Immaculate 1981 Surprise

[Airborne]

Hello Dave,

You are most certainly right, I was pleased that work was progressing fairly smooth, but now it's getting to be more complicated. I might be very naive, but looking at the condition of these carbs and very limited use before the bike was stored, is there a chance that I could be fine without doing the o-ring job? Perhaps they are not worn out and if left alone may work just fine? Please tell me straight away if my thinking is naive, as I understand the rubber may decay regardless of whether the bike was used or not. If I have to do the o-ring job, so be it! :)

Furthermore, I have noticed on many carb repair kits, that there were 4 different o-rings per carb, but when I was just trying to see if I could only get o-rings without jets and needles (as I will be getting larger jets elsewhere), there were only 6 o-rings available. I have opened each carb, took floats, needles and jets and I have not encountered a single o-ring just yet. I'm assuming there will be an o-ring for each connection, but should I expect 4 o-rings of different sizes per carb to yet be discovered?

Finally, I tried navigating through multiple sites, but cannot find a good step by step guide on how to separate carbs from the rail. Would anyone happen to have a link or a document that might help with that...?

Following your advises, I'm getting all new seals and o-rings (providing you verify I have to replace them), but I'm getting larger jets rather than stock ones that are available through most repair kits, therefore I am buying all these parts separately. I believe however, that this is sill a home run, as considering how clogged these jets were, I believe this to be the reason why the bike did not run.

Please kindly advise on the questions I have and I will keep you posted as I progress!

Kind regards,
Airborne

[daves79x]

Ok - I'd probably chance it if I were you and just clean everything you can the way they are. If the carbs haven't been subject to overheating, the O-rings will likely hold for a while, but you never know. Since you have the individual filters, the carbs can be removed easily enough later.

An aside - do you still have all the stock airbox and plumbing? I would strongly suggest you consider putting them back on and stay with the stock jetting. It will be a much better-running bike and be a lot less hassle jetting. I can't recommend this strongly enough.

If you decide to keep the pods, you'll need much larger main jets (120-125). The bike will still have spots where it won't pull cleanly, but that's what pods do.

Randakk has the best kit for the rubber parts.

Let me know if I can talk you into reinstalling the airbox (did I mention that?).

Dave

[Airborne]

Hello Dave,

Thank you kindly for the response. Sorry for the delay, but i was gone on a motorcycle rally to south IL, it was time to enjoy riding my bike as well, than just working on the cbx!

I'm back working on the CBX and I will do as you recommended. The bike has always been stored in a garage which has climat control, always protected under the cover, therefore I will give those o-rings a shot. If they do leak, I will bow my head and go through the process again, but now that I know everything that needs to be done to get to this point, it will be easier.

Furthermore, it may please you to learn that I decided to follow your advice and stick to the original airbox (please find a pic attached). Since the jets look great right now, it seems like a better idea to give it a shot and see if the bike runs well or whether there are any other problems in the engine I need to address, before I go though the process of getting larger jets. If all works well and my father still likes the idea of individual air filters, I will happily swap these jets as now I know how to do it, where to get them and what size to get, thanks to you.

At this moment I am waiting on float bowl gaskets in order to close the carbs, after cleaning all of them. Then once the rail is back on the bike, the critical test will be awaiting, which I'm estimating sometime at the end of next week.

I will keep you posted and will keep posting pics as I go. If you want any info while I have things apart, holler at me. I'm sure I will be asking plenty questions as I go and put things together. Most importantly however, keep your fingers crossed!

Kind regards,
Airborne

[steve murdoch icoa #5322]

Don't know if you have already ordered parts yet but the kits from Randakks are top quality.
http://randakks.com/products/randakks-o ... erhaul-kit

[EMS]

Dave is on his way to the ICOA rally at Fontana Valley and has no computer access during the day. Please be patient. He will respond as soon as he gets the time in the evening.

[daves79x]

Just make sure you bench test the carbs wet for several hours for leaks. During this test, verify the accelerator pump nozzles all work. This has to be done before you install the carbs.

Dave

[RJ CB650]

They are very different from the jets I pulled from the CBX (please find pics attached). Since I am not familiar with the bike just yet, could you please kindly confirm whether these jets will still work, despite being so different? Also, I am understanding that I only need to worry about main jets, not slow jets, correct?

For your interest, please find pics of both jets and carb rail in progress!

download/file.php?id=1860&mode=view

Airborne

Hopefully the inserting of attachment works.

Anyways, trying to get the just, it was missing airbox and is pod filtered? Been busy working on the bike to lurk much so speed reading and spotted the picture with the pilot jet. My brain is saying that the jet seems to be a larger than stock unless it is stamped the 35. My 35s seem to be quite fine holes and those seem beefier, similar to the 50s I pulled out of my pilots.

[Airborne]

Hello Dave,

Hope the rally was good and I hope to be there next year with my dad or at least bring his CBX to meet y'all!

Gaskets finally arrived and I began the assembly (pic attached). I will certainly pressure test every carb once i'm done with the assembly and will keep you posted, hopefully this week!

Yes, I'm sure these are stock jets, as this bike never had carb job done since new.

Kind regards,
Airborne

[RJ CB650]

Never had carbs done since new? What is the length on the low speeds. Those looks like 23.5mm, not 28mm length. I will snap pics of my spares. I won't be back in garage til tomorrow, so it could be mind playing tricks or I have the wrong jets. Mine originally did have oversize jets but I swapped back to what was supposed to be original and they are the same dimensions?

I am nowhere near the expects on the detailed ins and outs compared to majority of the guys here, but am pretty good with mechanics and fine details of design. Those jets just seem shorter. This issue is specifically clear in my mind when I received the wrong jets which were the 23.5s and visibly shorter. Specifically the tube end with the driver slot. The length from the diver slot end to the threads is where the variation in length is but rest is the same in regards to fit. I noticed in a previous picture you had the carb assembly out and before that the carbs still on engine and I didn't notice or see the bracket for air cutoff valve for the fuel.

I do not want to comment too much on what mine has and had since somebody on mine quite clearly tried to work on it without knowing what they were doing prior to when I got it. But that said, that jet picture is just nagging at me and would absolutely hate for you to go through so much work then have to remove them again or not have it running right when it is finally all back together.

[daves79x]

I think you are referring to the vacuum fuel shutoff bracket - not the air cut-off. It looks to be in place on the first carb pic.

Dave

[RJ CB650]

I think you are referring to the vacuum fuel shutoff bracket - not the air cut-off. It looks to be in place on the first carb pic.

Dave

Quite right. I was thinking about that later, my apologies!

[RJ CB650]

Okay, now i am feeling very, VERY! Stupid, and a bit more mad. It was a cross reference I never caught before, and now just completely flubbered.

When I got my CBX, first thing I did was pull the carbs. I had all sorts of butchery to fix. Stuff like carb service parts, I don't ever trust previous person to have done it right so just straight up got new parts. Doing my latest service, I got the stock jets I had bought and just pulled out and put them beside the ones I originally put out. Reason for my confusion was that the butchery tuning put in 28mm, and that is what my brain was referencing. So when I got new jets a bit ago, I had ordered the next size up from 35 in the 23.5mm length which I thought they were. Well, when they came in, I put them beside my junk 50s, and thought, oops so re-ordered them in the 28mm... so 23.5 is correct, but i was seeing the longer ones in my kit. Was tough to reference the correct length in the carbs. Sorry bout that! I really hope I did not cause any concern or issue.

My carbs really were butchered and it didn't cross my mind that the incorrect length was put in. I mean the vent tees had been cut off with side cutters, fuel line and fuel vacuum valve replaced with cheap rubber vacuum lines and a plastic air tee, etc.

[Airborne]

Hello Gentlemen,

I have been traveling for business recently, therefore took a little time to finish the job, but I have finally gotten all carbs cleaned up and assembled. I must say, that looking at jets' condition, I am quite confident this was the problem and look forward to testing the bike again. I hope none of that junk is clogged further down the engine.

Please find a picture of fully assembled carbs with old gaskets out. Now, the next step, per Dave's recommendation, is pressure testing. I do have a compressor at home with a standard tire gauge. What would be the best course of action regarding pressure testing? I've never done it before, therefore any detailed explanation or a link to a manual on how to do it would be greatly appreciated. Where should I test it on a carb and anything I should know, please kindly let me know.

Thank you and I look forward to hearing back from you!

One step closer to making her run this summer!

Kind regards,
Airborne

[NobleHops]

No, not pressure testing, simply leak testing. Hook up an aux fuel bottle, put the carbs in some kind of catch pan, level, and fill them with fuel. See if they are leaking. I'll leave it to others to detail the accelerator pump test, but I think it's as simple as working the throttle (with fuel on) and verifying that each nozzle gives a good squirt when you actuate the throttle.

[daves79x]

You pretty much got it Nils. Detail on the wet testing - do yourself a favor and buy a 'T' and 3 feet of 5/16 fuel line. Fashion up a by-pass for the vacuum valve so that you can run gas straight into the carbs via the 2 inlets. Otherwise, you need a vacuum source to open the valve.

I like to prop the carbs up with a 2x4 to nearly their installed angle to wet test. Turn the gas into the carbs and any leaks will be pretty apparent. However, several hours of no leaks is preferred. To test the accelerator pump, many times it will prime by quickly 'blipping' the bellcrank to operate the pump arm. If a dozen or so blips don't produce fuel squirting from the nozzles (you do know where they should be squirting from?), carefully grasp the accelerator pump rod with needlenose pliers and manually stroke it fully to get the fuel squirting. It then should squirt by operating the bellcrank. My guess is this won't work at all since proper operation depends on about a million little things being checked/fixed/verified when rebuilding the carbs. You should then go about fixing this before installing the carbs.

Let us know what you find.

Dave