Racing: the 4-stroke class

[scotto-]

I'm just moving this post from an un-related thread to hear some thoughts on this subject. The thread was from the " Motorized Bicycle: Engine Kit Forum > Motorized Bicycle
Paint Booth & Chop Shop
and the post was from " Custom Frame For Thumper Motor".

I moved this here as to not pollute Jeff's thread with unrelated discussion.....

#104 Today, 04:53 AM
BiMoPed
Motorized Bicycle Elite Member Join Date: Jul 2010
Location: SoCal, OC
Posts: 858

Re: Custom Frame For Thumper Motor

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Quote:
Originally Posted by scotto-
Looks like I'll be building a race specific bike next for these go-kart tracks we be racin on......seeing as how my 49cc bike is way undersized and under-powered compared to what they're letting race in the 4-stroke class.....the wheels are turnin!

Reply:
Scotto I tried letting those 6? hp Briggs bikes in the little 4 stroke class
at Willow Springs and they won too easily and the new track is probably
going to favor faster bikes?

Briggs bikes are going back into the Unlimited Gas class at the next race
on Oct 22nd.
The 49 cc 4 strokes will only have the 79 cc HF as a larger engined
competitor this time so please do some work on your Q Matic as that
bike was slow. lol
Thanks for letting me ride it at the track.

OK, here we go.

As I understood it from the beginning, the 4-stroke class would be 4-strokes less than 100cc and 3hp and under. Thinking this I don't mind running my stock 49cc Huasheng (with 2+hp) against bikes with slightly larger motors, such as the HF 79cc as I know what these 4-strokes can do because I build them. But when you let larger 150+cc and 5+hp engines in the class......gee, I wonder who's gonna win?

After getting pretty much smoked by larger engined bikes in this class, I asked if it would be ok to run the tandem in the 4-stroke finals race and Neil said ok as there were more bikes with greater than the 124cc's that the tandem has. All that cost me was winning the 1st prize of a 4-stroke shift kit given away by SBP's. But I placed much better on the tandem as I beat bikes I couldn't have come close to with an under powered, under sized 49cc HS.

You can bet I won't be racing a 49cc HS (under) powered bike again, but to keep it fair I think the 4-stroke class needs some division, ie. > 100cc and < 100cc.

Any thoughts on this subject?

 

[The_Aleman]

I posted in the newest race thread that I think the little high-revvers should get their own race category. Ofc that means enough people need to show up for that to be viable.

These little 49-50cc 4-strokes just don't have the ability or capability to hang with the larger 4-strokes, apples to apples. They have no performance parts aside from carb, cam, and exhaust, and even with all of that, probably don't make but 3-3.5HP A HF 2.5 can make that just with the governor removed, and it's making more torque than the GXH50's peak at the GXH50's idle RPM lol

 

[scotto-]

I posted in the newest race thread that I think the little high-revvers should get their own race category. Ofc that means enough people need to show up for that to be viable.

These little 49-50cc 4-strokes just don't have the ability or capability to hang with the larger 4-strokes, apples to apples. They have no performance parts aside from carb, cam, and exhaust, and even with all of that, probably don't make but 3-3.5HP A HF 2.5 can make that just with the governor removed, and it's making more torque than the GXH50's peak at the GXH50's idle RPM lol

Yes, I read that Aleman and I agree. And if enough people show, there will have to be more classes to keep things fair, otherwise why race?

 

[Samford&Son]

just out of curiousity. what motors were in those agk bikes that were battling with us in the 4-stroke class?
i do agree that we had a big advantage over the 49cc guys
i would love to see a smaller 4-stroke class like <100cc
and a larger 4-stroke class like 101cc-350cc

we had the same concerns you did, scotto. originally we were put in the unlimited class and you can see how well that went. we would have been in the back of the pack for sure. the first race i viewed as an experiment....now we know what to expect from some of the bikes....i think this second race coming up is going to have some heavy-hitters and some sleepers that are going to be gunning for the faster guys

i think the best way to improve all the classes is to get more people involved and base the classes on motor size instead of hp displacement...that way we dont extinguish creativity

 

[scotto-]

AGK are running an HS 49cc and a HF 79cc and they are very tricked out with great riders on board.

I think that is a good start for classes S&S; <100cc and 101cc-350cc.

just out of curiousity. what motors were in those agk bikes that were battling with us in the 4-stroke class?
i do agree that we had a big advantage over the 49cc guys
i would love to see a smaller 4-stroke class like <100cc
and a larger 4-stroke class like 101cc-350cc

we had the same concerns you did, scotto. originally we were put in the unlimited class and you can see how well that went. we would have been in the back of the pack for sure. the first race i viewed as an experiment....now we know what to expect from some of the bikes....i think this second race coming up is going to have some heavy-hitters and some sleepers that are going to be gunning for the faster guys

i think the best way to improve all the classes is to get more people involved and base the classes on motor size instead of hp displacement...that way we dont extinguish creativity

 

[bairdco]

if i build a twin engine 2 stroke, can i run it in the 4 stroke class?

 

[MotorBicycleRacing]

You guys are making a lot of assumptions and speculations.......

There has only been one Motorized Bike race in SoCal. This new
motorsport is in its infancy and until there are more entries there
is no way to have more defined classes.

The current classes below are not really based on cc's or hp.
They are more based on the realities of number of bikes racing
and track time which will be limited by daylight hours on Saturday
Oct 22nd of about 7am to 6pm.
This is 2 more track hours than we had at Willow Springs so it may
be possible to add a couple of classes if entry numbers justify it.

We have about 4 months to Sat Oct 22nd so you have lots of time
to help promote the race so more classes can be run.

1) eBike
definitions to be announced later.

2) 4 Stroke
Any other small 4 strokes.
Robin Subaru 25cc and Honda GX 25 cc
Robin Subaru 35cc and Honda GX 35 cc
Honda 49 cc GXH and Huasheng 49 cc clone Titan 49.4 cc Super Titan 49.4 cc
Harbor Freight 79 cc
Whizzer 136 cc stock motors

No limits on motor modifications, Shifter kits are ok,
No real motorcycle tires allowed. Bicycle tires only.

3) 2 Stroke
49 cc to 66 cc Chinese bicycle motors.

2 groups run because of large number of entries.

No limits on motor modifications, Shifter kits are ok,
No real motorcycle tires allowed. Bicycle tires only.

4) Gas Bikes <11 hp
Includes Morini, Briggs & Stratton, 6.5 hp HF, etc
When there are enough Morini's and B & S, etc this class
may split it into 2 classes.
Not enough entries for 2 classes yet so you will be racing
together on the track with another class.

No real motorcycle tires allowed. Bicycle tires only.

5) UNLIMITED Gas OR eBike
Includes any motorized bicycles that are over 12 hp and don't
fit in any the other classes but still meet a few basic common sense rules.

 

[scotto-]

if i build a twin engine 2 stroke, can i run it in the 4 stroke class?

Yes, as long as the strokes are opposed to one an other, thus making it a 4-stroke so to speak. The 2 engines must fire opposite each other on the power stroke otherwise you will be forced to race in the super-duper unlimited 2-stroke class of the century, which isn't a bad thing....just different for all intents and purposes......really.



Don't worry about the pink spandex Baird.....it's just one of BoMiPeds fantasy's......one of many!

 

[MotorBicycleRacing]

if i build a twin engine 2 stroke, can i run it in the 4 stroke class?

Yes, you can run it, but you have to be shaved down and wearing that
spandex outfit and awesome aero-helmet that is shaped like the
Alien's head.
PS: The only other requirement is it must be pink spandex.

 

[bairdco]

"bimoped" says it all. goes both ways...

with all the friendly comments you're leaving allover this place neil, you'll be lucky if anyone shows up at your race. LOL.

 

[culvercityclassic]

LOL

How did he get that name?

 

[MotorBicycleRacing]

"bimoped" says it all. goes both ways...

That's right, I like 2 strokes and 4 strokes.......

Seeing you like discussing rules so much what class would a
47 cc 4 hp 2 stroke pocket bike motor like the one Dax sells go in?

There was not one at the race and they can be rear mounted chain drive
and a few people have mounted them in frame with their own mount.

Friction drive too of course and the pocket bike motors can make a lot
more than 4 hp.

Would they go in the 2 stroke class with the Chinese bicycle kit motors?

 

[scotto-]

I would put that in the 2-stroke pocket bike class.......must have pockets for this class however! lol

That's right, I like 2 strokes and 4 strokes.......

Seeing you like discussing rules so much what class would a
47 cc 4 hp 2 stroke pocket bike motor like the one Dax sells go in?

There was not one at the race and they can be rear mounted chain drive
and a few people have mounted them in frame with their own mount.

Friction drive too of course and the pocket bike motors can make a lot
more than 4 hp.

Would they go in the 2 stroke class with the Chinese bicycle kit motors?

 

[agk]

just out of curiousity. what motors were in those agk bikes that were battling with us in the 4-stroke class?

We had two bikes in the 4-stroke class. One was a 49cc q-matic bike. The engine has our performance cam, big bore carb, high flow air filter and custom exhaust. My son races this bike. He's 15 years old and has very limited experience on motorized bicycles. His biggest advantage is his power to weight. Blayze weighs about 135lbs. he has done very well with this bike.

The second bike we entered was a 79cc HF motor using our jackshaft. This engines modifications include a custom exhaust, govenor removal, big bore carb, high flow air filter and some very mild port work. I had knee surgery after the death race and asked my friend Bryan to ride this bike. He hung with your Briggs bikes for a while, but just couldn't compete with the power. Bryan has experience racing motorcycles.

It would be nice to see more separation in the classes, however, it doesn't make sense if there aren't enough bikes to create a new class. We may have had the only 79cc 4-stroke out there. It's a bit stronger than the 49cc motors and cannot compete in the unlimited class. We'll run it wherever Neil decides it needs to be.

We're hoping to build a bike with that new 99cc HF engine for the next race. Curious how much difference we'll see versus the 79cc engine.

 

[SoSauty]

Could motor size rather than motor type may be the primary class leveling consideration?

E-bikes had a very similiar situation as the 4 strokes (excepting the big e-bikes which DNFed). The 2 of us that did finish were under 3 horsepower just as some stock 4 strokes were.

I had looked forward to racing Scotto and those with less powerful setups after watching his Tucson DR vid which stated, 32mph top speed. My ToyRacer, top speed 33mph yet sags to 30mph, I thought was perfectly matched to the small 4 strokes if I built everything right (came close to perfect setup). He wound up racing a tandem and I wound up in the unlimited class!

Of interest, if you take the length and width of my half soup can motor and square that, one gets 49. That's length 3.2" X width 2.2" = 7.04. Square 7 and one gets 49. Hmmm.

Most e-motor dimensions are known, if not a brief google lookie will tell. Take a soup can that's 3.2" in diameter, paper it, and write the length/width dimensions on it. If less than a soup can length X width, it runs <100cc class; if equal (Astro 3220) or greater, it runs >100-350cc class. For example, the Astro 3220 has a 3.4" length with same diameter. 3.4 X 3.2 = 10.88 (11) square that 118.3 or rounded just 121, > than 100. The 5.6 e-horsepower Astro 3220 runs in the 100-350cc class.

Whatever Neil or the MB community comes up with, I can build to comply. Yet my primary interest is assisting a standard for entry level racers. Needs to be easy and inexpensive to jump into this sport. The Huashengs, HFs, (others?) and small Astro/Turnigy's would be just the ticket to attract newbies, young and old alike, into our sport.

Thought for discussion, Keep It Stupidly Simple (KISS) management technique. Fun to discuss, but after rereading Neil's class disignations, think they're great, I'm happy.

<100cc class above >100cc class below

 

[scotto-]

OK.....that's it, I'm running full cans of Progresso ministrone in the Unlimited Class from now on! It tastes great, gives me gas and I'm sure the electrics will have a hard time understanding how I beat them without catching on fire......lol!

Love's me Progresso......and I'm not even Italian hahaha!

 

[SoSauty]

Yep, I'm going to have a really souped up electric next race!

 

[The_Aleman]

Don't break, buddy

Yep, I'm going to have a really souped up electric next race!

 

[scotto-]

Well all of this discussion has led me to think that we do need two 4-stroke classes and I think it most fair for them to be < 100cc & 101cc and larger. I don't think a stock Whizzer (136cc) should be allowed in the < 100cc class because it is larger than 100cc and how will you know it is stock without tearing the engine apart?

And it is now time to build a race specific bike as the competition demands this.....I love this stuff!

 

[MotorBicycleRacing]

That's right, I like 2 strokes and 4 strokes.......

Seeing you like discussing rules so much what class would a
47 cc 4 hp 2 stroke pocket bike motor like the one Dax sells go in?

There was not one at the race and they can be rear mounted chain drive
and a few people have mounted them in frame with their own mount.

Friction drive too of course and the pocket bike motors can make a lot
more than 4 hp.

Would they go in the 2 stroke class with the Chinese bicycle kit motors?

This was a serious question so I am still waiting for a non spam type joke reply of which there seems to be a lot lately.
Does anyone have some actual input?

 

[scotto-]

This was a serious question so I am still waiting for a non spam type joke reply of which there seems to be a lot lately.
Does anyone have some actual input?

Well seeing as how this is my thread, I will feel free to respond anyway that I feel.....just sayin'.

Now to seriously answer your question, that would race in the china girl 2-stroke class because it is under 66cc and it is made in China. And you also stated that unlimited performance mods and the use of shift kits were acceptable in the china girl catagory.

That wasn't so difficult was it now?

My thread is pertaining to 4-strokes and your question pertains to 2-strokes, soooooo......no thread jacking please

 

[strotter]

I just put one of those pocket bike motors (from Dax) on my bike with a Staton friction drive. After breaking it in, I staged a drag race. The competitors were as follows.

1. Beach cruiser. 50cc pocket bike motor, Staton 1.5" friction drive 250lb rider
2. Beach cruiser, 35cc Subaru, Staton axle mount 165lb rider
3. Mountain bike, 50cc Honda, BMP 1.25" friction drive 225lb rider
4. Beach cruiser, 35cc Honda Golden Eagle (stock gear) 225lb rider

First race: 1 block, #2 won by a bike length
Second race: 2 blocks, #3 won by a bike length #4 was right on his heels
Third race: 3 blocks, #1 won by 3 bike lengths.

I have driven all four of these combinations. I feel that they are all about equal. The pocket bike engine definitely has the best top speed, but doesn't have the best acceleration.

MB racing on a go-kart track isn't about top speed, it's more about who can accelerate the fastest and who has the guts to take the turns fastest....

I stick to my reccomendations.... 0-50cc, 51-135 and unlimited engine size. Regardless of 2 or 4 stroke.