Motor Preferences

[KWiKSand]

I have been riding quads for a number of years, but am thinking about getting into a mini if I can work it into the budget.

I basically know nothing about the current crop of motorcycles out there.

It sounds like the 1300 Hayabusa motor is the top dog, but the ones I have seen for sale are well out of my budget.

What are the other main motors people are using. I know the rest of the GSXR ones are popular... 1000, 750 and 600. What about other brands and where do they fit in the mix with the GSXR motors?

Unfortunately it is looking like my budget would only get me a 600, but I am wanting to build a 2 seater for mainly sand use. I just don't know if that would cut it?

I guess what I am looking for is your personal ranking of motors

Thanks for any replies

[diirk]

From a cost effective standpoint, you might looks for a 750 motor. They've been around for a very long time thus providing a huge selection to choose from. Another option would be one of the larger motors from an ATV.

[02RedWS6TA]

I really don't see a difference in price other than the Busa. It really seems like it's about 1200-2000 depending on what you get with the motor.

The GSXR's are popular because squids get them and crash them so fast. There are more motors going around out of GSXR's than other motors that's why you see them so much.

I'm a newb to this whole mini sand rail deal but I've ridden motorcycles for awhile. I sold my 600 due to lack of torque on the street, you have to keep it above 8000rpms to have any power, most of them only make 50rwtq peak.

My R1 makes power all around, or atleast as much as you can ask from a 4 cyl. My buddy says his 750gsxr is the same way.

I'd bet you won't be happy for long with the 600, just look until you find a good deal on a 1000 or a 750 and pick it up.

[tenaja]

I have one with an old 550 that seems to have plenty. Sure, it's not a racer, but if it's fun. Yoshi put a modern 600 in his rail, and he seems happy with it. He beat a YFZ450 (I think) in a drag race. From what I hear, having EFI makes a difference for low end torque.

You won't have use for an engine for quite a while anyway...why not save up while you start the frame? Then you can get what you want...or start out with a 600 and upgrade it after a year. You'll be able to sell it for close to cost, if you get a car kit with everything.

[Reflex]

I think there is a lot of good motor opinions on The Edge's hp under FAQ.

(This is for two of The Edge's buggies but it applies to all mini buggies)

Q/ What type of motors are best for the Piranha or Hypersprint?
A/
The Piranha / Hypersprint designs use a motorcycle motor mounted behind the driver, commonly termed as mid mounted.

The rear central mounting of the motor creates a well balanced buggy with very good handling characteristics.

The best suited motors being a motorcycle chain drive type, water cooled with anything from one to four cylinders.
A motor with electric start is important as access to a kick start is limited.

Air cooled motors can also be used with care taken to divert air to the motors head & cylinders with the aid of scoops as well as a suitable oil cooler installed.

Motorcycle motors in the range of 500cc up to 1100cc are suitable.
The following is a general list of available motors, most coming from road bikes.
There are many more suitable models not included here.

VTR1000 Honda
CBR900 Honda
CBR1000 Honda
NX650 Honda
XR650 Honda
GSX750 Suzuki
GSX1100 Suzuki
TL1000 Suzuki
Suzuki 1200 Bandit
FZ750 Yamaha
FZ1000 Yamaha
TRX850 Yamaha
TDM850 Yamaha
RSV1000 Aprilia
ZXR750 Kawasaki
ZZR1100 Kawasaki
KLX650 Kawasaki
KLR650 Kawasaki

Q/ I see a lot of talk about using motors with lots of low end torque, why is this ?
A/
Torque is a matter of leverage, acceleration of mass & the motors resistance to the mass slowing down.
For example, a motor with a long stroke has more leverage because of the crankshafts offset. The distance from the crank center to the big end is the amount of leverage. The bigger this offset, (the stroke) the more torque a motor will have.
This is because when you increase the offset it also has to be counter balanced to make sure the motor is balanced & runs smooth. This also means that a larger stroke offset will have increased mass, (weight) compared with a short stroke motor.
This increased mass rotating at a larger diameter than a short stroke crank has more inertia, the mass at a larger diameter has more centrifugal force & inertia which means its hard to slow it down. Now combine this with a heavy flywheel & you end up with a crankshaft assembly that is hard to stop.
This would be the combined mass of the crank, flywheel, con rods & pistons. But, because this rotating assembly is heavy, it also takes longer to accelerate. That is why a short stroke motor, ( large bore & short stroke) picks up its revs very quickly.
But a short stroke motor is also very easy to slow down, it does not have the leverage of the long stroke crank & the weight in the rotating assembly.
Now the higher you can rev a motor the more fuel you will consume over that given time. This equals more power.
So a short stroke revy motor will consume more fuel at high revs & produce more power than a motor of the same capacity with a very long stroke & small pistons.
Look at an F1 car, its 3 litres in capacity, very short stroke & revs in excess of 18,000 rpm. BUT, some drivers have problems on race starts because the motors have very little low rpm torque.
This means they have to rev the motor to increase power & torque to increase the rotating mass to a higher rpm, thus more leverage to get the car moving.
You will find that super short stroke revy motors have a very narrow usable power band. That is, the motor is really only useable within a certain rev range. Like a two-stroke motor that has a narrow power band, outside of this rev range it wants to stall.
This brings us to the relationship between horsepower & torque.
Horsepower is a product of RPM & torque combined. The higher the RPM the higher the inertia of the rotating mass, so the higher the RPM the harder it is to stop or slow down the motor.
So look at the two types of motor. A long stroke motor of High Mass that only revs to a low rpm can have high torque at low RPM.
A short stroke motor that revs to high RPM can have high torque because the motor is consuming a large amount of fuel at the high revs & producing power.
So we can see that a short stroke revy motor generally will not have any torque at low rpm, it does not have the mass or leverage to keep it going.

A long stoke motor will take longer to build up its revs & it will not rev as high but it will have more torque at low revs because the mass is greater & harder to slow down.
As far as motorcycle motors are concerned look at a KLR600 Kawasaki, it’s a single cylinder motor with a big bore & a long stroke.
Compare this to a Kawasaki ZZR600, a four cylinder motor of small bores & short stroke. The KLR600 will take longer to pick up its revs & will only rev to around 7,000 rpm. The ZZR600 will pick up its revs quickly & rev out to an easy 12,000-RPM. The KLR600 is good for about 50 hp, the ZZR600 around 100hp.
But the KLR600 has a broad spread of torque from low rpm right up to its 7,000 rpm. You do not have to keep working up & down the gearbox to keep the vehicle moving.
The ZZR600 has high power & torque, but only when its revving high & consuming all of that fuel.
If the revs drop, so does the torque. The KLR600 you can dump the clutch at an idle, the motors rotating mass is keeping the momentum moving, so it’s hard to stall.
The ZZR600 has to be revved to take off, it has little rotating mass so you need to increase the RPM to increase the torque.
Now both motors are great, but for different uses.
The ZZR600 has twice the power, but to use that power it has to be revved. Offroad driving is different to on road driving.
On the street traction is easy to come by, so the ZZR600 can be used right across its rev range.
But take that motor off road into a boggy situation & the load on the motor increases. To take off you need the torque to get the weight of the vehicle moving, so you give the ZZR a good rev so it won't stall, but that makes the rear wheels spin faster & you start digging a trench.
If you have very wide tyres & lots of floatation you may get out of that trench & get moving.
The KLR will take off at low rpm without spinning the wheels, you are getting positive traction & you start to accelerate, you are moving through the boggy sand fast because the torque is hooking up & the lack of rpm is preventing the wheels from spinning.
As soon as you get some speed up you can roll on more revs as you have some momentum now. The ZZR is still stuck in its trench, it can't climb out of it because as soon as you back off the revs to stop the wheels spinning the motor wants to stall & you slow down. The ZZR600 would be more usable with lower gearing, this will increase the torque as the lower gearing is increasing the leverage. But its power delivery is still at a high rpm & the power band is narrow, so you have to work the gears up & down hard to keep it in this power range, you are thrashing the motor hard.

What is great for the street is not always great for offroad, two totally different situations that require different solutions.

Horsepower = TORQUE x RPM divided by 5252
TORQUE = Horsepower x 5252 divided by RPM

[02RedWS6TA]

Here are a couple motors on ebay

2005 GSXR 750 car kit (1065 miles), buy it now of 850 plus 170 shipping. http://cgi.ebay.com/ebaymotors/2005-05- ... 8434QQrdZ1 item number 4602418434 if the link doesn't work. I'd buy this if I wasn't broke.

2003 GSXR 600 "car kit" (although it doesn't include a lot of parts you need and the case is beat.) for 700 plus 139 shipping. http://cgi.ebay.com/ebaymotors/01-03-SU ... 4987QQrdZ1 item number 4601844987

[KWiKSand]

Originally Posted by 02RedWS6TA

Here are a couple motors on ebay

2005 GSXR 750 car kit (1065 miles), buy it now of 850 plus 170 shipping. http://cgi.ebay.com/ebaymotors/2005-05- ... 8434QQrdZ1 item number 4602418434 if the link doesn't work. I'd buy this if I wasn't broke.

Thanks for the link. I just bought this one. I emailed the guy to get some more info, and he bumped the price up $50 at the same time as he answered me. :x But still it was a better price than the others I was watching, and appears to be cleaner. Now I just have to hope it is in the shape he says it is.

Guess I need to get a little more serous about working on the chassis design now :wink:

[diirk]

[quote="Reflex"]
Q/ I see a lot of talk about using motors with lots of low end torque, why is this ?

Reflex, thanks for providing some very detailed info. I think for many folks here, the desire for more torque is a function of the intended use, which is primarily sand and off-road. In the sand, torque translates to faster sand displacement which is the sand equivelent of traction.

[02RedWS6TA]

Originally Posted by KWiKSand

Thanks for the link. I just bought this one. I emailed the guy to get some more info, and he bumped the price up $50 at the same time as he answered me. :x But still it was a better price than the others I was watching, and appears to be cleaner. Now I just have to hope it is in the shape he says it is.

Guess I need to get a little more serous about working on the chassis design now :wink:

Glad you got the motor, it really was a good deal. I wish I had the money to buy it myself.

[02RedWS6TA]

I take it everything worked well with the motor? If so I'll probably use them when I need to get a motor.