Question about testing for bad crank seal.

[bleeds]

Is it safe to spray carb cleaner on the Mag-side (charging system)of the engine to diagnose a bad crank seal? I want to spray it on it while it is running. IS this bad? Is there another easy way.

Backstory:
Rebuilt top and bottom on a 97 Yamaha Rt-100. Fired right up on the 6th kick and ran great. Made small adjustment on carb, and ran flawlessly. I let it warm up, and then rode it very easy and light for about 15 mins. Then let it cool completely, and did it again. Then a week later, did the same thing. Then when we went riding the next week, the owner of the bike rode it for about 1hr, but he was a little hard on the throttle at times. Then suddenly it bogged out and died. Thought maybe he sucked some water passed the air filter (we found it wasnt all the way on). WOULD not start. Pushed it to the truck and rode the other bikes the remainder of the eve.
We noticed the plug wasnt getting any gas . Staying totally dry. Even when we sprayed starting fluid into the carb, and cranked, it wouldnt even hit. Finally we pushed it for a half a block and it started. It will start without pushing it now, but it takes a lot of kicks. When it does start, it revs up a little on its own. If y ou rev the motor (after it warms up), it does the run-on rev, where the RPM;s take a while to settle down. ALSO MAJOR peice of info. The carb air screw has to be totally in the stay running. I think we are sucking air thru the crank seal. It doesnt smoke, so I dont think it is on the oil side, but I think it could be on the mag side.
I am thinking he may have burnt the top end out too, but if it is sucking air, it wont run right, correct? Sorry for the book, but I have been told whatever info I can give helps.. thanks guys,,,

Is it safe to spray on the mag while it is running?
Bleeds

 

[bleeds]

Darn I was hoping someone would know if it was safe..
Bleeds.. :)

 

[matt-itude]

I have seen carb cleaner take off the coatings on the windings in electric motors before. I dont believe all carb cleaners do this. Some brake cleaners are also listed as contact cleaners and would probably be safe to use. you might try ether (starting fluid) it wont hurt anything.

 

[ellandoh]

there is a home made leak down tester here if you can search it out

 

[bleeds]

Ellendoh, does this sound like an air leak to you? Just curious..
Bleeds

 

[ellandoh]

well it sounds lean to me, for what reason not sure . since you found the air filter not on properly i would definitely start with a good carb cleaning. one grain of sand will clog a pilot jet and cause grief like you explained

 

[nickyd]

yes you can do it. i've done it many times. its not a very conclusive test however...a leak down will tell you more. I'm inclined to think you have something else going on. confirm your jetting is good and then do a leak down - search the threads, there's one you can make for about $20

 

[bleeds]

I dont think it is jetting as it ran flawlessly and then happend all of a sudden. The plug when removed was chocolate brown, and no oil soaking... the new plug that we changed "just in case" is white, and somewhat bleached.. will do the search, and a leak down test..
Bleeds

 

[nickyd]

how suddenly? and how did it die? Like a BAWwwwwwppt......

I'd be inclined to look at the top end - check the piston through the exhaust(pull the pipe and look up) - I'd want to be positive that the piston didn't get fried or a ring didn't decide to find a new home. What killed the bike the first time? was the piston sized correctly, bored, etc, etc.

 

[bleeds]

I have looked thru the intake side, and there are no seize marks on the piston, and the rings APPEARED to be ok..but I will pull the exaust side and check that too.

It died like you described. Wasnt a sieze..bawwwwpppt bawwww bawww ..dead, and like I said it now will not run without the air screw all the way rich. It ran flawlessly and STRONG before all this happened. There wasnt any funny noises that I know of either.

The reason it had to be rebuilt, was the last person ran it with a failed oil injection pump, and it burned it up. We replaced:
Crank pin, Crank bearings, Rod, rod bearings, wristpin, Piston (wiseco) Rings, Crank seals, crank was professionally inspected and balanced, cylinder measured and honed, cleaned afterwards with pressurewasher, and dishsoap. Cleaned again in the sink with laundry soap. New gaskets, and cleaned carb (which was just damned nasty), and torqued all down. Like I said it ran great from the get go. It had maybe 3.5 hours on it at the most..I am just wondering if the crank seal has popped out part-way or something..
Bleeds

 

[nickyd]

i would:

1 - check compression
2 - make sure you are getting gas to the carb
3 - check the reeds
4 - open beer
5 - check for air leaks.
6 - repeat #4 as necessary

a sudden problem like this would make me inclined to pull the head and have a look see...but then again, I like to take motors apart any chance I get....i know I'm weird...

 

[bleeds]

I think those are all good ideas. I think I will pull the mag, and check the seal. If there is no help there, time to pull the top and check the rings/piston...
Bleeds

 

[Bandit9]

Use starter fluid. It is ok to spray it on the left side, although it might not reveal whether the seal is leaking or not. Best thing is to do a proper leak down test. I have been chasing a similiar run on/surging problem and I am positive that it is an air leak from one or both of the crank seals. You are on the right track.

 

[Ford357]

Spray carb cleaner all over your rubber seals. it wont hurt anything. NOT! Carb cleaner will eat seals up dont do it. Leakdown tester would be the best way, freeze plugs in the intake and exhuast port and a leak down tester in the plug hole. Piston @ BDC and youll get crankcase retaining pressure :) I am not sure how eays you could blow out the seals so find that out form someone who has done it! if you pressurize it too much youll blow the seals for sure.

 

[BDAY]

i didn't really read this thread so if it has already been said, my bad. get out your oxy-acetelene torch and turn on just the oxygen and spay it at the seal. if it revs up you have a bad seal.

 

[TimberPig]

i didn't really read this thread so if it has already been said, my bad. get out your oxy-acetelene torch and turn on just the oxygen and spay it at the seal. if it revs up you have a bad seal.

Doesn't pure oxygen react violently with oil, as might be present on a crank seal of a 2 stroke? I can't see trying this and burning the bike down as being a good idea. The other methods mentioned are safer.

 

[+30]

timber is right. O2 and oil/grease are a very bad mix.Aircraft have burned to the ground as a result of a mechanic getting a small amount of grease on a oxygen fitting. Do not use that method. There is a good thread in here about how to make your own pressure tester. I recently used the same method. A $12 low pressure gas gauge from home depot. a $1pipe fitting and a 1$ pvc fitting all plugged into my intake port. A 2in expansion plug from autozone-$2. Sorry I dont have the exact prices. One thing when you do the search and make your shopping list, make sure to accurately measure your exhaust opening and intake boot to get the right size fittings. Motion pros web site sells a kit for several hundred bucks, nice kit but not cheap. They do have a pdf on how to use it and if I remember correctly it says not to exceed aprox 8 psi during your press test so as not to blow out seals. I think a psi per minute was acceptable leak down...Dont forget to plug vent hose if your bike has one. There are some nice photos of this cheap but accurate tester, youll have to do the advanced search. Good luck.

 

[Faded]

Click Here for the leak tester, cheap and effective. :cool:

 

[ecy063]

i use propane for finding vacuum leaks with a long small rubber hose. good also for freezing components real fast.
use caution of course.

 

[bleeds]

Man you guys are never going to guess where the air leak was. I guess you have to learn as you go sometimes..

Well, this bike has an Oil injection system, and it had failed. We werent going to buy a new pump we decided to just mix our own. The hose that goes from the pump to the carb had some oil in it, and it slowly pumped it out. Once it was empty.. well you know.. it WAS SUCKING AIR. On a whim, I was thinking on the way to Dayton this morn, "I wonder if it is sucking air from the old oil system. DUH!! :bang: :bang: As soon as I plugged the hose the engine Immediatly smoothed out, and throttle response returned to normal, and ran like new again. Rode it for about 15 mins without one hitch. Damn..LOL Oh well, all a part of learning right guys!!?
Bleeds
Ps thanks for all the great ideas guys.. :) :cool:

 

[nickyd]

Now you can do these.....

4 - open beer

6 - repeat #4 as necessary