are modern motorcycles still flat tappet cam drive

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Hi,

as we all know almost all motorcycles of today still need periodical valve adjustments. So they aren't hydraulic lifters.

But there comes my lack of experience: Are modern motorcycles still flat tappet cam shaft driven or do they rely on roller cams?

For example: The Piaggio 125cc Quasar engine, used in the GTS 125ie - I have googled pictures of their cylinder head - but I can't tell the system they've used, I can see two actuator arms, springs and hidden underneath is the camshaft. What kind of system is that?

Or a Suzuki Boulevard C50, first picture on the right on this site: http://www.bikerbits.com.au/adventures/boulevard_adjust_valves.shtml
what kind of system is that?

More pictures of the C50 cylinder head here, should be the first offer: http://www.bikerbits.com.au/adventures/boulevard_adjust_valves.shtml
-> btw. I'm not sure If I'm allowed to directly link this?

Thanks for the education,

Alex
 
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Ive seen finger-follower rockers with jam nut, SUB OHC and Desmo. IIRC the last nice engine I worked on was a gixer DOHC 16V with finger followers.

Had a Yamie 5 valver 700 I4 but never cracked the covers.
 
Moto Guzzi's are still [air cooled] and pushrod but went from flat to roller tappets in model year 2012.
 
The bikes I've owned have been:

Shim over bucket, no roller
Shim under bucket, no roller
Screw and lock nut type (Honda XL600R)
 
Let me youtube that for you
smile.gif


Piaggio + 125 + valve adjustment ( or clearances)
 
Whats modern? Some motorcycles have been essentially unchanged for 20 or 30 years or longer. They wouldn't meet US emissions standards for a newly introduced motorcycle, but they are grandfathered in.

I have a Suzuki Boulevard S40 that has a single cylinder 652cc engine. Its essentially unchanged, and the 1980's models are identical to the 2017 model sold today. It has a cam in the head that actuates the valves. I dont know the technical term, but its similar to a flat tappet with no rollers.
 
Flat tappet engines almost have to be push-rod engines. There are no overhead cam configurations I can think of that have a flat tappet system ...

Older V-Twins are more likely than any other to have flat tappets ...

Flat tappets can be either hydraulic (as introduced by Buick in '49 IIRC), or they can be solids as run in a gazzilion older Fords and Chrysler products ...

Flat-head motors are almost all flat tappets too. But they usually act directly on the valve stem ...
 
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...oh, Thought you said modern bikes.... Shim under bucket is the standard. Most modern, oxymoron, cruisers and Gold Wings are hydraulic...
 
Originally Posted By: BrocLuno
Flat tappet engines almost have to be push-rod engines. There are no overhead cam configurations I can think of that have a flat tappet system ...

Any cam lobe directly actuating a flat shim or flat bucket (with shim under) is a "flat tappet" design.

Modern high performance motorcycles still all use that design for good valve train control at high RPM. The design has been around for 40+ years, so it obviously is a design that works well.
 
Originally Posted By: alex_at
Hi,

as we all know almost all motorcycles of today still need periodical valve adjustments. So they aren't hydraulic lifters.

Alex


Errrrrr... Harleys never need valves adjusted. For all their backwards tech, hydraulic valves natch!
 
Originally Posted By: WANG
Hydraulics and rollers are mainly used in more agricultural mc applications.


Honda got 11,000rpm from hydraulic lifters 35 years ago.
 
"Most modern, oxymoron, cruisers and Gold Wings are hydraulic..."

^ I resemble that remark.....
crazy.gif
 
Originally Posted By: sunruh
Originally Posted By: rubberchicken
Most bikes are shims over buckets.


try shim UNDER bucket
That"s too heavy for big HP - NO tappets NO buckets on rocket bikes. Just tiny rocker cam followers (finger followers) acting on the valves. I bet if its got a redline over 9000rpm its got that valvetrain. At least that's the way it was in the late 80's
smile.gif


Here a GIXER head ( 750 I think):

 
Originally Posted By: ARCOgraphite
That"s too heavy for big HP - NO tappets NO buckets on rocket bikes. Just tiny rocker cam followers (finger followers) acting on the valves. I bet if its got a redline over 9000rpm its got that valvetrain. At least that's the way it was in the late 80's


The late 80's to early 90's was around the time when sportbike engines began switching over to shim under buckets. These days liquid-cooled high-revving multicylinder sportbike engines* are mostly shim under buckets with a few shim over buckets with finger followers in very recent years (e.g. BMW S1000, Yamaha R1).

The 250+ hp supercharged Kawasaki Ninja H2R that revs to 14K rpm - shim under buckets. So not really too heavy for big HP.


* - Gotta be real specific here since motorcycle engines run the gamut. As some other posters have mentioned, some motorcycle engines still in production haven't changed at all in the past 2-3 decades, with a few even still using carbs.
 
Originally Posted By: ARCOgraphite
Originally Posted By: sunruh
Originally Posted By: rubberchicken
Most bikes are shims over buckets.


try shim UNDER bucket
That"s too heavy for big HP - NO tappets NO buckets on rocket bikes. Just tiny rocker cam followers (finger followers) acting on the valves. I bet if its got a redline over 9000rpm its got that valvetrain. At least that's the way it was in the late 80's
smile.gif


Here a GIXER head ( 750 I think):




30+ years ago, that valvetrain on the old oil-boilers was ok, but required frequent checks/adjustments. Today, as has been mentioned, most Sportbikes are shim under bucket.

There are some exceptions: Ducati Desmodromic valvetrain, BMW individual finger followers, etc.
 
Originally Posted By: ARCOgraphite
Originally Posted By: sunruh
Originally Posted By: rubberchicken
Most bikes are shims over buckets.


try shim UNDER bucket
That"s too heavy for big HP - NO tappets NO buckets on rocket bikes. Just tiny rocker cam followers (finger followers) acting on the valves. I bet if its got a redline over 9000rpm its got that valvetrain. At least that's the way it was in the late 80's
smile.gif


Here a GIXER head ( 750 I think):




One more time: Honda got 10,500RPM out of HYDRAULIC lifters more than 30 years ago! (And note: the valvetrain wasn't the limiting factor!)
 
One more time: Honda got 10,500RPM out of HYDRAULIC lifters more than 30 years ago! (And note: the valvetrain wasn't the limiting factor!)

. . . and on their larger V-twin, like the 1100 Shadow, AFAIK, they've always been hydraulic lifers
 
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