[Brady]

Ok, so I'm making progress but still not all the way there... New points, condensor and coils, wires, spark plug caps, connectors, carbs clean, float height set properly, cleaned advance mechanism, etc. The bike fires up immediately and idles fairly smoothly at about 1500rpms(with the occasional popping on the right side). The left side seems to be working brilliantly. The right side on the other hand does not...

With both sides hooked up and firing, the bike will ride okay and rev up to about 4-5000rpms before bogging way down. (Parked, it'll rev up to the redline) If i lift the throttle on the right side carb, it'll start reving up to about 2000rpm then it'll bog way down. If I remove the left plug cap, and run solely on the right side, it completely dies.

Any ideas or things I should check? Thanks in advance!

-Brady

 

[Flugtechnik]

Have you checked compression?

 

[Brady]

I'm having a hard time getting the actual compression... I have one of those stupid psi testers that doesn't screw into spark plug threads, you just have to push and try to hold it in place. The highest I can get the meter to read before it blows off the hole is 120 on each side... Maybe later I can try to get my roommate to help me hold it in place while I kick...

 

[Flugtechnik]

Go borrow one from Autozone or one of the other auto parts places that lend tools. Make sure the throttle is wide open when you turn the engine over. Turn the gas off and turn the kill switch to STOP. I had to turn the engine over about 4-5 times to get the max compression reading when I did mine.

 

[Brady]

Okay, thanks. I'll see if any places around will loan one out.

Question about the compression... would low compression (120-140psi) actually keep the right side from running at all? Or would the bike just not run as well as it should? Thanks!

 

[66Sprint]

The engine will run (no load) down to about 90 PSI....But it won't produce any usable power...

 

[shark81]

dash pot gasket is leacking

 

[Brady]

What do you mean that the dashpot gasket is leaking? Is there some way to verify this? Thanks!

 

[cowley]

I have put 2 450s on the road in recent years and both ran poorly intermittantly until I fitted new condensors. I have heard that the problem with the condensors is their age so you can get new old stock condensors that don't work.

 

[66Sprint]

What do you mean that the dashpot gasket is leaking? Is there some way to verify this? Thanks!

I believe this is the same problem as " bad Chrome Muffler Bearings"..... It's a joke....(inappropriate, but relatively harmless)

 

[shark81]

a dash pot is what sits on top of your of your constant velocity carb's they have cork gaskets and they sometimes dry out and brake or shrink with age. your carb. may not work properly if this is the case I have had this problem with my 71 maybe two times in 39years

 

[Brady]

hmmm, thanks guys. Hopefully I'll get some time this weekend to investigate further...

 

[66Sprint]

Dashpot huh?.... I thought Honda called them Vacuum caps or Vacuum bells.....
I'd believe dashpot on an SU.....LOL.... :lol:

 

[66Sprint]

Wasn't trying to be a smartass....Just never heard that terminology before and thought it WAS a joke......Sorry, No offense meant.... Steve

 

[solarae]

Not to hijack but that term has always baffled me as it shows up in various vehicle manuals but I've never really known what one was.
Feeling a little OCD today so I looked it up.

Definitions of Dashpot on the Web:

A dashpot is a mechanical device, a damper which resists motion via viscous friction. The resulting force is proportional to the velocity, but acts in the opposite direction, slowing the motion and absorbing energy. ...
en.wikipedia.org/wiki/Dashpot

A mechanical damping device consisting of a piston that moves through a viscous fluid (usually oil); used, in conjunction with a spring, in shock absorbers
en.wiktionary.org/wiki/dashpot

 

[boogiesg]

So, I've got a similar problem frustrating me to death as well. A cb500T that should be in perfect tune after a fresh rebuild with all new goodies. Carbs jets didn't need replacing but I did do the mixture screws and o-rings. The gasket that rests under the cv piston seemed fine, it was dry and clean anyways. It's maybe a year old but the carbs have been shelved during most of that time. The other night while checking floats, I noticed the cv piston stick halfway when the carb was returned to it's normal upright position after being inverted. Of course I took it apart and cleaned made sure it was clean, used some mothers polish and a microfiber towel. Didn't really pay much mind to the dashpot other than setting it aside. I'm going to look at it closely first thing after work. I do remember hearing the cv pistons clanking inside the carbs before. Could this be the reason?

 

[borzwazie]

pull the tops of the carbs off. clean out the body with a lint-free cloth with light oil on it. clean the crap out of the slider the same way. bet your slide is sticking. this will free it up.

 

[jensen]

Hi,

A simple check before opening your carb is to see if it gets petrol. My float valve is sticking once in a while after not using the bike for a few weeks. Just remove the float bowl and see if there's petrol in the bowl. As soon as you remove the bowl, the float drops down and the valve is opening, petrol starts to flow.

My bike is on the side stand when not using it, and strangely it's always the right side, never the left side.

Jensen