my bike starts and idles and cruises properly but missfires under medium/high load

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apsolus

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How are your rubber diaphragms? Check for cracks, holes, etc.
yeah it acts just like a torn diaphram. i checked them when i did the peashooter carb clean and they were ok. im going to check the spark plug wires at the coils asap
 

apsolus

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So you are not trying to establish float height?



From the above there are several issues that need to be addressed.
  • Fuel - unless you have fresh fuel I'd be inclined to drain what you have and fill with fresh. Also have a butchers inside the tank and check for corrosion. Unless I've missed it you haven't confirmed when the fuel filter was last changed. You seen to be assuming that the carbs are synchronised but IMO you need to do that properly with the requisite tools.
  • The problem is isolated to one cylinder? If that is so then the fuel pump is not the issue and if the plug is black then that cylinder is over rich. Have you checked the float heights? Have you also checked that the offending cylinders slide moves up in concert with the others? Also check that the right jets are installed in the right position and that the need les are installed correctly.
  • As you have indicated you need to sort the leaking fuel which makes me wonder if the were re-assembled correctly.
  • Your spark tester will give an indication if the coil is an issue. If all four show a similar result then don't worry.
  • It is a wasted spark system.
the problem developed all on its own. i installed the jet kit years ago. im sure the carbs arent synced because the bike will idle a bit higher unless i pull the grip shut then it idles down. that tells me a few of the butterflys are cracked open more than they should. another none issue i have with the bike. im headed down to autozone to pick up some new plugs now. i hope thata all it needs i see on the forum coils like to go to shit. seems like a spark issue to me . oh and yes the fuel filter has been changed

here is the reply i posted up top. after purchasing the bike the carbs were clogged. so i took them apart and put them back together. i didnt replace any orings i just installed the dynojet kit. my goal back then (2 years ago) was to make sure i had a runner. seems the leak may be coming from the float bowl drain screws. i think im going to check the spakr plug wires first. i want to check for corrosion. once im done putting my race bike together ill get back to the old girl. i named it blunt force trauma
 

apsolus

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they arent. i know that for a fact. when warmed up the idle will creep up a few rpm. if i close the throttle manually the idle drops back down. if i end up going into the carbs im gonna do em right this time for sure
 

apsolus

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ok ive cleaned the plug wires at the coils and they were indeed green. figured that might fix it. took it out for a spin and its just as bad as it was. ill have to pull the carbs and to a good rebuild next. oh well
 

Fire-medic

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Did you trim-back the green primary tension wires to shiny metal?
 

apsolus

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took me a long time but i finally opened up the carbs. first one i opened i found one of the two rubber plugs that go into the jet holder block had fallen out. it was just chillin at the bottom of the bowl. so after looking at things it makes sense. with that plug gone the main jet is being bypassed and it was dumping fuel when i opened up the throttle but fine when i wasnt using the main circuit. Wow! now ill take this chance to bench sync the carbs and replace the bowl drain plug screw orings cause they are hard and causing that small leak.
 

Fire-medic

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A surprise to find the rubber plug floating freely, eh?

As long as it's torn-down this far, remove the jet blocks and the brass jets, get the bodies ultrasonically-soaked, make sure the pilot jets (all brass jets) are clear, along with your passageways, use new jet block gaskets, carefully reassemble things, paying attention to the float levels, and upon reassembly, synch the carbs properly. The bourdon tube gauges to do this are inexpensive and will pay for themselves with one use. Ensure the gas tank is shiny-clean on the sides and bottom, if not, that needs to be cleaned, and there needs to be shiny metal going back into service. Of course, an alternative: you can coat it, but you have to follow the directions. Use the search function for gas tank cleaning & coating, if desired, ideas.
 

maleko89

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A surprise to find the rubber plug floating freely, eh?

As long as it's torn-down this far, remove the jet blocks and the brass jets, get the bodies ultrasonically-soaked, make sure the pilot jets (all brass jets) are clear, along with your passageways, use new jet block gaskets, carefully reassemble things, paying attention to the float levels, and upon reassembly, synch the carbs properly. The bourdon tube gauges to do this are inexpensive and will pay for themselves with one use. Ensure the gas tank is shiny-clean on the sides and bottom, if not, that needs to be cleaned, and there needs to be shiny metal going back into service. Of course, an alternative: you can coat it, but you have to follow the directions. Use the search function for gas tank cleaning & coating, if desired, ideas.
All this....plus make sure each of those rubber caps are in the correct hole in jet block. Small pilot plug at far left and bigger in center emulsion tube opening. Far right has nothing as it's blocked off. Worked on a couple of sets that had 'em in the wrong places.

Mark
 

apsolus

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yeah im just slapping it back together. im using some loctite 660 i had from another job to hold the plugs in place. i looked it up, seems the stuff will hold up in fuel. i did do a complete carb clean and replaced the drain plug orings. i bench synced the carbs using the ol paper clip method. works for me! ill let the 660 set over night. ill let yall know how it goes!
 

02GF74

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yeah im just slapping it back together. im using some loctite 660 i had from another job to hold the plugs in place. i looked it up, seems the stuff will hold up in fuel.
No.

How is it possible for the plugs to come out when the jet block is fitted?

The plugs butt up against the carb body and have to be fully pushed in else it's not possible to fit the key block.
Screenshot_20210911-051211-1.jpg
 

apsolus

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mine is different. weird. i was wondering why they didnt make the plug longer so it would rest against the carb body. interesting. the two plugs are different sizes so you cant swap them over. based on the picture you provided the hole on the right has the longer plug thats got the flat spot, like the one in the middle in your pic. also the plug on the right in the photo has to be pushed in flush or it wont plug anything. they look stock but maybe someone over the years installed the wrong part. well in any case this is good info . ill take the carbs apart again tomorrow and fix this one way or another. maybe ill shove something in there to take up the space
 

02GF74

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below is best picture i've found to date showing the parts exploded - if your bungs are not like those, then someone on the past has bodged the job.

The bungs come as part of the $14 cheap chinese kits, the brassware in those are suspect but i don't see why the bungs would be bad (famous last words). I'd recommend you fit the correct part and be done with it, getting the carbs off is a right pain in the a%%%e.

1631344452870.png
 

Fire-medic

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Be careful if you use a long pry bar or something similar to remove the carburetors! The wrong purchase point on the carb body, and that will crack like a hard-boiled egg!

You don't need, nor do I believe you should use, any sealant on those rubber plugs.
 

apsolus

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yep, the plugs on my carbs are different. im going to use a piece of rubber hose to hold them up. i know i should do it right but, yah know, whatever..if i cant figure out a way to make what i have work ill order stuff. and yes i know what you mean as far as prying. i only use my hands to pull them up. over the years ive had to be careful with aluminum. that stuff is easy to crack
 

apsolus

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its alive and runs just so so sweet. this bike fly's!
 

Fire-medic

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Glad you've sorted things. The collective knowledge helps another member to enjoy a charismatic motorcycle. They are a lot of fun, and especially if you do some handling mods, like radial tires, front end work like better springs, cartridge emulators/RICOR's, four piston brake calipers and HH pads in the front, or Sean's Suzuki six-piston Suzuki caliper & adaptor, and better-quality rear shocks. A lot of guys like the frame braces and the braced swingarms too. That's all $$$ but you should see how it works for you now, and prioritize. A pair of HH brake pads for each front caliper is probably the easiest to-start, since you already have the four piston front calipers.
 

apsolus

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Glad you've sorted things. The collective knowledge helps another member to enjoy a charismatic motorcycle. They are a lot of fun, and especially if you do some handling mods, like radial tires, front end work like better springs, cartridge emulators/RICOR's, four piston brake calipers and HH pads in the front, or Sean's Suzuki six-piston Suzuki caliper & adaptor, and better-quality rear shocks. A lot of guys like the frame braces and the braced swingarms too. That's all $$$ but you should see how it works for you now, and prioritize. A pair of HH brake pads for each front caliper is probably the easiest to-start, since you already have the four piston front calipers.
i was finally able to join a group ride after a month or two. yes, the first thing i want to do for the bike is suspension improvements. the rear shocks feel awful. going down the road the rear end of the bike is jarring to the point my eyes blur. the front sucks too but it seems that its not causing the harsh ride like the rear shocks are. And ive had the bike on the track as you can see on the profile pic. the brakes feel like wood but when they get good and hot they do well. why do radial tires make it handle better?
 
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