Machining, lightening, BMW Airhead Motorcycles Flywheel, lightening flywheels

3 Май 2015 | Author: | Комментарии к записи Machining, lightening, BMW Airhead Motorcycles Flywheel, lightening flywheels отключены
BMW R45 (reduced effect)

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Lightened Flywheels


60, sub-part 2A

© Copyright, 2012, R. (except the photo)

Below is a of a properly lightened flywheel. Airhead flywheels are sometimes on the early heavy flywheel (pre-1981). After that BMW changed to a totally different of ‘flywheel’, which is called a Carrier and is much lighter, and the parts were totally and the transmission input shaft was shortened to match.

The entire was much lighter. This for some of the lack of smoothness of the models, as the engine had less mass at the crankshaft output. was particularly noticeable at idle but also noticeable at higher while actually riding.

The models generally required shifting, as the rpm drop was faster the throttle was chopped, not to mention the sudden effect on the rear upon a throttle chop. The shifting is generally regarded as a

Lightening the flywheels on the early will enhance shifting, by faster shifting, because the has inertia, and with less less inertia, so the flywheel. engine crank, etc. will slow down at a rate during shifting. You have smoother shifting IF you FASTER, before the rpm drops too (assuming downshifting). The acceleration be somewhat faster, as less is being speeded up.

Engine generally is reduced with a flywheel.

There ARE downsides to a flywheel. Engine vibration increase, but not too excessively. In my opinion the to the preciseness of the carburetor synchronization increase.

Some of the smoothness. of this is almost intangible. be lost, but, not excessively. on the year and the transmission and if it has the so-called kit, shifting can be LESS in actually finding the gear/neutral. You need to shift just a bit and perhaps spend a bit more on matching rpm when shifting.

However this is offset by less clunky shifting. The may be a bit more prone to stalling if not warmed-up; and you will have to the clutch a bit more when out. this is a reason I do NOT recommend lightened flywheels on rigs.

One final thing to be said. It is my belief that a flywheel will promote WEAR on the transmission input I can, however, argue ways on that subject.

In any engineer-types read this, NO, I never heard of crankshaft from lightening the old flywheels. to this, flywheels act as dampeners for torsional vibration modes.

The old are never going to shift a Japanese crotch rocket, no what you do to the clutch or transmission. You can things by fine-tuning the transmission but, just how far DO you want to go? Are you taking this bike a racetrack. or do you like its smooth manners when out for a ride?

You PROBABLY would like the flywheel. I know I always and I think most riders of BMW Airheads WILL like the flywheel effect. Do I recommend it.

but ONLY if you understand and are willing to the modest to minor drawbacks, see

The photo below is of a properly Airhead flywheel. This was furnished by Beemershop at my request, as I did not any photos from when I flywheels.

The Beemershop (Ted is an independent BMW motorcycle repair located in Scotts Valley, (831) 438-1100.

They have the ability to these flywheels, or machine by numerically controlled, and thus machining methods. It is VERY that flywheel lightening be properly. There is NO NEED, and I AGAINST, machining off the flywheel edge marks (S, OT, F).

BMW R45 (reduced effect)

NOTE the needed outer meat was left to support the starter threaded clutch attaching places, etc.

HINTs: installing any Airhead flywheel, the pistons at TDC, and OT showing in the window, otherwise you may install the in the wrong position onto the Do NOT tighten the 5 flywheel bolts away, but have them loose, and CENTER the flywheel on the shoulders, by trying to move the circularly clockwise and counterclockwise. sometimes show a slight of play. Progressively, criss-crossedly, tighten the bolts in stages.

to other pages for the tightening which vary considerably years and models. Be very not to overtorque the early (/5 and earliest /6) which are 10 mm.

The last of the airhead models per BMW, oiled threads, and a high torque. I prefer a lower torque, although I seen no reported problems the high torque settings. are two other articles on the flywheel, one a WARNING article . on this

The main article that has all the on the flywheel torque values, and information. is the CLUTCH.htm article. It is 60, subsection 9, but you can click that

When the flywheel is lightened on an BMW Airhead, the engine rpm can and will much faster on downshifting and Because this TIME is a helpful modification is the SHIFT which BMW installed on later A complete description and details are in

When working on Airheads, you may need to know the spacing markings on the flywheel (or clutch You may need to know the distance per on the circumference.

The diameter of the larger flywheels are all the same, and there is 2 mm each degree.

For the R45/R65, it is 1.5 mm each degree.


NEW and released 01/28/2011

01/29/2011: go fix minor typos, and clarify a few

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