4 stroke goes boom!

[Karchiveur]

heh,

About 2 hours ago.. i just finished tuning my modded xr100... and i took it out for a test ride.. my little bro has the same bike but his is STOCK... So we raced down the highway beside my house and just as i was about to shift in 5th the bike started to rev really high (guessing 9500+rpm) and as soon as I hit 5th full <meanwhile my bro is about 20 ft. behind me...> I suddenly take a huge gain on him.. than i knew.. i didn't even have enough time to kill the engine... and all i could do was smile and say to myself "here we go.."(you know when seen as I always ride @ top speeds and the highway was clear i just went in my shorts.. and nothing more.. what an eye opener it is when ya got a locked tire and your going 120kph and a guy behind ya @ 100... All is well tho.. i managed to kick the back-end into a 90-degree spin so i am skidding along the highway with nothing on... and its @ a 30-degree tilt and burning rubber on the road as i slide...(and for some reason i was calm?!?)

So i kinda leaned ontop of the engine and let it go until I hit the ditch and landed in a bunch of water and mud ... yet my bro is right behind me watching this happen.. and trying to aviod me... (he had all his gear on, from a chest protector to a helmet to gloves) now the only thing that bothers me is... i just finished investing about $300 into the bike.. only to go and have to spend another $599... but this time it'll be faster.. and i'll have protection The Engine Kit

Or should i just save up for a car?!? or maybe a gsxr 1000?

haha and in the end of this all, i walked my bike home.. (1/4 mile) and no one could tell what had happened...so i kept my mouth shut until i come to a decision.

[eGoCeNTRoNiX]

But I've got a story for ya.. heh.. Well, not a story.. Just my experience with modding my Suzuki DR Big 50.. he he.. Lemme dig up the picture.. hmmm.. ahhh.. here it is..

btw my bike was a 2 stroke.. So I'll repeat that your speed on yours isn't bad for a 4 stroke..



This bike was my favorite thing in the world before I got into computers. Yes, it's only a 50CC bike on about a 125 frame. But it was a great bike for me to ride to school and back since I couldn't get a license where I lived. Well, after adding a custom Kit Yasuni exhuast and changing the sprockets out (You might try that for more speed heh) from a 12 in the front to a 14 and a 72 in the back to a 36 I gained about 25kph.. So I went from 60kph max to 85. Next step, went from the stock 12 carburator to a 16 gained another 5kph but I also got way more pick up. Well, I was happy with that for a long time. During my senior year in HS I blew the motor up.. Well, at least I blew the piston and rings. Cracked it to hell, wish I had pictures. So here I am without my bike.. I go to the shop and see what it costs for a new head.. They tell me $125. I say ok.. Then I start looking around.. I see a 90CC head kit for $250... Well, I think that's too much for the crank case. The next thing I see is what I bought.. 75cc Head kit for $180. Took it home and got my grandpa (over for graduation) to help me mount it. About 3 hours later and lots of Italian inginuity I got it all put back together. Oh, and I put an 18 carb on it as well. Took it out and first thing I did was ride a wheelie through the first 3 gears (5 speed). Went from there to the highway, and gunned it.. Had a buddy with me that had a Ninja 250 and I pegged by Speedo, but his kept climbing. We hit 140 and I ended up doing the same thing you did.. Except I just kept a straight line. Yah, it's scary, but it's certainly controllable.. Just thought I'd share that with you..

eGo

[PreDatoR]

When the wheel locks... can't you just kick out the clutch and allow the tire to roll again?

[eGoCeNTRoNiX]

Originally posted by PreDatoR
When the wheel locks... can't you just kick out the clutch and allow the tire to roll again?

Well, on my bike no. It would actually get so hot that the engine or crank shaft would seize. But it didn't take long for it to cool off and free up. The small crank case of the 50cc just wasn't used to all that speed/heat.

[dadx2mj]

Or should i just save up for a car?!? or maybe a gsxr 1000?

You eat it on an XR100 and now you are talking about a GSXR 1000? Dude the XR100 seems to be a bit much for you to handle the GSXR1000 will kill ya for sure.

[Karchiveur]

Originally posted by PreDatoR
When the wheel locks... can't you just kick out the clutch and allow the tire to roll again?

the road is slippery.. and the burning rubber makes it even easier to slide.. so the kick just helped the bike do a 90* spin. Making it easier and safer when you stop...

[Karchiveur]

Haha.. the XR100 isn't too much.. I ride a 125 motocross too... hell, i bet you couldn't of handled the xr100 any better than i could of at the time..
Just saying whether should I save up for a street legal bike? or invest into a small offroad bike? or even a car..
and I live by a race track where they race all types of bikes.. I know how much power a 1000 has... Got a few friends who store them at my place inbettween races... so i get to drive them aswell too...

[jayscybertrhs]

two reasons that could happen;

1. you forgot to back off on the throttle b4 shifting,

or

2. since you were 1/4 mile from home probly the enging was still warming up..

and theres a break point where the choke cuts out and until you hit that temp,
the engine will jump by itself if you pull the clutch too slow.



Motorcycles 4EVER!!

better have the frame checked too.

as to the panic reflex - those who cant ride - DRIVE! it its too hot out puhleese go Get a Car.

anyways - the wheel locks up because the friction harmonics in the tranny/clutch arrangement are thrown out of whack by the over-rev and unless the tranny is expensive enuf to have a compensator - you'll lock up every time.

[Karchiveur]

1st - 4 stroke won't blow due to not warming up. (it was plenty warm before I drove it anyways)
2nd - 4 stroke won't blow if you power shift, or shift improperly. (although the cdi might of messed up when i power shifted, but doubt it)

My bike blew because it could not handle such high revs.. One mod I had on my bike was a top end cdi box. and it happened to kick in the revs before i hit 5th gear.. even if it kicked in after i was in 5th it woulda still blown, my poor little honda engine couldn't handle the high rpms and intense heat (even for a 4 stroke). and the carb and pipe didn't help much either

and the frame is bent terribly.. I'm thinking of just selling it as-is, its still worth alot, i'll still be making more than i paid for it.

EDIT: i'll post a pic of it b4 the crash aswell

Heres what some of the mods looked like: