82 GS1100 Conversion to GS1150 ???

[Hap Call]

are you talking about the straight cut gear for the outer clutch hub that came from the 750???

Yes...but you also have to have the straight cut gear on the crank. Straight cut gears are also called spur gears. They put the spur gears on the 750 because it is a less expensive gear to produce. The 1100 get the helical gears for a couple of reasons. One is that the teeth are longer, thus stronger. Greater surface contact allows them to carry larger loads, and they are quieter than spur gears.

The reason a lot if racers go with the straight cut gears is that there are two advantages that the spur cut gears offer - they are more efficient and they do not have a thrust vector, or force that moves parallel to the transmission input shaft, which in turn places stresses on the clutch basket and transmission.

The best gear would be a herringbone gear which when viewed on end looks like two helical put together forming a stack of "V"s on the gear. It has both the strength of the helical and the ability to counter the thrust vector. It is also VERY expensive and is not as efficient as the either the spur or the helical gear and takes up more space than either, which is critical in small engines.


Did that help?

Hap

[Anonymous]

its what i was trying to expose Hap Thanks for doing the work as you are always so willing to do for all of us.
Dom
I never knew about the V shaped gear though

[Anonymous]

I once thought changing the gears to straight cuts, but with my modest hp output it isn`t necessary. My friend who was European champion with turbocharged 1150 drag bike (over 450hp) said that after 200hp the helical gears are self exploding grenades inside the engine, which indeed destroys everything when that happens... 8O Do you anyone has had such explosions? I think there are few...I changed the backplate and springs immediately to stronger ones.

[Hap Call]

I once thought changing the gears to straight cuts, but with my modest hp output it isn`t necessary. My friend who was European champion with turbocharged 1150 drag bike (over 450hp) said that after 200hp the helical gears are self exploding grenades inside the engine, which indeed destroys everything when that happens... 8O Do you anyone has had such explosions? I think there are few...I changed the backplate and springs immediately to stronger ones.

You are right about the problems after 200HP...that is a result of the angle of the teeth meshing on the two gears that cause a thrust vector force that is perpendicular to the gear...BANG! the gear comes apart because it was not designed for this force. The straight cut gear does not have this angular mesh of the teeth thus it reduces the chance of this happening.

Hap

[cbxchris]

I agree that straight cut gears are needed in drag racing and for the street guy that is extremely rough on his bike. On one of my 1150`s I`m thinking of a small overbore and possibly larger valves on the stock seats. Then possibly a 355 lift cam or so. I do not think I will need straight cut gears for this. I`ve already got 2 heavy hubs here now for both bikes. I guess on the 750 gear issue I`ll agree to disagree also. I`m just scared of them from what I`ve seen happen. When this was happening was late 80`s and early 90`s. APE had also made some overdrive oil gears that had a bad reputation for trouble. I guess I may have to rethink when I do a engine when my back recovers...I like for them rockers to live!! After screwing with shim motors for the last several years these rockers are a dream!!!