roller rockers should be ok for the lower rpms the 1200 turns. Port injection is better then tb. But they still got the butterfly to control the air a slide would of been better for air flow.
With this setup valves can be opened and closed quicker, not only because of the roller but the rocker ratio is probably better than one to one. the potential for making power is there.
lighter the valve train the better dohc bucket set up is best for high rpm work if the shim is under the bucket instead of on top like our bikes have been. with a bucket set up there is much less to break or wear out. roller rockers are much better then rockers with out. with buckets you can turn 12000 rpms+. rockers are good for about 10,000 rpms
They are still 4 valve heads, the follower is forked so a single rocker activates 2 valves. Looking at the photo'it looks like they've done this to create a more compact package.
I've always found rocker actuated valves way easier to adjust. No cam to pull so no worries about screwing up the timing.
I guess in this case you may have to pull the rocker arm, but you don't need to deal with any cam bearings/cam chain tensioner in getting it done...just TDC, measure, pull rocker(s), correct the shim(s), and reinstall. Probably the right design given the target rpm for power generation on this motor....
:grin2: My W800 has a single camshaft driving 8 valves via rockers. It also features the sliding rocker design ala Ducati. I cannot understand why Triumph, or any other manufacturers, don't utilise this system. It makes clearance adjustments so easy as nothing inside the head needs to be removed. Apart from that it promises to be a great engine, and may even tempt me back into the fold. providing it isn't too heavy!
I don't think the rev limit was lowered because of the valve train (the valve train should work just fine. I think the reason they lowered the rev limit is because they cant feed the big 1200 enough air to run in the 8000+ range and still pass epa laws. I read they have a off road race kit for the r1200 that has better cams and pipes with rev cones and no cat convertors. I wonder how much that will pick the hp up on the new motors. from what I can figure from the info out there now the r1200 probably wont make over 80 hp on the rear wheel. Sure hope the race kit picks them up a bunch. That migh be all the ecu will let you do to them with out spending big $$$ to build custom controls.
Generally, there is little difference in price between a regrind on a SOHC motor and on twin cam motors. Go to Megacycle cams and check pricing if you want, but it's probably no more than $100 cheaper to regrind a single cam.
Oh, and to answer your question, I want to rev to 9,000....maybe even 9,500 if the motor's power development warrants it.
Any way you look at it, it's going to amount to a lot of shop time ($$$) striping the bike to where you can actually remove the valve cover, and replace shims once the head is open. Experience has taught me that there are numerous chances for sloppy work, error, or actual cheating along the line before that job is done and the bike is back to you. This is where shops make a lot of their money. If your not competent adjusting valves yourself, get a BMW with "anyone can do it" accessible, adjustable rockers and spend less than an hour doing it yourself. Or forget about adjustment and ride until something else makes you buy a new bike. How many posts have you seen on this site about a ruined engine because of valve adjustment?
I wouldn’t over think the valve adjustment process.
I think adjustment will be very simple. Just rotate the engine so that the roller of one rocker is on the heel of its associated cam lobe. Then Triumph probably have a tool to compress the springs on the valves just enough to remove the shims and replace them with ones to provide the correct clearance. Then release the spring compressor and rotate the engine and measure the final clearance. Pretty easy work I think.
Kawasaki did much the same with their Z1 back in ‘73. The factory had a tool that was inserted on the compressed valve bucket follower. Then the engine was rotated and as the cam rotated the tool kept the valve and bucket from rising. Then you popped the shim out of the bucket recess, and replaced it with another. Then you rotated the engine again until the nose of the cam was pressing on the shim. Then you slide the tool out from the head, rotate the engine and do a final check on values clearance.
Triumph could have designed the head of the 865 to allow the use of such a tool, but then fewer people would have brought their bikes to dealers to have the valves adjusted when they realized how easy it was to do their own adjustments. Less dealer revenue.
Now, something total unrelated: I did notice that it appears from the publicity photos of the 1200 engine that the swingarm pivot on the 1200 does not pass through the rear of the engine cases as it does on the 865. That’s unfortunate since this one feature did use the 865 engine as a structural member of the chassis. A good thing, but I guess not on the 1200’s.
I am not really a fan of SOHC engines, but if Triumph are telling us that these 1200’s will have locomotive style, stump pulling torque, maybe 7000 RPM will be sufficient.
The real limiting factor when it comes to performance on these new motors is if they screw us over and lock the ecu like they have been doing on these later bikes.
The real limiting factor when it comes to performance on these new motors is if they screw us over and lock the ecu like have been doing on these later bikes.
who knows that maybe a dealer only up grade for the race kit. They could have the program for the race kit all ready in the ecu and the dealer may be the only one that can change it.
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