myths: 2 strokes

[poormanracing]

wanna get a ysr or a nsr.........seem to be a downgrade in displacement but.............looking for a cheap track bike, cheap track day and improve riding overall...............however, im not really that mechanically inclined...............i work on maintaining and repairing issues with my GS as far as i can................ but i read 2 strokes engine needs to be rebuilt a lot or something..................dont really have the place to do a lot of work...........would having a manual and some tools be good enough to maintain this little boogers?... :mrgreen:

[Roadstergal]

Read the Aprilia thread just down the page.

They have odd engine characteristics.  A good solid fast launch will be hard on the clutch.  They burn oil as part of their regular running, so they're kinda nasty.  Since no two-strokes over 50cc are street-legal in the US anymore, parts are sparser.  I'd get a GS.

You will find a 50cc two-stroke to be the nuttiest bike you have ever ridden.  You will literally be able to run faster than it until you get to 8K.  From 8-12K, it will jump forward, and seem a lot faster than it is for how little power it had before that.  It'll teach you to stay in gear.  You'll be lucky to see 60mph.

[RVertigo]

But a 400 2-stroke is HOLY shaZam! fast for being a 400.

[jake42]

RG you can stilll run 2 strokes here in PA as long as they are registered as classics or antiques.  I have a 67 yamaha 2 stroke 180 that I still ride sometimes.  I'd love to get an rd350 or rd400. They're monsters and there are a million parts available out there for them.

jake

[island515]

But a 400 2-stroke is HOLY shaZam! fast for being a 400.

I completly agree....this is actually what my theisis was based upon.

[werase643]

ysr-50's 5-7 HP   55-58 mph
aprilla RS-50 10-15 HP   60-75 MPH

seriously overpriced...but they have them and you don't
I can't replace the ones i got...for what i paid for them....


yes i have several ysr's and a RS

the engine needs to be rebuilt more often...true
but it only takes 30-60 min
top ends in 15
rebuilds cost about 200-250

[poormanracing]

RG...yeah...im not going to run these boogers on the street...just on the track......local (wel semi-local) kart tracks to be exact....$20-25 the whole day......these bikes have nice corner speed which i want to improve on...and flies decently in straights well...im not that big of a guy so i think these 50cc can carry me around (seen videos with 200lb 6 ft guys riding them) ..the GS well..mine sucks...ill keep it for the street...i just dont feel confident with it still (maybe itll come to me).....

right click save as...
http://home.comcast.net/~wsr308/CMRRA.wmv

it looks fun...as for parts... calamari racing here in ca and some sources seem to have them

but yeah i cant do engine overhaul  if this two strokes needs them often   ....can someone explain to me the "premix" thing about oil and gas with this two stokes...i though i just put gas  :dunno:

[poormanracing]

the engine needs to be rebuilt more often...true
but it only takes 30-60 min
top ends in 15
rebuilds cost about 200-250

whats the normal interval or indication for rebuilds?

[werase643]

once every yr or two depending on how much you race...

top end....piston/rings    every 6 months....depending on how much you race

http://www.oldengineshed.com/twocycthry.html


http://www.deepscience.com/articles/engines.html

[poormanracing]

very helpful.... ....one more thing(total noob)...what are the symptoms to rebuild it....like will it run like crap, dark smoke on exhaust or complete engine seizure?..

.....at least every 6 months, huh....not bad looks like i can afford have a mech to do rebuild if i cant do it  

[werase643]

10 mm socket
4 nuts
pull head
carefully pull cylinder
inspect cylinder
check clearances
install new rings or rings and piston...  needle nose pliers
2 new gaskets
install cyl
install head
4 nuts....

you loose power due to the rings wearing out..compression gets low
or you run it lean and the piston melts down
or you run it lean on oil and the piston siezes to the cylinder
this happens when you are going down the road...53mph and the back wheel locks up and leaves a skid mark til you stop or pull in the clutch
i highly reccomend pulling in the clutch.

your other option is a mini supermotard...yz80/cr 80 with race tires

[Chris_B]

The NSR400

[werase643]

back in the 70's
4 strokes reved to 6-7k
2 strokes reved to 10-13k

today
4 strokes   16-18k
2 strokes    10-13k

the double the power from a 2 stroke have been equilized by double the RPM of the 4 stroke

[RVertigo]

2 strokes to smell awful...  and the more load you put on 'em, the more they smoke.  BLEH!

[indestructibleman]

But a 400 2-stroke is HOLY shaZam! fast for being a 400.

I completly agree....this is actually what my theisis was based upon.

submitted to the review board:
HOLY shaZam! FAST:  An Examination Of The 400cc 2-Stroke In Modern Society.




don't 2-strokes tend to have really narrow powerbands?

[Church6360]

yeah, i'm pretty sure they aren't known for their low end torque but i'll still take the 500cc honda, i've heard they are pretty mean.


http://cgi.ebay.com/ebaymotors/Honda-CR-HONDA-CR-500-cr500-clean-with-extras_W0QQcmdZViewItemQQcategoryZ50001QQitemZ4594663281QQrdZ1

or the trump card in the WTF contest.

http://cgi.ebay.com/Honda-CR500-RGV250SP-supermoto-hillclimber-project_W0QQitemZ4593154054QQcategoryZ9806QQrdZ1QQcmdZViewItem

[dgyver]

....can someone explain to me the "premix" thing about oil and gas with this two stokes...i though i just put gas  :dunno:

Gas and oil are premixed in a container then put in the tank. There is not an oil sump in a 2-stroke. Just like a string trimmer. The oil in the fuel mix lubricates the parts.

The power range is small, around 10-12k on a 125.

I always hated dealing with the jetting.

The GS has been the easiest to maintain bike for the track that I have owned/ridden, if could ever leave anything in stock form.

[werase643]

the new thing is installing XR-100 4 stroke singles in a YSR 50 chassis

i could find the link if ya really want it

[ktrim]

my brother-in-law used to have a 2cylinder 2stroke honda,  it was a mid '70s about 400cc (maybe, dont rember for sure) OMG was it fast and UGLY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[werase643]

honda didn't make many 2T bikes for street after 1969

most likely a RD350 or RD400 yam     damn popular
Kaw made 350/400/500/750 tripples     super evil handling in 500/750
Suz made a hella turd GT750....i think they were 4 FT wide  


i can't think of a single honda 2T......twin cylinder street???