Sticky substance in carb on 125 6d

[sdm]

Here is one I have never seen before so I thought I would check
with you guys and see if you have any experience with this problem.

 I have a 73 125 6 Day that I have been doing some light riding and
resto work on and noticed that the throttle is starting to stick in
the closed position after sitting for a day or so. I pulled the carb
apart to find a sticky almost parafin or cosmolene type substance
coating the needle and jets. I cleaned all the carb jets and needle
in gas and blew everything out, rode it for about 15 mins and the
next day the same thing happened. I thought that maybe the oil on
Uni filter was reacting to the premix or something but there is
no film before the carb. There is a coating of the sticky substance
in the metal intake tube between the carb and engine. Also the pilot
jet had the stuff on it so I would think that would eliminate the
filter oil.
  I am using Torco GP 7 synthetic 2st oil for premix and it seems to
work ok in my 250 EXC.
  I have not been draining the gas tank because I have been riding
the bike off and on. The carb is stock and in good shape otherwise.
Also I am using 91 octane pump gas.
Anybody had this happen??
Thanks for the help
Sam

[firstturn]

Sam,
  Several things could be going on here, but just for the exercise of going by the numbers lets try first things first.
  Have you really ever cleaned out the gas tank???  If not this is where I would start.
  There other things we can look at, but I'll start here first.


Ron Carbaugh

[sdm]

Ron
 Yes I did clean out the gas tank when I first got the bike. I did
not know what the previous owner used for premix so I thought I
would dump the old fuel and start with something that had worked ok
in another bike. I did take some fresh gas and slosh it around
before I remounted the tank  and that is as far as I went. There
is an inline fuel filter on the bike also with the normal grains of
crud in it but not a large amount.
  I have not pulled the petcocks yet to see if they are plugged
I'll do that next and see what comes out.
Thanks Ron
Sam

[firstturn]

Sam,
  You may be living on the edge as far as losing a big end crank bearing it your tank has some of the left overs of old oil and what is left of gas additives after the light fuel of gas evaporates.  Let me know and there are several things you can use to clean out the tank.

Ron Carbaugh

[Doug Wilford]

Clean the gas tank with Lacquer Thinner one quart.wash around let set and do it again.   You had dried up oil in the tank and with the new fuel it has turned to a varnish like substance,  You may have to pull the cylinder and flush the bottom end also.   Just finished writting a tech tip about this for the next POG newsletter.

[sdm]

Thanks guys
 I think you nailed the problem. I pulled the tank yesterday and
there was some goo around the petcocks. I flushed with water and
degreaser first to get any loose stuff out and now I will put some
lacquer thinner in to cut it further. I think I will pull the engine
and top end and flush it just in case also. I don't know which bore
this engine is on anyhow so it will be a good oportunity to find out.
Thanks for the help!
Sam

[LINDEMAN]

This may be a longshot as I have only seen it twice in 33 years but when I hear Sticky I think sugar! I had a customer bring in a 77 175 penton with a burned up  bottom rod bearing.I was inspecting the parts after tear down and they looked different than normal.Glazed and slightly sticky feeling.So being the dedicated redneck Indiana mechanic at the time,yes I licked the rod and it had a slight sweet but burnt flavor.After talking with owner I discovered it was stored outside and someone had put sugar in the gas tank.This may not be the case for your bike but may be point of intrest.When cleaning out sugar hot water seemed to work best to dissolve the glaze.

[Rain Man]

Hey lindemen, thanks for saying that, I thought I was the only mechanic that would taste the metal:).  
   Doug just one question:  with the Lacquer thinner, I've always used denatured alcohol to clean the goo outta the carbs on multi's. Is there any difference between the 2 [?] I know the alcohol cleans  the residue out of the bowls and brass parts real well when left sitting all night. I also noticed that the thinner leaves kinda white chalky substance occasionally and it usually wipes right off. Any preferences out there[?]


Raymond
Limington Me.

[Richard]

When I read the title of your post I knew what your problem was going to be. I had the same experience you are having two years ago. It starts with a slight sticking of the throttle when opening from idle and progresses to a motor so gummed up that I could not spin the engine fast enough to start it with the kick starter. I had to disassemble the engine completely to clean all the sticky gunk off the cylinder, piston, crank, and crank cases. The goo was so sticky that the only solvent that would remove it was MEK.

After the second time of disassembling the engine I found what I think the source of the problem was, the pump gas I was using was dissolving the resin in the fiberglass fuel tank. After dumping the fuel from the tank and allowing it time to dry I could still feel the sticky goo on the inside of the tank.

I have not had a reoccurrence of this problem after changing two things. I do not use pump gas, and I do not allow fuel to remain in the tank after riding.

Best regards, Richard

[sdm]

Richard
 My throttle is sticking in the closed position with a molasses
type substance on the needle and accumulating in the carb and
intake. I guess it sets up after running it and glues the throttle
shut. I was also considering the pump gas theory but I am going to
try to do a good flush first. This problem didn't start until I got
the bike and drained the tank originally and started with my own
premix.
  I may change oil brands and see what happens also. Who knows what
kind of gas we are getting. Maybe putting some gas tank liner stuff
would help the tank from being eaten up if that's a problem.
Sam

[Rain Man]

Richard, thats a different and a new concept to me. I've never heard of the fiberglass tanks dissolving.[?] The only thing I've experienced    and it was recently, was the cream liner in my steel tank feeling sticky to the touch. I  resealed another tank and installed it.
   I've never heard of the fiber glass ones doing that, but .. maybe after 32 years of use on a Penton... and todays fuels. hhhmm  this sounds like a real sticky problem, to say the least...any other experiences out there[?]

Raymond
Limington Me.

[Doug Wilford]

Raymond
I use the lacquer thinner because it works faster and easy to dry out.   I don't know about gas making the fiberglass sticky.   I think I would try to rinse the tank good with the lacquer thinner and then see if is still sticky.

[firstturn]

OK,  last try.  The only background I have with fiberglass is we(my brother and me) use to build Bass Boats (Cooper Bass Boats) and my understanding from those days is that gas doesn't attack fiberglass period.  So I only know what I have been told by engineers(I am not an engineer).  What I have seen over the years in the stickyness, for no better word, is  the inside of the tank has either  oil or other substances on the inside surface OR someone has tried to clean the inside of the tank that has attack the finish.  That is all I have seen, but I am still young and see new things all the time with vintage bikes.
  One final note: I have seen people use Acetone to clean their tanks.  DON'T DO THIS UNLESS YOU ARE AWARE OF THE CHEMISTRY INVOLVED.  We used Acetone to clean up fiberglass overspray and our hands after finishing a job.  So it will actually destroy fiberglass.
  I agree with Richard about draining you fuel if the bike isn't going to be used for say 5 to 6 weeks.  That's it, thats all I know, except to listen to Doug, so people can do what the want with their tanks.  Just my take.  
Respectfully,


Ron Carbaugh

[tomale]

Seems to me this topic has come up before. Some one was asking about how to fix a tank that the petcock had come loose and was spinning in the fiberglass. I for one have had some trouble with leakage in my tank around the petcock. I ended up sealing it with JB Weld from the outside of the tank. I made sure that I only filled the potholes and cracks that were around the Petcock. This solved the leaking. That was last year and I have not had a problem since. At least in this situation I am certain of the history of the tank because I have owned this bike since it was new and I have always been carfull as to what I put in the tank. I only use a premium gas from a premium station. I may use cut rate gas in my truck but never in my bike. To me it is just not worth it. The only thing that answers the question of why my tank was leaking had to be the new style of gas I was using. Some one on the site explained this and It seems to me it had to do with some of the additives which are Petrolium based as well. I do have a friend that works at a refinery and He was telling me that the formula changes during the summer to help control the Emissions. He rattled off all the different Additives that are used and it amazed me. The Gas of today is much different than the gas of even a few years ago. As Emmission laws have changed so has the Gas that we buy. Believe me oil companies do not care about your Bike, only how it affects the cars we drive. Just the same the cleaning out of the tank and engine seems logical to me. Last year I was having a problem with my tank... It took some time but eventually the varnish that was on the inside of my tank was coming loose and it was plugging up my Petcocks and to some degree the carb. I cleaned out my tank and carb as Doug has suggested. The problem went away and did not come back. I do empty my gas tank at the end of the day and dump it in the tank of my truck. That way it is not a total loss and I try not to mix up more fuel than is reasonable for what ever event I am doing.
As Ron said so well... Just my take.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.