Question about 1973 Yamaha DT 360

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1973 Yamaha DT 360 oil leaking from compression release valve.

Just bought the bike. got it home and started it up. it ran but oil started leaking out of the compression release valve on the front of the motor. at least that's where it looked like it was coming from. any thoughts. i'm getting ready to tear it down to redo the whole bike. any help will be appreciated. thanks

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  • Dustin May 01, 2013

    i noticed it was really loose.

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  • Yamaha Master
  • 42,985 Answers

Hi, Dustin you may want to try tightening it for more information about your question and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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Posted on Jan 01, 2017

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6 Suggested Answers

6ya6ya
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Posted on Jan 02, 2017

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rselvy
  • 83 Answers

SOURCE: Bad compression after 3 year slumber- Yamaha Fazer 700 1986

With compression that low you are in trouble. I'm sorry to say but you are going to need to spend some money to fix the old girl up. A few things to think about first:

  1. How may miles does the bike have on it? Reason being the connecting rods may be of concern. If you spend the money to rebuild the "top end", (pistons, rings, bore, and valve job), you darn sure want to make sure the rods are good.
  2. Think about refreshing the clutch because when the engine is fresh it will most likely slip. This can be a very minor expense, you may need to simply replace the clutch springs.
  3. Consider the condition of the rest of the bike. If it is cherry and you plan on keeping it then it may be worth making the repairs.
  4. You may get away with a nice AN 400 hone job and a new set of rings but I'm confident you are going to need to do a valve job.
  5. These newer bikes use a stellite coated exhaust valve and therefore are not to be ground, if you do you will ruin the valve. So any exhaust valve work means replacement. The exhaust valves will be pricey, they can be anywhere from $11.00 - $30.00 US each. So be prepared.
  6. Before you decide to do all this work find a reputable shop that can do the honing/boring, and the valve job. No sense in starting the job if you cannot find the help you need to complete it correctly.
This information should give you something to think about. Hopefully I have given you enough to consider so you can decide which way you want to go. Personally if you like the bike and it's in good shape, then you can afford to spend another $900.00 and have a cherry running bike. I dont think you can find a bike of that caliber with a "newly rebuilt" engine for that price. So it may be a good investment. I'm a fixer upper guy and I like the older stuff as well.
Good luck and holler if you need more help.
Regards,
RSelvy

Posted on Dec 26, 2008

  • 3567 Answers

SOURCE: 1995 fzr 600 spits and sputters

Personally, I would go back to the stock jets, stock air cleaner and stock exhaust then get the carbs balanced and synchronized. Aftermarket stuff is usually flashy and sounds like a good thing.. Sometimes it is but sometimes it ain't. Sometimes one add-on interferes with another. Put some faith in the guys who designed the engine in the first place. Go back to stock equipment and settings and see if the problem disappears.

Keep the cool aftermarket product stickers on the bike. No one will ever know.

Please rate my solution a " FixYa " if all goes well. Thanks!

Posted on Mar 26, 2009

  • 3567 Answers

SOURCE: dead pw 50 and sad boy.

Many things could cause the problem. Let me see if I can help out.
You have spark, but is it enough spark? A weak battery can rob power from the coil so only a weak spark is present. Get a new stock NGK spark plug to eliminate the possibility of a problem plug.

It is good that you cleaned the carb because that would be my second target. Reset the air and idle screws. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Clean or replace the air filter and be sure the bolts are tight on the carb manifold. INSTALL AN IN-LINE FUEL FILTER. Let the float bowl fill then start the engine. Set the idle speed with the idle screw.

Remove the cylinder head. run the piston down to the bottom of the cylinder. look inside the cylinder. On th carb side (intake) you will see an intake port > a large hole that lets gas into the cylinder. Now look at the exhaust port. It is possible the exhaust port is pretty plugged up with carbon. The intake and exhaust ports should be approximately the same size. Are they? If not then remove the muffler and take a screw driver and plastic hammer and knock the carbon into the cylinder, thus enlarging the exhaust port to its' proper size and allowing the exhaust gases to escape. Vacuum the carbon out of the cylinder. De-carbon the piston top and the cylinder head.

Get back to me and tell me what you find. If more is needed we will go further.

Posted on Apr 12, 2009

  • 136 Answers

SOURCE: yamaha dt 125r power valve

Your barrel? LOL. Sounds like the valves need to be gone through. I would suggest taking and valve train apart and put it back together correctly then go from there.

Posted on Aug 08, 2009

pugwash814
  • 377 Answers

SOURCE: Hi I have an oil leak @ the front of the engine.

is it The cover behind the front tire with the 2 allen screws holding it on ?, this is the cover for the lifter adjustment. i believe its chrome. Remove the cover and you'll see the valve spring and rocker arm. This is where you make the valve adjustment. The cover has a rubber type gasket around it. You can purchase them from your Yamaha dealer. Replace the rubber gasket and your problem is over. Once you remove the cover you will see. Good Luck!

Posted on Jan 23, 2010

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