A great design is rarely a complicated one. A good design makes great since, I dont think your proffessor will think less of your motor cause it is smaller and more primative design. To me taking a 20+ year old motor and biulding it with todays technology to beat the 21st century F4 CBR honda engines is WAY COOL OF A DESIGN.

Think about this, all of the Flat Track racing motors are Air Cooled and run wide open for 30 laps without fail or over heating. , With todays lighter wieght internal parts and synthetic oils. The air cooled engine can last for well over your 20 laps. Also if you Cryo treat all your internal parts then put a performance coating on them they will be literally twice as strong and more effecient(all the top fuel dragsters use these methods for performance and strength in their 8000Hp engines)

The honda 500 and 600XR's are great engines to biuld,and Rotax 500/600's has dominated the Flat Tracks for years. take a look at Ron Wood Racing website.

you were right about the XR's using twin 28mm carbs, but the intake ports are still way smaller than todays more modern head designs. you dont need big intake ports with a turbo. Also look at the 1982 honda CX500 turbo street bike. Honda used a very small turbo that spooled up to 200,000 rpm, producing 18lbs of boost and the 500cc(STOCK) street bike motor made 80hp @8,000 rpm. To me this is the type or turbo that you would want on your motor, especially being restricted to 20mm.


Also remember with a single cylinder engine, Especially turbo charged you will make ALLOT of low/mid range torque. you litterally will not have to use but 1 gear the whole race if your geared right. Example: My friend ScoobDFW and his turbo DS650 takes off in 3rd gear, geared WAY high, with 14 paddle rippers , and can easilly run 70mph in 300 ft. without shifting once.


just food for thought, I would really like to see you win your competition!!!




Bigger.

 

I see your point with the smaller motors breathing through the turbo. Last year we ran a ltz-400 bored to 470 by thumper racing, and turboed with a garrett gt-12 which spooled to 220,000 running around 10psi boost. Except we went though two transmissions and a clutch. After that point, our team said no more singles. and I really want to use a cvt which is a little more difficult on a transmission style motor

Thanks for the great ideas though

 

Hey Hondabill, (Edited by ATV Connection moderator)! When you have been here for a few years and have helped people half as much as I have (yes I have extensive hands on with CVT trannies) then you might gain a little respect.

I am sorry modedwarrior and wont post here again. I knew what the FST was, just overlooked it initially. Hope you get it all worked out, sounds like you'll be having fun doing it. In the meantime I'll be watching my wife wax 65hp 4-strokes with her R. Have fun, Bubba

 

don't tell me to do anything for a few years. posting on a forum does not equal experience. all the experience you impart over a forum can be read in a book or copied off of someone elses work. and i don't need respect from you as canadian tire bolt on "goody" racers don't cut it in my book. talk to me after you've designed a full suspension system, machined all its components, assembled and raced it. you might have built frames from the ground up, i'll give you that, ever worked with carbon fiber, ever done any electronics work? just because you're old and sour doesn't mean you have experience in everything. thats awesome that you own several atvs/bikes, how many did you build from the ground up? and i mean build, not assemble or repair or add BOLT ON crap to.
so please, do what you said and not post again. you clearly have nothing intelligent to add as your only posts have been directed at me. i on the other hand started out by first getting people on track and then gave something constructive to the discussion. did you?
so keep living in your little world, and i don't think your wife will be waxing anything anytime soon, except maybe my kitchen floor.

 

Honda Bill,

no matter what you have or have'nt accomplished in this industry, YOU ARE A PUNK!

and please don't take any credit for "keeping people on track" from your first post. That like your last posts was a total waste of words. You have not helped ANYBODY yet so far and your cocky smart a$$ attitude paints the picture of a true PUNK. IF you do possess the talent to design,make and race parts its a shame no-one will ever give you the chance to tell/teach what you know, cause no body wants to listen to a smart a$$.





bigger.

 

well you know i posted on this thread because i've been in the same situation as modedwarrior. rarely will you find a thread on a forum where you don't have people just throwing nonsense out for the sake of posting something.
maybe i take what i say on these forums too seriously, but i wanted to check the facts before i offered modedwarrior a design suggestion. it didn't seem like anyone else wanted to go that far, so people can use what i said in my post as a reference to the rules.
i have respect for what you have been saying in your posts, biggerisbetter, as they are all intelligent comments. there are in fact other teams which do well in modedwarriors competition that run autoclutches, but perhaps money is less of a hinderance for them, as it seems modedwarrior already had the price of one on hand and had already considered it. what you have said about intake runners and ports is exactly right, once you choke through a restrictor, you don't want to be running through large ports. other teams have installed sleeves or used JBweld to decrease the port and runner sizes. where you were a bit astray was the suggestion of other motors. the name of this thread is deboring cylinders, and modedwarrior hasn't asked for people to give ideas for other motors. the only time he brings up another motor is the sportsman 600, which is a similar configuration (leading me to believe he wants to run a sled motor with a cvt, which i think is true), and on my first post i gave some potential reasons for wanting to do so.
i got pissed at bubba because he simply entered this thread, and his only comment was telling me to screw off. that is even less constructive than what i said, as it offered other people absolutely nothing in terms of information. so i responded to him, which caused you to make your most recent post.
so for modedwarriors sake, and because i didn't really find what i was looking for here, which was more engineering type discussions, i'm leaving this forum and i hope you all can give modedwarrior some help with his question and any further questions he might have.
i don't need people posting more stuff like "good, get the hell out of here" or "screw off hondabilletturbomugenracing", and hopefully the next post on this thread will be something constructive.
later

 

NO need to leave the forum. Their is nothing wrong with respectively diss-agreeing. IF you will do a search on Bubba, you will see 99% of his posts, are helpful and respectful.

If moddedwarrior, is dead set- on using a CVT engine than that is cool, nothing wrong with a CVT, we all know the benefits of a CVT tranny. My points were more towards the size of the the engine and head flow potentials given his restrictions. The real reason I was bringing of the whole manual tranny suggestions up, was cause I don't know of any lighter-weight sled 4-stroke engines in the CC range he needs, and all the ATV CVT engines are HEAVY,and cumbersome.



Bigger.

 

Deboring will most likely not get the job done . Besides the problems listed you will have no room for the valves to open , they will probably hit the sleeves .

I understand that this is a school project and the purpose is to learn . But I thing trying to shrink this engine even by destroking may be a little to optomistic .

If you want an auto tranny ever think of trying to graft one onto a Honda F-4 ? I would rather try that than what you are thinking about with your current idea .

Rick Ritter

 

This is the information I came on here to get. How do you know the valves will hit the sleeves? where did you get tis dimension or is it just what you believe will happen.

 

Most of these new 4 strokes that really make power have a lot of valve area in the head . Even if it does work the valves would be shrouded by cylinder wall . Going big bore is pretty easy , shrinking them down is hard to do . I am just guessing with some experience that shrinking a bore like you are planning is not going to work .

Deboring even a 2 stroke is more complicated than a big bore , back in the day when we debored
250's to run with the 200X's it was not an easy ordeal .

I guess my thoughts are that we all know the F-4 works , so why not try to make it an automatic ?

Rick

PS ----> Bubba , come on back .