Running but not really

[Oldman99]

Hello again.
I got my 450 back together after all the issues I had with the broken bolts debacle.
After checking and rechecking, I thought I had my timing set. Turned the engine over a few times with a wrench to insure nothing made contact (valves).
I went for a start up and she wanted to run, but only with some help from the throttle. Had some popping and back-firing. Also noticed a ticking sound from the pickups. One was making contact. I just wanted to insure I had TDC on the correct mark. I'm also not able to find a clear cut answer on what year has what type of points or pickups and the proper place to set the timing to. Heres pics of what I have.

 

[tom203]

I'm unfamiliar with this model ,but I'd say that the casting mark (at 10 o'clock position) is the spot you want to have your "T" mark line up with for TDC : you can peek thru the round window.
make sure your mechanical advancer is not froze up and interfering with timing .

 

[Oldman99]

Did some more checking and I'm thinking I failed to get all of the slack out of the cam chain before installing the exhaust cam. We'll see I guess.

 

[Oldman99]

Yep. That was the issue. I also forgot how poorly they run without the air filter.
On a related note. The pickup advance is what was making the clicking sound I thought was the cams. Still looking into that.

 

[dungdn93]

I am not familiar with this model, but I'd say that the structure is the position you want. Please tick up to TDC.

 

[Oldman99]

Good news is that I got her back together and running again.
Bad news is that its running very hot and is lacking power.
My current guess is that the air filter setup I'm using is no better than pod filters and I would have no idea how to rejet.
Never done it. I used some carb cleaner while it was running and did not find any kind of a vacuum leak.
How much of a restriction should the filter have to be close to the stock box? I just made it to fit where the stock box was and to use a filter that is still made.
I'm not looking to set land speed records, just daily drive it to work.
Thanks for the help so far!
(I'll get a better picture of my set up when I get back home. I just had some time to post this on my brake)

 

[Oldman99]

Finally made it home, but its too late to do much tonight. After reading the symptoms of running lean vs rich here.
http://mechanics.stackexchange.com/...of-lean-or-rich-carb-settings-on-a-motorcycle

I pulled back the dust sleeve on the filter and put a ring of duct tape to reduce the amount of air that can flow thru it. I'll give that a try and adjust things as needed.

 

[tom203]

The stock airbox tends to reduce the pressure in airbox (as throttle loading goes up) to make it easier for vacuum diaphragms to lift and supply more fuel/air. Your gizmo filter should work- maybe not well in mid range, but it shouldn't cause a power loss. Did you hold your diaphragms up to a light source to check for pinholes? Is the thru slide hole aligned to engine side?

 

[Oldman99]

Got a buddy to haul myself and the bike to my local repair shop. Mechanic was a fan of older bikes and seemed stoked to just chat about it.
During our talks, he said I would need to fix the uncorked mufflers and up the main jets; maybe even the pilots.
At the end of the day I ended up with most of an old gs air-box. The back half is cracked badly.
Some 137.5 mains, up from 115. (Thanks Pete, for the tuning thread!)
I used some old metal pipe from my scrap bin just to test the stock mufflers.
Stated right up with 1/2 choke and ran better than it ever has.
I might still need to move the needles up later on, but I've only done the basic tune to get the ball rolling.
I should have more permanent pipes welded into the mufflers tomorrow and I'll move on from there.
Here's a look inside the stock mufflers if you've ever wanted to see. The red circle is where I'm assuming the pipe should be.
Dose anyone know if the pipe should be vented or have any kind of holes? Maybe if you could pop out to the shed with a flashlight and check? lol

 

[Oldman99]

Sooo..... I got some large washers and tack welded the pipes to them and then to the mufflers.
Started up and ran like crap.
I swapped the stock main jets in and now it runs better, but still has no power under load and a weird exhaust sound.
It has good flow from the mufflers.
I'm really starting to hate this engine. Please help...

 

[cowboyup3371]

So if the pipe is closed off like that how is your exhaust venting?

 

[Oldman99]

It's not closed off. Its back to how it was stock.

 

[Oldman99]

Sorry. I did not notice with the photo. (I put old black brake caliper paint on it) here's a better shot.

 

[Oldman99]

So when I had the head off to repair the broken bolts, I seem to have mixed up my shims.
3 where like 2.65 and one was a 2.70.
The weird thing is that I cant get my thinnest feeler gauge under any lobe at any point in its rotation. You can watch the point of contact and see that the lobe is always holding some small amount of pressure on the valve. Will an engine still idle and rev to 3k even i the valves are not closing fully?

 

[Steve]

The stock airbox tends to reduce the pressure in airbox (as throttle loading goes up) to make it easier for vacuum diaphragms to lift and supply more fuel/air.

Sorry, but this is the typical mis-understanding of how the slides work.
It is NOT the vacuum caused by airbox restriction that lifts the valves, it is vacuum created by the venturi effect when air rushes past the bottom of the slide. That air does not care if there is a vacuum in the airbox or even a supercharger that is PRESSURIZING the air, it is simply the amount of air going under the slide that creates the vacuum that lifts the slide.

The main reason that the carbs work so much better with the airbox is because of the lack of turbulence at the carb intake. Without the smoothing effect of the intake boots, air gets very turbulent at the intake, wreaking havoc with the air jets that live there.

During our talks, he said I would need to fix the uncorked mufflers and up the main jets; maybe even the pilots.

Why would you need to "up the pilots"? Just look at the physics of the whole situation: The jets in the carbs are based on the amount of air that is expected to flow through them. During high-flow situations (near redline), the airbox can be somewhat restrictive. If you remove that restriction by installing pod filters (or some other means), yes, you will need to increase the size of the jets that feed the fuel during that situation. The MAIN jets. When you are operating at idle and very low throttle, which is when the pilot jets are used, it doesn't matter if you have an airbox or not, let alone what type it is. Your main restriction there is the throttle position, not the airbox. Since your restriction is not changed, why should your pilot jets be changed?

The weird thing is that I cant get my thinnest feeler gauge under any lobe at any point in its rotation.

Sounds like a refresher in terminology is in order. The "lobe" on the cam is the part that is not part of the circle. It is the section that actually lifts the valve. The rest of that area is the "base circle". There are specific names for different parts of the lobe, but they are not necessary for this discussion.
Second, what is your "thinnest feeler gauge"? Until we know what your thinnest feeler is, there is no point in continuing.
Based strictly on your wording, "I cant get my thinnest feeler gauge under any lobe at any point in its rotation", it's not surprsing, as you should not be able to fit ANY feeler under the "lobe" because it will actually be pushing the valve open. Since your bike is a twin, you should position the lobe so it is pointing directly away from the valve when you attempt to check clearance. Your clearance should be 0.03-0.08mm. If you only have inch feelers, you will need the 0.0015-0.003" feelers. If your "thinnest" feeler is larger than those, it's no wonder that it won't fit, but you have not told us what your thinnest feeler is.

.

 

[TxGSrider]

Sorry, but this is the typical mis-understanding of how the slides work.
It is NOT the vacuum caused by airbox restriction that lifts the valves, it is vacuum created by the venturi effect when air rushes past the bottom of the slide. That air does not care if there is a vacuum in the airbox or even a supercharger that is PRESSURIZING the air, it is simply the amount of air going under the slide that creates the vacuum that lifts the slide.

The main reason that the carbs work so much better with the airbox is because of the lack of turbulence at the carb intake. Without the smoothing effect of the intake boots, air gets very turbulent at the intake, wreaking havoc with the air jets that live there.


Hey Steve, I've wondered about this for some time, and Im not sure this is entirely correct. Ive got a couple Polaris atvs at the house, and if I simply remove the lid, but leave everything else connected, they'll idle just fine but not take any type of throttle. Admittedly it probably has nothing to do with the slides opening and more to do with them perhaps going lean from the extra airflow. I really don't know but I don't think it would effect the main air jets or pilot air jets as the flow across them would still be pretty linear with the intake tube in place.

 

[Oldman99]

Update:
I'd like to speak to whoever is in charge of the stuff listed near your name. If you could put "dumb" near mine, that would be great. I pulled the spark plugs to check them. Wait... What's that inside the cylinder? Its one of the little rags I placed in the intake boot but forgot to remove. It was tiny but enough to hold the intake valve open. I'm not happy right now.

 

[Guest]

You can put "dumb" by your name in your signature, but I wouldn't. It's always trial and error when you're learning.

For instance, I work on "X" brand copiers. I had to put in a new component that had two wires to connect. I put it in, and ran it, and it ran fine. The next day, I get a call to go back as it came up with an error message. I pull out the component and notice the wires are not connected. Do I go ahead and connect them both? Heck no! That would be too easy. I just connect one. Guess what happened the next day? I have done this same component replacement several times. Why this time did I decide to totally forget all I've learned?

That's life. Hang in there and you'll be good to go.


By the way TxGSrider...I'm in Denton covering for someone at the State Supported Living Center on State School Rd (or something like that.) Nice town, despite the construction!

 

[TxGSrider]

You can put "dumb" by your name in your signature, but I wouldn't. It's always trial and error when you're learning.

For instance, I work on "X" brand copiers. I had to put in a new component that had two wires to connect. I put it in, and ran it, and it ran fine. The next day, I get a call to go back as it came up with an error message. I pull out the component and notice the wires are not connected. Do I go ahead and connect them both? Heck no! That would be too easy. I just connect one. Guess what happened the next day? I have done this same component replacement several times. Why this time did I decide to totally forget all I've learned?

That's life. Hang in there and you'll be good to go.


By the way TxGSrider...I'm in Denton covering for someone at the State Supported Living Center on State School Rd (or something like that.) Nice town, despite the construction!

I'm actually in a small town about 10 miles north of Denton, but I use Denton so people will have an easier time figuring out where in Tx I am. Im at work right now in Lewisville so I'm only like 7 or 8 miles from State School Rd... and yes, they have I-35 all messed up. You were "lucky" enough to catch us in a cool spell... its only in the low 90's today.

 

[TxGSrider]

So did you get the rag out?