Project Bike Performance Mods (aka The Heretical Speed Junkie Thread)

[Freelancer]

Hi Guys,

Since I have started collecting parts and information for my K120RS project it has become apparent that there is no central collection of information on how to Hot Rod a Brick.  :dunno

When I first started asking about performance mods for the older K-bikes(Long Before I joined this site) it was almost like I was suggesting that the Pope should convert to Judaism. :yow The over-whelming number of responses to my questions were pseudo-dogmatic statements such as "Don't Waste Your Time/Money" and "Buy a Gixxer If Ya Wanna Go Fast".
Now I admit that these are reasonable statements, but Hot Rodding isn't about reason. It is about the almost instinctual/primal drive of many to "Make Better", "Go Faster" and/or "Making It Uniquely Mine".  :2thumbup:

Over the past couple of years, I have noticed an increase of those who are willing to commit heresy and alter the perfection that is a Flying Brick. The reasons for this seem to be a mixture of some spare parts no longer being available, the B.E.A.R.S. Cup, a resurgence in the old 70's style Café Bikes and other reasons to numerous to address.

What ever the reasons, there is now a need for a centralized collection of useful info about performance mods that work, where to find the parts and those who can do the specialty work. That is what this thread is about. I will post a few of the ones that I know of and will ask that any who want to contribute to please do so. Any contributions not already covered will be added to this first post in the appropriate subcategory.

Specialty Services and info
Anton Largiader-  http://www.largiader.com/articles/gearing/
Bruno's-  http://www.brunos.us/Bevel%20drives.htm

(More to come later)


2V K-BIKES (The early years) Includes all K75 non-paralever bikes except where noted differently


Suspension Tuning(Better Shocks and Fork Springs)-
Ohlins rear shock (if you can find one)
Works performance rear shock(Very rare and not as good as the Ohlins)
Progressive rear shock(Readily available but considered a low end replacement)
Realm Engineering Ram Shock(Very popular and readily available)
Wilburs (Decent quality though a bit expensive)
Y.S.S.(Gets my best bang for the buck award. Performs like a wilburs for less than the progressive shock)

Ohlins Fork Springs(Again, if you can find them)
Works Performance fork Springs(Seem to have the best reputation after reading many comments from K-bike owners)
Progressive Suspension Fork Springs

Engine Mods-
Decking the Heads
(For 2V K100's-There are those who are now swapping in the more powerful 4V K100, K1100 and K1200 engines)
Have little to no info....Will post info and links as I get details from those who have done these swaps

Exhaust-(Due to nature of early F.I. systems many say that exhaust has little to no benefit while using stock F.I. System.)
Staintune(Hard to find)
Luftmiester(These are very rare.)
Blackhole Exhaust(No info on these)

Fuel Injection-
Series II Bosch injectors(Word has it that these are one of the few mods to a stock system that really works.)

Turbo Kits-
Luftmiester(Now Defunct, these kits are very rare to find in working condition)
will post others as they become known to me


4V K100 & K1


Engine-
(Swapping a K1 Motor might be going to far considering the collectable nature of these....though a 130 hp 1200 motor would be interesting when combined with this models purported aerodynamics :yes. Now a 1200 motor in a K100 would be just fine  :yes :yes)
Will post links and info of those who have done these swaps as the info comes available and I get permissions.
(Will post more engine tuning tricks as info becomes available)

Exhaust-(Due to nature of the Bosch Motronic 2.1, many say that exhaust mods have little to no effect while using the stock F.I. system.)
Remus(No longer produced but the K1100 ones are the exact same thing and may still be in production. Is possible that K1200 ones will fit, though don't know if there would be problems.)
Staintune(Hard to find)
Luftmiester(These are very rare.)
Blackhole Exhaust(No info on these)

Fuel Injection-
Series II Bosch injectors(Word has it that these are one of the few mods to a stock system that really works.)
L-Jetronic retrofit(Some claim that they can be tuned like CV carbs)
Megasquirt/Microsquirt Aftermarket Kit(Waiting on wmax351's results but looks promising)
BBR Eprom (Gas guzzler with little to no effect from reviews, though some have claimed that it works better on heavily modded motors) Does not live up to advertised claims
Harman Eprom (Moves the powerband around and makes the bike run a little richer/cooler but lose about 1 mpg)Mixed reviews but does not live up to advertised claims.
Rhinewest Eprom (Rumoured to be actually have some positive effect but are impossible to find due to company no longer working on bikes)

Wonder what a Harmon or BBR enriched air/fuel mix would do on a 1200rs???(Just wondering)

Suspension Tuning(Better Shocks and Fork Springs)-
Ohlins rear shock (if you can find one)
Works performance rear shock(Very rare and not as good as the Ohlins)
Progressive rear shock(Readily available but considered a low end replacement)
Realm Engineering Ram Shock(Very popular and readily available)
Wilburs (Decent quality though a bit expensive)
Y.S.S.(Gets my best bang for the buck award. Performs like a wilburs for less than the progressive shock)

Works Performance fork Springs(Seem to have the best reputation after reading many comments from K-bike owners)
Progressive Suspension Fork Springs

Turbo kits-


K1100

K1100LT

K1100RS

Exhaust-
Remus-Expensive and not sure if still being produced. K1200 ones may fit, though not sure if there would be problems.
Staintune(Hard to find)
Blackhole Exhaust(No info on these)

Engine-

Fuel Injection-
up to July 93)Motronic 2.1 will take the same Eproms as the K1 & 4VK100.(Might be why the Eproms are hit or miss, They might need to be different based upon model but are sold as compatible for K1, 4V K100RS and K1100)
Aug 93 and on)Motronic2.2 does not allow for much

Suspension- pretty much the same as the K1 and K100RS 4V

Turbo Kits-


K1200

K1200lt- The 1200LT had a lower horsepower motor than the RS & GT. Any Horsepower gains in a 1200lt start in a deficit to the other k1200 power plants, though it has an amazing torque curve. Many would suggest a swap to either the RS or GT motor if looking for a Horse power gain. List as follows:

Engine Swap-
K1200RS or K1200GT power plant

Good Exhaust-
Remus

Fuel/Ignition-
Power Commander(III? I believe)

Suspension Tuning(Better Shocks)-
Ohlins,


K1200RS & GT-Thoroughly modern sport-bikes that respond to the usual tuning tricks for fuel injected bikes. List as follows:

Good Exhaust-
Remus

Fuel/Ignition-
Power Commander(III? I believe)

Suspension Tuning(Better Shocks front & back)-
Ohlins,



Outta Time for now, will come back later and add more. Input on content and lay-out will be much appreciated. Also, pls keep in mind that this is a work in progress and as it evolves more entries will be added.

Thanks,
Freelancer

[wmax351]

"Speed costs: how fast do you want to spend."


Suspension is a good upgrade point. Always worthwhile, though improvement tapers off with the really high end stuff.


Engine swaps: 2V: Easier to do a bike swap. You get the paralever rear, and better front end, and a better frame, for less money and work.


Turbos and other go-fast stuff: The 2v engines are very suited to turbocharging, with mild cams, and overbuilt bottom ends, but still limited by peak output, and other component failure. This guy got some decent power, but blew out the rings. [size=78%]http://robietech.com/fred/[/size]  His final power was 68 RWHP, compared to stock 50-55 RWHP. 7PSI boost, which is probably as much as you would want to go, and not either A: Turn your bike into a 2 wheeled hand grenade or B: need exotic race fuel or water/methanol injection to control detonation.


With megasquirt, you could convert to a flex-fuel system and run E85, which is octane equivalent to about 105, though with better charge cooling, due to the lower stoichiometric AFR. Your fuel mileage would suffer a lot, though, and you would need to re-do the fuel system (Seals and such in the tank).


For either 2V or 4V, you could play with the cams. Take them to a shop, and have them measure the stock cams, and suggest a higher performance cam profile. A word of warning though: You lose what makes a K bike nice: the torque. It also costs a lot of money, as it is all custom. They have to weld on new material, and grind it down. Then its trial and error on your part, as the cam may be too aggressive, or not enough, and your bike will barely run at idle. Your idle may be 3000 rpm. My friend's dad did this on his first-gen Camaro. And that is a 350, which is a particularly well trial and errored engine.


You would want to also do the following:


Larger intake valves: More airflow, from ccproducts. [/size][size=78%]http://www.sjbmw.com/parts.asp#s=store&bid=4&mid=&src=&p=1&pid=1004[/size]
Lighter valve followers, keepers, etc: not sure where to get these, may need them custom made. Allows for higher RPM, which is vital to power. Stiffer valve springs: same as above: more RPM


However, more RPM alone will not give you more power. The limitations of the inlet valve/cam put the peak power at 8500 rpm, after which it decreases. A more aggressive cam would increase the maximum rpm, by allowing more flow. A turbo would also let you increase the maximum RPM, and you could use the boost controller on the megasquirt to apply more boost at high RPM without detonation, due to the lower volumetric efficiency of the engine.


You could bump compression a little bit, though you run into the same problems with detonation. If you bump compression by decking the head, you shift the cam timing, which could be problematic. Custom pistons, you're looking at lots of money.


The place where most power is to be gained is by switching to chain drive. Think about it this way: a k75 has 70 HP at the crank. It has 50-55 at the wheel. Where did it go? The driveshaft, bevel drive, and transmission. The shaft drive is nice, but it is not optimum for power or efficiency. It's a lot of unsprung weight added to the bike. It's a tradeoff we make gladly, as we prefer the clean, quiet, and low maintenance of said shaft. Notice how many race bikes use driveshafts. Basically none. Those that do (BMW HP2, Guzzi) engineer around it, as they are forced to start with the shaft.


Before you start on this, you need to really know engine and fluid dynamics, tuning theory, combustion analysis, failure modes, etc.


There's not much to be gained without really radical work. That's why there is no market for performance stuff. BMW folks demand proof of improvement, and it simply isn't there. If it was, they would buy it, because they love gadgets.


The airheads on the other hand, can be really hopped up. The bottom ends are solid, as well as the whole driveline (except the final drive spline). The top end is all interchangeable, so you can cheaply and easily increase displacement, play with compression, etc. They use carburetors, so there aren't issues of needing to re-tune Jetronic systems, which really is not possible, as is the case with motronic. They are more rebuildable than K bikes. The cylinders can be replaced or re-sleeved.

[Freelancer]

Hey wmax351, thanks for joining in.

I can see that is probably going to be a massive undertaking and will appreciate all the help that I can get. Now for some of the issues that I want to address.

First, Q: "How to best organize and structure the layout of a central performance reference/database thread?"
A: "I will plod along adding info as it is given and will eventually be adding sections for not only each model and kustom part/service vendors but also for weight savings tips/ideas, necessary durability mods to handle extra power/heat."
As the central reference grows/becomes obviously ungainly, I'll happily listen someone has a suggestion for a better/easier to follow format

Second, I do not wish to discourage anyone from posting what they know or have heard, but also do not want to post inaccurate info. In order to meet these two goals, some form of "qualifier" will be used if a performance tip that is in question/unproven makes its way to the master list.

Third, For you seasoned moto-brickers and wrench turners out there. "How important do you feel it is to retrofit the 4V bikes with the older 2V Radiators and Water Pumps?" Especially considering that some of us may actually accomplish adding a few ponies.

Fourth, This is mainly at wmax and any other F.I. gurus. "Do you guys feel that enriching the air-fuel mixture a bit will alleviate the 4V motors tendency to have a hotspot near the exhaust valves?" If so, best suggestions on how to do such with both the factory F.I. systems and then with aftermarket systems too.

Fifth, "Anyone have a connection to any UK Mini racers that were taking the K-bike heads and mod-ing said heads?" These guys were putting the heads on a different motor but there must be some knowledge and sources for headwork tricks and custom camshafts.

Sixth, While we love our bricks, many of us are not as enamoured  with the 5lb instrument clusters/bricks. Seems like there should be some way of finding a lighter alternative or a plug-in module that will allow for us to swap in a K1200rs instrument pod.
I've heard of many people doing new clusters but each seems different. Any help collecting the various means of doing such will be very helpful. Heck, I'd pitch in on a project to make a sellable light-weight kit if it looked decent on faired and nakid K's alike.

Finally(for now), Will be looking for recommendations from all around the country and world for Kustom Paint shops for when the monochromatic paint scheme is no longer enough for a kool kustom K-bike. :2thumbup:

Later,
Freelancer

[wmax351]

Durability mods: not much to do. The bikes are darn durable to start with. Unless you are planning to run 15-20 psi of boost, really not needed.


Heat: the bikes are good to start with. People say they "run hot" but that is only in terms of rider comfort. K bikes rarely have any heat issues. The 4v radiator is a bit better though. A different SPAL fan would be worthwhile, and is covered in another thread, though primarily as a cheaper replacement.


One heat improvement would be to add an oil cooler. Not needed for most, but with high power output or especially turbos, it could be worthwhile. There is a tapped oil gallery plug at the front bottom of the head, where one could attach an oil cooler, or turbo feed line (as was done by the robietech guy).


Enrichening the fuel system at high load can improve power to some extent, tuning away from a efficiency and emissions profile, though on bikes older than 15 years, it is usually tuned towards performance, even at high rpm/load. Methods of doing this include re-tuning the Motronic eeproms, which requires a dyno and special programmer software/hardware. On a megasquirt, if you are looking for peak power, this also requires a dyno.


In general, power is best found in a stock engine by optimizing the ignition map. Allowing for less variation in fuel quality than the OEM, as well as using premium when regular was used previously. (This is a source of easy power on some 80's BMW cars. Buy a chip that bumps the timing to 33* btdc.) This can be done on a k bike by shifting the timing plate.


With regard to the Mini cooper conversions: there is a much larger range of things that are do-able on a car. Honda made turbo motorcycles, and they were awesome. However, their performance was too unpredictable, as the boost would come on suddenly, causing handling trouble. The CX500T and CX650T were rocketships. However, they were finicky, and the handling issues persisted. Think about the usage of ITB (individual throttle bodies) and multi-carb banks on bikes. They make tuning difficult, but improve throttle response markedly. Even on a conservative bike like the BMW's, they use the ITB's. Some cruisers have single carbs/throttle bodies.


Car engines are also heavier, with more meat to work with for machine work. They are more modular, and can be rebuild with overbores and even sleeving. No such thing can be done on a K bike, so there is no true "fresh start" for a rebuild. A Mini engine could pretty easily be bored out and overstroked for more displacement ("There's no replacement for displacement"). Their crankshafts do not have complex primary drive gears, or limited space constraints.


Instrument wise: that's very easy to do. There are a wide range of options. Trailtech makes some good stuff. I'll post others when I think of them. I've seen a nice single circle cluster with tach and speedo. There is a cleaned, logic level, tach signal accessible from one of the pins, and and some aftermarket ones have compatibility with a Hall effect speedo sensor. If not, a signal conditioner can be made with some op-amps or an LM1815.


I would be curious to play with 4v cams, some head work, and megasquirt. With some dyno time, you could get a good deal more power and a higher redline, at the expense of some bottom end torque and driveability.

[Freelancer]

I, too, would love to see some firm dyno research on 4v cams and other mods.
Personaly, I am thinking of wasting a bit of time and money this winter in order to definitively find out, on a dyno, if the performance chips for the motronic 2.1 actually work.

I have heard &read mixed responses on these and have been wondering if some people are installing them without advancing the timing.
Had a couple of chipped cars in the early '90s and they all required a timing advance bar to make any difference.
Basically, I'm betting that the chips were designed to work with an additional 3-6 degrees of advance over stock. (I'm listing a range because there are 2 eeproms. The "Harman" which is mild and the BBR which dumps tons of extra fuel.

Hmmm, motronic 2.1 with BBR might push enough fuel for the 1200 motor will try on the 1000cc motor first :2thumbup:
 
Also, Paul replied to my K120rs thread with how he swapped in a 1200 motor. He used the motronic 2.4 while retaining the older ignition. Just got to find out which pin in/outs are different on the motronic.

Later,
Freelancer

[wmax351]

Motronic does both fuel and ignition. The chips work by advancing the timing.

[drut]

"Personaly, I am thinking of wasting a bit of time and money this winter in order to definitively find out, on a dyno, if the performance chips for the motronic 2.1 actually work"

Can't help with dyno figures but have tried both Harman & BBR chips (both cheaply bought on ebay) in my 1990 K100 4V. BBR did not suit me,throttle response at lower openings below 5000rpm a little fluffy for normal riding although nailing it top end definitely felt more powerful,mpg less than standard if ridden quickly.Fortunately the Harman chip has proven a good improvement on standard,better throttle response,no flat spots & mpg about the same.Bottom line it has improved "rideability" for me.