Planet Minis

cyclerider57

Like I need anymore projects... but seeing how there seems to be a lack of enthusiasm from members due to the massive decline in technical threads here is a small opportunity to help change that.

THINK deep and hard. Truly think about what you want to see built and what you could ASK THE MOST TECHNICAL stuff about. Flame propagation in the combustion chamber, lobe separation angle changes, piston rock through the combustion process, surface finish and tolerance, cams, cranks, and pistons (etc).

Follow the four stroke internal combustion processes in your head and think about random things within the cycles. NOW, Tell me what build you would like to see. I will ONLY do a CRF50 based engine because it is the root of the pit bike plant right up there with the z50. And by CRF50 based, I mean CRF50 cases. No Chinese builds, no KLX builds (JUSTIN!), and preferably not large displacement.

Two examples of what I would like to see (and am already doing/ have done of the many projects I have).

stock bore and stroke build (49cc) for all out power and speed using as many stock parts as possible.

standard 52mm bore 88cc engine build with no purpose but hp peak numbers.

The base idea can be helped determined by the members. I'll then post decisions I am making within the build as and before it progresses. That is when the technical stuff can build up. That's when it comes time to ask questions about why certain things are being picked and addressed while others are not. Anyone is open to answering or asking but hopefully it will stir some minds to think more critically about all aspects of an engine rather than putting kits together or even mix matching kits.

Again, please keep displacement ideas lower. I'm not out here to build the fastest minibike on the planet nor build an engine with the largest displacement. Merely because big displacement and modifications for high power don't mix without blowing them up quickly (my chinese 146 to show that power is in the head blew the clutch and crankshaft after 5 minutes of running). With a small displacement build you can push the limits of power for that displacement without easily reaching the limit of life span on components. That allows for more technical details within the build without taking up time to modify parts for strength rather than power.

__________________
The wise understand by themselves; fools follow the reports of others. Goodness speaks in a whisper, evil shouts. -Tibetan Proverb

slapaho16

how about a short stroke 88cc build like a 54mm piston with a destroke crank to bring it back to 88cc i think that would be some high revving peak hp fun

trackstar

I'll bite.

Our kids under 12 class in Supermoto is a 125cc max displacement class. Most kids are running 88's. My son had all he could get out of it so we bumped him top the 125 so we could run different gearing for more top speed yet still have enough grunt for the dirt and getting off the corners.

So I would like to see an 88 build that focused on maintained top speed for a road racing type environment and the gearing necessary for that but still have enough grunt for 2nd gear dirt sections and getting out of tight corners.

schofell84

is it the torque that is blowing up tak 5spd kits? because if it is so, build a 12k rpm road race motor, low torque and huge hp numbers. raise the ports and jam as much air and fuel into them puppies as possible. i just want to hear a high compression single hit 12k

vetmxer

Only thing I would want to see would be a bigbore build that can last but thats not your point. 88's and such appeal to me about as much as a moped.

Sorry I have no suggestions.

firepower354

Back to back test with standard and coated (friction/thermal/shedding) parts. Ceramic bearings. 1 vs 2 compression rings. Flatter valve angles. Ring seal test hot. Gapless rings. 15k is more in line

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kawasakicoby125

a motor that would make alot of torque, speed doesnt help on sx tracks, but torque does.

arlindsay1992

How about the best stock motor? What I mean is, you can only use the stock parts, but you can modify them. So you can use the stock piston and lighten it, port the stock head, weld and re-grind the stock cam, bore the stock carb, lighten the stock crank. So only stock parts modified by cutting, machining, welding etc...

chrisc161076

As above, a 50 build that can match a larger engine.

jRob409

Well as long as the KLX build you did for me doesnt blow up you wont need to work on it again..................Oh wait, I built it, just did it in your shop. My bad. LOL
And I've always heard there's no replacement for displacement.

How about a stroked, 2mm overbore, stock head, stock carb, IRK. Just make it look stock. See what kind of nums can come from that. Could you find the parts laying around to build something like that. Maybe mostly assembled, sitting on the floor next to a set of LT6's. (EVIL LOL)

fatcaaat

How about a 88cc with full mod since that is the most common upgrade. Porkchop the crank and knife it. Lighten up the rockers, retainers. Grind, weld the cam for a bigger profile. Ceramic bearings, treated gears.

How about a custom clutch cover that runs a dry single plate heavy duty clutch (al la bmw boxers).

burch753

+1 minus the clutch..

I would be curious to see a Kitaco off the self SE 88cc kit built with Higher hp and a higher RPM toruque curve than stock... everyone wants to built the taky kit because of the rollers... lets make the Kitaco kit just as good!

LongMooie

As you know im all about the 50cc tuning right now as ive been down the 88cc and 124cc path!
Are you building an engine or going to show us how to build said engine?

schofell84

microsquirt fuel injection

cyclerider57

The point would be to kick up technical information on engine building and modifying rather than all the people bolting stuff together. I would be doing the project all the while trying to stir up peoples imaginations to ask questions or toss in information.

People are tired of there being no technical information on the boards. I am only considering this to help bring that information. It is up to the MEMBERS to want that information and probe for it. I'm not going to offer it blindly because there are way to many things within the internal combustion engine I could spend literally hours talking about and never straying off that very specific topic, just ask jRob.

Keep in mind, we are looking for builds that will bring out those questions within the members. I'm not going to just start writing technical papers. I don't have the desire to merely start writing about random topics (If I want to do this, I'm in talks with an editor of engine magazine where my time would be more useful). On a forum, it takes a technical question to get a technical answer.

I do like some of the ideas posted. It's going to take more interest then this for me to to this though.

Research my 124SE.

I'm looking more for something that people can relate to and would make them want to work on their own stuff rather than just buying kits and engines (see avatar). These projects are better left to my design work that I already do.

Small cc requires more work to get power. Learn how to do it on a small build and translate that knowledge to larger displacement and you can have a medium displacement with the power of large build with much higher longevity.

I've said it before and I'll say it again... horsepower sells engines, torque wins races. Sadly, hp gets the attention and is a lot more effective in trying to stimulate peoples minds to think.

The best post so far but the results would be engine build driven. For example, flatter valve angles can change flow properties greatly but how effective it is will depend on bore and valve size of the project. Those could be tests driven after project is in process. 15k is my favorite zone... that's within the rpm range of the motogp engine I'm designing. I did have my 124SE as well as a few others to 15k on the dyno though.

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The wise understand by themselves; fools follow the reports of others. Goodness speaks in a whisper, evil shouts. -Tibetan Proverb

arlindsay1992

I agree entirely. I love modifying things to be better or work in ways they weren't designed to. Sure assembling an engine is fun but I much prefer "building" an engine. I am kind of used to modifying brand new stuff because there is not as much aftermarket for a 1984 Z50R as for a CRF50, at least not on this side of the ocean and not for cheap.

cyclerider57

Stock up now, I'm guessing in two years a lot of your stock z50 stuff won't even be available from Honda dealerships. Don't be surprised if there is no 2012 crf50 either.

__________________
The wise understand by themselves; fools follow the reports of others. Goodness speaks in a whisper, evil shouts. -Tibetan Proverb

LongMooie

oh no your not one of these guys that thinks the world is coming to an end 2012!!!

but on a serious note, most of us dont have a clue about motor stuff, some people dont like to give to much help as others, i started a thread not so long ago about porting a stock head and i didnt get as much help as i would have liked, some of the engine guys didnt even help.
i have no clue and would love some in depth tuning for my 50 with photos as im a visual learner lol

cyclerider57

Haha no. But I know various people within Honda who don't believe they will be making them in two years.

__________________
The wise understand by themselves; fools follow the reports of others. Goodness speaks in a whisper, evil shouts. -Tibetan Proverb

Z

But Honda of Japan will be making them in fuel injected flavor and will continue to do so in the future even with terrible historical sales of the Honda Monkey.