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Discussion Starter · #1 ·
hello, i am new to this forum; so new that this is my first day on hondatwins...

today i posted a trad on DoTheTon abut my problem and i was directed hire.
this was original problem. recently I got CB450 in perfect shape. She was a sleep for 7 years; after I put new oil, sparks, and battery and cleaned a tank she started up without any problems. I had bunch of small problems but that didn’t stop me down; squeaky brake, bad contacts, key switch problem, slipping clutch… but al that is normal and it wasn’t so hard to find and fix… but now I have bigger problem.
From time to time I have “power cut of” around 4000rpm and there is change in sound. My conclusion is that one cylinder is taking a “brake”. Again my assumption is that root of all troubles is in curbs; they are not returning properly and mix is too hard (gas smell). Also there is back firing from time to time and I cant solve that problem- put new 8ES plugs, points are new and gap is set same 014. So if timing is ok and there is a spark, plus all elements are new, my only conclusion is that carbs are to blame.
I removed a top from carburetors and they look OK but I don’t know what is inside… my problem is that am not familiar with this carb’s (and CB 450 I general) can you pleas help me with this so I can have couple more days of riding before Montreal winter kick me back to a garage in to a café project
nice gent on DoTheTon- Gage Werke (thanks) shows me the way to a post: CB/CL 450 Carb Setup (thanks tbpmusic). I did all the things and BUM it worked like a charm. Left carb is at 2 turns from fully closed and R carb is at 2 and ¼ turns. I went it for a ride around 4pm and after minor thwacking; sooth sale! Problem started at midnight (as in many films) when I wanted to go for a ride. Cold Start was like butter and she was idling in no time I wormed her up a bit and off we go for 30 yards! She lost power and motor was off. Not a chance to re start. Ok push to the garage! After all attempts noting. Plugs are good and there is spark; looks in time. Point’s gap is perfect. There is a gas in mix I can smell it when spark is removed… and noting… and then with no reason wrummmm! Beck to business. This time I wormed it up properly re-re adjusted carbs and all things that I could think of, and when I was 100% sure that we are good now I went out. Same ride like in afternoon, same response and same power. All was as smooth as it gets until; leak of power song; like empty cylinder- air compressor and then progressive drop to a engine stop! Somehow it started back on but it was all over the place until it gave up again! And that was that!
Should I look for a problem in some other place? Should I pull carbs and re do them is there a trick to all this?
Pleas help, only thing I would like to do Is just ride for couple more days and after that everything is possible: but now if I could just patch this and roll!

Thanks

Luka
 

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It might not hurt to check all of your chassis grounds in your wiring harness.. Remove and clean them up, then re-tighten.. At least it would eliminate that possibility.

GB :mrgreen:
 

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My bike did the same thing and it wound up being a float bowl issue. Bike would fire and idle but then when I took off it would use the available gas in the right side bowl then die or start popping and running like garbage. Adjusted the levels and all was good.
 

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My first inclination is a bad coil or bad battery.....
 

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:!:
 

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Discussion Starter · #7 ·
Hello everyone thanks for the help.
Battery is new and I don’t have any fuel filters.
I will try to measure resistance on coils hot and cold; also will look in a ground’s…
Now this is interesting point. Gas tank was rusty as it gets with a paste at the bottom. It was cleaned with acid, washed, treated with baking soda to kill acid, washed again and then one more time treated with some anti corrosive thing. That “thing” leaves some sort of protective film on a metal. Can it be that? Can that contaminate a fuel?
Hmmmm. Somehow when I put that tank on problems started to happen. Before I had old tank that is coated inside but it has big ugly dent…
My somehow am suspecting floats and coils! It is lovely sunny morning and am planning to go to garage solve a problem and go for a ride; will report back!
Thanks
 

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chewbacca said:
tbpmusic said:
If you set both your points to a specific gap, then you've done it wrong -

http://www.hondatwins.net/forum/viewtopic.php?f=18&t=883

thanks for the tip; left one was too wide and i set it as a rite one on 014 all the rest looks cool to me. is this ok?
Well, I'm not exactly clear on what you are trying to say - can we assume English may not be your primary language??

Basically, you set the left point's gap to 0.012" - 0.016" - then set the left timing by rotating the entire points plate itself. This should not change the left gap .....

Set the right timing by adjusting the right point gap. The right gap will end up being whatever it ends up at.
Hopefully, it will be somewhere within that range. Check it, but don't alter it..........
DO NOT set the right point to any specific value, or you'll throw the timing off for the right side.

Is that any more clear??
 

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Discussion Starter · #10 ·
Hello, it is clear as a day! And what an improvement this was! Did all as instructed and timing is much better now, no more beck firing engine is more alive and it sounds grate. Top end is bit better then it was. Thanks for this tip!
Now, coils look ok, resistance is almost the same, cold or hot. I also tried to clean all the ground contact that are in relation with ignition cruets. And re adjusted an air/mix on carb’s again. Bike was tight and responsive and over all it felt like completely new ride! Everything was nice until we went on a twisty uphill and then downhill; same old story… stopped at the side of the road and went thru all procedures again just to be sure. Timing was dead on no change in the gaps. Spark was there. Coils at same Om value as in the garage. Now there can be only one thing CARB’s!
What do you think?
Btw. At the end my battery was dead and I just put it to charge. Is this normal?
Its new battery but today in had contact on for 2h and I did 8km, not enough to recharge. Is it a easy way to see how much electricity is coming from a alternator?
Thanks for all your help I really appreciate this
 

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I don't know what I was thinking on the grounds but I second what 66Sprint said..

Sometimes you can buy a new battery that is still not good. It's sounding like a bad battery or the bike's not charging properly.

GB :mrgreen:
 

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With, the battery fully re-charged, test voltage at the battery with a DC meter, the bike at idle, If you e-started expect 11.5 or so, (high 11's or around 12 if you kicked it over)...... The voltage should rise as the revs do (starting to rise about 1800/2000) up to the charging limit (somewhere between 13.7 and 14.2 V depending on your meter and the regulator's condition.... IF you get similar readings, the charging system is OK... If not, we'll delve further into it.... Let me know what you find..... Steve
 

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chewbacca said:
Now there can be only one thing CARB’s!
What do you think?
Btw. At the end my battery was dead and I just put it to charge. Is this normal?

Wish I had a nickel for every time I heard that - "Now there can be only one thing CARB’s!"
Beginners just go and tear the carbs apart way too often......

Sounds like the battery to me - your 450 runs entirely off the battery, and will not act right with a compromised battery.
Just because it's new doesn't mean it's good, they can be bad right out of the box.
Further, these small batteries can only be run down all the way maybe three or four times before they're hurt badly.

Try again with a battery you know is good - if it goes dead again, you have a charging problem.

450 carbs should run with the mixture screws at about 3/4 turn out, no more than 1 turn out.
But until you know for sure about the battery, you can't tell anything.
 

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Discussion Starter · #14 ·
Just an update; alternator is working and charging a battery (@3000rpm voltage is 14.5); I just got a new battery and am hoping for the best!
Bill I tried to go with a ¾ of a turn and motor is working ok, but when I open screw’s more like 1 ½ it is working way better. I re adjusted to your spec and I will se now with new battery!
This electrical stuff is reminding me of my first Land Rover project… that car had resident devil in the “ wires” and only way to get it out was not to drive when he was up to no good! Electronic ignition and one extra battery finally got him out…!
 

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chewbacca said:
Just an update; alternator is working and charging a battery (@3000rpm voltage is 14.5); I just got a new battery and am hoping for the best!
Bill I tried to go with a ¾ of a turn and motor is working ok, but when I open screw’s more like 1 ½ it is working way better. I re adjusted to your spec and I will se now with new battery!
Well, if it runs better at 1-1/2 turns and seems to actually respond to the mixture screws, then I guess it's ok.........
 

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I wonder how he's counting turns...... One and a half times a (half turn) would be 3/4 turns.... Let's assume the screwdriver slot is vertical when it "bottoms" out... The next time the screwdriver slot is vertical is one half turn out......
 

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Discussion Starter · #18 ·
One full turn would be a 360 CCW and ¾ 270 CCW that is easy but am having BIG Problems now. New battery was fully charged and I had Hi hopes; o sweat dreams! Same problem all over again but harder and harder until I lost left cylinder completely and all that in 1 a.m 50km from home! Bloody hell!
I tried all the things that I could at this time and I don’t have idea.
Timing looks good and spot on as it is described in Bill’s tread. Working cylinder works good.

But left is dead as a duck. There is a constant and sync spark as motor is running on problematic side. Left cylinder is completely dead on all RPM’s and there is no change even when I change angle of the distributor… also experimented with a different gap’s… noting! After all that, I returned everything to a Bill’s spec and moved to Carb. Left carb looks OK I removed a top and a bottom, it looks clean; muck better and cleaner then my carbs on R90S! Float looks ok but I didn’t have anything to test a vacuum. Tried too re assemble and clean all the stuff and no luck.

Good thing in all this is that now I know that was left cylinder going off and on; but now I don’t know why and I don’t know what to do! Also in a left pipe there is oil and gas so it looks wrong.

I tried to make things better but am having a feeling that I made some BS somewhere and now am just getting my self deeper in to it

Thanks
 

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Have you run a compression test on the engine?.....On a 450, the MINIMUM spec is 163 pounds/sq in.

And, 14.5V @ 3000 is a little high, but should be fine IF it does NOT go higher even with additional revs.... ( If it goes much higher, you will overcharge and damage the battery, and it indicates the regulator is bad.....)

Still sounds like a bad coil to me.......(bad when hot)
 

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I thought it was the right side that was acting up ??!!

Oh well - Steve is on the right track here.
Get your compression checked first - if it ain't 160 pounds minimum, then you have other problems that override anything to do with your carbs.

Coils and condensors are suspect - neither component was designed for a 40+ year lifespan.
Condensors have a shelf life, even if never used. Coils commonly act up when they get hot, seem fine till they do.
Inspect your coils- any black stuff oozing out around the coil/wire junction??
Pull the plug caps off and inspect - sometimes the black ooze stays entirely within the plug wire and gets into the cap area.

The points themselves could be bad as well.

Make sure all your ducks are in a row before you mess with the carbs - their brutal simplicity means they're the last things you should mess with.............
 
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