Lennie's rocket sprockets for GS boxers

Hi all,

I went ahead and ordered a set of Lennie's rocket sprockets,after reading all the reviews posted on
advrider. After 2 weeks, I got an mail notice and then ran to the postal office to collect these two sprockets:



Last weekend I planned to have them installed, along with the crash bar, a new lambda probe and a set
of Hella FF 50.

First thing was to have the valve covers removed...






Nothing hard so far. Then, I loosened the screws that hold the OEM sprockets in place, using an 8mm
Allen key. Had a friend press the rear wheel brake wile the engine was in 5th so that the engine was
locked and the screws came loose.

While the screws were still loose, I had the engine turned to top dead center and started to remove the
sprockets when the piston was at TDC on the compression stroke. Then replaced the sprocket with one
of Lennie's, then moved to the other side of the engine. Okay, I might have missed enumerating some
steps here but I had lots of help from the install PDF that Lennie provided, which I have uploaded HERE,
so it may help others too.

After all was done, I checked that the marks on the new sprockets are horizontal for each side while the
piston was at TDC and that the valves were loose on just one side, then rotated the rear wheel and they
were loose on the other side, just like for valve adjustment.

Then I put the valve covers back on, performed a TB sync (nut sure if necessary, but I did it anyway)
and put the fairings and seats back on.
It was time for a test ride.

Wow! The bike felt like totally new. It pulled better from lower rpm's and had more grunt in it. When I
switched from my 1100 GS to my current 1100RT, the first thing I noticed was that the RT was lazier
than the GS, I guess from the final drive ratio that the RT has and the extra weight that the RT carries.
With the new sprockets, the RT feels like the GS used to, faster and gave me more confidence in
overtakes. There are a bunch of other benefits in this sprockets,listed on Lennie's site, among which
fuel consumption, making sense to drop a little,since the bike does not need all that revving like before.

Did not get the chance yet to measure the fuel mileage but will do it an report back with some numbers.
Although this post may seem to you like advertising, it's not. I have no affiliation with Lennie, just
installed this set of his wonderful product and like to report to others, so that they can enjoy a new bike
feel as well.

If anyone interested, this is the link to Lennie's website: http://www.boxerperformance.
com/products.htm . I liked them and recommend having them installed on your beemer
too, definitely!

Thanks,
Dan.

your link goes to the wrong site. http://www.boxer-performance.com/ that hyphen makes all the difference.

Sounds awesome. I'm getting interested in these now. Do they help with the fueling surges in the lower rpm's at all?

Did you order the ones with the crack (seconds)?

Yes, I ordered the seconds. But I have not seen any crack in them :) I don't say that there is not, just that I have not seen it.

Dan.

The bike does seems to run smoother, in the low range zone too. Lennie's site mentions something about this too, so it must be the sprockets doing their job.

Dan.

Dan,

Once I redrilled the locating pin hole the crack is there but without any pressure on the sprocket.

I am glad you have installed the sprocekts and are happy with the result.

Hi lennie, looks like Dan got a good result. Your install guide explains that the sprockets advance the value timing 9 degrees. Is that both intake and exhaust? The mid range is improved, does anything suffer? RB

Roger,

The intake and exhaust lobes are on the one cam so it advances both 9 degrees.

The only area to suffer is about 1 to 2 hp at peak revs but if you never run at peak revs it is not an issue and the benefits in the low and midrange far outway that loss.

Thank you for responding. Two more questions;

--is the metal and hardening/treating the same on your replacement sprocket the same as the original? And will it last as long?

--Low end and mid-range is where we spend our time. I added an Innovate Motorsports LC-1 and run a 13.8:1 mixture. That has added immensely to my low end. Will I get further benefit if I add your sprockets? What are your thoughts on why BMW chose the timing they did?

Thanks,

I did not mean to infer that the so called "seconds" should not be used. To the contrary, if I were going to instal your sprockets, I too would use the "seconds" without reservation.

Maybe you should choose a different descriptive term rather than "seconds" To me, seconds implies inferior.

roger,

1. the seconds (for want of a better term) are the orignal material with case hardening and are far superior to the soft oem sprocket. I had the originals and two different batches rockwell tested and the rocket sprockets are good for liong term durability.

the new sprockets are a material that is as durable or more durable than the earlier batches and only require nitriding and the hardening process was why it was changed. this is much easier for the manufactuing as there is less chance of distortion or shrikage with the holes.

2. the sprockets will always improve the low and midrange and only enhance what you have already done to clean up airflow and fueling in your motor.

As explained to me by an engineer I know is that there are compromises made during design and development of engines and that the current cam timing is to enable the engine to fire up easily and npossibly noise emissions. how true this is I am not certain but even at 9 degrees advance they still start easily and run well.

I hope this helps answer what you are asking.

def,

I never took it in any way negative. I am always a very positive person and sorry if I came across as negative.

The term 'seconds' does imply inferior and they are as good as the originals and I was just trying to clarify what the issue was.
As Dan says, you cannot notice the crack so easily and having redrilled the hole the pressure is gone and the fact it goes from the locating pin hole to the cam mounting hole means it will never propogate. The crack is covered by the thick washer on the early bikes and the crank breather paddle on the left side and cam position indicator on the later bikes.

I spoke to the manufacturer, a number of mechanics and a metalurgist about it before I decided to sell the sprockets and it is not a decision I took lightly. Now there are many happy customers taking advantage of the cheaper price of these. The savings in fuel pay for the sprockets in the short to medium term with ongoing savings dependant how hard you are with the throttle hand.

Enjoy.

Very interesting, thanks for the clarifications. How did you realize that the boxer engine could be improved by a change of valve timing? It seems like a hard experiment to try given that you've got to cut some gears.

Out of curiosity, does the benefit come from opening the intakes and exhausts sooner, or from closing them sooner?

roger,

I just applied general engine tuning techniques that I have tried over the years with other engines.

I had to get two blank gears cut then have them setup to be adjustable with locating pin holes drilled at 3 deg retarded, 0 deg, 3, 6, 9 and 12 deg advanced. This was a very expensive process.

We stopped at 9 degrees on the dyno and tried that on the road and it was a good result.

Opening and closing the valves early combine to move the torque curve and without trying cam regrinds or new grinds to test I cannot definitively answer whether one or the other is the best for the improvement.

Please report back on fuel mileage. (go easy with your new-found power!) I love the reviews and want these sprockets but I get 50mpg and don't want to lose that.

Andy

Lennie,

Thanks. That's a good clear explanation. Trying each advance position and testing the performance seems like a sound method.

On my R1150RT with Wideband O2 I'm getting about 60 lb.-ft. down to about 2000-2200 RPM in 4th and 5th gear. Would your sprockets get me 50-60 lb.-ft. down as low as 1500 RPM?

Roger

Roger,

If you have the prontout for the torque and hp, you will see that whaecer you are getting at around 2800 to 3000 rpm is close to what you will get that low.

Bravo for your full disclosure.

Ever consider running for political office?

73

Thats amazing and would make a further improvement.

Been following this and other Lennie sprocket threads for some time now. I apologize because this is probably a dumb question, but I need some help with the Dyno graphs on Lennie's web site.



The blue is stock the red is after sprockets (and some other mods, but lets assume that those did not contribute significantly to the change). I don't see anything for under 2600 rpm for either line and the red/with sprockets line, seem to be approaching zero torque at around 2600 rpm so how can it increase the torque at lower rpms? I also can't figure out why the stock curve starts so high, should it not start near zero as well?