M88 or Mikuni

Carb choice

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murl
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Re: M88 or Mikuni

#16

Post by murl »

Jugpam11 i have the same issue with my stripped down servi . 30 tooth , 34mm mikuni , #6 aluminum heads.

I swapped d16 plugs for colder d14 plugs seemed to help with the popping out the carb and power loss at full throttle.
JUGPAM11
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Re: M88 or Mikuni

#17

Post by JUGPAM11 »

Good plug info. Going to town for a couple now to try. Thanks you, murl . Now I checked my notes and find I was wrong about the flow. Should be 2:24 min. for 1 qt. Just pulled plug from carb to check flow through. It is 1:23 for 1 pt. About the same. One more thing guys. Could flash rust come loose and plug the screen? And Thanks to Kitabel for your input. Did you ever hear of a defective vm34? I know that sounds crazy but I have no body around here that has any smarts about these things.
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Re: M88 or Mikuni

#18

Post by JUGPAM11 »

Wow thought had something going by going to d14 plugs but it was just wind in my favor. Took screen off the petcock with no difference. Not going to give up yet so hoping someone will come up with more ideas. Any more you guys got something to add bring it on. Thanks
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Re: M88 or Mikuni

#19

Post by JUGPAM11 »

Kitabel, you still with me? Going to try floats at 20.56mm. Do you see any problems there and can I go more if that helps? Got new points coming and about to do another bubble test at 12psi. Last time leak test was fine. Did everything else. Anyone else got any ideas please help.
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Re: M88 or Mikuni

#20

Post by kitabel »

If it starts easily (no prime kick, choke switch with throttle closed only) and doesn't overflow the float is probably close enough.
Be sure to put the float arm back the right way on the pins.
Can't think of anything else.
JUGPAM11
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Re: M88 or Mikuni

#21

Post by JUGPAM11 »

An old buddy stopped to talk. So I said after 2 miles my motor acts like it running out of gas and backfires though the carb. Told him everything I have done and he said maybe it is about to seize up. Told him I have checked the temp of cylinders and heads and do not seem hot after I looked at the chart that Cotten has. Any body out there have one act like that and seize? HELP!
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Re: M88 or Mikuni

#22

Post by RooDog »

JUGPAM11 wrote: Wed Jun 23, 2021 4:43 pm An old buddy stopped to talk. So I said after 2 miles my motor acts like it running out of gas and backfires though the carb. Told him everything I have done and he said maybe it is about to seize up. Told him I have checked the temp of cylinders and heads and do not seem hot after I looked at the chart that Cotten has. Any body out there have one act like that and seize? HELP!
Gas cap not venting?
JUGPAM11
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Re: M88 or Mikuni

#23

Post by JUGPAM11 »

caps ok. ran without caps . no change. thanks
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Re: M88 or Mikuni

#24

Post by George Greer »

Just got done reading some of the knowledge base for similar issues

Check out your coil and see if it is getting hot and breaking down.

If you have a spare coil, swap it out and see what happens

George
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Re: M88 or Mikuni

#25

Post by JUGPAM11 »

Thanks George. New coil, points, condenser, copper wires 2 years old. New d14 plugs also. Working with electric and carb and getting no where.
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Re: M88 or Mikuni

#26

Post by JUGPAM11 »

Wife says there are no stupid questions. So here goes one. Could to much oil cause a hydrostatic problem that will mimic running out of gas after a mile or two down the road? After the rebuild I had 12 psi at idle and 35 at a higher rpm. No way to know after that what pressure or flow is. Had gage on just to check at that time. Getting a little extra oil splatter on the pipes makes me wonder. Tried another carb and had the same problem. Also running a full flow gas valve now. Thanks for all your help getting this oldtimer on the road after all these years.
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Re: M88 or Mikuni

#27

Post by RooDog »

Just how much oil do you have in the tank. It should not be above the "full" mark when warmed up. Never add oil to a cold bike as thee could be some sumped in the bottom end, and additional oil will over fill the tank. It needs head space to breath.....
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Re: M88 or Mikuni

#28

Post by JUGPAM11 »

Roodog, running a shovelhead oil tank under the seat so do not see a problem there. thanks
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