Airbox replacement with inline filters.#%&X

[67Thunderbird]

Hi

Has anyone had issues with these installed.
Specifically carb problems
Idling all over the place
Hard to start.

I have reset the pilot screw adjustment to 2 turns (wish I hadn’t of messed around with at all tbh)

First time I rode the bike with new air filters the bike ran well for about 15 minutes and then started choking up and wouldn’t rev past 4k. Plugs very black so I I thought I had a fuel issue.

How sensitive are these pilot adjustments

I’m seriously thinking about putting the original air box back in. It just makes pulling the carbs out/in so much harder.

I’m fairly new at this btw so any good advice appreciated. Just don’t send me down some worm hole to a place of no return.

Cheers.
Birdman.

 

[Old_Crow]

Most of the advice you're going to get on those CV carbs on the 2nd gen 750 is going to be to put the stock air box back on. The diaphragms in the CV carbs need vacuum to work right and the pod filters are just too free-flowing. Occasionally someone will claim to get their bike to run right with the pods, but those people are far and few between.

 

[67Thunderbird]

Most of the advice you're going to get on those CV carbs on the 2nd gen 750 is going to be to put the stock air box back on. The diaphragms in the CV carbs need vacuum to work right and the pod filters are just too free-flowing. Occasionally someone will claim to get their bike to run right with the pods, but those people are far and few between.

Thanks old mate
I’ll put the airbox back in.

These 750s are very sensitive. I can almost hear her swearing at me lol

 

[Old_Crow]

Thanks old mate
I’ll put the airbox back in.

These 750s are very sensitive. I can almost hear her swearing at me lol

Wait'll you hear what she has to say when you accidentally run into her with your Jeep and crush in the side of the gas tank with pristine factory paint...
I'd almost rather have a crazy ex-wife. Might be cheaper, too.

 

[67Thunderbird]

Yes I completely understand.
I bet you were in the dog house for a month.
750 reasons id still pick her instead of the crazy ex.

 

[Old_Crow]

This would be before the incident:

Then this would be the day of infamy (so to speak)

This was a month later (actually I rode it all last summer like this and people still complemented me on the bike)

I live winters in Arkansas and work summers in California. The painter was not done with the bike before I had to leave for Cali this spring, so this is the last picture I had before I left:

I found the stripe kit at vintagecb750.com and spent months (and a couple of hundred bucks on samples) looking for the correct paint colors. Finally gave up and took the tank to the paint store and let them match the paint as close as they could.
Like I said, the paint wasn't done by Easter, so I'm looking forward to November, when I arrive back in Arkansas, like a kid looks forward to Christmas.
Sorry to hijack your thread, but I thought you deserved the whole story. This is actually the first time I've put all 4 of those pics together in a post. Makes me sad all over again. Good luck with your baby.
BTW, I also had to have the intake boots replaced on the carbs. You can't see it in the pics, but apparently side loading 45-year-old rubber boots doesn't do them any good.

 

[67Thunderbird]

Cool mate

Looks really good.
Opposite seasons down here in Brisbane, Australia so getting into winter now.

That tank damage was painful to look at. Ouch!
Lucky it was above the engine line.
Did the HONDA logo badge on the tank come standard on that model.
My 81 just has the decal stickers and they’re hard to find. And rediculous prices.
I think now with advanced printing they can make them much cheaper.

I do a restore on my bike once I’ve mastered a few more skills.

Have a good weekend

 

[Old_Crow]

The sticker kit was a bit on the spendy side, but I bought the bike because it was the 10th anniversary limited edition bike and the paint and striping are unique to that model. I had another of these bikes back in the 90's and I painted that one teal and actually regretted losing the special paint afterwards. The side covers are getting painted too, so it'll all match and look stock unless I have the fortune to park next to another Ltd model somewhere.

Yes, the badge is OEM. You can see the mounting plate on the side of the bare tank. Just got realllllly lucky that I missed it. I hit the thing with my Jeep as I was unloading the Jeep from the trailer (wet shoes, foot slipped off the clutch pedal). There's a winch with a big fairlead on the front bumper and the fairlead is what hit the tank. If I had had a bare bumper, it probably would have crushed the badge and maybe the side cover too.

The carbs got tapped hard enough to crack the old boots, but not hard enough to damage the carbs themselves. Had a shop replace the boots and sync the carbs and it runs as good as new. Better than it did before actually because the carbs were a bit out of sync before they got tapped.

I used to own a hot rod and restoration shop. I've painted a lot of bikes, but around 10 years ago my wife and I sold everything and moved into our motor home. I no longer have the equipment or a place to work or I'd have painted it myself.

 

[67Thunderbird]

The sticker kit was a bit on the spendy side, but I bought the bike because it was the 10th anniversary limited edition bike and the paint and striping are unique to that model. I had another of these bikes back in the 90's and I painted that one teal and actually regretted losing the special paint afterwards. The side covers are getting painted too, so it'll all match and look stock unless I have the fortune to park next to another Ltd model somewhere.

Yes, the badge is OEM. You can see the mounting plate on the side of the bare tank. Just got realllllly lucky that I missed it. I hit the thing with my Jeep as I was unloading the Jeep from the trailer (wet shoes, foot slipped off the clutch pedal). There's a winch with a big fairlead on the front bumper and the fairlead is what hit the tank. If I had had a bare bumper, it probably would have crushed the badge and maybe the side cover too.

The carbs got tapped hard enough to crack the old boots, but not hard enough to damage the carbs themselves. Had a shop replace the boots and sync the carbs and it runs as good as new. Better than it did before actually because the carbs were a bit out of sync before they got tapped.

I used to own a hot rod and restoration shop. I've painted a lot of bikes, but around 10 years ago my wife and I sold everything and moved into our motor home. I no longer have the equipment or a place to work or I'd have painted it myself.

Ok thanks mate,

I’m restoring a couple C110s to my skills up.
I did an electrical fitter trade back in the last 80s as part of my 7 years in the Navy as a weapons mechantic (also did 6 months in San Diego leading the 5 inch gun)
Then the last 30 years as a Tax Accountant lol
So I know I can learn if you put in the effort plus I find it very satisfying and my lovely wife hasn’t complained YET

 

[67Thunderbird]

Hey Old Crow,
I’d really appreciate some advice on my 750.
I just put the airbox and carbs back in (what a pain)
Bike was hard to start but eventually fired up and seemed to idle again for 5 minutes so thought I’d ride around the block. Didn’t take long for the engine to start coughing and sounding terrible. I stalled half a block away.
I pulled the plugs and they weren’t too bad but I cleaned them and she started and I nursed home luckily.
I’m thing my pilot screws might need to be screwed in (currently at 2 full turns out)

I’ve hardly ridden this bike since I bought it in January. Initially I had a back fire on no. 3 cylinder but I found a bad plug boot so I’m getting decent spark to all 4 cylinders.

Only other thing I did since buying it was install a Delkevic exhaust and clean the carbs.

Starting do my heading to be honest.

Thanks

67T

 

[81cb750f]

Hey Old Crow,
I’d really appreciate some advice on my 750.
I just put the airbox and carbs back in (what a pain)
Bike was hard to start but eventually fired up and seemed to idle again for 5 minutes so thought I’d ride around the block. Didn’t take long for the engine to start coughing and sounding terrible. I stalled half a block away.
I pulled the plugs and they weren’t too bad but I cleaned them and she started and I nursed home luckily.
I’m thing my pilot screws might need to be screwed in (currently at 2 full turns out)

I’ve hardly ridden this bike since I bought it in January. Initially I had a back fire on no. 3 cylinder but I found a bad plug boot so I’m getting decent spark to all 4 cylinders.

Only other thing I did since buying it was install a Delkevic exhaust and clean the carbs.

Starting do my heading to be honest.

Thanks

67T

I have a stock 81 CB750F. Currently the pilots are 2 turns out (full turns, not half turns). Rather than use the tedious and time consuming idle drop method mentioned in the shop manual, I started at 3 turns after rebuilding and cleaning the carbs as that's what the Macgregor Manual says https://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revG.pdf.
I've been fiddling with the number of turns as I encountered an occasional "cough" when the throttle is slightly open, when riding, never when accelerating.
Anyways, long story short, is that I think you have other issues. From what I've learned (could be wrong) is that the pilot screws only affect running under idle and when the throttle is slightly open. Kind of makes sense as while I've been changing the turns out, the bike runs very good (except for the cough), and the only thing that changes is the idle and I have to re-adjust it. I've tried 3, 2 1/2, and 2 turns and the bike runs almost the same except for having to adjust the idle. I've scanned the forum for number of turns and most of the advice given is anywhere from 2 to 2 3/4 turns.
Have you synced the carbs? If not, I would try that next.
That's next on my list anyways.

 

[67Thunderbird]

Thanks.
I synced carbs about a month before I pulled the carbs out but I can try doing it again.

It’s just a bit confusing why the bike went from running at 75% ok on one bad plug cap to now choking up.

 

[81cb750f]

Thanks.
I synced carbs about a month before I pulled the carbs out but I can try doing it again.

It’s just a bit confusing why the bike went from running at 75% ok on one bad plug cap to now choking up.

hmm. how does it run with throttle half open?
If still not good then all i can suggest is timing, valves, both of which I'm sure you've done, or maybe cam chains and/or tensioners.

 

[67Thunderbird]

Thanks.
I’ll checking timing. I’ve never done it so something I need to learn.