dduelin
Site Supporter
The Half A Fit myth will be with us forever I suppose.
Darn you Uchida-san.
Darn you Uchida-san.
Valve adjustment tips and advice please
- Thread starter kumatae
- Start date
TNtim
New Member
I've got 81 k on the NC at 2Ok I checked the valves and they were fine again at 50k the adjustment was very minimal and I haven't checked them since. Fuel mileage may be dropping but I did go to a heavier oil since I was in some extreme heat. Being water cooled and valves in the front as well as rev limiter makes this engine solid.
Ferndiego12
New Member
I just adjusted the valves on my 2012 NC700X with 9700 miles on it. For the most part the valves were very close to the specs. I found one intake valve on number 2 cylinder slightly out side of spec (tight) and one exhaust valve on cylinder number 1 cylinder also tight but just barely in specification. From what I have seen, this engine appears to hold the valve lash settings pretty well. According to the previous owner, the valves were never adjusted until I checked them at 9700 miles.
I will be checking them again at 20K miles. The process to check and adjust the valves was pretty straight forward. Taking my time it took me about 2 hours . I also purchased the factory service manual which helped quite a bit especially to
properly align the cam shaft timing marks. If you have any questions on how to go about adjusting the valves, feel free to ask.
I will be checking them again at 20K miles. The process to check and adjust the valves was pretty straight forward. Taking my time it took me about 2 hours . I also purchased the factory service manual which helped quite a bit especially to
properly align the cam shaft timing marks. If you have any questions on how to go about adjusting the valves, feel free to ask.
mgkumar138
New Member
Hi guys! I bought the NC 2nd hand and not sure if the previous owner had done valve clearance. I just did the valve adjustment and to my horror all my valves were out of spec, not even 10mm gap. After finishing the adjustments and fitted everything back to test the engine and see if it was working fine, I did not top up the coolant at this time. The engine was much more noisy than when i first got it. But when i revved, the rpm increased from 1100 and steadied at 2000rpm. It did not come down in the 1 min i had switched the engine on. I immediately switched off the engine. Would like your advice on what could have gone wrong. I followed exactly what the manual said. T1/T2 align with notch for cylinder 1(clutch side) and cylinder 2 (brake side) and gap i 17mm/28mm for inlet and exhaust. Are these all correct? My bike has been grounded for the past 2 days cause of this. Hope yo get your insights on this!
Often when you are horrified to find the valves all tight on a working engine, it’s because the crankshaft was rotated to the wrong TDC when you did the clearance check and adjustment. Remember, the crankshaft goes around twice to complete the four stroke cycle, while the camshaft goes around once.
Take it apart again. Rotate to T1 and check valve clearance on cyl 1. Rotate crank 360* to T1 again. Check slack again. Of the two locations, adjust the valves at the crank location where the clearances were the loosest. Repeat for cyl 2.
I think you mean 0.17mm/0.28mm.
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Totally agreed with above----^
If *all* the valves are way out of spec too tight, it's almost guaranteed that the initial premise of crank/valve orientation was incorrect, or possibly mm versus thousandths of inch were accidentally transposed on the shims, etc.
If *all* the valves are way out of spec too tight, it's almost guaranteed that the initial premise of crank/valve orientation was incorrect, or possibly mm versus thousandths of inch were accidentally transposed on the shims, etc.
lootzyan
Well-Known Member
+2
When the cylinder is in a "false" TDC (end of the exhaust stroke) the valves do not have any clearance - both intake and exhaust valves are open. At this point, it is possible to create valve clearance but this would cause that, at the proper TDC (the end of the compression stroke), the clearance would be more than doubled - this would explain the noisy work of the engine.
Such a large deviation from the recommended valve clearance will cause significant changes in valve timing. The intake valves open too late causing a significant change in the manifold vacuum. This would lead to an incorrect interpretation of the MaP sensor signal by the ECU and, as a result, a change in the fuel mixture - and this would explain the increase in engine RPM.
The good news is that this should not damage the engine. All you need to do is set the valves correctly and everything will go back to normal.
When the cylinder is in a "false" TDC (end of the exhaust stroke) the valves do not have any clearance - both intake and exhaust valves are open. At this point, it is possible to create valve clearance but this would cause that, at the proper TDC (the end of the compression stroke), the clearance would be more than doubled - this would explain the noisy work of the engine.
Such a large deviation from the recommended valve clearance will cause significant changes in valve timing. The intake valves open too late causing a significant change in the manifold vacuum. This would lead to an incorrect interpretation of the MaP sensor signal by the ECU and, as a result, a change in the fuel mixture - and this would explain the increase in engine RPM.
The good news is that this should not damage the engine. All you need to do is set the valves correctly and everything will go back to normal.
booblinker
Member
Happy I read this, I was looking for a how to for my 8k valve adjustment this weekend on my 2015. Happy to know I don't need to bother until the end of this year.
Was visiting with the sales manager of a Yamaha dealership last week and even he - with his knowledge of the business, spouted that as fact.
I’d say the sales manager just demonstrated his lack of knowledge of the business.
Or was he just using misinformation in an attempt to put down the Honda NC in order to bolster Yamaha sales?
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I wasn’t on my NC at the time - just in kicking tires in the Yammy store - I got the distinct impression he was just mildly talking down the NC as compared to anything comparable in the Yama line. I just do what I do best - played dumb and let him ramble.
Got a look at their latest and greatest touring bike. Gawd what a monster motorcycle.
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lootzyan
Well-Known Member
"...with his knowledge of the business..." he should say that:
- Nobody should ever believe that NC/CTX family of engine design, especially its timing/valve system, came directly from Honda Fit/Jazz design and their i-DSI (intelligent Dual & Sequential Ignition) or VTEC technology (depending of model).
Honda Fit/Jazz engine design is decades ahead.... NC engine design is pretty archaic.
dduelin
Site Supporter
Features of the New Concept (NC) engine like roller bearing valve followers, exhaust header design & catalytic converter placement, and low friction coatings are actually well advanced for motorcycle engines. Instead of being purposed for maximum power output per displacement the NC engine is essentially the only motorcycle engine of this era purposed for volumetric efficiency. In doing this it does use design elements common to Honda automobiles.
lootzyan
Well-Known Member
It's got nothing to do with design of modern combustion engine. It's like to build new Cape Cod house and use the newest mold and UV resistant paints.
Jos
New Member
Still better than HD log houses 
ST13Fred
Active Member
I finished the valve clearance check w/8K miles. All of #2 were tight, .01 over the .07/.11 midpoint. Brought them back to midpoint. #1; both exhausts were at .11, one intake was .01 tight, brought it back to .07. Stay safe out there.
