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Ok
If the bike is (we will say cold) and you fire it up on choke, if you twist the throttle at ALL it kills the bike.
Hmm that says lean to me.
Does the sock trick work the same when it's cold or warm?
 

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Discussion Starter #23
Well, I won't harp on a motor if it's cold, so I only know the rag (sock) over the snorkel works while warm. I even rode it like that. Pretty fast. Hit 105mph in an stupid short section of road. Hate saying this but it had enough power that a hard shift into second felt like it slipped the clutch.

Message seen.
 

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Discussion Starter #24
Well, once again reassembled. Sock seems to help when cold. Throttle blips when choke is on and cold seem to kill it. Only improves with temperature it seems.

At this point carb sync has to happen and I think I'm going to try to check timing somehow. Any easy way to do that?

I think I just need to be SURE about everything.

It also backfired through the carb whilst abusing the throttle to check how it responds.
 

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Ok that makes some sense to it being lean. The cold is aggravating it. When it's warm does it fix it if you pull in some but not all of the choke?

Yes pull the reluctor cover and with a timing light connected to #1 trigger it and make sure it's hitting the F mark (3 punch marks) lign up with the index dot on the crankcase cover at 1100 rpm. then to make sure it's advancing bump it up to 1500 and it should move counterclockwise.
 

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Sorry to annoy you again but did you find the crankcase breather connection to the air box and is it ok? Dont know where or if it is on a carbie bird and the problem seems too big for that really. It seems to be getting masive amounts of extra air from someplace. Stalling out at 5k and spitting back through carbs looks like no airbox at all alomst. The sock trick also points at a major air leak.
 

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Discussion Starter #27
No annoyance. The bike is what is annoying. We all seem stumped. Beginning to think maybe it jumped a tooth. Advance or retard the intake and maybe that is the air leak, no?
 

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Discussion Starter #29
Unless just the intake cam jumped or something. Ignition timing will only speak for the crank. Have not worked on it at all today. Just thinking at this point. Ill probably pull the valve covers and inspect it all first.
 

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Years ago I had a 1980 cb900c (great bike btw) that had nearly the same symptoms and the problem was low amp/hrs out of the battery. Bike would start no problem over and over but ran like the timing was retarded. Just a thought.
 

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Discussion Starter #32
Interesting possibility, tomorrow it should be around 50 degrees. Ill play with it then, maybe put a jump box on it for some extra amperage and see if that resolves anything.
 

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Discussion Starter #33
Well its morning, tried the jump box trick, added way more amperage and nothing changed.
Played with a few more things like plugging vacuum lines to see what might make it worse or better and in this diagram:
129028


Number 29 (the banded together vents) if you plug one or another it amplifies the problem drastically. So I removed them, no change.
Then I tried 31 airbox breather thingy, nothing happens if it plugged, removed nothing. What is it? Is that bad?

My non cali bike does not have 39,40,41,42, 26 ect.

Oh and giving it mild choke (just barely raising idle like 1500rpm) simply moves the dead spot from like 4000 up to 6000 but revs way faster from 8000-redline. it also makes it burn your eyes rich. I think rich enough that it smokes (hazes) just a bit lol!

Given all this info, it seems like the carb diaphragms are not acting right.

I have a hard time justifying removing the valve cover to check timing (mechanical problem) when the problem is this variable (can be solved with a sock).
 

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You need to put the carb bowl vent back on. That vent needs to be there or your going start having flow issues. Where are the 4 taps going forward 39 40 41 and 42 attached.
I suspect you have altered the vent ports to the carb diaphrams some how. It tracks with the way they are acting. As mentioned before changing the air box flow or ports will drive them nuts.
 

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Discussion Starter #35
Are these usually glued like this?
129033

129034


And here is the old bike with evap:
129035


New bike no evap, no 4 taps at all.
129036
 

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I'm thinking no they shouldn't be glued. They should fit tight. You might be on to something there. I'd try laying a bit of grease over the seam as a temporary seal and see what happens to the response.

Ahh ok now I understand about the evap system. Cali's had the seal it the non cali vents back into the carb body.
 

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Discussion Starter #37
Grease or a finely placed bead of black rtv. Those never come apart anyways and it looks like the "glue" cracked.
 

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Have you synced the carbs recently? If the engine hangs up or the revs don't drop straight back, it's normally an indication that the carbs need synchronisation. Having said that, they don't normally suddenly go out of sync.

Sent from my LM-G810 using Tapatalk
 

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Maybe the previous owner was chasing the same gremlins, and this was his fix? Chunks of that old glue could eventually find their way into the engine. I'd remove it. As you say, careful RTV sealant if there are gaps.
 
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