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MIOB

Teilnehmer
Seit
02. Nov. 2008
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10
Hallo, ich habe eine frage. Ich hoffe das es kein Problem ist das ich die Frage auf Englisch frage, mein (technische) Deutsch ist nicht sehr gut, entschuldigung.

I have rebuild my 1988 R80RT into a caferacer. I had a megaton exhaust on it, but I changed it for a exhaust that I build myself last week. Now I noticed smoke comming out of the exhaust after a few seconds of full acceleration. I haven't noticed it before with the megaton exhaust. Anyone any idea what it is and if it could be harmfull?

I don't know how many kilometers the bike has done (I bought it without tacho's). The bike doesn't consume much oil.

You can see the smoke in this short video:

http://www.youtube.com/watch?v=ns7pDdQmVCY

kind regards, freundliche grüsse aus die Niederlände,

Michiel
 
Original von MIOB
Hallo, ich habe eine frage. Ich hoffe das es kein Problem ist das ich die Frage auf Englisch frage, mein (technische) Deutsch ist nicht sehr gut, entschuldigung.

I have rebuild my 1988 R80RT into a caferacer. I had a megaton exhaust on it, but I changed it for a exhaust that I build myself last week. Now I noticed smoke comming out of the exhaust after a few seconds of full acceleration. I haven't noticed it before with the megaton exhaust. Anyone any idea what it is and if it could be harmfull?

I don't know how many kilometers the bike has done (I bought it without tacho's). The bike doesn't consume much oil.

You can see the smoke in this short video:

http://www.youtube.com/watch?v=ns7pDdQmVCY

kind regards, freundliche grüsse aus die Niederlände,

Michiel
Zum Vergrößern anklicken....

Hi Miob,

was there smoke coming out of the mufflers before u installed the custom mufflers ?

Did u use exhaust glue or any other sealing/paint ? If so, it´s clear. the sealing (or whatever) vaporizes, after some time it´ll vanish.
If not it must have occured before the modification.
When changeing gears it´s O.K. if there´s some smoke, (i can´t watch youtube in the company, so I don´t know how it looks.)
If u need under 0,5 l Oil/100km there is no need to examine, except for flamable items on/in ur exhaust.

let us know about the solution

cu
Herbert
 
Hallo Herbert,

Thank you for your fast reply.

I welded the new exhaust on and didn't use glue or any flameable substances. It is the first time I'm seeing it and I have used the camera to film backwards quite a few times lately, so I'm pretty sure it didn't happen before I installed the new exhaust.
 
Original von MIOB
Hallo Herbert,

Thank you for your fast reply.

I welded the new exhaust on and didn't use glue or any flameable substances. It is the first time I'm seeing it and I have used the camera to film backwards quite a few times lately, so I'm pretty sure it didn't happen before I installed the new exhaust.
Zum Vergrößern anklicken....
so don´t worry....
always have a fire extinguisher with u :lautlachen1: :lautlachen1: :lautlachen1:

no joke: the smoke u see must be something in the new muffler, which didn´t exist in the old one.
Take a sniff and try to figure out what smell it is, i bet it smells of paint.
What kind of metall did u use?
I guess it will vanish after some time, something is frying down in the new muffler and when it´s burnt there will be no remains 1

cu and good luck.
 
I used stainless steel (unpainted/treated).
I just wanted to be sure that the smoke wasn't a indication for engine trouble, I thought I'd better ask the experts :). You reasured me, danke!

Michiel
 
Original von MIOB
I used stainless steel (unpainted/treated).
I just wanted to be sure that the smoke wasn't a indication for engine trouble, I thought I'd better ask the experts :). You reasured me, danke!

Michiel
Zum Vergrößern anklicken....
Well, assuming you are right in saying that u don´t need any Oil, if u do need oil, there are plenty of posibilities causing smoke.
 
Up untill recently I didn't have to use oil. I don't think installing another exhasut will have changed that :)

I'll check more frequently the next couple of rides.
 
Hello Michiel,

when I saw the video it seems to me as if the smoke comes out right after closing the throttle.

In this case the manifold air pressure is very low (you can call it vacuum).
So there may be a big play between inlet valve rod and the inlet valve guidance, where the engine can suck some oil through.

Maybe you can check this... :rolleyes:
 
I'm not 100% sure about what you mean. You mean I should check the clearance of the inlet valves?

I think you are right about the smoke comming out directely after closing the throttle. I'm not too sure if it is blue or gray smoke though (fuel or oil)

thank you for your advice.
 
Original von MIOB
I'm not 100% sure about what you mean. You mean I should check the clearance of the inlet valves?
Zum Vergrößern anklicken....

Not the valve clearance, that´s the distance from the valve plate to the valve seat. (normaly about 0,15 mm cold measure)
The engine sucks oil out of the valve guidance !

Here´s a picture of the opening of the valve guidance:
ventilsitze.jpg

(Not the valve seats around, hold your focus on the small hole !)

If the diameter of the valve rod is 8 mm (original material), then the diameter of the guidance is best at 8,04-8,06 mm.
If the size is bigger - for example more than 8,1 mm - your motor will get a problem with sucking oil through the intake section into the combustion chamber.
Mostly when the manifold pressure is very low, like a vacuum, when closing the throttle.
 
I also think what Stephan tells is the right solution.
It looks like a bit of oil steam -but not so much you need do something at once.
 
You are sure you want to open the motor now in spring?
I think this oil steam is not so dangerous. In my opinion open the motor next winter and have a contiuous look to this steam this summer.

And.. we will see some pictures of your nice bike.

Regards Bernd
 
Hi MIOB,

that is definitely not a lot of smoke, so why bother? If oil consumption does not increase dramatically, I would just leave the engine untouched and enjoy the ride. Not being a motorcycle mechanic, I feel inclined to support Stephan's diagnosis.

Does your engine overheat with the exhaust? Do engines overheat when run with non-stock exhaust systems?

best wishes

Alfons
 
I mainly wanted to know if it is an indication for a larger problem. I'm a student, I can't afford bog repairs so I try tor prevent them as much as possible.

About the engine temperature: I don't know. I don't have a temperature sensor. I know it's not running to lean (the sparkplugs have the right colour and the bike runs fantastic).

I don't have many recent foto's with the new paintjob (I had a leaking tank, so I had to redo it after using tank cure) and the new exhaust. only this one:

img9272b.jpg


this is one in the old colours (the colours aven't changed much though), without the new rearset and with the old exhaust:

http://img29.imageshack.us/img29/5048/img8134.jpg
 
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