Topic: One step richer?

[DaveI]

When you come up with a good solution let me know. I have a 4-1 pipe and pods with 40 idle jets and 120 mains and when I fired the bike up the engine got so hot I thought my fuel tank was going to explode. Not to mention the head was smoking like a chimney.

[lucky]

When you come up with a good solution let me know. I have a 4-1 pipe and pods with 40 idle jets and 120 mains and when I fired the bike up the engine got so hot I thought my fuel tank was going to explode. Not to mention the head was smoking like a chimney.

You need to say which motorcycle you are talking about.
You did not mention needle clip position.
You need to see if you have oil in your engine? Crazy.

IF you want free info you need to visit the forum.
I do not think members are going to do all the tuning work and carb removal and installation,testing and then remember your name and contact you to give you all the valuable info.

"Oh,yeah I better remember to contact DAVEI  and give him all this data." LOl..lol

[lucky]

Your setup will prob end up mimicking his closely. Maybe a turn of the idle screw a bit in either direction I think. Depending on the actual flow/backpressure of the 4-1 ( not to drag up flow characteristics and which pipe does which better etc) and pods maybe a needle movement, maybe one clip. Your setup should end up real close to Dimitri13 tho

I agree.
These two forum members need to collaborate.
I hope the report back on the final outcome and I can add it to the database I will put online.

[stereosilence]

It is annoying that the jets are so expensive. 

I found this link and decided 105's are probably still too small. I'll likely go with 110's or 115's mains and 40 slow like Dmitri.
http://forums.sohc4.net/index.php?topic=12012.0


I think I'll purchase this:
http://www.siriusconinc.com/pro-detail.php?pid=&product_id=177

If I have to change the jets from my first guess, it will be worth it.

[lucky]

It is annoying that the jets are so expensive. 

I found this link and decided 105's are probably still too small. I'll likely go with 110's or 115's mains and 40 slow like Dmitri.
http://forums.sohc4.net/index.php?topic=12012.0


I think I'll purchase this:
http://www.siriusconinc.com/pro-detail.php?pid=&product_id=177

If I have to change the jets from my first guess, it will be worth it.

Jets R Us has a very reasonable price if you do not insist on Keihin.
Remember people it is a brass cylinder with a hole in it. Thats it.

[stereosilence]

It looks like about the same price as the other. I didn't check the shipping though.

[Dimitri13]

Stereo, I've ordered all my jets from jetsrus. It does get a little expensive buying the slow jets, but you should only need to buy one or two sets from them (40 and 42). The main jets I'd get a set of 105, 110, 115, and 120. Probably won't even need the 120s. Hell, with 115s and the velocity stacks with filters it's way too rich. Maybe without the filters 115 would work.

But I'd definitely try 110 main, 40 slow, needle clip in the 5th notch, and MAYBE 1/4 turn in on the pilot screw (try stock 1.5 turn out first though).

[DaveI]

Alright Lucky, heres the update for your free information database 

I am running a 74 CB750k with carpy pods and an unknown 4-1 exhaust from the PO.  It does have a little insert in the muffler to take the noise down and provides some back pressure.  I am going to assume he probably did't pay for a mac.
I had 120 mains with 40 slows and brand new oil in the tank with a fresh petcock rebuild and a several day tank cleaning with rust remover.

It was running real hot (also on a 100 degree humid and not windy day in florida btw).  I just bumped it up today to 125 mains and turned the af screw out just a half turn and it sounds much better.  Without a dyno, tuning these carbs seems like guess work.  I did pull the plugs out and they looked a little black so maybe its a little rich and the 120's would be better with the clip moved to a richer setting?

Somewhere in the time I ran it for a few minutes hot the other day, the oil pressure light failed as it does not come on at all anymore.  balls!  I still have electrical gremlins with a short somewhere else that I cannot find. I get flicikering headlights with the switch in the off position and the headlight fuse constantly blows.  It's time to take it to a mech.

Here's a picture of her though.

[stereosilence]

I got my 40 slow jets and my main jet in the kit today. The kit came with 110's, 115's, 120's, and 125's. So once I get done, I guess I can sell off the others (plus I have two sets of 38/100's) if anybody wants them. Shipping and all it was $80.

I'm looking forward to getting them in there this weekend. Not looking forward to syncing the carbs again. 

[DaveI]

It is annoying that the jets are so expensive. 

I found this link and decided 105's are probably still too small. I'll likely go with 110's or 115's mains and 40 slow like Dmitri.
http://forums.sohc4.net/index.php?topic=12012.0


I think I'll purchase this:
http://www.siriusconinc.com/pro-detail.php?pid=&product_id=177

If I have to change the jets from my first guess, it will be worth it.

Have you tried going to a local honda shop?  I was able to pick up brand new original keihin main jets for a dollar a piece.

[lucky]

Alright Lucky, heres the update for your free information database 

I am running a 74 CB750k with carpy pods and an unknown 4-1 exhaust from the PO.  It does have a little insert in the muffler to take the noise down and provides some back pressure.  I am going to assume he probably did't pay for a mac.
I had 120 mains with 40 slows and brand new oil in the tank with a fresh petcock rebuild and a several day tank cleaning with rust remover.

It was running real hot (also on a 100 degree humid and not windy day in florida btw).  I just bumped it up today to 125 mains and turned the af screw out just a half turn and it sounds much better.  Without a dyno, tuning these carbs seems like guess work.  I did pull the plugs out and they looked a little black so maybe its a little rich and the 120's would be better with the clip moved to a richer setting?

Somewhere in the time I ran it for a few minutes hot the other day, the oil pressure light failed as it does not come on at all anymore.  balls!  I still have electrical gremlins with a short somewhere else that I cannot find. I get flicikering headlights with the switch in the off position and the headlight fuse constantly blows.  It's time to take it to a mech.

Here's a picture of her though.

A little bit of confusion here. If an engine is running rich it needs less gas and more air . Not more gas with a larger main jet.

The electrical issues do need to be solved before carb tuning.
Matter of fact all issues must be resolved before carbs are tuned.

[lucky]

It is annoying that the jets are so expensive. 

I found this link and decided 105's are probably still too small. I'll likely go with 110's or 115's mains and 40 slow like Dmitri.
http://forums.sohc4.net/index.php?topic=12012.0


I think I'll purchase this:
http://www.siriusconinc.com/pro-detail.php?pid=&product_id=177

If I have to change the jets from my first guess, it will be worth it.

Have you tried going to a local honda shop?  I was able to pick up brand new original keihin main jets for a dollar a piece.

Main jets for $1 each!!! WOW.  Maybe you could go buy some for the forum members and sell them for $2 We would all be happy.

[DaveI]

It gets even better, I went by today to swap out the 130's I bought after I realized 125 was too rich and he just gave me dyna jet 118's for free.  Hopefully that is the sweet spot for me.

[lucky]

It gets even better, I went by today to swap out the 130's I bought after I realized 125 was too rich and he just gave me dyna jet 118's for free.  Hopefully that is the sweet spot for me.

Could be. After you ride it a little do a plug check it it looks reasonable then do a WOT plug chop and after cooling a little check the plugs again.
USe anti seize.

[DaveI]

I put the 118 mains in and things looked a lot better with the plug chop. With the new battery, regulator and rectifier I am not longer sowing in the street. Just once and it was because idle dropped to about 500 rpm once the bike warmed up. One thing I did notice that may have been giving me issues was my Dyna s ignition was set to full advance and not timed properly.

The only thing I question about the carbs now is the idle. It will be steady at 1100rpm but after twisting the throttle and letting go, linger around 1800rpm for 30 seconds or so before dropping back down. That points at a lean mixture to me but everything else seems right.

[stereosilence]

I now have the 110's and 40's in. It was pretty tough to get it to start the first time and then I fiddled with it too much at the beginning. The trick is to get it started, WARM IT UP, and then work on the settings.

I am currently at:
Idle:   40
Main: 110
Mix:    1.5

and it seems to be running well.

At first, I had the issue with hanging after the rev, but once it got warmed up and I backed the idle screw out a good bit, that went away. I almost got caught in the rain, so I'll have to do some more riding, but it sounds a lot bass-ier and powerful even in the idle. There is still some sort of crackling in the exhaust and some uneven-ness below 5k...but welcome to pods and drag pipes, I guess.

Always make sure to set your timing first, it makes a big difference!

[lucky]

I am recording all of these reports.

[stereosilence]

Well, after being very happy with how it ran the other day, I took it to work (interstate and some stop and go). It did not run as well. It did not want to idle and the response would get slow below about 5k. After riding at 70 mph for maybe 10 min., I slowed down and (since I was beside a large paved shoulder in slow traffic) I dropped the throttle to let it idle. It just died. I tried to kickstart it (which is generally extremely easy when it is warm) and could not get it started. I had to use the electric starter to get going again.

After work, it kick started first time (maybe my adjustment of the idle screw helped?) and I didn't really have trouble at all. I pulled out some plugs and of the two on the right, the outside one was dark but dry and the inside one was dark and wet (I think the outside pod filter may have a loose cap and be letting in more air).

The only thing that changed was that I filled up with premium (it had made me run better before). I may try to keep riding and fill back up with regular and see if there is a difference. May also check my timing.

Should I move the needle a position leaner?

Also, I have an 18mm deep socket that was able to get THREE plugs out but cannot get the inside left one out. Can anyone direct me to a cheap socket that will for sure get them all out?

[lucky]

TALKING about Stereosilence's CB 550 now.

The plug on the right in your photo is wet. Did you put the choke on right before killing the engine?
Sure would like to see all 4 plugs.

So here are the facts again
The facts:

1975 CB550K.
Pods.
4 into 4 drag pipes,(baffles)
Main jet  #110 mm. stock was #100
Idle jet  #40 mm. stock was #38
Needle clip position 5th.
Mixture screws stock 1.5 turns out.


Is your slide needle in the stock position?

Try adjusting the mixture screws to get a leaner mixture but not so much that it starts popping on decell of the throttle.

With those baffles in the exhausts you main jet is probably right.
You can con firm that with a plug chop at WOT.

Remember it it does not rev upright in the shop it won't run right out on the road.
Make sure it revs up clean and crisp in the shop and it goes down to idle quick and stays steady.

Then take it out on the road.

I think you may be close.
When you think it about right put in some new plugs and ride it for a few days normally, then pull the plugs and see what you have. No plug chop, just a look at the plugs.

[lucky]

I put the 118 mains in and things looked a lot better with the plug chop. With the new battery, regulator and rectifier I am not longer sowing in the street. Just once and it was because idle dropped to about 500 rpm once the bike warmed up. One thing I did notice that may have been giving me issues was my Dyna s ignition was set to full advance and not timed properly.

The only thing I question about the carbs now is the idle. It will be steady at 1100rpm but after twisting the throttle and letting go, linger around 1800rpm for 30 seconds or so before dropping back down. That points at a lean mixture to me but everything else seems right.

Thanks for the feedback DaveI.

What size are the idle jets?
Usually if  it is too lean the idle wants to hang up - not come down fast enough.

[lucky]

Just to clear up some confusion. There are three forum members with similar set ups as far as air filters and exhausts on their CB550 Hondas on this thread.

Dimitri13.
Stereosilence (thread starter)
DaveI

They are all working on the nearly same situation.

[stereosilence]

I didn't turn the choke on. I just revved it up. I could only get three of the four plugs out. The two outer ones were dark and dry with the part around the center a dark shade of tan (I think this is what I want). The center right one was dark and all wet (as seen in the photo).

The needle position is as you have it listed. I think it is one notch richer than stock.

Which direction do I turn the mixture screws to get leaner?

[lucky]

I didn't turn the choke on. I just revved it up. I could only get three of the four plugs out. The two outer ones were dark and dry with the part around the center a dark shade of tan (I think this is what I want). The center right one was dark and all wet (as seen in the photo).

The needle position is as you have it listed. I think it is one notch richer than stock.

Which direction do I turn the mixture screws to get leaner?

Turn them all 1 turn out from bottom  and then see if it runs better or worse.
Each time you make a change ask yourself ....Is it better or worse?

I do not know on that CB550 if in is leaner but the workshop manual will tell you.

Also since the stock setting is 1.5 turns I would just turn them all 1 turn open and see if it is better or worse.

[stereosilence]

I have been fiddling with the AF screws. I have tried it at .5, 1.0, 1.5, and 2.0 turns out. The bike still had issues maintaining idle and every one (except I didn't get to check .5 cause it was popping so much on the low end I gave up). I think the bike ran best at 1.5 though.

I think what I am experiencing is this: I start out with the idle working pretty well. After I ride a while, it gets progressively worse. As I ride, the over-rich condition fouls up my plugs and makes it tough to drop back down to idle.

I think I am going to move the clip back up to the 4th position and see if that leans it out enough.

BTW, I just bought a 650 cam + tach + tach drive. That shouldn't necessitate a change in jet settings right?

[brewsky]

It gets even better, I went by today to swap out the 130's I bought after I realized 125 was too rich and he just gave me dyna jet 118's for free.  Hopefully that is the sweet spot for me.

Dynojet 118's are the same as keihin 125's.
There is a conversion chart between keihin/dynojet/ mikuni available if you google it