Input needed: carbs, fuel, timing or valves?

Ok group, I have run into a problem with my norton build. Some of you may remember me from my "please help with timing" thread. So now my bike is built, and I thought she was running good, but I was wrong. Long story short, I built the bike in my fathers garage in MD, which is in town. I am waiting on tags/title for the bike, so I never got to take it on a ride, just up and down the back alley. Last night we trucked it up to my house in PA, and I live in the boondocks. In a year and half, never seen a cop where I live. As soon as my dad left and I was sufficiently convinced he wasn't coming back, I took that bike for a spin on these lonely back roads :wink: she didn't run nearly as good ai thought she would...
I really thought we had it dialed in, she is a one or two kick bike, and idled good. Has good low end torque and had seemed to run good in my quick little tests on the alley at my dad's. But on my first real ride, she was woefully lacking power at rpms above 3k and under load. I'm talking lack of power as in I don't think it is rideable, I could barely get it to do 45-55 mph and it barely could climb a hill. But like I said, she kicks over and starts right up, idles smooth, and is solid in first from a stand still.
So my question to the group is where do you think my problem is? I was thinking timing, but it starts so easy, it seems like the timing is good, out at least close

Are you using points? Maybe not getting advance, or do you have an EI? Do you know what needle and jet are in the carbs? I assume you are getting enough gas to the carbs, blockage in the lines or poor petcocks? Floats set up right and carbs too by Bushmans page?

Dave
69S

Sorry, posting from my phone, I need to continue in a new post.

Also thinking carbs or fuel issue, it feels like it runs out of gas maybe? Sucking more fuel than will go in. but amal cabs are actually something I'm good at. They are rebuilt and good shape.

I've rechecked the valves and they seem set nicely, so I don't think thats it.

so please advise which issue you think I should start with; timing, carbs, fuel... Something else? And if you think its timing, do you think it is advanced or retarded? Btw, this is an electronic ignition, not points.

Thanks, dan

Choke off?

I put stock size jets back in it I think. 130 or 140.

New petcocks, new fuel lines. They are clear norvil lines. I did notice that I was having a vacuum problem with my gas cap, I actually had the cap loose when I rode it. Maybe the float though, didn't think about that, could still starve the carb. I remember them seeming good, but looks can be deceiving.

TIGHTEN out all slack in "choke" (enricher) cable, to fully pull carb slides up out of the airstream (choke off). That sounds like your problem.

westernjesus said:

I put stock size jets back in it I think. 130 or 140.

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Do you mean 230 or 240 main jets?

Are you certain you didn't set the choke lever the wrong way? Tight wire = choke OFF.

The mains jets will not have an affect what you are doing in this range. Lower the needle by raising the clip one notch. This is just standard procedure for mid range tuning and you may have to go the other way.

If you cannot get it right with the needle, you may have to change slides. Lower number richer (2 1/2) allowing less air. Higher number leaner (3 1/2) allowing more air.

What do your plugs show? Lean or rich? Double check your timing while you are at it.

Needle jet should be a 106. Rarely if ever have i seen 105's or 107's applied, but it is not out of the question.

Good golly, if I have my choke still on, I'm going to feel really silly for starting this thread

I am 99% sure my choke is off, but that 1% of doubt is making me nervous. I feel all flush sitting here, tempted to go home over my lunch break at work to make sure I'm not a bone head!

Don't forget to check cam timing. Classic symptoms of a cam off by a link or so.

aceaceca said:

Don't forget to check cam timing. Classic symptoms of a cam off by a link or so.

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I agree but hate the prospect.

I too do not like the prospect of cam timing being off. I have torn the motor down too many times in the last year, the thought of having to do that again sends shivers down my spine. I brought it home to PA because I thought major issues were done...
Short of pulling the timing cover off and counting the links on the chain, does any one have a quick "shade tree mechanic" way of checking to see if the valves are opening/closing at the right/wrong time? My garage is not equipped for a tear down. There should be a way to know when they open relative to the piston location. Couldn't find it from searching the forum. If someone has s link to share, I'm sure there is a thread on that. Sigh.
Thanks guys...

Read back through the suggestions and start with the easiest first.

...then pull the timing cover.

I would think you should be able to tell by piston TDC and valve lift, but don't ask me the numbers. But taking the timing cover off is not like breaking down the engine, but you'll need the pinion remover I reckon.



Dave
69S

You don't need to remove the pinion to verify the alignment of the marks...

You did mention starvation. This is easily confirmed by putting a bowl under the carbs and pressing the tickler on both carbs together and watching to see if you have a noticable issue.

I have the JS setup and the routings of the fuel lines are rather strange having to loop around each other to get to each carb. Thinking I could be creative I made a little T and shortened it all up only to go back to the big loop because of kinking and loss of power abover 5g's. to say the least, no more loss of power.

But again, I thing it's a needle thing the needles you. But float height could also play into it. If your's tickle up easily then i do not think it's the floats.
What say you about those plug colors.

Is the throttle cable fully raising carb slides!

Have you checked the Gas tank vent to see if it is not clogged? If it is, you will feel like you are running out of fuel.

grandpaul said:

You don't need to remove the pinion to verify the alignment of the marks...

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But to change it?

Dave

Home from work now, going to start in on suggestions. First thing I can say is that, no, I did not have my choke on