CB 450 Gremlin

CCRider

CCRider

Coast to Coast
Well this sucks! After about 2200 miles of pretty trouble free riding, yesterday my bike decides to start acting up. I rode to work a couple of times last week with no problems then changed the oil over the weekend. Started out yesterday on a short check out ride and to fill up the tank for the trip to Troy's and she started loosing power at low rpm's.

Spent all day yesterday dicking with it and can't figure it out. Once it starts, it seems to run OK above 2-3k rpm but won't idle. Even with the idle cranked up to 2-3k it settles there for a moment then drops off and quits. After it quits like that it's hard to start back up but if I shut it off when its running OK at higher rpm's it starts back up easily. After it shuts off, I have to start it up with about half throttle, but after it starts it will barely run and I can twist the throttle back and forth about 45 degrees with little or no change, but if I lean the bike way over to the right side it starts runnung OK.

I've pulled the fuel lines and seem to be getting adaquate fuel flow, I've run it with the petcock in normal and reserve position, with and without air filters installed, gas cap open and closed and I've removed/disassembled/cleaned the carbs.

HELP! CC
 
Man, that's a tough one.....hope you figure it out.

Wouldn't be the valves, would it? Just a stab in the dark.....
 
it is a fuel problem for sure, but I am baffeled as to what it could be....the working fine when leaned over thing makes me think it is a fuel delivery prob...but you have checked the petcock and fuel lines....so.....I HAVE NO CLUE......wierd!
 
tWistedWheelz said:
it is a fuel problem for sure, but I am baffeled as to what it could be....the working fine when leaned over thing makes me think it is a fuel delivery prob...but you have checked the petcock and fuel lines....so.....I HAVE NO CLUE......wierd!
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I agree - gotta be fuel. When I tilt it over a couple things could be happening - either the higher fuel level on the right side is pushing more fuel through the line or the fuel level in the bowls is changing making the mixture richer or leaner. I'm stearing away from low fuel flow/starvation because it runs fine at higher rpm's when fuel demand is greater. When it's doing the half throttle barely running thing, I noticed a little black smoke in the exhaust, making me think - too rich and tilting the bike over leans things out - BUT WHY? - float levels don't change overnight for no reason (though I should have double checked when I had the carbs off and didn't) and I'm getting no fuel through the overflow lines so the bowl levels can't be too high. And yes, I've been all over the place with the idle air screws. VERY PUZZLING!

CC
 
djelliott said:
Did the little rubber bung over the pilot jet in one of your carbs fall out?
Click to expand...
Just checked the carb diagram in the shop manual and didn't see a rubber bung at the pilot jet. Do you mean the O-ring at the air screw? It's OK. Also noticed in the diagram that the fuel level would have to be very high for the overflow tube t come into play.

Thanks, CC
 
Bad floats?
black smoke is rich, maybe float level has moved ? (brass or 'plastic' floats?)
You say you filled up, 'modern' gas has so many additive maybe it's dissolved shut off valve tip?
Personally, I think its a government ploy to get rid of old vehicles, you need special materials to cope with modern fuels
 
crazypj said:
Bad floats?
black smoke is rich, maybe float level has moved ? (brass or 'plastic' floats?)
You say you filled up, 'modern' gas has so many additive maybe it's dissolved shut off valve tip?
Personally, I think its a government ploy to get rid of old vehicles, you need special materials to cope with modern fuels
Click to expand...
Floats are brass and good as far as I can tell. Just adjusted floats on both sides (both a little rich) - no fix. Shut off valves are working properly. Didn't fill up yet - was on the way to do so when problems started.

Thanks, CC
 
oil pickup is on the right side... did you reinstall o ring in oil filter? sounds like fuel issue indeed, but could be lack of oil pressure causing excess friction
 
It sounds like its running rich. Youre saying that it takes a while to get it started back up if you let it die out at idle, but that it starts back up fine if you shut it off when its running good. Sounds like its flooding.

As for why, well, i wish i knew the answer. Mine is doing the same thing, on one cylinder only. Im about to swap the carbs and see if the problem follows the carb, or stays with the cylinder. When i pull my carbs off after idling the bike for a minute or 2, theres definately fuel pooling around the intake manifold. Ive rebuilt the carb twice, cleaned it about 20 times, and it still does it. If it follows the carb, im gonna have to assume cracked casting, or that someones drilled out the needle jet seat. Otherwise, im completely stumped.

Just a thought, how are you fuel lines routed? Is it possible that when you tip the bike, youre starving it for fuel? That could "fix" a problem with the float height, or leaking float valves.
 
My neighbor the auto mechanic stopped by last night to look at the bike. He hooked up his spark indicator, and the spark is very weak on both sides especially on the left which has been giving the most trouble. So looks like it may be an ignition problem after all. Time to order a point and condenser set from DCC.

CC
 
some good input from you guys....i have a goofy acting petcock which i need to change....i sometimes have to lean my bike over and back to get the fuel to flow down.....i have had it apart (petcock) at least twice....sometimes from off to reserve or run nothing happens i close it and reopen then it flows or have to do the lean thing....lol.
 
Garage_guy_chris said:
did you check the vacuum slides in the top of the carbs sounds like maybe there hung up and half open?
Click to expand...
Yeah, slides are smooth. Considering the weak spark I'm getting and noticing arcing at the points, I'm hoping new points and condenser will clear things up.

CC
 
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