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Ok, I've got some new boots and gaskets for the carb intakes (thanks Sonrier) & it's all yamabonded up. I have no air leaks....
I can get the bike to start, idle and even run the thing down the street.
Every once in awhile, seemingly for no reason the bike freaks the fuck out and revs out of control, to the point I have to use the kill switch so I don't throw a rod or something. Crazy shit.
Do I have bad carbs, or maybe something sticking in the carbs? I'm at my wits end try to carb this bike.
Also.. are you 100% sure there's no air leaks? Air leak is a symptom of what you're describing.
Next, double-check the health of your advancer. If it's getting stuck in the advanced position, this will cause the bike to rev high, too.
Are your throttle cable(s) moving freely with no kinks or tight bends?
Finally, double-check those gaskets I sent along. I wasn't 100% comfortable with them as I think the inside diameters (as they were designed for the CB360, not the CB350) didn't perfectly match up between the manifold and the head. If the gaskets are too big in diameter, fuel can pool in between the manifold and the head and get sucked into the cylinder at strange times.
Carbs showed up pretty spiffy clean. I don't know how to set the float heights or if there's even a setting there for that.
I'm 99.9 on the air leaks, but I'll spray some carb cleaner around them this weekend at some point.
I've got a pamco ignition now, so my advancer is out of the picture, is that correct?
The gaskets weren't in the way, but I'll pull them off this weekend as well to double check. It absolutely feels like this is what's happening... a big blast of fuel being sucked into the cylinder.
Also, I should mention I have no idea where my air mixture screw should be set at. I think they are in all the way right now on both carbs.
Double check the manual for the initial air mixture screws, but to set them you basically turn then 1/2 a turn at a time (one side at a time) and wait five seconds. If the revs go up, do another half turn. Continue doing that until revs go down when you turn them and then back them off another 1/2 turn. You may need to turn down the idle during this process if revs get too high.
The Pamco ignition still makes use of the mechanical advancer, so it will be something that could do with being checked out.
The process for checking float heights is in the manual as well, but we can go into that once you rule everything else out.
You know now that I think of it. It was doing this before your gaskets. I think it's something with (or in) the carbs. What else would cause fuel to "dump" in like that ?
I got this once after getting my 72 cl350 running but it only happened once and when it did it was when I had the choke set to warm the bike up.... then i took the choke off and opened up the air intake on the carbs and the damn bike revd so high without my hand on the throttle..... I just shut the bike off and turned my air mixture screws all the way in and put the idle speed screw at their minimum before the screw doesnt touch the carb anymore.... also check to see if your carb throttles are syncd to open at the same time just some random rambling... dont know what I did that worked but its not happening anymore...
as far as carb float height goes its pretty easy just time consuming... I pull the carbs off to do it and what you do is you look at your floats at the point where the push against the jet needle... at the point of minimal contact between your float tab and the jet needle measure the distance from the top of the carb to the flat gasket surface of the carb body ....not sure what year cb 350 you have but its usually between .75 inches and up check your manual or if you have a 72 I can get you the right specs from my manual.... hope this helps and is easy to understand how to set carb float heights if they are set with too much space then you dont get enough fuel in the bowl if to little space then you get too much fuel and the the excess fuel will drip out your over flow tube.... .good luck
Try removing each boot and switching it. I'm not a 350 expert, but it could be that they're designed for a left or a right side? You could also try clocking them 180° as there could be a top or bottom.
Either way, it should be as smooth as possible for that transition and sanding it down is definitely an option. I know folks who even sand their gaskets to fit. A rough intake is just robbing power, even if it isn't causing you other problems.
It's not just too much fuel or too much air, its a combination of the two. The throttle is what should be controlling the amount of air going into the engine, and so running stacks, pods, or even no intake should make little difference.
Go through the carbs again and make sure the slides aren't sticking and that everything moves freely. Double-check to make sure all of the jets are in the correct place and nothing is dirty or gummed up.
I'd still recommend cleaning up that transition though... manifold to head should be as smooth as possible.
Yes, still trying to do that first too. I'm trying to hook up with Teazer here on this forum, he's a carb whiz.
I'm not adverse to picking up another set. The mikuni's hold their value very, very well.
But yes, I'd like to send these out to eliminate the possibility. Thanks for the reminder, I'm going to make a post to see if there's anyone else who's really familiar with these carbs and possibly has a DYNO.
Cafe-Zuki said:
Agreed, unsafe
However,
Have you considered taking the carbs to a good shop, fix may be WAYY cheaper than replacements.
Just a thought,
Good luck
don't quote me on this but i had the same problem on my 350 w/ CV carbs. when it warmed up and i came to a stop, the idle would start to rev higher and higher. i had improper adjustment where the cables where they attach to the carb, it was out of balance a bit. by adjusting cable seat up and down, i could both fix the problem and reproduce it by adjust one further out than the other. i found this by retracting the idle screw on one side and then depressing that until the engine slowed.
i'm not sure of the mechanics behind the high rev. could have been that side cable adjuster creating more air/fuel to that cylinder or it could have been a high idle on one side creating a vaccuum on the other which inturn increased the engine speed from the CV....either way it wasn't inside the carb that was the problem, just a rather pain in the arse adjustment of those cable seats between the carb under the tank.
i have no idea if this is what is making your bike do this, but before you rip everything apart again or alter any internal settings etc, just futz with those adjusters first and see what hapens
oops, i just read mikuni's, if that's what you're using and i missed that along the way, please disregard everything i said because it probably doesn't even apply! ; )
greg
thank greg, they are stockers -- I was going to pick up mikunis if I cant fix the issue. I'll give your suggestion a go, sounds like it might be a possibility.
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