Carb synchronizon

[MaximX]

  My bike was starting to idle poorly and just did not sound right when cold, etc.  So did a bit of looking on line on how to sync the carbs. I never did this before, but I had this bottle of mercury a friend gave me about 25 years ago, so I went to PA and got 20' of 1/4" clear tubing and cut it into 4 pieces.  I taped them together at the end that goes into the bottle of mercury, then up the board in the sequence of #1-#4 cylinders.  I was able to keep the tank connected to the carbs and set to Prime to feed the motor fuel.  I was surprized that the mercury did not go up very far at idle, but blipping the throttle made it rise quite a bit, about 1/2 way up the board.  I wish I'd taken a shot of how far they were off at first, but did not....anyway it was then not so hard to tweak 1&2 then 3&4 and finally the center screw to align those pairs of cylinders to each other. 
What a difference this made.  Idles much smoother, sounds much better all around.  Lots of you probably have done this before, just thought you may be interested in how I did mine.

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[Dennis]

Wow.   That is pretty resourceful.  I currently have Russel's in my shop.  It s a motion Pro model with screw in tubes for the carbs.  I had never balanced carbs before.  I did this the first time with Russell and Guy's assistance on the BMW.  It made a huge improvement. 

I just received new float valves for my GS650, so once I balance the float levels, I want to balance the carb vacuum pressures.

Peace & Grease, Dennis

[MaximX]

Even though synchronizing the valves did make the bike run better it still did not seem right at lower rpms.  So today I figured it was time for a compression check.  I had rebuilt the top end 2 seasons ago and had compression figures of 150psi, where  it should be.
I figured something was not well and the psi for cyl 1-4 are this:  150, 75, 10, 125 or so (after the 3rd cylinder number I was not paying as much attention to the last reading).  The amazing thing is how hard these motors still pull with those numbers.  I did not buy what is now Jer's new Fazer because two of it's cylinders were at 50 psi and I figured I did not need another bike.  Now I am wishing I had done a deal on that Fazer....somebody here has said it well in that you ought to have a backup bike....I had some nice hot day rides on my bike but now am thinking I should not ride it much more before doing another rebuild.  This time I am thinking I should get a proper valve job done instead of lapping the valves as my engine builder friend suggested.  It did have the compression, just did not last for some reason.... except for that one cylinder.      At least it got me through the summer...the last time it died was at the start of the season..that was bad going without a bike for most of that summer.

[fast1]

  I suspect tight intake valves on both your bikes. While the 5 valve Genesis engine makes power out the ying-yang it is very labor intensive to set the valves. All 20 clearances need to be measured, cams removed, shims changed then re-time cams, measure and pray you got them right. A warm compression check would reveal much different numbers. CHEERS.

[fast1]

  Now that I have time I should elaborate. Generally speaking an internal combustion engine  as it wears Will burn up the intake valves due to relatively dry fuel going by and of course the hot dry explosion on the power stroke, remember the explosion happens 2 to 6 degrees before the intake valve closes causing the intake  valve to "burn" up in to the valve seat, decreasing the valve clearance to the point where the valve is held slightly open when cold, causing said loss in compression. On the other hand, the exhaust valves are releasing cooler,dirty gases, small particles of which attach themselves to the valve face building up to increase the valve clearance. As the cold gap of the intake valve increases so does the cold start time. Once you warm it up clearances increase as does the compression and power. Have a hard time believing with your riding style and mileage you wore out a top end in two years. Jeremy's bike looks to be around the age where this happens 25 to 30 thou?. Your valves are of the shim and bucket variety, unfortunately the shims are under the bucket-- warned this job is flat rated at around 7 hours, which is what the dealer will quote you but they actually charge what it takes and it is almost impossible to do it that fast. It is expensive to have done so everybody waits too long. Once you have a valve with zero clearance it's hard to guess how far down to go causing a potential do over. Unfortunately I don't have time to help either of you with this dilemma. My best advice would be to try K&K motors on Nicholson. CHEERS.

[MaximX]

I appreciate your input Fast1.  I should have explained a bit more than I did.  I did the tear down and re-assembly myself the first time round.  I took my time and did it as best I could, getting the valves within tolerences was hard, I had those cams off and on several times working at that.  CARS speed shop verified that each cylinder was sealing as it should after I lapped the valves, so I figured if they thought it was good to go it was.  I will check the valve lash on all the valves soon I guess, but I have resigned myself to the probable fact that I need to tear it all apart again.  10 psi on one cyl. is like deadsville.  I did get the valves adjusted at the recommended 42,000km by Yamaha many years ago, it was about $200. then.  My motor let go because rubber grommets shrunk and allowed grit into the motor without my knowing for years....  The thing with Jer's bike is that it was put together from 2 bikes.  That motor may have 25,000km on it or it may not, can't be sure that is accurate.  The first thing to do with his bike is to check the lash on all valves to see if they are in specks. .11-.20 intake and .21-.30 exhaust.  Bottom line is that one cylinder on mine is at 150 where it should be cold, that is where they all were just after I got it running again...the rest are now a mess, something is really wrong there and it is not running as it should hot....soooooo it looks like tear down time this winter.

[thejij]

I'm going to do a compression test tomorrow sometime, I rode it today and yes was still impressed with the power. Actually everyone who has ridden it has been impressed. I'll post the results here when I get it tested. I have to work in the morn for a bit but after that I'll do it.

[fast1]

  Always do a compression test with the throttle wide open. this will give you the most accurate numbers. A wet/dry compression test will tell you if it is rings or  valves. First do a dry test. Record the numbers. Then spray a liberal amount of WD 40 down each cylinder. If it goes up it's rings. If it stays the same then valves are the issue. Cheers.