[wackmorris]

Hi all. My bike has struggled with maintaining a consistent idle when hot since day 1. Paid hundreds of dollars at my local shop with no positive results. The bike has been sitting for over 3 months ever since I busted my throttle cable. Finally got out yesterday and started removing the old throttle cable when I discovered one my air filter pods has large gaping holes in it. It's obviously been modified to fit flush against the battery mount by the previous owner. Could this have been the culprit all along?

I ordered a new set of pods on ebay (pictured) which are oval-shaped and should fit more easily. Do I need to change my jets to accommodate for the difference in airflow? Also, has anyone used these pods before?

Thanks!

 

[ancientdad]

I've never used those myself but I can certainly tell you the seriously reduced intake restriction caused by a set of pods themselves - even good ones - would require jetting changes, which is probably what you're referring to about money spent at the dealer. The factory air filters provide more intake resistance than most people realize, and the complications it creates when changing to aftermarket filters is often overlooked. Greater intake flow = need for more fuel to match, but achieving the proper balance that the factory designed into the OEM system is more difficult than most realize... it's trial and error

 

[wackmorris]

Thanks for the tip! I'm not opposed to picking up a set of OEM filters, I just bought these because they're more narrow. Based on the photos, would you say my old filter was contributing to my idle issue?

I've never used those myself but I can certainly tell you the seriously reduced intake restriction caused by a set of pods themselves - even good ones - would require jetting changes, which is probably what you're referring to about money spent at the dealer. The factory air filters provide more intake resistance than most people realize, and the complications it creates when changing to aftermarket filters is often overlooked. Greater intake flow = need for more fuel to match, but achieving the proper balance that the factory designed into the OEM system is more difficult than most realize... it's trial and error

 

[ancientdad]

Thanks for the tip! I'm not opposed to picking up a set of OEM filters, I just bought these because they're more narrow. Based on the photos, would you say my old filter was contributing to my idle issue?

Possibly the idle, but not nearly as much as anything above idle - when the volume of air increases through the carbs, the added restriction of the factory design helps it draw more fuel through the jetting circuits. there can be many other factors involved in your low speed/idle performance. Since you're unsatisfied with the shop you've used (which is not surprising to hear, believe me - we hear it all the time here), you might start by going over all aspects of the tune-up to be sure of what you're dealing with before digging too deep into just one. Check the valves, cam chain tension, then points and timing (at the very least do static timing with a test light at the F and LF marks) and go from there. Retarded timing will affect idle in a hurry on these engines. Do you have the Factory Service Manual (FSM)? Someone here will get one to you if not, there are links at the website for them

 

[wackmorris]

Thanks Tom. My most recent tune-up included: points, timing, needles & seats, multiple gaskets replaced, etc... I rode it a maybe a total 4-5 hours before my throttle cable snapped a few months back. Prior to the tune-up the bike would struggle to stay running after reaching operating temp. After the tune-up I experienced the opposite problem. The bike would run okay for the first 20-30 minutes, then reach operating temp and would start revving high uncontrollably. Everything I read suggested an air leak causing it to run lean, then I discovered the air filter just yesterday.

Do you have a set of filters you'd recommend?

Possibly the idle, but not nearly as much as anything above idle - when the volume of air increases through the carbs, the added restriction of the factory design helps it draw more fuel through the jetting circuits. there can be many other factors involved in your low speed/idle performance. Since you're unsatisfied with the shop you've used (which is not surprising to hear, believe me - we hear it all the time here), you might start by going over all aspects of the tune-up to be sure of what you're dealing with before digging too deep into just one. Check the valves, cam chain tension, then points and timing (at the very least do static timing with a test light at the F and LF marks) and go from there. Retarded timing will affect idle in a hurry on these engines. Do you have the Factory Service Manual (FSM)? Someone here will get one to you if not, there are links at the website for them

 

[FrankyV]

I think with any pod filters will run lean without re-jetting the carbs. I am really surprised whoever worked on the bike never took off and inspected the pods, don't take your bike back to them. With those pods, your bike has been sucking unfiltered air and the uncontrollable revving suggests major carb issues so it is time to rebuild them. Then start from scratch- stock jets, stock air boxes and filters, stock (style) mufflers.

 

[wackmorris]

Thanks Franky. I too am surprised they overlooked the pods, makes me wonder what else they might have overlooked. I live out of state now so I won't be returning there. Still hurting over how much money I threw at them to fix this problem.

I think with any pod filters will run lean without re-jetting the carbs. I am really surprised whoever worked on the bike never took off and inspected the pods, don't take your bike back to them. With those pods, your bike has been sucking unfiltered air and the uncontrollable revving suggests major carb issues so it is time to rebuild them. Then start from scratch- stock jets, stock air boxes and filters, stock (style) mufflers.

 

[WintrSol]

I think these work better than pods: Scrambler Cycle - Honda 68-71 CB450 67-71 CL450 Air Filter Set Left and Right - Reproduction
You can go back to stock jetting, and they use the crossover tube, for better peak flow.

 

[paulcmalone]

Take a good look at the inlet side of your carbs, and again at that big old lip on the inside of those pod filters. You should notice that the lip blocks your intake air jets. That blockage leads to more fuel being sucked out of the carbs, and less air - making a rich mixture that will foul your plugs. If you plan on sticking with PODS, spend the $$ on K&N filters that don't have that lip on the inside.

If my bike wasn't already butchered when I got it, I would have used the OEM filters and air box; The POD filters require time and patience to get sorted. They also allow any moisture (i.e. rain) to get sucked straight into your engine, making you a "fair weather rider" and unwilling to leave your bike outside in the elements for fear of rusting out your cylinders.

 

[WintrSol]

Take a good look at the inlet side of your carbs, and again at that big old lip on the inside of those pod filters. You should notice that the lip blocks your intake air jets. That blockage leads to more fuel being sucked out of the carbs, and less air - making a rich mixture that will foul your plugs.

All that, and worse; without the air entering the mixing chambers, the droplet size of the fuel exiting the jets is larger, making for poor combustion, and some clinging to the sides of the intake and not burning at all. Overall, a bad situation.