The International CBX Owners Association

daves79x wrote:As I said in a previous post, yes, the special bolts are available, but you need the special washers also to make a tight fit - make sure you get them.

Yes, thanks, I ordered them both - 20 & 21 on this fiche:

I'm with Nils. I prefer the stock bike. Slight mods to make the bike more reliable, but the mods are from the same time era. Mods to my 80 consitited of a sport kit and black steel braided brake lines. The only other additional mod I would like to make is to install an RC Engineering 6 into 2 exhaust, if I can find a nice one.

With that being said I love reading the posts. I am amazed at the wealth of knowledge the people on this web site have. Keep up ther good work.

The airbox screws have finally arrived - I'm having the lid fitted, the filter cleaned & oiled, and the carbs synced on Thu. I should have a chance to do a bit of riding over the weekend and next week to see how everything's working before deciding on next steps - but a dyno run & rejet is looking very likely.

My backup screws arrived at my door today, so I installed the lid and did a quick test ride.

Vast improvement. I wasn't able to do a real test ride as it was just a few degrees above freezing and it started raining as soon as I left the garage. Also, the nearby highway where I wanted to open it up was chugging along at 20kph.

Despite the challenges, though, I did get it wound up a few times, and was also able to pull from low revs in high gear. It's running much better now although it still has some off-idle stumble and some light-throttle midrange hesitation. The awful induction resonance is much abated. I'm looking forward to seeing how it runs with the carbs synced, but I do expect that the dyno will show that it needs jetting.

Very cool, great to hear Phil.

N.

+10 and sunny for Saturday, Phil.
Don't be the first guy caught this Spring for for 50kmh over.

steve murdoch icoa #5322 wrote:+10 and sunny for Saturday, Phil.

I'm well aware.

And I'm gonna be driving a stupid car out to go visit family for Easter. Sunday is supposed to be nice too, but my wife and I are going for a bicycle ride. But today is my last day at work for probably a few months, so I'm looking forward to plenty of fun riding. :)

Don't be the first guy caught this Spring for for 50kmh over.

Don't worry. I'm mega-careful about that. I could get plenty of tix for 48 over, but shouldn't ever get dinged for 50. :)

The bike is at the shop this morning for the sync. Riding it out there this morning in heavy stop & go, I found that the off-idle and part-throttle hesitation below 3k are still pretty bad, despite being much improved from the no-lid configuration. The sync can't hurt, but I'm looking forward to having the jetting sorted out, too.

Phil,

If you see James tell him Rick Pope says "Hi".. It's been a long time since I've seen him.

Will do, Rick.

Picked the bike up after having the sync done yesterday and it's another quantum leap in rideability. I could probably just ride it as-is and be OK at this point, but I'm looking forward to getting the jetting dialed in a bit better.

and it's another quantum leap in rideability.

Good on ya, Phil. You just gotta love it when a plan comes together
Now....get out there a rack up some mileage

Syscrush wrote:I could probably just ride it as-is and be OK at this point, but I'm looking forward to getting the jetting dialed in a bit better.

I take it back - I was a bit over-enthused. :) When the temps dropped a bit, the off-idle stumble became quite a bit worse. Stop & go on this bike kinda sucks right now, although it's pretty good once underway. The rejet has been re-promoted from "nice to have" to "necessary".

This is where I feared you'd be after all the stuff you did. Your pipe alone is not causing the low-speed problems - in fact has very little to do with it. Perfectly clean and properly operating '79 carbs with stock jetting compensate quite well for aftermarket pipes and the bike should run just fine. So we're back to the carbs. Certainly the accelerator pump is not working very well, but with perfectly clean idle circuits, the bike should run pretty well w/out the accel pump. My guess is there is still blockages in the idle/pilot circuits. This assumes that you have no intake-side air leaks. They all run good above 3000-4000 rpm - it's getting them to run right on the low-speed side that's the trick. You see how annoying and tedious the bike is now. Does it run better down low with the choke slightly on? If so, that's a dead give-away. Someone that knows exactly what they're doing needs to go completely through the carbs again to see what's not right. I'm assuming you have a lot of money tied up in this bike now and it needs to run like it should. I'm sure you'll get more suggestions, but from my experience, the carbs have to come off again, but they have to come off anyway if you decide to just try rejetting. You are actually just taking someone's word that the carbs have stock jets in now, I assume? Have you looked to be sure? I'd be starting at square one with the carbs.

Dave

Thanks Dave.

Since I'm not in a position to do my own work on this bike (or any others for the forseeable future), all I'll ever have to go on is someone else's word.

I'm going to call 2 separate shops tomorrow and pick one to handle the next steps. They're both shops that I've had good experiences with in the past, I'll make the decision based on who is more comfortable with or enthusiastic about dialing in 6 vintage carbs. I'm also going to call the guy who did the last round of work on them (setting stuff back to stock and fixing a leaking issue) to get the whole story about what was and what wasn't done.

Whatever he says, I'll pass on the heads-up about the idle/pilot circuits and accelerator pump to the shop I take it to.

I do want to get this stuff sorted out and correct, and don't want to take a penny wise, pound foolish approach by applying costly bandaid fixes over more fundamental issues. But I also don't want to preemptively spend money unnecessarily. The core dilemma of taking over ownership of a vintage bike, I guess.

Thanks again,
Phil.

Little update: the first shop I called (Cycle Improvements in Waterloo, ON) made basically the same suggestion as you, Dave. He said that the current behavior points to issues other than jetting, and before he takes my money to do a dyno tune we should have a look at the fundamentals: leakdown test, valve clearances, and thorough cleaning for the carbs.

I'm going to put the last guy to work on the carbs in touch with my local mechanic (Tom at Cyclewerx in Toronto) and let them decided on the best course of action for next steps.

Another little update: 5 of the 24 valves were a bit out of spec (I forget the numbers, but they were tight), but they're all right in the middle of the range now (only 5 were out of spec, but the mechanic ended up adjusting 18-20 of the valves to get them uniform). Carbs have been taken apart, inspected, cleaned, and reassambled with new gaskets and o-rings and a Dynojet Stage 1 kit. They're doing a leakdown test too, don't have results for that just yet. My CBX-tras alternator showed up yesterday, so that'll be going on, too.

If the leakdown results look OK, I'll have the bike back by the end of this week. I'm looking forward to putting some miles on it and seeing how it feels with these items addressed.