Doesn't like to go past 4000rpm

[qwerser]

So we recently had some carburetor issues, where it was leaking out fuel. We took it apart and cleaned out all this junk, and now it doesn't leak. We put the carb back on and it starts right up, idles fine, and runs through the gears fine until about 4000 rpm when the engine starts to sound a little throaty and deep and wont go any faster. My suspicion is the accelerator pump, but I'm not sure.

[Blaine]

Sept 12, 2011 5:49:22 GMT -6 qwerser said:

So we recently had some carburetor issues, where it was leaking out fuel. We took it apart and cleaned out all this junk, and now it doesn't leak. We put the carb back on and it starts right up, idles fine, and runs through the gears fine until about 4000 rpm when the engine starts to sound a little throaty and deep and wont go any faster. My suspicion is the accelerator pump, but I'm not sure.

There is no accelerator pump.make sure that the diaphragm is seated properly and not leaking,or the slide cannot open properly to lei fuel in.The needle controls fuel delivery between 1/4 and 3/4 throttle.Also be sure that the carb vent(clear hose)is not pinched or obstructed in any way.If it is pluged the bike will not rev up.

[qwerser]

I forgot to mention something else...I took the air box off and I'm waiting for the cone filter to come in on Wednesday. I told someone at the place where I was getting it inspected and they told me its because its getting too much air. So while I was riding I palmed the carb a little to restrict some air and it was able to get up to 7000 with just one covered. So I'm guessing once the filters get in I'll clean the carbs out one more time and then put the filters on. So when the filters come in, I'll post what the results are.

[Blaine]

Sept 12, 2011 22:44:09 GMT -6 qwerser said:

I forgot to mention something else...I took the air box off and I'm waiting for the cone filter to come in on Wednesday. I told someone at the place where I was getting it inspected and they told me its because its getting too much air. So while I was riding I palmed the carb a little to restrict some air and it was able to get up to 7000 with just one covered. So I'm guessing once the filters get in I'll clean the carbs out one more time and then put the filters on. So when the filters come in, I'll post what the results are.

That is right.When you put the pod filters on you may need to restrict some of the air flow so the bike doesn't have a hesitation when you crack the throttle.

[eaglerider]

You never mentioned that you had removed the airfilters. I am surprised that it would run half as good as it did, if at all. The 454 usually will hardly run, if at all, without filters.

[wanchesenative]

Having read other posts in the past, you might need to change your main jet as well. Some have been lucky and not needed to but others had to go with a different size jet.

[qwerser]

Yea I'm looking into different size jets already, and I might mess with the needle. Supposedly there's a clip that can be set on 3 different levels of the needle that change the ratio. What are the stats/specs for the stock main jets and how much larger would I need to go.

[Blaine]

Sept 13, 2011 21:36:23 GMT -6 qwerser said:

Yea I'm looking into different size jets already, and I might mess with the needle. Supposedly there's a clip that can be set on 3 different levels of the needle that change the ratio. What are the stats/specs for the stock main jets and how much larger would I need to go.

When I changed to pod filters,I had to go from a 125" M.J to a 130".You may need to go larger,130" is a good starting point.There are no clips on the needle,you will need to shim them if needed.I have one shim under mine.

[qwerser]

I just bought some 130's and they should be here Tuesday, but in the meantime, my bike decided to call it quits. It'll still idle, but any twist of the throttle and it wants to die. Once I start going it only likes to get to 3000 and only for about half a mile. Almost like I'm running out of fuel or something. I'll check to see if the fuel line is being pinched in the morning, but I don't feel like messing with it anymore till my jets come in. Looks like I'm back to riding my bicycle to work. ;D

[qwerser]

Dude, 130's, they worked, so stoked. How far do I back out the air/fuel screw and, where do I get a vacuum gauge?

[Blaine]

Sept 23, 2011 21:19:15 GMT -6 qwerser said:

Dude, 130's, they worked, so stoked. How far do I back out the air/fuel screw and, where do I get a vacuum gauge?

You start with them at 2 1/2 turns out.Start and let the bike warm up.With the bike idling turn the mixture screw out (rich) until the idle starts to roll,than slowly turn the screw in (lean) until the idle starts to slow.Than out to were the bike idles smoothest.(About the middle of both extremes.)Although a vacuum gauge is no needed,it makes the job easier.Should be able to pick one up at any auto store.Good Luck.

[qwerser]

My friend just got an old 1973 CB and hes going to need a vacuum gauge for his four carbs. I'll just use his. Its running a lot smoother now that I wrapped about 4/5 of the pod filter with blue painters tape. I'm guessing once I get the vacuum thing and mess with the air/fuel screw I wont need the tape. But for now I'm just to busy to start messing with it. I'm hoping I'll be able to fix it enough to where I wont need to ride the bike on choke all the time.

[Blaine]

Sept 27, 2011 11:19:05 GMT -6 qwerser said:

My friend just got an old 1973 CB and hes going to need a vacuum gauge for his four carbs. I'll just use his. Its running a lot smoother now that I wrapped about 4/5 of the pod filter with blue painters tape. I'm guessing once I get the vacuum thing and mess with the air/fuel screw I wont need the tape. But for now I'm just to busy to start messing with it. I'm hoping I'll be able to fix it enough to where I wont need to ride the bike on choke all the time.

Some people can use them with no restriction.I have mine about 1/2 blocked.