GT80b???

[spydey98]

Hi everyone,

So, earlier today I bought a GT80 for one of my kids for about 300. It looks great, has great compression, no major leaks.

The kids were riding it around today at the farm and it was going great!!! I mean this thing really pulled for a 30 year old bike. Anyways, after about 30 mins the thing started blowing whitish smoke out the tail pipe and bogging down after we put it in gear and pulled away. In neutral it will rev up, but not in gear.

Any ideas??? My kids are really hounding me on this one...they love the bike (we have two others of different years).

Thank you in advance.

[Airhead]

Possibly the clutch side crank seal has gone

Which also begs the question...Are the crank bearings rough?

[Joeleol]

White smoke generally means metal-on-metal with high friction, I am not familiar with a GT80 but I did a quick google to discover its 2-stroke (hopefully google hasn't let me down again) I'm guessing perhaps not enough oil in the fuel mixture or some internal damage to bearings?

[spydey98]

Hey guys,

Indeed the clutch side crank seal...however...it wasn't because it was worn, it had popped right out.

Didn't have time to check the bearings as the day was over and I was pretty tired. I'll check them in the

morning and see if I can figure out why it popped out. It definitely had some work done in the past couple of

weeks. It was spotless in there and the seal did look fairly new.

Cheap seals maybe????

Thanks for the input.

[Airhead]

Hey guys,

Indeed the clutch side crank seal...however...it wasn't because it was worn, it had popped right out.

Didn't have time to check the bearings as the day was over and I was pretty tired. I'll check them in the

morning and see if I can figure out why it popped out. It definitely had some work done in the past couple of

weeks. It was spotless in there and the seal did look fairly new.

Cheap seals maybe????

Thanks for the input.

on my 175 there is a seal retainer plate screwed inti the case to stop that happening

[spydey98]

I wish I had that.

So, I pushed the seal back in and it ran fine for about 2 hours. After that you start to to see the tell tale

white smoke begin and the motor started bogging down...so...here is my dilemma. Does anyone have any suggested sealants I could put around the seal when I push it back in? Anybody had this problem before and found a fix?

Thank you, any input VERY much appreciated towards a fix as I don't want to do this every 2 hours of riding lol

Jesse

[drewpy]

try some bearing retainer. bit like threadlock

[Airhead]

try some bearing retainer. bit like threadlock

sounds like a plan, or more likely to have liquid gasket, try that...try anything !!

Clean off all traces of oil first.

[2 Wheels]

Clean off all traces of oil first.

Brake cleaner, the stuff in a spray can is good for cleaning anything that you are sticking something to, just ley it dry fully first.

Are ya sure it is the correct seal that was put in there in the first place ?

[spydey98]

Well, finally going to get the time to get at that seal today. I'll keep posted on the results. I did verify and it is indeed the correct seal.

[spydey98]

Ok, so I got it opened up this morning but the seal had not popped out????

It's still in there. Good compression, ran fine for a couple of hours and then...started bogging down.

Any ideas on this one?????

[Airhead]

No more white smoke then? so is this another issue?

[spydey98]

No, same issue, bogging down and white smoke. This is where it's baffling me. The seal is in it's place but the same symptoms occured. Last time it was blatently obvious...now???

[Airhead]

Hmm same issue = same reason, perhaps the sealing surface got damaged when it popped out

[spydey98]

Normally I would agree with you, however, when I took it apart I examined the sealing surface (metal) and it is pristine...and I'm not exagerating on that...it looks perfect. you can't even feel the tinyest scratch either. I'm an automotive and marine technician, so taking from that knowledge I decided to pressurize the cylinder with air (much the same way we test marine outdrives for leaks), and no air escaped except on the exhaust stroke through the exhaust.

[Airhead]

Can you elaborate on the 'leak down' test, Usually the exhaust and every other inlet or orifice is plugged isnt it?

I was refering to the other side of the seal, the little VEE moulding that seals on the crank, not the carrier ;)If you can pressurise then block off the exhaust and place a pipe from the transmission breather spigot into a glass of water, that will test the integrity of the crank seal.

[spydey98]

I see your point, but as of right now I have the clutch side cover off so I have a direct visual of the crank seal. I've put oil around the seal and pressurized and there are not bubbles from the seal and the air does hold in the cylinder.

[2 Wheels]

Does the bike start easy every time ?

Where is the temp gauge at when the bike starts to bog-down ?

Try making the bike more rich or rather over rich see how it performes.

[Airhead]

I see your point, but as of right now I have the clutch side cover off so I have a direct visual of the crank seal. I've put oil around the seal and pressurized and there are not bubbles from the seal and the air does hold in the cylinder.

pressurised with the exhaust blocked?

If baffled, white smoke is transmission oil being burned. On the one hand you have white smoke and on the other you say the seal is good. i'm not familiar with the bike in question though. How else can transmission oil be burned? Unless the crank bearing has play in it and when running the seal cannot keep up with the movement.

[Airhead]

Does the bike start easy every time ?

Where is the temp gauge at when the bike starts to bog-down ?

Try making the bike more rich or rather over rich see how it performes.

No temp gauge Pat, It's an old fashioned aircooled jobbie like my DT175