doesn't matter how stressed the other bike's engines might be. All I was trying to say is, in response to post #31, is that the NC is not necessarily stressed or revved more than typical car engines.
dduelin
Site Supporter
And I'm saying it is but I get your drift. You accelerate to 45 as slowly as possible then stay there. Low stress, low revs, I get that. Most motorcycles, even the NC700X, aren't ridden like that.
Done.
Ferndiego12
New Member
670cc I completely agree with you that the NC700X red line is pretty close to most automobile engines. After all the NC700X engine is partly based on the Honda Fit automobile engine.
The point I was trying to make was that in general, motorcycle engines (including the NC700X) will usually run at a higher rpm range . As an example , when cruising at 70 MPH in my 2015 Nissan Altima , the engine lumbers along at 1900 RPM. My NC700X at 70 mph the engine runs at around 3700 RPM which is significantly higher. So in my opinion, it is
more critical to check valve lash adjustments on a motorcycle at the recommended intervals (or sooner) if you like to ride "enthusiastically". Thanks again for your reply, Fernando
The point I was trying to make was that in general, motorcycle engines (including the NC700X) will usually run at a higher rpm range . As an example , when cruising at 70 MPH in my 2015 Nissan Altima , the engine lumbers along at 1900 RPM. My NC700X at 70 mph the engine runs at around 3700 RPM which is significantly higher. So in my opinion, it is
more critical to check valve lash adjustments on a motorcycle at the recommended intervals (or sooner) if you like to ride "enthusiastically". Thanks again for your reply, Fernando
