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  1. #21

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    Well, the carbs I have look exactly like the ones in your photos. Which, after some digging, look like vm32? I mean even the filters look like the ones in your photo. So maybe the dude was wrong? Same story every time with how it walks down on the speed. No backfiring or sputtering as she slows. If I pull the clutch it's coming down, the engine will review all the way up as if nothing is wrong, it just doesn't do anything with the clutch out. Alwaysto kick it down to 3rd and 4th to regain speed. I've tried the choke on once, and didn't seem to affect anything, but I'll give that another go.Click image for larger version. 

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  2. #22
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    To help determine if they are 34 or 32s:
    Mikuni Carburetor dimension chart
    Click image for larger version. 

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    https://procycle.us/carb/mikuni_dimensions.htm

  3. #23
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    Does the sound of the engine change when it slows down in top gear - like breaking up or running rough?
    Did you ever look under the cover on the right side of your engine - two screws and should be looking at your ignition system - is it stock points? How does the advance mechanism look? Can you turn it manually to advance it? Start it without that cover on to see what the points (if that's what's in there) are doing. Got a timing light? What about your coils? Have you tested them? Do you have a testing tool like a multi-meter?

  4. #24
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    Quote Originally Posted by Tattooo View Post
    Yes sir, and those inline filters are notorious for causing your kind of problem.....
    Yes they are, because many of them have TINY inlets and outlets, which restrict flow in what is already a pretty small fuel line. When you consider a filter, look at those hose barbs.

  5. #25

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    Quote Originally Posted by TriNortchopz View Post
    Does the sound of the engine change when it slows down in top gear - like breaking up or running rough?
    Did you ever look under the cover on the right side of your engine - two screws and should be looking at your ignition system - is it stock points? How does the advance mechanism look? Can you turn it manually to advance it? Start it without that cover on to see what the points (if that's what's in there) are doing. Got a timing light? What about your coils? Have you tested them? Do you have a testing tool like a multi-meter?
    Doesn't run rough or sputtering, just seems slow. Tried throwing on the choke, that didn't seem to have much if any affect. I do have a timing light, and plan on popping the cover off it this Saturday when I'm home from work. Found see other issues too, like oil on top of my oil tank yet, it only has 3qts of oil. Pretty much just about over this bike.

  6. #26
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    Quote Originally Posted by 72Savior View Post
    Doesn't run rough or sputtering, just seems slow. Tried throwing on the choke, that didn't seem to have much if any affect. I do have a timing light, and plan on popping the cover off it this Saturday when I'm home from work. Found see other issues too, like oil on top of my oil tank yet, it only has 3qts of oil. Pretty much just about over this bike.
    I think you have not done enough investigative troubleshooting to determine the cause.

    You questioned if the exhaust valve clearance is 0.003" - it is cause I looked it up - but tell us if you checked all valves and what you found at each intake and exhaust, then what you adjusted them to.

    Here is a great link for setting valve clearances:
    Valve Adjustment Made Easy: The E.O.I.C. Method
    The E.O.I.C method for valve tappet clearance can be used on almost any single cam engine. E.O.I.C. stands for Exhaust Opening, Intake Closing. Setting the cam in a position where the valve is closed and the rocker is completely loose is one of the critical steps in setting your valves properly...
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    http://draftcycleworks.blogspot.com/...ic-method.html

    Then check your timing and points - again, if you got points...

    Static and strobe timing an old houndog CB750
    http://www.hondachopper.com/garage/c...obe_Timing.pdf

    Then confirm the floats in the carbs are set properly:

    http://www.mikuni.com/pdf/vmmanual.pdf

    read size of main jets while you're in there to confirm they are the same, and let us know the size.
    Do some initial setting of the carbs and record the info so you know where you are starting.

    now you should be ready to do your plug chop - just hold it WOT in 5th for while, while it is runnin' like shit:

    WTF is a Plug Chop????
    http://www.hondachopper.com/garage/c...lug_chops.html

    This will help to do this:

    Basic Carb Setup and Tuning (it's NOT Rocket Science) by Houndog750
    http://www.hondachopper.com/garage/c...carb_tips.html
    Last edited by TriNortchopz; 09-07-2018 at 7:56 AM. Reason: spacing, punctuation

  7. #27
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    Yep,^^^^^ And it's a pain in the ASS to do it right and most people get part of the way through it and say fuck it , it will be ok...

  8. #28

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    I'll check the valves cleaances again. I set the intake to .002 and exhaust to .003. Carb main was 240. I adjusted the floats, but I'll triple check them. Timing definitely needs to be looked at. I'm also going to take the fuel filter off and see if that helps at all. I didn't notice some air in the line yesterday and it looked to me like not enough fuel was getting to the carbs at all times. Looked like a little just above the inlet but not filled lines at all times.

  9. #29

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    Quote Originally Posted by Tattooo View Post
    Yep,^^^^^ And it's a pain in the ASS to do it right and most people get part of the way through it and say fuck it , it will be ok...
    Definitely not afraid to do it right. Just getting pissed with this MFer. This new oil thing has me pissed as well.

  10. #30
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    Quote Originally Posted by 72Savior View Post
    Definitely not afraid to do it right. Just getting pissed with this MFer. This new oil thing has me pissed as well.
    If your getting pissed at it it's time to walk away from it for a few days.....

    I can't say I've ever seen anyone fix anything that they were pissed at it....

  11. #31

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    Quote Originally Posted by Tattooo View Post
    If your getting pissed at it it's time to walk away from it for a few days.....

    I can't say I've ever seen anyone fix anything that they were pissed at it....
    You know what? That's a valid point. I've gotten loads of information from you fine folks, I'll let that all simmer for a few days, then get back after it.

  12. #32

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    Quote Originally Posted by 72Savior View Post
    Same story every time with how it walks down on the speed. No backfiring or sputtering as she slows. If I pull the clutch it's coming down, the engine will rev all the way up as if nothing is wrong, it just doesn't do anything with the clutch out. Alwaysto kick it down to 3rd and 4th to regain speed. I've tried the choke on once, and didn't seem to affect anything, but I'll give that another go.
    Earlier post :
    "I cannot get the bike to stay above 50mph, even at WOT...I can run it up to 60-70 in 3rd and 4th, but as soon as I hit 5th, she starts to slow."
    and
    "So, I ran it up to 70 in 3rd on the way home. 4th will slightly lower the speed, and 5th brings it all the way back down to 50ish."
    and
    "I guess what really confused me is that I can run it up to 70-80 but when in 5th it walks down."
    and
    "my first bike so this is very frustrating."

    My guess.. Gearbox tightening up in fifth..

  13. #33

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    Quote Originally Posted by Hawkstone View Post

    My guess.. Gearbox tightening up in fifth..
    So, how do I go about checking that out and fixing it?

  14. #34
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    Quote Originally Posted by 72Savior View Post
    So, how do I go about checking that out and fixing it?
    That's a very good question..... I know the answer but you don't want to hear it..... He know's I'm sure...

  15. #35

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    Quote Originally Posted by Tattooo View Post
    That's a very good question..... I know the answer but you don't want to hear it..... He know's I'm sure...
    At this point, I do. No matter what the answer is.

  16. #36
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    Quote Originally Posted by 72Savior View Post
    At this point, I do. No matter what the answer is.
    Lets eliminate the easy stuff first....

  17. #37

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    Quote Originally Posted by Tattooo View Post
    Lets eliminate the easy stuff first....
    Probably a good idea. I did set the points today, set the timing by ear, but I'm going to use the light on it tomorrow. I have to pull the tank so I'll recheck my valve tappets then. Didn't see any air in the fuel line today, so that's a good thing. Still had the same issue, so we'll see about the timing, valve train, cam tensioner and jets tomorrow.

  18. #38
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    set the timing by ear, but I'm going to use the light on it tomorrow.
    You can set the timing statically using the F mark - no need to set it by ear. The double lines are for full advance which you can check with your timing light.

    During my several hours of research for this issue, I read about a KZ650 had a similar problem; it turned out to be a sticky advancer mechanism - during the lower gears, the RPMs rise rapidly and it threw the advance weights out, but when in 4th shifting to 5th, the RPM would drop down and the advancer would get pulled back into the retarded position by the springs, stick, and the slower roll on in 5th would not be fast enough to throw the weights out, resulting in the timing not advancing and poor running. He pulled the advancer apart, lubed it and rode fast in 5th...just one more thing to think about and look at while your in that ignition side cover.

    and when you are checking the timing with your light, full advance should be at about 2,500 RPM - you got a tach?

    Watch for arcing across the points which can indicate faulty condensors - an easy thing to change.

    In another thread, a SOHC 750 Honda had poor high speed operation, mainly in top gear - it turned out to be a low float level in just one of the four original carbs. He reset it and went full out in 5th...

    Install new spark plugs before you go out to do your plug chop test, and bring gloves - them plugs will be hot.

    It's tough when not knowing what's inside that engine...but with methodical plan and patience, and the knowledge to understand what each component does, and the effect of each change you make, you'll get it - my brit bike boss used to say; "man made it run, man will make it run again", and
    "just because that's the way it is, don't mean it's right.".
    Last edited by TriNortchopz; 09-08-2018 at 12:01 AM. Reason: spacing

  19. #39

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    Quote Originally Posted by TriNortchopz View Post
    As noted, it could be lack of fuel; by the time you get it to 5th, there is not enough fuel left in the carbs to allow full throttle operation...Maybe only one carb is not getting enough fuel...
    but we can't be sure, because we are not getting all the details.
    This. This seems to be the culprit. After setting points, timing, and valves I've been riding her around. I've been paying very close attention to the fuel in my lines. Looks like the right carb feed has barely any fuel in it at higher speed. Some air in the line on the left as well, but generally full of fuel. So, I guess now it's time to change up my lines and make sure they are both feeding properly .

  20. #40
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    What did the manual say the exhaust clearance was? .003 or .004 very important. You must get this right before ANY carb tuning.

    Turn the crank to 1-4 mark See if one or 4 rocker arms are both moveable,loose
    Adjust those on that cylinder.

    Turn the crank one rotation do the other cylinder.
    Same for 2 and 3.

    Basically when a cylinder has both cam lobes facing downwards on 45 angles ,THAT cylinder is on the compression stroke and you can adjust its valves.

    IF you have small LED flash light you can peek through the valve cap and see the cam lobes.

    I double checked....Intake .002 and Exhaust is .003
    Last edited by Luky; 09-13-2018 at 9:45 PM.

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