75' CB550 carb confusion.

[Drey6]

Well I'm not entirely confused ( thanks to my manual). Yesterday while attempting my first carb rebuild I was confused at why the slow jet does not match the new replacement in the kit? Here is a picture.

Both have a 38 stamped on the side, the new and the old. But the manual says that the slow jet is "No. 40"

Is that just a rounded up number?
Any help is appreciated because as of right now I want to clarify some things before I continue.

 

[Drey6]

Shit, even the main jet and the replacement main has 100 stamped on them but appear different. Is it just the new kit is a reproduction so there will be some differences?
Here is what is all in the kit.

To my understanding.
1. Carb top gasket
2. Main Jet No. 78
3. Main Jet No. 80
4. Main Jet No. 100
5. Jet Needle/ Bar clip/ Spring
6. Slow Jet No.38
7. Adjuster screw (air)
8. Float Bowl Gasket
9. O- Ring (drain bolt ???)
10 . Two identical O-Rings (not sure where this goes)
11. Valve Seat (not sure how to remove this)

 

[Drey6]

Bump.

 

[Drey6]

http://youtu.be/vATndqkDTGs

 

[UNCOILED]

Have you tried asking over on SOHC4? They are super knowledgeable over there about the Honda 4 cylinders.

 

[Drey6]

Have you tried asking over on SOHC4? They are super knowledgeable over there about the Honda 4 cylinders.

Not a member in that forum. Unless that is a section of DTT.

 

[canyoncarver]

I have that same set of carbs. I can tell you that the carb kit makers vary by quality, fit, and finish. Some of the cheap ass aftermarket stuff really sucks. I try to stick with oem parts if possible when it comes to jets, floats, seats, etc. I tend to clean a good condition old jet rather than replace where feasible.

 

[Drey6]

What would you define as cheap? The kit was $90 and everything seems to be correct other than what (to my eye appears to be different. I would rather not make the situation worse with these. Thanks for your input, I may set them aside. Any idea on removing the valve seats pictured above? Also, the manual recommends setting the float height. Other than adjusting the leaf springs, is that the only way to adjust them?

 

[titan5699]

I have noticed that as well. I have a 76 and I noticed the books say 40. After I already ordered and installed the rebuild kits I realized the slow jets were 38 and the books say 40. After that I started checking all the rebuild kits online to see what they say, all the ones I saw say 38. The bike seems to run fine, though, but I am curious about the 40 too. I wrote it off as a misprint (I have found a misprint in the Clymer manual before -pertaining to the points gap). I would like to hear about this too, I am not all that experienced with these bikes, it's my first one, so I would like to hear from people with more experience.

 

[surffly]

Is the carb kit OEM?
But I don't think the brass comes in the kit.

Aftermarket parts are a no no in carbs.

Try jetsrus

 

[Drey6]

http://m.ebay.com/itm/130995208020?nav=SEARCH&sbk=1

Here is the link. The description says "new reproduction". Which sounds like aftermarket to me. I also must have been looking at another order when I said it costed $90. This was only a little over $50 obviously with shipping.

 

[titan5699]

Is the carb kit OEM?
But I don't think the brass comes in the kit.

Aftermarket parts are a no no in carbs.

Try jetsrus

I don't seem to have any noticeable problems with mine. They were after market. Same company DCC carries.

 

[Drey6]

I don't seem to have any noticeable problems with mine. They were after market. Same company DCC carries.

I'm assuming mine may be okay as well. Obviously, I'll keep the originals and if all fails I will go back but I guess it won't hurt to try. They need a good cleaning as they are anyways. Still much different from my CM400 carbs so I'm taking my time to ensure I learn as much about each parts function. I may end up polishing them as well.

Anyone have experience setting the float bowl height? Also, after the cleaning and rebuild from my understanding I will need to sync them once they are back on the bike. In which case I need to purchase a synchronizer. It will be good to have for my KZ550 as well. Any recommended brands that won't break the bank?

 

[focusinprogress]

the 74-76 cb550 carbs are a terrible carb to try to tune for anything other than factory airboxes.....I have extensive first-hand experience with this.

The subtle differences you've noted between OEM jets and what came in your rebuild kits are nothing to worry about, if you look more closely, the difference is not in the part of the jet that is INSIDE the carb body, it is merely only a hair shorter in the bowl side of the slow jet....worst case scenario is you will have to adjust the height of the floats to account for that exact difference in measurement....but it likely isn't enough different to need to do so.

Stock slow jets were indeed 38. 40 is for sure a misprint....I upgraded to 40's in mine for velocity stacks (and 118 mains)

 

[Drey6]

the 74-76 cb550 carbs are a terrible carb to try to tune for anything other than factory airboxes.....I have extensive first-hand experience with this.

The subtle differences you've noted between OEM jets and what came in your rebuild kits are nothing to worry about, if you look more closely, the difference is not in the part of the jet that is INSIDE the carb body, it is merely only a hair shorter in the bowl side of the slow jet....worst case scenario is you will have to adjust the height of the floats to account for that exact difference in measurement....but it likely isn't enough different to need to do so.

Stock slow jets were indeed 38. 40 is for sure a misprint....I upgraded to 40's in mine for velocity stacks (and 118 mains)

Thanks for the input boss. I am indeed keeping it all the same along with the stock airbox. This is a resto/ rider project and I just want a solid running bike. Thank you for restoring confidence that it was a misprint and that my kit should be fine.

 

[focusinprogress]

just remember that after you rebuild the carbs, if it's still running poorly to check the boots from carb to motor don't have any leaks/cracks by spraying a bit of carb cleaner at them and see if idle speed changes. After that, just follow routine maintenance procedure and do cam chain tension, valve tappet clearance, points gap, and then check carb sync (always sync last).

that should get her running nice for ya. I've done a LOT of cb550's lol.

 

[titan5699]

I'm assuming mine may be okay as well. Obviously, I'll keep the originals and if all fails I will go back but I guess it won't hurt to try. They need a good cleaning as they are anyways. Still much different from my CM400 carbs so I'm taking my time to ensure I learn as much about each parts function. I may end up polishing them as well.

Anyone have experience setting the float bowl height? Also, after the cleaning and rebuild from my understanding I will need to sync them once they are back on the bike. In which case I need to purchase a synchronizer. It will be good to have for my KZ550 as well. Any recommended brands that won't break the bank?

I completely rebuilt my carbs, so I did have to adjust the float heights. Not too difficult, just make sure they are right! Off hand I forget what the spec is for it, but it should be in the manual. Just purchase a float height gauge, the how-to is also in the manual, just follow the directions and you'll be fine.

Yes, it is best to sync the carbs. It is a must if you are separate the carbs from each other. I bench synced them, just roughly making sure the throttles sit evenly, then synced them with a gauge on the bike. The one I have was given to me with the bike and its an old mercury liquid style. Works well enough, but I do wish I had the dial gauge style. I normally see them go for around $100, but I think I have found them on ebay for closer to $70 or so. If they don't come with the brass vacuum port adapter tubes, make sure to pick up a set, 6mm I believe is the diameter. It's not too hard to do, just more of a pain in the ass lol. There should also be instructions on how to do the syncing process in the manual.

 

[titan5699]

the 74-76 cb550 carbs are a terrible carb to try to tune for anything other than factory airboxes.....I have extensive first-hand experience with this.

The subtle differences you've noted between OEM jets and what came in your rebuild kits are nothing to worry about, if you look more closely, the difference is not in the part of the jet that is INSIDE the carb body, it is merely only a hair shorter in the bowl side of the slow jet....worst case scenario is you will have to adjust the height of the floats to account for that exact difference in measurement....but it likely isn't enough different to need to do so.

Stock slow jets were indeed 38. 40 is for sure a misprint....I upgraded to 40's in mine for velocity stacks (and 118 mains)

I have a 76 CB550, I got rid of the OEM air box and got some cone "K&N Style" filters from DCC. The bike definitely didn't like those.. too restrictive, the exhaust just shoots out black from running too lean. She runs pretty well with just open carbs, as of right now I don't have any other filter to put on. I did however just order the UNI pods. I have heard that these bikes run better with the UNI pods than the other pod style filters. Can you confirm this? If they don't work, I guess I'm going to have to get some velocity stacks..

 

[focusinprogress]

I have a 76 CB550, I got rid of the OEM air box and got some cone "K&N Style" filters from DCC. The bike definitely didn't like those.. too restrictive, the exhaust just shoots out black from running too lean. She runs pretty well with just open carbs, as of right now I don't have any other filter to put on. I did however just order the UNI pods. I have heard that these bikes run better with the UNI pods than the other pod style filters. Can you confirm this? If they don't work, I guess I'm going to have to get some velocity stacks..

The experiences I described were in fact with UNI pods. the issue is that the pods cause some turbulence in the air which no matter what you do cause surges and "hunting" in the rpms depending on outside temp, wind, etc. Mine ran differently every time I rode it on pods.

I would recommend going with velocity stacks from Steel Dragon, he is the main supplier for DCC and other sites selling them and is a REALLY stand-up professional guy. I bought them from him and quality was bar-none. Either that or swap to 77+ cb550 carbs and enjoy how well they run with a simple main jet swap and adjustment of the mixture screw with pods/stacks.

 

[SONICJK]

Theres really no reason to replace old brass unless its buggered.
Clean it really well and stick with OEM quality if you can.