Boxerworks.com

I will have at some time have to replace the corroded pushrod tubes on my 1989 R100 Mono, now while the heads were off I could get some tuning work done on them. What are my options - I don't want to lose any of the bottom end to mid range torque and of coarse I would like more top end grunt. Am I asking for too much?

Does the mono 1,000cc engine come with the 44mm inlet valves? If not you could always pop a couple of those in along with a bit of gentle porting and polishing. A pair of lightweight gudgeon pins could be worthwhile too.

No you are not asking too much,
Ring Jim Cray, he does various tuning options that will work, not that cheap, but you can reduce the labour charge by sending him the components that need to be worked on. His tuning will usually involve aa higher compression ratio, squish band mods,porting of the intakes, dual plugging and some mods to the air box. It will all work together so that you get an engine that will perform very much better throughout the rev range with a really good increase in mid range torque. Reliability should stay the same and at similar speeds my heavily modified 72 bhp bike uses 10-15% less fuel that my mate's R100R.

His no is 07870414929.

I am a satisfied customer, currently running in the 2nd engine that Jim has done for me, this is a R90/6 tuned for an increase in smoothness, fuel efficiency and mid range.

He is also a straight up guy and you will get what you pay for.

Charles

IMHO, compression ratio is what you want. An engine develops power (torque) based upon the amount of fuel it's given and compression ratio. If mixture is a constant, to get more fuel, you need more air. That's either better breathing efficiency (bigger cams, valves, porting, etc) or some form of supercharging. The cam/valve usually comes at the expense of bottom end. Compression ratio power across the entire rev range. It also allows for a bigger cam, if you want. Your current is 8.2 to 1, but could probably go up to 9 without other changes. Dual plugs helps reduce detonation.

http://bmwmotorcycletech.info/dualplugging.htm

I am another satisfied customer of Jim Cray, he is just as Charles describes. My advice is to stick with your idea of keeping the low end torque and follow Jim's advice. He is excellent. Sam

That's you isn't it Martin ? Hello again. Sam

First thought - What you are asking is vague at best.
2nd – You will not easily have your cake and eat it too ...
(as defined by low end torque AND top end "grunt")

Beyond that, and in all reality,
achieving the results, (what you are asking)
will be exactly proportional
(and given the law of diminishing return)
to the amount that you are willing to spend.

No way to escape the fact ...
Define your terms then break out the wallet.

note: Jim Cray is an excellent airhead tuner, worth every dollar spent –
but certainly not typical-airhead-mentality-cheap.

vanzen@rockerboxer.com wrote: note: Jim Cray is an excellent airhead tuner, worth every dollar spent –
but certainly not typical-airhead-mentality-cheap.

"He is also a straight up guy and you will get what you pay for". And that is a quote from one of his customers. For me, there couldn't be a better endorsement. I'd love to be able to take advantage of his services.

Chuey

Chas's list is pretty nice: mods which will not have a negative impact on midrange. However, as noted, not much bang for buck, more lots of buck for nicer bang.

As the saying goes, there's no replacement for displacement. Bigger jugs is the simplest, cheapest, best solution for most people with smaller engines. When starting with a 1000cc Airhead, every good choice is much more expensive per additional HP.

Jim has done a little work for me on my 90S and it was faultless and he is a great Bloke to chat with but I'd like to have a bit of understanding of what can be done before taking up his time - a little research. Every one seems to talk about big valves, Carb's and cams - but that's tuning for speed and detrimental to what I think I want. Yes big CC's would be good but the engineering involved makes it a little fragile.