Valve check?

[Phat Ham_imp]

Anyone know how easy or difficult the valve check procedure is on these bikes?

 

[the Ferret]

Checking them is not that difficult. Adjusting them is pretty difficult and requires different thicknesses of shims.

 

[Deftquiver_imp]

Checking them is not that difficult. Adjusting them is pretty difficult and requires different thicknesses of shims.

Although I kind of like dealing with shims better than the old overhead valve design on my XS650... It's super annoying to check the clearance... only to have it change when you tighten it down.

 

[the Ferret]

I had 3 Yamaha 650 s, a 73 TX, a 79 XS and an 81 XS Special. You have to have a real feel for using feeler gauges, but at least you didn't need an assortment[/i] of shims. The best set up was the hydraulic valves on the Nighthawk 750 which never needed adjusting. I wish this bike had those.

 

[flynrider]

I had 3 Yamaha 650 s, a 73 TX, a 79 XS and an 81 XS Special. You have to have a real feel for using feeler gauges, but at least you didn't need an assortment[/i] of shims. The best set up was the hydraulic valves on the Nighthawk 750 which never needed adjusting. I wish this bike had those.

You can say that again! I put away my feeler gauge back in the 90s, when I no longer had to measure valve clearances or point gaps.

I wonder why Honda chose not to use hydraulic tappets on this bike? Generally, you don't use them on high revving engines because the rpms will ovewhelm the rebound capabilities of the lifter (called float). The CB1100 has a nice low redline, just like the last series of Nighthawks. I just can't figure why they wouldn't incorporate such a great feature when designing an engine from scratch.

I'm really disappointed because I truly hate adjusting shim and bucket valves. On the bright side, they usually don't need actual adjustment that often.

 

[the Ferret]

I read somewhere that the Japanese, all of the big 4, really believe in the bucket and shim valve adjustment system. i have seen over the years fewer adjustment issues using this system over the old locknut and screw system, but as Flynrider said, in this low revving application, hydraulics would have been fine.

 

[Lord Popgun]

I read somewhere that the Japanese, all of the big 4, really believe in the bucket and shim valve adjustment system. i have seen over the years fewer adjustment issues using this system over the old locknut and screw system, but as Flynrider said, in this low revving application, hydraulics would have been fine.

You're really gonna love it when you find out you have to remove the cams to get to the shims--its in the manual...

The service manager at the dealer said that shim under bucket (I think he called it) was historically very reliable on other engines and didn't need a lot of adjustments.

 

[Phat Ham_imp]

What's interesting is a lot of car engines have gone back to solid lifters even in applications that don't rev past 6 or 7k. Of course their service intervals are much longer than on our bikes at 100k miles or so.

 

[jimgl3_imp]

I might check mine at 100k miles...

 

[Scotty_imp]

I read somewhere that the Japanese, all of the big 4, really believe in the bucket and shim valve adjustment system. i have seen over the years fewer adjustment issues using this system over the old locknut and screw system, but as Flynrider said, in this low revving application, hydraulics would have been fine.

You're really gonna love it when you find out you have to remove the cams to get to the shims--its in the manual...

The service manager at the dealer said that shim under bucket (I think he called it) was historically very reliable on other engines and didn't need a lot of adjustments.

You're really gonna love it when you find out you have to remove the cams to get to the shims--its in the manual...

The service manager at the dealer said that shim under bucket (I think he called it) was historically very reliable on other engines and didn't need a lot of adjustments. I've got two 1993 Toyota Land Cruisers one with 178,000 miles and the other 260,000 miles. They have shim under bucket and are still within spec after all these years and miles. I don't rev 'em as hard as my CB though!

 

[PowerDubs_imp]

I read somewhere that the Japanese, all of the big 4, really believe in the bucket and shim valve adjustment system. i have seen over the years fewer adjustment issues using this system over the old locknut and screw system, but as Flynrider said, in this low revving application, hydraulics would have been fine.

Ehh.... show me a car with hydraulics and a 8,500 rev limiter?


There might be one... but not off the top of my head...and certainly not the norm. Low revving for a bike is not low revving for physics of oil movement.

 

[the Ferret]

Don't know about cars..hardly ever drive them, but Honda has a history from the mid 80's -early 2000's of using hydraulic valves on some of it's motorcycles

The 84-86 Honda CB 700S had hydraulic valves (and shaft drive), about the same hp as the CB1100 and revved at least 1500 rpms higher than the CB 1100 with peak hp coming in at 10,000 rpms

The Honda CB700SC is a motorcycle produced by Honda from 1984 to 1986 and more commonly known as the Nighthawk 700S. It could reach a top speed of 147 mph (236 km/h). Max torque was 44.99 ft/lbs (61.0 Nm) @ 8000 RPM. Claimed horsepower was 78.32 HP (58.4 KW) @ 10000 RPM.

83-85 650 SC Nighthawk also had hydraulic valves ...and shaft drive

In 1982, the Nighthawk replaced the Custom of the previous years and featured a re-designed tank and side covers. In 1983-1985 a new DOHC engine replaced the SOHC engine used from 1979-1982. The new engine had hydraulic valve lash adjusters and was rubber mounted. This year also saw the move from chain drive to shaft-drive for this model.
Honda CB650SC
1983 Honda 650 Nighthawk.jpg
Manufacturer Honda
Also called Nighthawk 650
Production 1982–1985
Class Standard
Engine 656 cc (40.0 cu in) DOHC, air/oil-cooled inline four
Power 72 hp (54 kW) at 10,000 rpm

The CB 750 Nightawk 1989-2003 (Flynrider has one of these...and I had a 2000 model)
Nighthawk 750

1992 Honda Nighthawk 750 Also has hydraulic valves
From 1982 through 2003, with the exception of several years, Honda produced a CB750 known as the Nighthawk 750. Early models were designated the CB750SC Nighthawk while later models were simply known as the Nighthawk 750. The Nighthawk 750SC had a 4-stroke engine with a 5-speed manual transmission, chain drive, and front disc and rear drum brakes.
Power 51 kW (68 hp) @ 8500 rpm

My 2000 CB750 Nighthawk

 

[GoldOxide_imp]

Great reference Ferret.

I had the '83 CB650SC Nighthawk and the '84 CB750SC Nighthawk and they were wonderful and good lookin' pieces of Honda. I found the fuel tanks small, but boy were they a joy to ride. I remember the hydraulic valves, DOHC engine, shaft drive, TRAC anti-dive forks (air adjustable), hydraulic clutch (only the 750), and taper cut exhaust pipes (only the 650). The CB750SC had an oversized ("Chuckk style") front tire.

 

[jtopiso_imp]

I read somewhere that the Japanese, all of the big 4, really believe in the bucket and shim valve adjustment system. i have seen over the years fewer adjustment issues using this system over the old locknut and screw system, but as Flynrider said, in this low revving application, hydraulics would have been fine.

Ehh.... show me a car with hydraulics and a 8,500 rev limiter?


There might be one... but not off the top of my head...and certainly not the norm. Low revving for a bike is not low revving for physics of oil movement.

Ehh.... show me a car with hydraulics and a 8,500 rev limiter?


There might be one... but not off the top of my head...and certainly not the norm. Low revving for a bike is not low revving for physics of oil movement.
Indeed, not the norm. But just for curiosity:

Toyota celica/corolla t-sport vvtl-i 192cv

I think it red-lines at 9.600. I drove one: the fun started at 6400rpm

(The engine was developed by Yamaha, so it's basically a big bike engine )

 

[PowerDubs_imp]

Wow- 9,600 redline!

Most cars I've played with, guys would start switching to solid lifters around 7,500

 

[jtopiso_imp]

Wow- 9,600 redline!

Most cars I've played with, guys would start switching to solid lifters around 7,500

Sorry, my mistake: I think 9600 was the honda s2000.

Toyota's vvtl-i redline was at "only" 8400. And mostly useless on normal use: power would kick-in abruptly only at 6200rpm, below that was "dead". Above, everything happened very fast, and you only had 2200rpm range to accelerate.

If you can find a dyno curve for that engine, have a look. It's impressive, fun for a while, but not nice for my taste.

Anyway, this is off-topic on this forum...

 

[Gone in 60]

Not looking forward to checking or adjusting valves on this bike. My BMWs had screw adjusters, as did my VTX cruiser. Miss the hydraulic valve adjusters on my Nighthawk.

Last time I had to adjust shim type valves was last year on my Bonneville, and ended up dropping a piece down into the engine. At least I will try harder not to do that again.

 

[GoldOxide_imp]

Not looking forward to checking or adjusting valves on this bike. My BMWs had screw adjusters, as did my VTX cruiser. Miss the hydraulic valve adjusters on my Nighthawk.

Last time I had to adjust shim type valves was last year on my Bonneville, and ended up dropping a piece down into the engine. At least I will try harder not to do that again.

I hear ya.

Not on the CB1100, but a Yamaha 1100 I dropped the tappet nut inside the engine block. The room went dark. It didn't help it was about 104F with humidity factored in and every mosquito saw my blood. Long story short: I got the nut out after much curse word practicing.

 

[LakeWylieJoe_imp]

The CB1100 would be perfect, in my mind anyway, if the valvetrain from the original Nighthawk S series were utilized. My '86 CB700SC (tariff beater for you non-US folks) had the maintenance free hydraulic tappets and the valves never needed checking. It had a much higher redline, too. The valves basically self adjusted every time they opened and closed. It was compact system, too, and would have easily fit in the existing head. Did Honda think we were so nostalgic for retro classics that we missed fiddling with the inner bits, too? Sad.

As for me, I dutifully check and precision adjust my valves via shim replacement every 8,000mi and set them back to center of spec... all the while wishing I didn't need to.

 

[peterbaron]

Well said LWJ =

P.S. seen cars with 450K kms, never needed shim replacement..lol