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Discussion in 'Honda 250cc In-line 4's' started by markcm02, Oct 9, 2021.
oh I see, I thought they were mismatched, my bad.
Set them to 2 and 1/8 turns
do you have any threebond or carb cleaner. ?
I’ll try new plugs before pulling carbs out, I do have carb cleaner
I have tested caps 1 and 4 are ready 24.2Kohms but I cannot for the life get a reading out of 3/4
when I clean mc22 carbs, first job is to lift each slide half way up, you should hear a whoosh and when you release it it should drop back down, if it doesn't "swoosh", then the diaphragm is not seated properly so you have to pull your top cap off and make sure it is sealed.
Next job is pull the bowls off and remove the slow jet #2 ( flat blade) , main jet #3 ( flat blade) and main jet holder / emulsion tube under #3 (7mm ) and the air fuel mix screws #1.
Check each slow jet and make sure you can see a pin ***** of light through it, if there is no pin ***** of light, it wont start.
Next step is to check you have complete air fuel mix screw setups, you should be ato assemble the screw, then spring, then metal washer then rubber washer for all 4 carbs, do not refit them yet
If you have threebond \ carb cleaner, pop some safety glasses on then spray it down the air fuel mix hole, you should see it come out the hole where the pilot screw usually resides. Cover the hole for the pilot jet with a finger and spray again down the air fuel mix screw hole and you should see it come out of the front of the carb from these holes marked in the red circle, this makes sure the pilot circuit is clean.
inspect the jet holder \ emsulsion tube while it is apart, you will see heaps of small holes, make sure all are clear
have a look at tis video so you can see how the CV process works , at 55 secs, you see the pilot jet circuit working, which is what you would have just cleaned
Okay, so that it will make it hard to start , the caps screw onto the leads and possible the leads has been pulled away from the caps, try turning the caps on the leads to tighten them and retest , if you cant get them to a point where you get a reading , unthread the cap and snip about 2 mm of lead away then rethread the cap back on ( this exposes fresh wire in the coil lead for the screw in the cap to thread into)
Lets us know how you get on
I had followed a guide on cleaning carbs and it matched what you had said completely I have inspected each and every jet, but I have not inspected the pilot screw to make sure it has the springs washer and rubber seal etc.
So this just happened, think this might be my issue.
The plug is also full of corrosion on the lead side
Same thing just happened to plug 2
it looks like the leads were just stuffed over the screws on the inside, is there a way to fix this?
Pretty standard problem with the old bikes
pilot screw ....
Pilot screws look like the above
Plugs for reference
Hi. Does the manual suggest the 2.5 turns out on the mixture? Sounds like a lot. If that is a fuel mixture screw you could be flooding straight away. What about possibly sucking air around the vacuum line to the fuel tap which would then make it too lean but only on the cylinder the vacuum line is connected?? I know pretty well nothing about the MC22 but am assuming it has 4 carbies and you have adjusted all four mixture screws to 2.5 turns out? I have never come across a bike that runs in that setting. I usually get the best idle result at around 1.5 turns or less, even on each BMW, Bing carby. Single-cylinder engines may require a richer mixture but multiple cylinders should be ok with a lesser number of turns on the mixture I would think.
yeah that’s what they were set to, currently have them set to 2-1/8 as described above, yet to try that out. I guess I could also try 1.5?
Does this new plug not having a shank mean it’s incompatible with the block
Have you sorted the coil issue ?
Vp20b should be set at 2 and 1/8 turns
coil issue was sorted. I had put the pilot screws at 2-1/8 with no start, turns out mate had flipped the kill switch on me whilst I was on the other side of the bike looking for sparks, however even with kill switch off and sparks from the coils again still didn’t start. i was going to try and crank it with carby cleaner however the battery died on me, so tomorrow morning I’ll be borrowing a battery charger. compression tester was delivered however battery was flat at that point. Will also try checking if the pilot jet hole is clear as per one of your previous comments
Carbs off for the comp test, remove all 4 plugs then test each pot and let us know the readings
Have you cleared the choke circut?
It is the long brass tube next to the main jet and the passage runs up through the body to the plastic nut with brass rod on the side of the carb body. Without this clear you will not get the rich mixture necessary for starting a cold engine. Take out the choke plunger on side of body and spray three bond through the brass tube next to the main jet. I have seen these so badly blocked that a drill bit was necessary to clear the dried up gunge from fuel being left in the bowls.
I will try this too, cheers.