Interesting ( to me, anyway) New Bonnie valve actuation

[ohiorider]

I re-read a recent Motorcyclist article about the new Bonneville 1200's.  And was pleased to read that the cams were driven by an intermediate gear.  If that means it's like the current 865 Bonnies, it means the timing chain stays connected to the intermediate shaft when the cam(s) are removed to replace a shim.  Hope that's true, since the more I look at the write-ups on the new Bonnie, I feel a pull on the bank account. 

I suppose it isn't difficult to remove and replace camshafts if one follows procedures to remove camshafts that are directly driven by the cam chain, but my level of confidence rises dramatically if I don't have to fiddle with removing camshafts and then figure out how to retime things when replacing them (other than aligning some hash marks on the cam gears with marks on the intermediate gear.)  That's all due, no doubt, to having no experience working on dohc cam engines with cams driven directly by the chain.

Sorry if this makes no sense!

[guzzisteve]

Makes perfect sense. But I knew what you were talking about.

[Penderic]

Looks simple.

 

[ohiorider]

Makes perfect sense. But I knew what you were talking about.

I knew you would!  Have a great Thanksgiving, Steve!

Bob

[Bisbonian]

My DL1000 V-Strom was set up this way also.

[Vasco DG]

A ot of Aprilias use a similar system. The Shiver/Doso motor springs to mind. The V4 uses a similar system with a chain driving one cam and the second one geared to it. It's a lovely system, just a PITA to get to!

Pete

[ohiorider]

790/865 Bonneville cam actuation system.  Copy and paste with added open/close specs.  Showing cam driving gear, timing marks.

I made up several slides when I attempted to modify the cam timing of my 790 Bonnie in an attempt to move the torque band closer to that of the newer 865's.  Wasted effort, but the good news was, I didn't break anything!

It was unfortunate (for home mechanics) that Triumph didn't make all 8 valve shims accessible without the need to remove the camshafts.  Unfortunately, one or two of them couldn't be reached without popping the cams out.  The strangest thing was removing the torx bolts holding the cam caps ... though they were torqued very low, the damned things required me to use an impact hammer to break them loose, first time anyway.  Other guys borrowed a second set of hands.  While one person put all his weight on the torx driver, the other turned the driver with a wrench.

[Kev m]

Actually that looks like a nice system, relatively easy to service.

It was unfortunate (for home mechanics) that Triumph didn't make all 8 valve shims accessible without the need to remove the camshafts.  Unfortunately, one or two of them couldn't be reached without popping the cams out.  The strangest thing was removing the torx bolts holding the cam caps ... though they were torqued very low, the damned things required me to use an impact hammer to break them loose, first time anyway.  Other guys borrowed a second set of hands.  While one person put all his weight on the torx driver, the other turned the driver with a wrench.

Loctite???

[jackson]

This is a good thing for the person who wants to do their own maintenance.  I'm looking forward to reading more information/reviews from the people who purchase them.  I think that (despite the price keeping some from buying), Triumph will sell a lot of them in the USA.

[Kev m]

This is a good thing for the person who wants to do their own maintenance.  I'm looking forward to reading more information/reviews from the people who purchase them.  I think that (despite the price keeping some from buying), Triumph will sell a lot of them in the USA.

Have we got the official word on prices yet?

I thought the early reports were the Thruxtons were a little high, but the rest seemed pretty reasonable/competitive (actually you could argue the Thruxtons are reasonable/competitive for what you get). No?

[ohiorider]

Actually that looks like a nice system, relatively easy to service.

Loctite???

Pretty easy to service, actually.  I found from the TriumphRat forum that shims from several Japanese bikes would work, and knew a dealer that would swap shims at no charge with me.  Nice folks.

Here's a brief quote from "Motorcyclist."
....... and a hybrid cam drive with a central chain running up to idler gear(s) which then drive the twin cams.  While the engine qualifies as 'all new' it's a familiar kind of new.
I'll take that as gospel when I see a service manual with some drawings.

[jackson]

Have we got the official word on prices yet?

I thought the early reports were the Thruxtons were a little high, but the rest seemed pretty reasonable/competitive (actually you could argue the Thruxtons are reasonable/competitive for what you get). No?

According to this: http://www.eurosportcycle.com/?page_id=419
the Thruxton R (the model that most enthusiasts will probably want to buy) is $14,500.  And that's probably plus freight, setup and of course, taxes, title, etc. which means an out the door price of very close to $16,000.

[Kev m]

According to this: http://www.eurosportcycle.com/?page_id=419
the Thruxton R (the model that most enthusiasts will probably want to buy) is $14,500.  And that's probably plus freight, setup and of course, taxes, title, etc. which means an out the door price of very close to $16,000.

Ah yes, thanks, that was it:

The first bikes to arrive will be the new 900 Street Twin variety starting with a sales price of $8,700 for Black, and $8,950 for all other colors. They are to hit our store in January.

“But I want the 1200 cc motor,” you say. Those are slated to come next as the T120 Black and T120 ($11,500 for the Black, $11,750 for Matte Gray and Cinder Red, and $12,000 for all two tones) in March.

The Thruxton R is then set for April with a price tag of $14,500, and bringing up the rear will be the Thruxton in May for $12,500 in Black and $12,750 in Green or White.

One could argue the Street is a bargain, the T120 and base Thruxtons are quite reasonable, and the Thruxton R is a premium, but you get an awful lot for it.

[Bisbonian]

Pretty easy to service, actually.  I found from the TriumphRat forum that shims from several Japanese bikes would work, and knew a dealer that would swap shims at no charge with me.  Nice folks.

On my CB500X the valve actuation is by some sort of rocker arms that sit on a shaft (I haven't had to do anything yet and really have no desire to look at it until I do). Evidently to replace shims you remove the rocker arm shaft as the shims sit under the rockers, no need to remove the cams and timing is not affected.

[ohiorider]

On my CB500X the valve actuation is by some sort of rocker arms that sit on a shaft (I haven't had to do anything yet and really have no desire to look at it until I do). Evidently to replace shims you remove the rocker arm shaft as the shims sit under the rockers, no need to remove the cams and timing is not affected.

Sounds a lot like the W650, which was even easier.  It was a single overhead cam design with rocker arms.  The really neat thing was the fact that the rockers were also on a shaft, but were spring loaded, so they could easily be slid on the shaft.  Take two fingers, slide the pair of rockers toward each other (or away from each other??), and the little shims were exposed.  Remove old shims, and slip in the correct shims and release the rockers and they slid back into place.