Tank-slapper on a Hyobag 250

[xwhatsit]

To be honest, I don't know much about bikes. But I am sure that it isn't normal for a bike to have an overflow tube for oil to pour into the tracks of the wheels - that's insane.

I don't know about the GT250R (quite a lot of modern bikes I see have the crankcase breather piped into the airbox, I've seen it labelled in workshop manuals as relating to US emission laws or summat), but my 250RS, C50 and plenty of other bikes I've seen run the crankcase breather straight down and out the bottom of the frame just before the swingarm U-bend -- right in front of the rear wheel.

The amount of oil that comes out the breather should be miniscule anyway, unless it's drastically overfilled or the rings are scuppered (combustion chamber blow-by, pumps oil out the breather).

I know TSS can do no wrong by most people here, but, er, how did they check the shock wasn't fecked? You say it's been like pudding since new, yet all these other people are saying the rear-end is quite solid on the GT250R? Could be they just pushed down on the seat, it seemed OK-ish, and wrote you off as a nincompoop squid talking bollocks (understandable if you pulled the `Ima Rossi and R6s are just like soooooo coool' spiel on them too ).

Oil has to come from somewhere. If it hasn't cropped up again on your back wheel, are you sure you didn't ride through something? Also, as others have said, you didn't just hit something on the road to cause the head-shake? With apologies to Hanlon, `never attribute to your bike that which can be adequately explained by yourself'

[bull]

Been having a read over at Korider and couldnt bring up any similar issues that you raise so it looks like yours is likely to be the guinea pig.

I had my 2006/7 GT250R from TSS for 16000km(1yr) trouble free and its happily still going with its new owner.

Once it gets sorted please post up what the official problem was and how it was remedied for future GT250R owners.

[johan]

Does the front wobbles when you take your hands off the bar?

This is what the service manual suggests:

Steering oscillation.
1. Loss of balance between right and left front suspensions.
2. Distorted front fork.
3. Distorted front axle or crooked tire.

Wobbling front wheel.
1. Distorted wheel rim.
2. Worn-down wheel bearings.
3. Defective or incorrect tire.
4. Loosen nut on axle.

Was it really oil on the rear tyre, or was it brake fluid?

Leakage of brake fluid.
1. Insufficient tightening of connection joints.
2. Cracked hose.
3. Worn piston and/or cup.

[hmurphy]

Will do!! Cheers mate.

Also it's wicked to see the amount of riders on this forum who really know their stuff! All your ideas are being written down and taken to TSS. There was a hell of a lot of oil that came out of the bike on to my rear wheel (also splattering everywhere). And this happened about 3 weeks ago but was much minor the first time, but enough to give me a decent tail kick!!! (also happened on the takas).

I can take my hands off the handle bars at 100 - 110km/h and coast the bike right down to 20km/h and the front wheel does not wobble.

Haha I like to go reasonable quick, but not Rossi styles!! I actually don't like the idea of racing on dodgy New Zealand roads where horse shit and sheep on the roads are as common as mud. That's what the track is for! I am going to a track day at Taupo in November (all booked!).

[henry]

If you're going to be dumping oil on the road every time you go out, stay the fuck away from the hill. It's hard enough to get up there in one piece as it is. And I'm not trying to be funny.

[lostinflyz]

You'll probably find the bike mechanic at the local shop will only be able to look things over and spot obvious issues. If there was mountains of oil (a wee bit of oil spreads easily all over tyres easily) then it should be obvious but just only a smallish amount might be harder to spot.

Tracing all the breather overflow pipes should be pretty easy to do and find if one is possibly spewing oil. could someone (or has??) someone had the motor out or fiddled with the hoses and connected one up wrong. (airbox off, radioator fix up, boredom?)

But that being said if it dumped oil once it should do it again. usually. a once off oil leak is probably more concerning as thats rather different. that may be a shocky spewing its oil out. Ive found if you ride a bike with a soft rear end and stiff front they tend to slap quite alot, everywhere.

But either way sort it out before you ride it. for everyones sake.

btw: if you lean into a corner with your shoulders and dont shift your arse you get a curved spine. In order for said spine to be parrallel with the bike, the bike must be curved. If this is the case it will be the source of your problems.

[avgas]

Please educate me, how does clipon bars relate to tank slappers?

lower riding position, arms closer to total bike - when issue occurs requires more effort due to torque effect to combat issue.
Hyosungs bars are good for learners and well spread - also rising position is more upright allowing for less "race" issue and more "riding bike" style.
its all geometry.
I didn't mean to be so hard in my last post - its obvious to me that your fairly new to all this. However what i say is true in regards to bike size is true.
I would be puddle with teeth if i didn't progress slowly up the bike chain.
From what i can see when i messed around the Hyosungs is that they share alot of the same issues - cost cutting.
Hyosung is an OK bike, the Jap bikes are just about OK.
I just replaced by footpeg bracket on my fazer......i didn't break it or anything - alloy just got a hairline fracture and all of a sudden i had no rear brake. Crap alloy. Also google "GSXR frame fractures" or "ZXR engine blown" and you see they all have faults.

[DarkLord]

Yeah man that's no good at all. I've got into a couple of tank slappers, mainly from hauling ass up over a hill and been going a little too quick and come down a little harder than expected, but 3-4 quick slaps and it's over.

For that few k's on the bike, I would absolutely take it back to the shop. Rear tyres soaked in oil never ends well..........

[hmurphy]

btw: if you lean into a corner with your shoulders and dont shift your arse you get a curved spine. In order for said spine to be parrallel with the bike, the bike must be curved. If this is the case it will be the source of your problems.

Yep I usually move my ass off the seat but only to the point where I am parrallel with the bike. I have had knee down a few times like when I was following my dad up the takas, trying to keep up with his cbr1000. Although it was/is a great rush, I didn't like pushing hard at the end of the day on those roads. I just enjoy a 60% - 70% run on the takas, sometimes slower! I just love to ride.

Couldn't agree with you more, I do not want to dump oil on the road and get other riders in trouble. I would rather my bike's diarrhea just throws me off and not anyone else!

The amount of oil that came out was substantial, hell it suprised my dad when he saw it and he was a grease monkey most of his life! Until he became a computer programmer haha.

Cheers

[Rev DJ]

Just want to echo Bull's comments - it will be good to know what the technical/mechanical findings are in this instance. It is definitely an unusual incident/s and would be useful for all riders to learn from this...

And well done on catching and riding out both!!

Cheers

DJ

[hmurphy]

Cheers mate! I am heading to the shop now so I will see what they have to say.

[flyingbrick]

what did they say?

[hmurphy]

Hey! The plan is to put a bottle over the engine breather (NOT an overflow tube, a breather) and see if oil is finding a way to spurt out of there when the bike is getting a bit of a hammering from the rider, i.e. flicking her around a bit (takas) etc. Also, a damper is going to be fitted to the bike. So, the next short while will be a testing process. Hopefully there will be some conclusive/positive results.

I will be in touch about what happens, whether we find out what is wrong and/or I come off the bike. I have been pretty cautious on it since Sunday, but she is now sitting in my garage exactly on 10,000kms (I got home from Wellington at 9,995 and took it out for a quick 5km blat haha). It is nice to see the bike got there in one piece (same with me), but I must admit that it hasn't got there in style!

[CookMySock]

Did they not take it for an open-road ride ? No sign of the tank slap ?

Steve

[johan]

Take it to the next trackday where you can analyse it over the same corners over and over and understand what's going on.
Doing it over the takas is only foolish.

My bike tank slap slighty occasionally. But I usually know where and how it happens. Leaned over, coming out of a particular corner on the gas, the front skimming over the ground, going over a few peculiar bumps in second gear, at Taupo track. In third gear it's fine.

Did the shop offer to setup the suspension for you, instead of band aiding a maybe poor geometry with a steering damper?