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Motorcycle Repair/motor wont start


QUESTION: Hi Joe: Now that you helped me out with my carb problem, with my
1984 1000cc Yamaha virago with only 23,000 miles on it .I would  like to ask your advice regarding this same bike.  I have what seem to be a deep tone knocking only when I accelerate under load .But not when I rev. it up standing still. It actually sounds more like a noise a 2 stage  air compressor would make?
 I would hate to tear the motor down before knowing for sure exactly if its a rod noise or just a characteristic of this motor
can you help me figure this out. I ruled out any exhaust leak. I would also like you to email  me your address so I can send you a little token of my appreciation for you taking the time to answer my inquiry. . Happy Easter to you and yours...  Bob Evonits.Sr.

ANSWER: Bob. Man I wish I could pin it down for you but it could be several things.
A worn chain glide, chain tensioner. rod bearing.
I think it would take a tear down to discover what is making the noise.
I am building a 1983 XV750MK Midnight Virago. I installed rings and cams and lots of other parts.
We removed the engine 3 times, and it not to bad the third time.
Email me at and I will send you a Yamaha Parts Manual.
A chain tensioner adjustment sometimes Eliminated noise issues.
A Clymer Virago Manual gives info on tensioner adjustments.
I would start there first.
William (JOE) Stack
511 E San Ysidro Blvd. # 1544
San Ysidro, CA 92173
Lets keep in touch via Email. I will help you all I can.

---------- FOLLOW-UP ----------

QUESTION: Hi Joe.  Boy O Boy  As soon as I get one thing fixed another problem occurs. I finally got this 1984 Yamaha virago 1000cc running like a champ. and  it quit  down by adjusting the tensioner .And figured my troubles where over.  When  I went to start the bike this morning it  just about  started, and when started it would just about run. I pulled the plugs and they looked fine. First thing I did was check the fuel
and the fuel was fine.  I then changed the fuel filter which was quite dirty, and before putting every thing back together I ran a check on the electric fuel pump .I disconnected the reserve tank and ran a hose to a separate fuel supply, I then turned on the key and the fuel pump has full flow for 5 sec. then stops. I repeated this process several times with the exact same results. I do not have the large gas tank on the bike doing these tests and the low fuel supply sender wire on the bottom  is not plugged into the harness . I don't think this would make the fuel pump shut off constantly after 5 sec. Maybe the carbs got some dirt in the starting circuit The bikes acting like it did in the very beginning when the rear carb was running to rich and fouled the rear  plug .but no fouled plugs where evident and  the first thing I did was replaced both .It made no diff. I hope you have some ideas? Im about burned out with this bike.   Thanks Joe for any help you can give me.

First Off my Friend let me try to ease some of that Virago Tension.
I am resurrecting a 1983 XV750MK Midnight Virago. I went the whole 9yards on this one, I plan to keep it. I installed new rings, new cams, new clutch plates, new master cylinder kit and rebuilt the front brake caliper. And removed both side covers and custom painted both covers and the tank. The first time I started it. It smoked like Crazy. Way to much smoke, oil I guessed. So I pulled the engine a second time and checked the rear cylinders head and rings.
I put it back together and the front cylinder would not fire. So I pulled the carbs and rebuilt them. It started and ran but had a very hard time starting. So I purchased a new stator and pulse coil pickup and installed them. Now it starts better but still smokes a Bit above 3000 RPM's. So off comes the engine again and this time I am installing a different rear head, new rings and head gasket again.
To learn and know your machine it takes Patients and Perseverance.
I have to get away from this Project sometimes to regain my passion, so I know what you feeling. Think of it as a Hobby and a Project. If you stay committed you will finally succeed.
I would install the Tank and hook up all wires, The CDI box may be effected if any wires are undone. If there is no change, the screens on the bottom of the needle valve seats may have gotten clogged. you would need to remove the bowls and floats and needle valves. blow compressed air up into the needle valve seat, and with the fuel line removed any debris will be blown off the screen and out the fuel line inlet port. You can cover the port with a tissue to see what comes out of it when you apply air. Keep me informed. And take it slow and easy. 1 step, 1 test at a time to locate your problem.
contact me and I will help as much as I can. Stay focused, Stay committed....

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william joseph stack


I specialize in Virago carburetors. Internal parts sizes, Needle and jet sizes for each and every year and model. Hitachi and Mikuni. I also can give tech support and Tech Support for carburetor problems and issues. Carburetor tuning and syncronization. Carbburetor rejetting and dynojet installations for engine modifications. I know every needle and jet size for every Virago made. I have done over50 Virago carb Salesand Rebuilds in 2012. I have over 50 sets ofVirago carbs in stockright now. I Build, Ride and Breath Virago. I have both the 1983 Midnight Virago's. The XV750MK and the XV920MK. 1 of my 1981 XV750H is is Premier Cycles, Billy Joel's Bike Museum.... I am an Honest and Fair man. I am also a Finicky Perfectionist withmy carb work. Ihave all the obsolete hardto find carb parts. I have new diaphragms, new floats, I have the float level setting down to an art. I have fabricated transparent bowls for both version 1 and version 2 carburetors.


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