Engine angle

[Parker]

Well, I havent heard much if any discussion on the topic, but what affects the angle at which you can mount one of these 4 cylinder bike motors? my first guess would be the sump location, but other than that, is there anything keeping one from tilting the motor down to a shallower angle?

[Parker]

Well, I havent heard much if any discussion on the topic, but what affects the angle at which you can mount one of these 4 cylinder bike motors? my first guess would be the sump location, but other than that, is there anything keeping one from tilting the motor down to a shallower angle?

[VFR750R]

As far as I can tell, you could rotate one around ALOT. As long as the head and clutch housing can drain to the main sump and necessary mods are done to the pickup you should be good.
For some confidence in those worrying about it. Yamaha FZR and YZF cases are nearly identical but the YZF is tilted about 10 degrees back from a FZR.

[Duff]

if your going to tilt by any significant angle i would be looking at modifying the oil system ie moving the feed for the pressure pump. better yet, dry sump

[Diablo_niterider]

i believe u wouldnt have to do anything for plus or minus 15 degress
it depends a lot on the engine type

let me know the engine u guys plan to use maybe i will be able to help

or just study the sump urself and check if u can still keep the oil pumping

[Tony K]

Well, I can tell you from experience that +/- 15 degrees is a horrible answer. In '04 we experimented with tilting the R6 engine 15 degrees to try and lower the CG of the engine but ended up burning up the camshafts instead. The buckets that hold the oil for the tappets don't like to be tilted downward as all the oil runs out and starves the tappet surface, hence trashing the camshaft lobes.

However, on the other side of things, if you end up tilting the engine so that the head is more upright, that forces the oil from the buckets to drain back into the tappet, which is a good thing. Our '04 and '06 cars run this configuration and have never had any lubrication issues.

If you're running a dry sump system, that obviously affords you a lot more leeway with engine angle, just be sure to place your scavenge pickups and possibly sprayer bars to compensate for the lack or addition of oil flow due to gravity.

[Parker]

so Tony, You're saying that by tilting the engine more towards vertical that there will be better oiling in the head? Obviously our two applications are different, as we are using a GSXR powerplant.

We are really just trying to get some more room for the driver to fit, as we would like to lay him down a little more without lengthening the chassis.

[Big Poppa]

Our GSXR has been at 11.7 degrees for 3 years with no problems...knock on wood

[Tony K]

I don't know if I'd go so far as to say better oiling, but it's not nearly as bad as tilting the engine the other way and emptying the oil buckets.

I'd look at the way the camshafts and valvetrain get oiled in the GSXR engine and try to imagine the oil flow and what would get changed if you were to tilt the engine. Maybe take the valve cover off and spark plugs out and crank it over a little bit at varying stages of tilt angle to see where the oil drains.

[MikeDutsa]

it makes sense that you can only tilt the engine back, just think wheelie. its all about the wheelie.