After installing Lennie's rocket sprockets

[Hookalatch]

Originally Posted by roger 04 rt

From an article on cam advancing (and I'm not saying nor do I have any opinion on whether 9 degrees is the right or wrong number for the boxers):

When the cam is advanced, the intake valve will open earlier during the exhaust stroke and the exhaust valve will shut earlier during the intake stroke. If the cam is advanced too far, reversion will occur and the exhaust gasses will not be adequately scavenged. Four degrees advance is usually the most that you can safely advance a cam beyond the manufacture’s recommended LC. When the cam is retarded, cylinder pressure will be reduced but the scavenging process is increased. If you are experiencing pre-detonation, retarding the cam will help. It also has a tendency to move peak hp to a higher rpm. Again, care should be taken when changing cam timing. Another consideration when playing with cam timing is piston to valve clearance. When you change the valve events (timing), the clearances will change and should be checked.

Make sure you are making accurate comparisons about the different degrees or advance or retard for the camshaft. Normally, when quoting advance (or retard) cam timing the figure is stated in degrees of engine revolution. In Lennie's sprockets that is 9 degrees of engine rotation. That results in 4.5 degrees of camshaft rotation since it rotates at 1/2 crankshaft speed. The above quote refers to camshaft advance of 4 degrees- which is 8 engine degrees. What it amounts to on Lennie's sprockets is about 1/4 of a tooth difference on the sprocket.

What really surprises me about the sprockets is why they haven't caught on in a big way. If you run your engine at or near redline all the time the sprockets will work against you. If you run the bike between 3000-6000 rpm most of the time the sprockets make it a much better riding machine. I have had the sprockets in my R1200GS for quite a while now and have posted my positive results before. I don't want to sound like a Lennie salesman so I won't go into it again except to say I would have to do this again if I changed bikes because I would not be happy with stock anymore.

Chuck

[roger 04 rt]

Originally Posted by Hookalatch

Make sure you are making accurate comparisons about the different degrees or advance or retard for the camshaft. Normally, when quoting advance (or retard) cam timing the figure is stated in degrees of engine revolution. In Lennie's sprockets that is 9 degrees of engine rotation. That results in 4.5 degrees of camshaft rotation since it rotates at 1/2 crankshaft speed. The above quote refers to camshaft advance of 4 degrees- which is 8 engine degrees. What it amounts to on Lennie's sprockets is about 1/4 of a tooth difference on the sprocket.

What really surprises me about the sprockets is why they haven't caught on in a big way. If you run your engine at or near redline all the time the sprockets will work against you. If you run the bike between 3000-6000 rpm most of the time the sprockets make it a much better riding machine. I have had the sprockets in my R1200GS for quite a while now and have posted my positive results before. I don't want to sound like a Lennie salesman so I won't go into it again except to say I would have to do this again if I changed bikes because I would not be happy with stock anymore.

Chuck

That's a very good clarification, thank you. I had missed that he's specifying degrees of engine rotation as opposed to cam rotation.

I've had a large/measurable boost in the 2000 to 3000 RPM range from my Wideband O2 installation and running with 6% more fuel. Now I'm wondering if advancing cam would boost further in that range or even lower.

You feel the same about the cams as I feel about the fueling boost.

Hopefully Lennie will confirm this cam advance vs crank advance.

[Ken Fritz]

I understand the logic behind this mod. I'd have done this sooner, but only just now stumbled across it on ADV. Mine are now on order for my 1150GS. I just wish I had known earlier so I could get them for less $$$. Lennie - ever consider a discount for ADVriders?

In the '70's Datsun was into racing and offered different cams and sprockets for the overhead cam engines. In fact, a stock 4 cyl OHC Datsun 510 had three locating holes drilled in the stock cam sprocket - you could advance valve timing by remounting the sprocket on a different pin for the cost of a valve cover gasket (under $5) and some time.

[dirtsurfer]

Originally Posted by Dan Cãta

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




................

Must the valve covers be removed to do the install?

[The Other JC]

Originally Posted by dirtsurfer

Must the valve covers be removed to do the install?

Yes

[Dan Cãta]

Originally Posted by Ken Fritz

In the '70's Datsun was into racing and offered different cams and sprockets for the overhead cam engines. In fact, a stock 4 cyl OHC Datsun 510 had three locating holes drilled in the stock cam sprocket - you could advance valve timing by remounting the sprocket on a different pin for the cost of a valve cover gasket (under $5) and some time.

You will never see that in BMW. Apparently, their politics is "get everything new, from us".

Originally Posted by dirtsurfer

Must the valve covers be removed to do the install?

Yes, you need to do this in order to get the ole sprockets out and the new ones in. Also, I adjust the valves after this job, then sync the bike.

Dan.

[Andrew]

Originally Posted by dirtsurfer

Must the valve covers be removed to do the install?

Apart from removing and replacing tire valve stem caps, removing engine valve covers is probably the most frequent maintenance item on Boxer engines. No reason to shy away from it.

[lennie]

Roger,

I have quoted the changes in crankshaft degrees so the cams are advance 4.5 degrees. We found that the dyno graphs are no indicative of the real gains in the bike. It was the same with the InDuct that it does not show the full benefit once on the road.

I have left the dyno many times disappointed until I twisted the throttle.

Hookalatch,

You are not a sleasman for me but simply a satisfied customer.

Yes I am amazed that the sprockets have not taken off and that the sales are a slow steady. That is ok as it is just a sideline for me and I hope that it can pay for more development on my next bike. I am considering a R1200GS watercooled later in the year and possibly a F850R for road so more work to do.

Ken,

I will post your sprockets this morning Eovernight express so they will be there tomorrow.

[roger 04 rt]

Originally Posted by lennie

Roger,

I have quoted the changes in crankshaft degrees so the cams are advance 4.5 degrees. We found that the dyno graphs are no indicative of the real gains in the bike. It was the same with the InDuct that it does not show the full benefit once on the road.

I have left the dyno many times disappointed until I twisted the throttle.

Thanks for the further clarification.

I've noticed generally that many dyno charts don't appear to have reliable data at low RPMs--the area where your sprockets should show gains. Some charts don't seem to kick in until 2500-3000 RPM. (The AFR data on many charts I've seen looks wrong, in some cases even at 4000 RPM. Below is an example of clearly wrong afr data below 4000 rpm; no way is it 15:1 at WOT between 3000 and 3500 rpm.) I have no reason to doubt your sprockets work; so if there is a gain, there must be something that is measurable.

[Hookalatch]

Originally Posted by lennie

Hookalatch,

You are not a sleasman for me but simply a satisfied customer.

Yes I am amazed that the sprockets have not taken off and that the sales are a slow steady. That is ok as it is just a sideline for me and I hope that it can pay for more development on my next bike. I am considering a R1200GS watercooled later in the year and possibly a F850R for road so more work to do..

I had already established that I was not a salesman for you.
Good to know you don't consider me a sleasman either, although there may be some who would disagree.

Chuck

[BobLoblaw]

my 1150GS runs very nicely on regular fuel. Does the 4.5 degree advance increase the compression ratio enough that higher octane fuel is required.

[lennie]

Roger,

Most dynos have a control button to start collecting data. THe other thing is that you run it at part tghrottle then to WOT for each run. Dynos only show part of the story with changes and hence why I woulkd leave dejected sometimes until I rode the bike with part throttle on the road.

II dont take to omuch from the dyno graphs but I do understand many like to see the results before they purchase.

Hookalatch,

My fingers are not so good lately and I need to sack my proof reader for the sloppy work as it really is not my spelling.

[roger 04 rt]

You can use a GS-911 as an accelerometer or something like it to log a bike's acceleration before and after a change of configuration. That's about as real world as it gets—accelerating a bike, on the road, into the friction of air. You can also use that approach for role-on acceleration tests—how long to get from speed A to B in a given gear. Whatever best shows the product.

[lennie]

Roger,

I am sure they are not an easy thing to find.

[madpuma13]

So, after reading all this I want to pick up a rocket sprocket. My problem though is r1200gs isn't listed in the list of bikes in the shop.
The site says the rocket sprocket fits all r1200gs up to 09 (I have an 08).
Don't want to get the wrong one and have to pay international shipping to send it back from the US
Do you know which is the correct one?

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