Raising Motor

[LCampbell]

Does anyone know where I can access information on Raising / moving the motor forward in the frame for more ground clearance. The bike is an R75/5 used for road racing.
Thanks

[20774]

Vanzen posted progress on his project which was doing some major redesign of the frame. You can read more about it here and get some ideas.

http://www.bmwmoa.org/forum/showthread.php?t=22383&

[108625]

I can't recall the name, but there's a german company that makes performance parts for airheads, including exotic stuff like titanium connecting rods.
One of the items that might help you was a narrow engine kit; it featured shortened cylinders and pistons and pushrods etc. required to make it work.
That would improve your cornering clearance without raising your center of gravity... If the rules will allow such a modification.

[20774]

I can't recall the name, but there's a german company that makes performance parts for airheads, including exotic stuff like titanium connecting rods.
One of the items that might help you was a narrow engine kit; it featured shortened cylinders and pistons and pushrods etc. required to make it work.
That would improve your cornering clearance without raising your center of gravity... If the rules will allow such a modification.

HPN? http://www.hpn.de/english/english.html

They sell a 1043 ccm big bore kit that reduces the engine width by 26mm, according to the website.

[PGlaves]

I can't recall the name, but there's a german company that makes performance parts for airheads, including exotic stuff like titanium connecting rods.
One of the items that might help you was a narrow engine kit; it featured shortened cylinders and pistons and pushrods etc. required to make it work.
That would improve your cornering clearance without raising your center of gravity... If the rules will allow such a modification.

You can do a lot of this stuff - but start only if you have cubic dollars. You will spend more than if you bought a new bike. But then it wouldn't be an Airhead race bike would it? :)

[108625]

You can do a lot of this stuff - but start only if you have cubic dollars. You will spend more than if you bought a new bike. But then it wouldn't be an Airhead race bike would it? :)

Racing of any sort (whether it's on wheels, keels, wings or hooves) involves way different thinking about spending money than is usually discussed here ;)

[LCampbell]

We've been racing this (my son)bike for several years with AHRMA. We are stuck with an engine displacement of 750. He drags the valve covers every race so the only way to go faster thru the covers is to raise / move forward the engine. Thanks for the responses but all we need is any information that is available to help us raise/ move forward the motor & I understand that it will require a spacer between the transmission output flange & the drive shaft.

[PGlaves]

We've been racing this (my son)bike for several years with AHRMA. We are stuck with an engine displacement of 750. He drags the valve covers every race so the only way to go faster thru the covers is to raise / move forward the engine. Thanks for the responses but all we need is any information that is available to help us raise/ move forward the motor & I understand that it will require a spacer between the transmission output flange & the drive shaft.

See what you can find out about the old Butler and Smith superbike race efforts back in the early 70s. Udo Geitl built those R90S bikes with the motor raised and re-angled in the frame. This is a fabrication/welding job to move the location of the motor mounts.

You might be able to get some information from Tom Cutter at the Rubber Chicken Racing Garage. www.rubberchickenracinggarage.com Tom worked on Udo's team in some capacity back then. Tom also races. So it is possible he might be willing to give you some tips on how to proceed.

[nealart]

Here is a photo for reference how one racer did it:

http://www.pbase.com/r80ks/image/21801223

[R90S]

http://i44.photobucket.com/albums/f13/R90S/redbikeengine.jpg

This really isn't something that you an pick up over the internet. If you have to ask for directions, you shouldn't be attempting the task.

[vanzen]

if your welding / fabrication skills are better than adequate, the job of raising the engine is not that difficult.
An 'old school' method involves:
1. with front (stock position) mounting bolt in place, raise the rear of the engine such that the rear engine mountings are centered on the frame rail. precisely mark that location. drill, weld in mounts.
2. with the rear of the engine bolted in this new location, pivot the front of the engine upwards to locate the new front mountings on top of the frame rail.

I Have not used this technique, but Randy Illg (fabricated the X-frame) used his bag-o-tricks, some complicated geometry/alignment measuring/experience to position those mounts ... and was amazed that the results were quite the same.

if modifying the frame by repositioning the motor-mounts is not an option,
Motoren Israel (http://www.motoren-israel.com/product_info.php?info=p187_Motorhoeherlegungssatz. html) sells a pair of CNC machined aluminium brackets that 'bolt on' to accomplish the task.

http://www.motoren-israel.com/images/product_images/info_images/116520_1.jpg

http://www.motoren-israel.com/images/product_images/info_images/116520_2.jpg

another forum questioned the integrity of the fasteners used,
but discussion was hypothetical, as noone had used these parts – suffered / heard of failure. Nor have I used them.
– but still an option to consider either for purchase or as a model concept for fabrication.

no affiliation with MI, but I have done business with them and will vouch for their integrity as good folks.

[108625]

if modifying the frame by repositioning the motormounts is not an option,
Motoren Israel (http://www.motoren-israel.com/product_info.php?info=p187_Motorhoeherlegungssatz. html) sells a pair of CNC machined aluminium brackets that 'bolt on' to accomplish the task.

another forum questioned the integrity of the of the fasteners used,
but discussion was hypothetical, as noone had used these parts – suffered / heard of failure. Nor have I used them.
– but still an option to consider either for purchase or as a model concept for fabrication.

no affiliation with MI, but I have done business with them and will vouch for their integrity as good folks.

Ingenious...

I used billet aluminum mounts to lower and move back the engine in my Mustang, I don't see why such a solution wouldn't work in a bike. At least if it doesn't, you haven't cut the frame and can still go back to stock.

[vanzen]

You can do a lot of this stuff - but start only if you have cubic dollars. You will spend more than if you bought a new bike. But then it wouldn't be an Airhead race bike would it? :)




On ALL 3 counts: AMEN !

[nealart]

Yeah, I imagine stuff like this cost more than my house:



http://www.ritmo-sereno.com/customfile/archives/images/r80hp-2.jpg

[LCampbell]

Well thanks to all who offered advice & provided sources of information. We have an person who is doing the mods for us who has done it before. It's been a while & he is not sure of the exact dimension needed when you move the engine forward.

[vanzen]

Well thanks to all who offered advice & provided sources of information. We have an person who is doing the mods for us who has done it before. It's been a while & he is not sure of the exact dimension needed when you move the engine forward.

the specific dimension of 'up' or 'forward' is not so important as maintaining correct alignment
–coincident center-lines of the axis of the output shaft & driveshaft at it's position in mid suspension travel.
it is critical to allow the driveshaft to be centered in the tube of the SA and without fouling the tube at either limit of suspension travel.
limits are encountered first when moving the engine 'up', as centerlines cannot be matched beyond a certain point –
moving the engine 'forward' is, theoretically, limitless, a simple matter of adding a spacer
to retain the original location of the driveshaft u-joint relative to the SA pivot.
if that dimension (u-joint relative to the SA pivot) changes even slightly, binding will occur at the driveshaft spline / FD coupling.

[AntonLargiader]

the specific dimension of 'up' or 'forward' is not so important as maintaining correct alignment

Exactly. Think of rotating the entire engine/tranny assembly around the swingarm pivot. People who move the engine forward also add a spacer between the tranny output flange and the driveshaft to keep the front U-joint concentric with the pivot.

[vanzen]

Exactly. Think of rotating the entire engine/tranny assembly around the swingarm pivot. People who move the engine forward also add a spacer between the tranny output flange and the driveshaft to keep the front U-joint concentric with the pivot.

this is literally what is done when the "old school method" described previously is employed ...