Honda CX 500 Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
124 Posts
Discussion Starter #1
Hi there, You guys have a wealth of knowledge out there and you have helped me before. I have a 1984 650E UK spec and have successfully rebuilt engine , new seals, big end bearings etc and no water/ oli leaks and runs fine from 3000 revs but will not pull cleanly below about 3000 and it stutters and hesitate on very low throttle openings. and it does not like to tick over very evenly.
Not being a total novice here is what I have already tried /checked:-
1. New plugs (best quality Iridiums)
2. New HT leads (red in colour)
3. New Plug caps
4. Stripped carbs several times, removed jets and jet housing , blown air through the jets especially the slow run idle jets.
5. Checked carb intake rubber tubes for leaks
6. Replaced O rings on inlet manifold
7. Screwed fully in and then out 2.5 turns the idle jet to get approx adjustment then tried turning both out/in one turn
8. Cleaned out petrol tank and fuel lines,(spotless)
9. Got very frustrated
10. Getting angry now
11. Asking for specialist help from other owners (not yet played out)

Its a nice bike and I enjoy riding it but I would like it top be able to potter along those old country roads in top gear below 55mph Could all this be caused by leaking diaphrams?


Help and suggestions welcome......Thanks in advance

Henners:mad:
 

·
Registered
Joined
·
24,186 Posts
have you done a carb sync vacuum balance test?

when you separate the carbs on a 650 you casn throw the linkage badly out of sync at idle so the bike even runs on one till it gets going

so re syncing the carbs is very important
 

·
Registered
Joined
·
3,999 Posts
What Murray said, and I would add that on the 650's the idle jets are removable(I think), if they are it wouldn't hurt to pull them out to make it easier to clean out the idle circuit.
If you just blow air through the idle jet you have to be sure ther air is not just blowing through the hole that goes into the main jet tower. You need to find a piece of small hose that fits in the tower tightly and goes in past the hole to the other tower.

edit; In this pic you can see the hole that is between the two towers, the red line goes through it.

 

·
Registered
Joined
·
124 Posts
Discussion Starter #4
ned at same time visually
have you done a carb sync vacuum balance test?

when you separate the carbs on a 650 you casn throw the linkage badly out of sync at idle so the bike even runs on one till it gets going

so re syncing the carbs is very important

Thanks for the response. No I have not checked the carbs for sync but I have never disturbed or separated them. When I had the engine out I checked the throttles opened together which they did by looking at the butterfly valves as throttle opened.
 

·
Registered
Joined
·
24,186 Posts
yes all jets unscrew on a 650 as do emulsion tubes

visual confirmation may not be accurate a vacuum gauge will tell you what is what right away

also when you installed the iridium plugs sis you remove the resistor from your plug cap or are you running reduced spark

due to 2 resistors?
 

·
Registered
Joined
·
124 Posts
Discussion Starter #6
PS that sync carb suggestion made me think and tomorrow I will unscrew each synch inlet manifold screw and thereby disable each carb in turn to see which one is pulling the other down.
Watch this space.....
 

·
Registered
Joined
·
3,999 Posts
PS that sync carb suggestion made me think and tomorrow I will unscrew each synch inlet manifold screw and thereby disable each carb in turn to see which one is pulling the other down.
Watch this space.....
You could also try removing each spark plug wire in turn to see if it will run on one cylinder.
 

·
Registered
Joined
·
124 Posts
Discussion Starter #8
Brilliant diagram Allen very helpful, I did wonder where the air and petrol mix went in and out of these holes and jets, just sorry you had to ruin a carb to show me!

More confident I am working on the right carb and on the right jet now..
 

·
Registered
Joined
·
124 Posts
Discussion Starter #9
Crikey , not thought about that on plug caps, another avenue of investigation awaits next visit to the garage. I have pulled out an old Honds S90 for a winter project so will keep myself busy, getting a bit chilly to ride out but at least I am not expecting any major carb issues with it !
 

·
Registered
Joined
·
3,999 Posts
Brilliant diagram Allen very helpful, I did wonder where the air and petrol mix went in and out of these holes and jets, just sorry you had to ruin a carb to show me!
That would be LRCxed (Larry) that cut up the carb for that pic, not me, thank him. :)
 

·
Registered
Joined
·
3,501 Posts
Another basic thing to check is that the carbs are fully pressed into and clamped snugly in the rubber insulators (boots, manifolds, etc...) to omit air leaks, and check for cracks in the rubber.
 

·
Registered
Joined
·
124 Posts
Discussion Starter #12
Yes it does but likes one cylinder better than the other so will investigate.
Thanks for response
 

·
Registered
Joined
·
124 Posts
Discussion Starter #13
Yep thanks, found some cracks in rubber inmets which I have now sealed and taped over. Bit of botch but cant get these new anymore and adds character to the bike??

Thanks for reaponse
 
1 - 14 of 14 Posts
Top