Topic: CB550 - CR29s is this the best it gets? Will CR26s be better street carbs?

[Godffery]

You referring to this:
http://www.Minamoto.org/gallery/v//album03/-123/Cafe+Overkill/DSC+229.JPG.HTML

[akabek]

You link does not work for me.

I meant the video half way down this page at about 2:25PM.  I am sure a few can relate.   http://mamatriedshow.com/theshow/

[Godffery]

Oh, yes.
Classy man right there!  = ]

[akabek]

After a long cold winter it was time to get back in the garage.  I had a buyer before advertising and ended up selling the CR29 carbs.  I purchased the CR26 kit from the Power Barn minus the pod filters.  I also bought the Pamco ultimate kit and an analog mini tach.  The tach on my Acewell gauge is all over the place and I was tired of trying different resistors so I wanted something more steady.  Over the last few days I installed the new ignition, coils and NGK wire kit.  It has been a while since I assembled wires and I could not believe I just had to screw the wires into the resistor caps.....no more crimping.  I does not get any easier than that.  Then I installed the mini tach, moved my ignition to where the gauges are and installed the CR26 carbs with the shorter rubber boots and intakes.  I hate working with brand new rubber boots but at least it is done.

I quickly cleaned my plugs and checked for spark on each cylinder.  I almost got it started tonight but I need to move the timing around a little.  Hopefully tomorrow I can set the timing and sync the carbs.  I have a feeling the jetting will be much easier this time around now that I have some experience.

[FunJimmy]

Looking forward to following your jetting progress.
You did an excellent job of the 29's.

[bwaller]

Those carbs will be easier for you to get sorted. Big carbs on the street are difficult.

[akabek]

It turned out to be an eventful weekend with the bike.  On Saturday I got the bike running but I could not get it to idle to check the timing.  Than the bike would not start.  I rechecked for spark and the ignition was fine.  I unscrewed one of my my carb float bowl bolts and no gas.  What the heck....  I disconnected my fuel lines from the tank and blew into the hose and air came out the secondary hose so no blockage.  I reconnected the lines to the tank, turned the gas on and after a few seconds of filling the bowls she started right up.  I have no idea why the fuel stopped flowing....

My CR26s came with 55 pilots, 105 mains and YY8 needles in the 3rd position. I figured rather than messing around anymore to get it to idle I should take the bike for a ride to warm the bike up and see how it performs.  On the side streets everything seemed to run well.  Once I got on a major road I quickly realized the bike maxed out at 68KM/h in 6th gear.  I was only able to apply 1/2 throttle, above this the bike hesitated.  I turned around and when I got home the bike was idling nicely at 1500RPM....sometimes you just need to ride it to sort it out.  The tach on my digital Acewell gauge reads much higher than my analog mini tach I installed so I will ignore those flashy lights.

I recently moved so before I did any jetting I decided to install additional lighting in the garage.  To make room I moved my bike over and as I was walking aware over it went.  After a quick curse I picked it up and the only damage was my seat separated from the mounting bracket.  Tonight I will reglue to the seat to the bracket using PL Premium.

To jet the carbs I will first lock down my main jets and work from there.  The bike is running lean so last night swapped the 105 to 110s.  I believe the CR26s and CR29s are the same physical size but I have less room below the carbs to remove the float bowl screws which makes it a real pain.  I use to be able able to change the jets in under 30 minutes with my micro socket set but now I will have to rethink how I will go about this.  I bought a set of socket head cap screws to replace the standard screws so working with an allen key may make the removal of these screws easier.

[MRieck]

  I bought a set of socket head cap screws to replace the standard screws so working with an allen key may make the removal of these screws easier.

It will

[turboguzzi]

CRs have the luxury of a drain plug to change the main jets.....

[akabek]

CRs have the luxury of a drain plug to change the main jets.....

I will go this route the next time I change the mains.  I am sure I will have a few changes to go before I find the sweet spot.

[akabek]

Thanks turboguzzi for the suggesting.  Changing main jets is much quicker now.

A few months out of not jetting carbs and I already feel like I am out of practise.  What I do like about the CR26s with my CB550 is that the choke actually works.  Now I also put in the Pamco untimiate ignition kit but what I have noticed is the bike will start no issues with the choke fully on.

With the way the bike was running using 105 mains I thought I was running lean so I went to 110 mains.  After making this change I found the bike was less inclined to excelerate beyond half throttle.  Than I decided to drop down to 102s and while the bike was more responsive it still hesitated.  It got worse the longer I rode and the warmer engine became.  It occured to me on my last run I should be doing plug chops so moving forward that will be part of my testing to see what the plugs look like.  I now 100 mains installed so depending on the weather I should be able to test them out today or tomorrow. 

Based on my engine mods, electronic ignition, running stacks/filter socks, 4-1 with open cone engineering muffler I thought my main jets would be in the 105 range but then I am not an expert.  My understanding when jetting a carb is to start with the mains.  Just a thought but if my pilots,  needle diameter size and height are way off (which covers the 0-3/4 throttle range) can that prevent me from getting the bike to > 3/4 throttle to see what the mains are doing?  I still think doing plugs chops will help me get better readings. 

[bwaller]

It can be a perplexing job, but think it through! When the problem worsens with increasing engine temperatures it usually means a rich condition. Plug chops are a good idea, have a supply of new sparkplugs.

[akabek]

It can be a perplexing job, but think it through! When the problem worsens with increasing engine temperatures it usually means a rich condition. Plug chops are a good idea, have a supply of new sparkplugs.

Perplexing at its best...  I ran the bike today with 100 mains and the same senerio, the bike will only accelerate to half throttle.  After that it hesitates and begins to slow down.  Somewhere along the way the bike is running rich because my swingarm spool after the exhaust pipe is covered in carbon.  Before I deal with the mains I need to sort out my mid range.  Next logical step is the needle height as this effects mid range throttle position. 

[akabek]

I tried going from 55 pilot to 50 and moved the needle to the 4th position but I still can't seem to get the bike to accelerate past half throttle.  Than I changed the pilot to 60 and still the same but the plugs look good....little tanned.  Is is possible the main jets could be causing this?  I put changed the mains from 100s back to 105s.  I figured the main jets only dealt with > 3/4 throttle.  I may try going from YY8 needles to YY7.

[Godffery]

I've had good results in this range:
 jetting:
Main Jets – 100 #105
Pilot Jets – 52 #65
Needle – Y8 #YY0
Needle clip - #3
Air Jet - #220
Mixture screw – 1/2 to 8/5 out

Timing - near full advanced.

Godffery

[FunJimmy]

It doesn't sound like a jetting issue Rick.
Sounds more like a fuel starvation problem.
You had a supply issue a few days ago that mysteriously cured itself.
That might still be effecting your higher RPM range.
I'd check any inline fuel filters including the in tank screen.
You might also want to confirm the float heights.

[akabek]

It doesn't sound like a jetting issue Rick.
Sounds more like a fuel starvation problem.
You had a supply issue a few days ago that mysteriously cured itself.
That might still be effecting your higher RPM range.
I'd check any inline fuel filters including the in tank screen.
You might also want to confirm the float heights.

I have two clear fuel filters inline on both fuel lines and at one point one was half full and the second looked empty so starvation me be the problem.  Are you running inline fuel filters yourself?  Some people remove them to eliminate a failure point but I find it an easy way to monitor fuel in the lines.

Today I am going to look over my fuel cap, petcock filter, fuel lines, inline filters and float height.  You would think the floats would be adjusted correctly since these are brand new carbs but I guess you never know.  It is also pain that the petcock hits the top of the carb but I will deal with that another time.

[bwaller]

RE float heights.....never assume. Make it job 1.

[FunJimmy]

Are you running inline fuel filters yourself?  Some people remove them to eliminate a failure put but I find it an easy way to monitor fuel in the lines.

No inline filters, just a brand new in tank screen.

It is also pain that the petcock hits the top of the carb but I will deal with that another time.

Same!

[akabek]

Well we are back on track now.  I removed the carbs to check the float heights and one was slightly lean but the rest were set correctly.  I removed my gas tank and while moving the petcock into different positions the fuel was not coming out....bingo.  I remove the petcock and there ended up being a lot of particles in the gas and sediment all over the petcock and filter.  I cleaned it all up with compressed air and reassembled it.  My petcock is only 1 year old and it had a slow drip in the off position but after reassembling it drips much more now in the off position.  This makes for a messy job when changing jets.

After reassembling the carbs I went for a spin.  I was running 105 main, 60 pilots, YY8 needle clip 3rd from the top.  I did not warm the bike up so it hesitated again in the mid section but I kept going to see what would happen when it warmed up.  After pulling away from a stop sign I pinned the throttle and quick hit the point of hesitation.  I eased up on the throttle and than went WOT again.  All of a sudden the bike hit the power band and launch like a rocket.  I would not be surprised if someone told me my front wheel lifted for a moment.  I will leave my main jets at 105 since I get serious pull on the top end now.  Not much further to go to finish up the jetting.       

[akabek]

The CR26s jetting is getting close.  Currently I having the following setup:
main 108
slow 60
needles YYK8 (5th position)

The bike is rideable but there is slight hesitation during quick acceleration.  I am a little  lean so 65 pilots will be next.

I noticed a vacuum cap was cracked so I should check for leaks.  What is the nay wsy to check vacuum leaks?

[Tintop]

I noticed a vacuum cap was cracked so I should check for leaks.  What is the nay wsy to check vacuum leaks?

starter fluid...spray it where the rubber cramps to carbs, engine, and your vacuum take-offs.  If the rpm rises, thats were it's leaking.

[akabek]

I noticed a vacuum cap was cracked so I should check for leaks.  What is the nay wsy to check vacuum leaks?

starter fluid...spray it where the rubber cramps to carbs, engine, and your vacuum take-offs.  If the rpm rises, thats were it's leaking.

What about propane?  I hear that should work and less mess.

[Tintop]

Just needs to be a flammable spray.  Preferably something that evapourates quickly to reduce mess, and won't damage the rubber boots.  Do not try this in an enclosed space, or near any open flame.

[akabek]

I did not check for vacuum leaks yet but after comparing part numbers for the intake rubber boot clamps for a 1975 and 1978 I bought a new set.  My bike is a 1975 and since I am using 1978 intakes and boots the clamps are different.  The ones I was using did not fit well....very tight fit

Question for you guys on jetting.  Does the needle size or clip level effect the main jet?
When I was using a YY8 needle a 105 main jet was on the money.  I am now trying YY7 needles which are richer and the 105 pilot is hesitating 3/4 and above so I assume it is rich.