JohnnyL's 1980 GS550L Cafe Build

[JohnnyL]

Ouch indeed ! ! ! K&N's are cheaper, lol

I know...unfortunately they don't fit between the frame and the carbs on my bike.

[Rich82GS750TZ]

Johnny, we'd all probably be interested in a total $ figure on this build, parts and pieces, outsourced work when you're finished, if you wouldn't mind sharing. Hard to put a number on all your untold man-hours, though.

[JohnnyL]

Johnny, we'd all probably be interested in a total $ figure on this build, parts and pieces, outsourced work when you're finished, if you wouldn't mind sharing. Hard to put a number on all your untold man-hours, though.

Ummmm....do I have to? Lol...I actually deleted the row on my spreadsheet that said "Total spent" because it was stressing me out.

[Rich82GS750TZ]

lol. I'm sure it was. I think I would have done the same, just so my wife couldn't see it.

[salty_monk]

Got a link to the catch can? Looks better than my setup...

[JohnnyL]

Got a link to the catch can? Looks better than my setup...

https://www.amazon.com/gp/product/B00514BR5C/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

[JohnnyL]

Ok carb experts. Please come out of the woodwork and offer me your suggestions.

The bike needs to be choked for a couple of minutes before it will idle without it. I warmed the bike up for a few minutes and it idles nicely at about 1200 RPM. You can hear pops coming from the exhaust. Every once and awhile, a carb will pop and backfire. Whop the throttle and it revs up to 5-6000 nicely but is slow to return to idle and when it does, it drops below idle and nearly dies. I've tried getting the revs above 6000 and it doesn't seem to want to go. Like a fuel starvation problem?

Current main is at 100(stock 92.5). Current pilot is at 42.5(stock 40). Air screws are one turn out(tried 2 turns and 3 turns also. Doesn't seem to make much difference). I'm running high quality pods. I haven't messed with the needle height. The exhaust is a reverse cone quieter muffler so it has a baffle in it. In other words...it's not open. For the hell of it, and I don't know if this tells anything, I put an infrared thermo on the exhaust manifolds. Cylinder 1 reads 579 degrees, Cylinder 2 reads 517 degrees, Cylinder 3 reads 503 degrees and cylinder four reads 475 degrees. I don't know how accurate this harbour freight thermo is either.

I'm open to suggestions. Tuning carbs is my least favorite thing to do and I'm just not very good at it. I really wish I could just give it to someone and say call me when it's running great. I also understand it is difficult to tune a bike without actually taking it for a test ride. That's just not an option here with the weather the way it is plus I don't have a seat. It seems like I should be able to get it close to running right sitting still. It seems close to running right. I just don't possess the know how to know how to make it perfect. Someone that knows carbs should be able to diagnose this pretty quickly I would think.

[Cipher]

Buy a front fender and an exhaust gas analyzer.

But seriously I doubt the infra red is coping well with a textured wrapped exhaust pipe. Likely causing more confusion to use it than putting it aside.

Also holy hell what is the size of the intake port on the oem airbox? Them pods have a massive surface area. I just got some new filters for the Kbike and you can breath through em with 0 impediment whereas my old 550 element was highly resistant to being blown clean with compressed air.

[JohnnyL]

Buy a front fender and an exhaust gas analyzer.

But seriously I doubt the infra red is coping well with a textured wrapped exhaust pipe. Likely causing more confusion to use it than putting it aside.

Also holy hell what is the size of the intake port on the oem airbox? Them pods have a massive surface area. I just got some new filters for the Kbike and you can breath through em with 0 impediment whereas my old 550 element was highly resistant to being blown clean with compressed air.

i have a front fender on. It just wasn’t on when I took that photo.

I wasn’t shooting the header wrap with the infrared. I was shooting behind the exhaust flange where the pipe comes out of the head.

Your point to the surface area of the pods?

[Cipher]

i have a front fender on. It just wasn’t on when I took that photo.

I wasn’t shooting the header wrap with the infrared. I was shooting behind the exhaust flange where the pipe comes out of the head.

Your point to the surface area of the pods?

Point is there is a greatly reduced restriction on airflow meaning youre likely jetted far too lean even three increments over stock.

Call me crazy then try 110s with no other mods.

[Cipher]

Those are nice filters I looked em up on the makers url. They looked to be well oiled on the pics there.
Are yours oiled? it hard to tell. Might just be the lighting but they look whitish and clean.

[Steve]

I can't fully the support the number, but I agree with needing a bit more main jet.

I will also suggest going back to the stock pilot jet.

Jetting depends on air flow. The reason you need bigger main jets is because you have removed the stock airbox, which is a bit of a restriction on air flow at, and near, full throttle. At anything less than full throttle, your throttle butterflies are the restrictions, not the airbox, so air flow is pretty much unchanged. It is usually good to raise the needle a bit to allow a bit more transition to the richer jets, but air flow at idle is virtually unchanged, so no need to change the pilot jets.

Go back to the stock 40s and turn the MIXTURE* (not 'air') screws out three full turns to start with. After the bike warms up a bit, turn each one in slowly, listening for a rise or drop in engine speed. If it rises, keep going. When it drops, stop, back up 1/4 turn, move to the next screw. After you have done them all, do them again, but only back out 1/8 turn. See if you have crisp throttle response and return to idle. Of course, this should be done AFTER a valve adjustment and a vacuum carb sync. You need to ensure that each cylinder is getting the same amount of air so that you know that your adjustments are fuel-related.

* I use the term "mixture" screw because it controls a pre-set mixture, not just air. Suzuki's official term for them is PILOT screw. It is important to know that turning them OUT will richen the overall pilot mixture, turning them IN will lean the overall pilot mixture.

This is just <my> opinion. I'm probably wrong, and somebody will be sure to point it out.

.

[bwringer]

Thanks for the input, Steve!

I've been helping with this as I can, but I'm a bit lost with carburetion on modified bikes; I've always been in the "stock is best" camp, but that's not an option here.

Thus far, we haven't been able to find any solid jetting/adjustment info whatsoever from anyone who's actually running pods on a CV carb 550. Surely there's one out there...?

[JohnnyL]

I can't fully the support the number, but I agree with needing a bit more main jet.

I will also suggest going back to the stock pilot jet.

Jetting depends on air flow. The reason you need bigger main jets is because you have removed the stock airbox, which is a bit of a restriction on air flow at, and near, full throttle. At anything less than full throttle, your throttle butterflies are the restrictions, not the airbox, so air flow is pretty much unchanged. It is usually good to raise the needle a bit to allow a bit more transition to the richer jets, but air flow at idle is virtually unchanged, so no need to change the pilot jets.

Go back to the stock 40s and turn the MIXTURE* (not 'air') screws out three full turns to start with. After the bike warms up a bit, turn each one in slowly, listening for a rise or drop in engine speed. If it rises, keep going. When it drops, stop, back up 1/4 turn, move to the next screw. After you have done them all, do them again, but only back out 1/8 turn. See if you have crisp throttle response and return to idle. Of course, this should be done AFTER a valve adjustment and a vacuum carb sync. You need to ensure that each cylinder is getting the same amount of air so that you know that your adjustments are fuel-related.

* I use the term "mixture" screw because it controls a pre-set mixture, not just air. Suzuki's official term for them is PILOT screw. It is important to know that turning them OUT will richen the overall pilot mixture, turning them IN will lean the overall pilot mixture.

This is just <my> opinion. I'm probably wrong, and somebody will be sure to point it out.

.

Thank you Steve! Everything you said makes a lot of sense. Brian is coming over today with his carb sync tool and long reach snap ring pliers. We will change out the pilot jet back to stock. I only have the 92.5, 100 and 117.5 mains so I will probably put the 117.5 mains in for now and order some 110s and maybe some sizes in-between.

I'm a little confused what the "mixture" screw is. Is this what I know as the "air screw"? The little screw on the top of the carb? This one:

[Steve]

Yep, your "air screw" actually controls a MIXTURE, that is the screw that Suzuki calls a "pilot" screw.

I am out of town right now, but have a few jets at home that I might be able to send you for experimentation. Should be home Monday evening, will check my inventory on Tuesday.

.