Ideas for performance upgrades while it’s apart?

[bigscience]

So, the left side upper cam-chain slider shattered, showering plastic bits all about and dropping the tensioner into the pan. Oh well. Reading shad’s recent posts about a similar problem (his was the right side slider) it seems there is no alternative but to split the case to effect the repair. Sooo, while we’re in there you guys have any suggestions for performance upgrades?

The bike is a ’99 with 60k miles on it. It’s been my occasional track bike and is going more and more in that direction as it’s been down a few times and has zero resale. For daily transpo I also have an ‘03 which is clean and pretty (the date bike). The internals on the ‘99 are clean and in great shape- the cylinders still have cross-hatching on them after 60k: it’s not even broken in yet! The only mods so far are a wide band Power Commander, a Z-Technic and having the exhaust crossover deleted.

I’m not super rich but am willing to blow a few bucks on this since, by my thinking, it’s trash if it don’t run. With that in mind, how worthwhile are cams and porting and polishing? And any suggestions for what cam grind and who has them? I’d still like to maintain some streetability, if for no other reason than I ride it to the track, but am considering shaving the heads and shimming the valves, although I’m not clear on the particulars of either. I think N8 had his decked by 0.008 which worked out to 13:1. Too much for the street? Obviously I won’t be running the crap winter-mix fuel served up in Maryland anymore. I’m willing to consider just about anything at this point though I think I’ve ruled out an 1150 kit. Seems a shame to bin those perfectly good pistons.


Also, in an earlier post to shad, Roger had suggested some prophylactic maintenance in replacing the transmission input seal, the rear main seal and perhaps the friction disk. Anything else worth doing?


In the interest of full disclosure let it be known that I’m not doing this myself. I don’t have a space anymore and there just happens to be a great shop down the road from me with an old time BMW wrench in charge. I’ll take pics though!

Thanks for your ideas

Carlos

[roger albert]

Let the wrench look over the heads and check valve-guide/valvestem clearance. At least lap the valves.

Don't assume just because you can see crosshatch, that the cylinder is still in spec for taper and oval and piston-to-cylinder clearance. Often not the case. If it isn't, then you can go big bore anyway. If so, hi comp pistons are still nice (not just for the compression, but because they're lighter, allowing better revving and with less vibes)

Listen to whatever your head guy has to say.

[Bob Hancock]

And Carlos yes please take lottsa pics! I've never been that deep into one of these but I sure would like to "be there" when it happens, even if it's vicariously. Pics pics pics. We got high speed!

[Bob Hancock]

And Carlos yes please take lottsa pics! I've never been that deep into one of these but I sure would like to "be there" when it happens, even if it's vicariously. Pics pics pics. On a side note...if it was mine I'd go for the 1150 kit and high comp pistons....no replacement for displacement...or somethin' like that.

[bigscience]

san jose offers an 1150 kit I believe. I'll look into prices. any others out there to consider?

[R111S]

A few years ago I called Chris Hodgeson to ask about performance mods for my previous motorcycle, a '94 R100GS/PD. I told Chris I wanted at least ~85 RWHP and reliability for touring. His advice really opened my eyes to the absurdness of my idea and what kind of businessman he is. He told me that it wouldn't be reliable and that if I wanted that kind of power to just get an Oilhead. I thanked him for his good advice and remained content with my Dual-Plugged Heads, 9.5:1 Pistons, and SuperTrapp till it blew up in 2004 (dropped the right exhaust valve at '81K Miles).

I would advise a call to Chris Hodgeson, surely he can give you some good words of whats the best route for your particular needs.

I myself would strongly recommend Dual Plug Heads if you decide for higher compression pistons. It was simply amazing what it did for my old Airhead when I replaced the stock 8.5:1 Pistons for the 9.5:1 Pistons. Power improved at all RPMs and gas mileage increased from 12-25% depending on various factors. With the 8.7 Gallon PD Tank I could routinely reach ~400 Miles before running dry. With the stock setup it could go ~350 Miles at the most.

[roger albert]

Very good advice.

[bigscience]

hadn't thought about the plugs; good point. the airheads could be drilled to accept the second plug, but with the oilheads you just replace the head altogether, right?


I've gone through some of the discussions on the forum surrounding the 1150 kit and the jury doesn't seem to have come up with a unanimous verdict. folks seemed against the idea if there is nothing wrong with the bike to begin with, that the money is better spent on an R12S. but if the engine is lunched then the kit was the way to go- bump displacement and compression. unfortunately I'm somewhere inbetween. heads are fine so there is no imperative to replace them yet the labor involved is happening anyway. guess I should have driven it longer in teh hopes of really breaking something. (well maybe they'll be out of spec for taper and oval as Roger mentioned. I can hope I suppose)

if I keep the heads what is the best way to go about bumping compression- mill the heads or replace the pistons? milling is cheaper but does it do the same thing?

I emailed Chris yesterday and willl post his reply when I get it.

[roger albert]

No,

Chris offers a Dual-plugging service for the original heads.

General comment (in case one should not like the results, perhaps because of accidentally going too far) Changing pistons is easily reversible. Unmilling a head less so.

[R111S]

Originally posted by bigscience
hadn't thought about the plugs; good point. the airheads could be drilled to accept the second plug, but with the oilheads you just replace the head altogether, right?

As I understand it, you can do the same as on the Airheads and drill holes for plugs...here's some pics from Wudo in Germany.







The best thing about Dual-Plug is that your engine will have better resistance to detonation when you go to higher compression pistons. The air/fuel charge is burned over a shorter period of time, before compression pressure gets too high, thus avoiding the very conditions that lead to detonation. You even have to retard the timing because this quicker burning effectively advances the timing. Lean limit stability is also improved. This explains why the latest OilHeads are Dual-Plug. I dare say the 12.5:1 CR on the R1200S would not be achievable with single plugs on pump gas.

I checked out a book on Combustion Theory by Charles F. Taylor at MIT when I was researching doing it to my Airhead...He directed the Sloan Automotive Laboratories at MIT from 1926 to 1960. It really helped me to understand the real benefits of Dual-Plugs. He experimented with even more plugs on a Flathead engine, up to seventeen plugs I faintly recall. Basically, 2 or 3 plugs per cylinder was the best trade-off between valve area versus room for plugs.

http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=6992

[pmc847]

I don't know where the .008 yielding 13:1 figure came from because all my calculations came out as follows. I also CCed the heads. Stock came out at 43.4 cc and after cleaning and polishing they were 44.7.

Mill heads---------.020-------39.5cc------12.1
------------------.025-------38.5cc------12.4
------------------.030-------37.5cc------12.6
------------------.035-------36.5cc------12.8
------------------.040-------35.6cc------13.1

I used http://www.turbofast.com.au/Tfcomp.html to calculate compression ratio and head volume.

I milled .025 off of my heads, installed 2mm larger intake and exhaust valves and degreed cams to 3 degrees advance (2 degrees ATDC). Stock was 10 degrees retarded (15degrees ATDC) from published figure of 5 degrees ATDC @ 3mm (.120) lift. I still have adequate valve to piston clearance with this set up but if I install high lift cams might mean machining the valve pockets for clearance or buying new HC pistons with valve pockets for high lift cams.

Philip
"It's a great bike but I can make it better".

04 R1100S BCR # 195
03 R1100S BCR #44 R.I.P. new home with 'onekiwi'
Adjustable cam sprockets
Milled heads .025
Larger Valves +2mm intake & Exhaust
Ported and polished heads (just a little)
SJBMW Exhaust Accelerator Kit (modified)
Laser Exhaust
InDuct
SJ PowerFilter
Laser 2 spark Chip
K's 3.5 bar regulator
Ohlins
Sargant Seat
Throttle bodies matched to rubber mounts matched to heads
Throttle bodies venture steps smoothed out.
Exhaust pipe welds ground down
Aux Fuel Tank (6.8 gallons total)


Please note that your results may vary.

[bigscience]

R111S,

Thanks for putting me in this direction.

I haven’t seen the Taylor book but I got Ricardo’s book and biography for my old man- he’s got time for theory. All of it amazing stuff. You’d think after all that it wouldn’t be up to us to build a better engine.

http://www.ricardo.com/ricardoStore/


Meanwhile….
I just got off the phone with Chris at San Jose and got an answer I think I can live with.

So there are two issues here, one is what maintenance to do since the motor is apart and the second is what performance mods can be done on a reasonable budget for a bike that will not dramatically improve regardless of money is spent (in proportion to buying a hexhead, say).

First the boring stuff:
Since the bike has 60k on it Chris recommends replacing the rear main seal, rod bearings and piston rings in addition to the cam-chain sliders. He would not bother with the cam chains (says he’s seen them with 300k on them) or the tranny seal unless it is leaking. Check the clutch obviously, but other than that, there’s nothing to do. Bottom ends last forever.

Fun stuff:
The most bang for the buck seems to be mild porting, valve grind, larger valves and a cam.

Porting: 300
Grind valves: 90 per hour
Valve seals 5 x 8 = 40
New valves: 37 x 4 = 148
Disassembly, cleaning etc = 180
Cam = 500

For a total in the 1200- 1300 buck range.

Other possibilities:
We spoke about the 1150 kit and he steered me away from it as too expensive an option. Money better spent on a trackday or the new bike fund.

Decking the heads would provide no meaningful gains. 0.010 to 0.020 would be doable but, as pmc points out above, you need to grind .035 to .040 to get a compression boost you’ll notice and at that point there is a problem with slack in the cam chains. This was also pointed out to me by my wrench Shawn. Okay, now two people have told me this same thing so I guess I believe it.

Extensive porting and polishing. They offer a thousand dollar job that reshapes the whole port, but if not in conjunction with a ridiculous cam and huge valves, it’s not worth it.

Dual plugs. Chris says the benefit to this on the oilheads is to prevent surging, or to get through European emissions. He doesn’t do it for performance gains and said they had never even bothered to chase down how much compression you could get away with by switching. Again, money better spent on a trackday or a new bike. (Also, if you have ABS (which I don’t) there is no place to put the new coil).

K-bike fuel pump. No benefit here either because the bike already has a wb power commander on it. The K pump adds fuel everywhere, even where it hurts performance, whilst the PC adds it where it needs to be.

He did recommend a power filter to get air to the newly warmed heads. Other than that, nothing.

So ~$1300 for parts and about $1300 for labor and I’ll have a fresh, tight, spunky motor for another tens of thousands of miles. A fairly fun investment with some margin of practical value. And the block will make a nice coffee table some day.

I rather like confining the investment to the heads for the ancillary reason that should I put the bike into a wall and decide to part it out I can simply pull the heads and drop them on my other bike.


I’d like to point out that Chris didn’t try to sell me a bunch of stuff I didn’t need or wouldn’t want. I told him I wasn’t going to run Daytona (with this bike, lol) and he conscientiously pointed me towards the best performance for the dollar option in all cases. All the more notable since he developed/makes/sells the more pricy options. Next bike might just be bought from him even if I have to drive it home cross country.

Carlos

[Bob Hancock]

Solid info Carlos....thanks. So....are you gonna let your local wrench do the bottom end and send the heads to Chris or is the whole project something the normal mech can do?
Wonder how wild the cams are.....lumpity-lump or not something you can hear.

[bigscience]

the heads will go to Chris and come back assembled, and the cams are the midrange improvement variety. He also has a more radical grind that wouldn't be appropriate with out the rest of the more major changes, but that would put me past the point of increasing returns.

I should have mentioned that Chris tells me the one scenario where the 1150 bump makes sense is if you can get a set of 1150RT jugs. the RT has the same compression as the S whereas the GS and others have lower compression- no point in bumping cc's and loosing compression. He said he just fitted a set for a guy for $150 who found them used for $200!

don't bother.... I already checked beemerboneyard.

car

[roger albert]

Seems like good advice.
I'd take one significant exception. The trans input seal.
I've just seen SO many leak, and they cost next to nothing to do while you're there (<$25 P&L???) That seal was probably manufactured in '97 or 98, and has been undergoing oilsplash and heat for >8 years. Will soon be 9-10 years old. Tell me again why you'd skip it (even if it were $75 instead of $25???)

Good plan overall.

Now, one other thing to at least still consider. If you weren't doing rings already, then I'd definitely stay with your old pistons. I'd wait for actual oval and taper results before finally deciding. Even if that is in spec, if you're doing rings, what do they run? 100 bucks? For 300-something more, you can get Chris's high comp pistons. They'll make nearly the same power difference as the cams (and more than anything else you're currently contemplating) and given their lower mass, will smooth some of the vibes, which is good for both rider and machine.

Just a (slight) counterpoint. You'll be fine either way I'm sure.

[bigscience]

Roger, true, I do still have to wait and see what the specs are on the cylinders- if they are off it's a whole new ballgame. the piston suggestion does seem to make sense and I'll bounce that idea around and check prices. I would appreciate any increased smoothness I could get if nothing else.

as to the the tranny seal, Chris simply said he doesn't routinely do seals and gaskets unless indicated. said is pisses him off when a seal he just replaced leaks, especially if it wasn't leaking before. my own tendancy would be to replace regardless. I suppose I'll wait until someone actually looks at it, but it would piss ME off if it starts leaking after just having the thing right there and not doing anything with it.

hopefully Shawn plans on working right through the holiday. I want answers now!

[JonyRR]

'------------------.030-------37.5cc------12.6;'

that static compression ratio is only part of the story.

what about cranking compression pressure?

Phil (PMC), what do you get for a cranking compression pressure value after your mods?


the OLD rule of thumb was anything over 200PSI is getting on-the-edge for pump gas, but with a good combustion chamber shape and 2 plugs, this isn't so radical anymore.

I believe in running as much compression as you can tune for, given a baseline of 92 octane pump gas...but I'm sure that SJBMW massaged heads will perform quite nicely.

[pmc847]

I milling my heads .025, my cold cranking PSI was 215psi, stock was 180 and 185. I run regular gas or midgrade, preferably without alcohol. I have no pinging.

Philip
"It's a great bike but I can make it better".

04 R1100S BCR # 195
03 R1100S BCR #44 R.I.P. new home with 'onekiwi'
Adjustable cam sprockets
Milled heads .025
Larger Valves +2mm intake & Exhaust
Ported and polished heads (just a little)
SJBMW Exhaust Accelerator Kit (modified)
Laser Exhaust
InDuct
SJ PowerFilter
Laser 2 spark Chip
K's 3.5 bar regulator
Ohlins
Sargant Seat
Throttle bodies matched to rubber mounts matched to heads
Throttle bodies venture steps smoothed out.
Exhaust pipe welds ground down
Aux Fuel Tank (6.8 gallons total)

[roger albert]

Hi Big Science.

I understand Chris' rationale perfectly. As a pro (or in my case, semi pro) it's no fun to have to go in a repair something on your nickel that you chose to preventatively replace, right after a fluke, post install failure (or outright installation mistake)

It DOES make one want to say "If it ain't broke, don't fix it"
After all, a pro really has more to lose than gain by doing it preventatively. Might have to do a an all day redux for a mistake on a job that only netted you 15 extra dollars. That's painful, and it does happen once in a while to even the very best wrenches. Otoh, leaving it til it fails is never the mech's fault, or is at least defensible, and you get to charge for the 2nd repair. It's a very tough call for a mech sometimes.

If it were 4 years and 40,000 miles, I'd probably leave it alone too. At 12 years and 150,000 miles, I'd always do it. Yours is a tougher call. It's certainly not a must, and you can thank Chris for not throwing every possible option at you and inflating your bill to the max. Shows good character in its own right.

This is a tough call. Since it is a fairly easy and cheap replacement while the trans is already off, and a fairly darn low risk one, I'd still lean towards doing it. But I totally understand why some would prefer not to.

Good luck either way.

On the rest, I'd prefer the vibration lowering of the new pistons as much as anything. If vibes never bug you, then the small power bump alone is less compelling.

[R111S]

Originally posted by bigscience
I’d like to point out that Chris didn’t try to sell me a bunch of stuff I didn’t need or wouldn’t want. I told him I wasn’t going to run Daytona (with this bike, lol) and he conscientiously pointed me towards the best performance for the dollar option in all cases. All the more notable since he developed/makes/sells the more pricy options. Next bike might just be bought from him even if I have to drive it home cross country.

That is the exact same impression I got from talking with Chris as well...just the kind of person you'd take pleasure in doing business with.