Helical gears

[Rif Raf Racing]

Im building my 81 gs 1100 engine over the winter.1327 cc 10.25 comp.,street/strip port work,grind #203 cams,welded crank.My question is when does it become nessary to run straight cut gears.150 ,170 ,200 hp ? I will be using nitrous also. thanks, Steve

[biker66]

That's a good question ! Also one that I've never got any really good answers to.
The specs you give will give you an output between 150-170bhp:s, it can be used quite safely on the street. Meaning rolling starts.
Nitrous on that means serious horsepower, usually found in combination with hard launches equals more stress on the engine.

I wouldn't hesitate to use straight cut gears if I were you !

[Rif Raf Racing]

Helical gears

Thanks,I know that cartire bikes with big HP like to force the clutch against the case with the helical gears.This is a daily driver/bracket bike,Im just curious if someone knew of a breaking point. Steve

[lecroy]

I never broke the stock gears, but I have always heard the magic number was 9.0.

[Anonymous]

i used to break the inner hub in the clutch in the 140 hp range, did it once on the street, twice at the track,

If you are gonna have the crank done spend the money and put the gears on it. that and the left end are the GSs only true weak links (until heavy nos use)

[Rif Raf Racing]

Helical Gears

Thanks,Ive heard that late 83 cranks were welded from the factory.Steve

[biker66]

They're only partly welded.
When you get it done at a shop they balance the whole setup and welds all around the edges. Much stronger.

[lhanscom]

My bike has the stock gears, and runs about 200hp with nitrous, and Its been that way for a long time. So yes, you can run stock gears, but if you're in there anyway, straight cut wouldn't hurt.

[gsbill]

Stock gears would work OK on a no bar slick bike to live at about the 200 hp mark. If it was mine, I would do the straight gears now. If you keep the stock gears, go ahead will the basket mods. Our bike had an air shifter.

We had a small 1197 motor we hit with 100hp shot of nit. Having your nitrous controlled as it comes on helps also. We started the nit right from the get go off a throttle switch. We broke clutch hubs. It was a no bar, street tired bike.

[Rif Raf Racing]

Helical Gears

Thanks guys,I appreciate the info.This is a 10.25 comp/1166 with stock cams/head,34 mm carbs,pco pipe,welded basket,baby shot of nos (16n 18f).ran 10.20's @ 135.A few people told me I was already flirting with disaster with the stock crank,so I figured it best to straighten it out over the winter. do the gears now while its apart,and of course go big cc. Steve

[Anonymous]

Have a used 1428, mtc no name block, cut for nozzles 13.5 je pistons. was checked out last winter by Franco honed and new rings, made 15 passes this year and cracked the case. going 1570 cc. $500

[RacingJake]

Hey NoBars where did you crack the case at ??

[Rif Raf Racing]

helical gears

no bars,can you run a 1428 low compression(10.5)street motor or not possible.Also can the stock cases be bored without break thru? thanks, Steve

[Anonymous]

Cracked the case in front of the #4 cylinder
Went my personal best on that pass 7.87, pass before MPH was 183.

I dont know about what constitutes a "street " motor anymore. Can you make a 1428 hi comp race gas motor live for a 10 mi ride over to the car show let cool and come home?, Sure, I did that with this motor.
Ride all day, lo compression pump gas? unlikely with a big block. it would get too hot. big blocks dont cool worth a *@%^$*@%^$*@%^$*@%^$. I have heard that you can do a lo comp 1428 cc in an 1150 stock block, but spray it and you will see the inside of your motor from the outside.
If I were to do a pump gas street motor(which may be in the near future, i have enough crap lying around)I would do a 10.5/1 1327, stock 1150 block resleeved, 28.5, 24 no epoxy head G7,G9 cams, straight cut gears, OB alt. 41 keihins, bassani pipe. All in a gsxr suspended 83 ES.I would think that could be ridden all day but its not gonna go 20,000 mi between rebuilds.

[Anonymous]

yes, stock cases will not break through