Topic: uneven cruising

[keener]

When I am riding at a constant speed I feel the bike jerk forward and back a little, not much but it is noticeable at lower speeds. I am wondering if its the carbs? Points? I know my points are gapped right... and at idle there is more noise when it fires like something small shaking in a box perhaps is a good way to describe it? Any hints would be great!!

[martino1972]

show us pictures of the sparkplug tips,so that we can read them

[keener]

they are new plugs and they are gapped, I am also unable to get the plugs out cuz I am at a friends house who has no tools.

[333]

The first thought that pops in is a loose cam chain, or more likely, something going on with the spark advancer.

[keener]

i did just get a new breaker points and condenser assembly...

[mystic_1]

Uneven carb tuning can cause this, I think.  Have they been vacuum synced?

mystic_1

[333]

Did you check the advancer when you were there?  And what did you lube the points cam with?  I've found that a silicon based grease works best.

[keener]

I have not checked the advancer i will look at the manual now...

[Bido]

I don't know what setup you are running. I had a the same problem with off idle stumble and raised the main jet needle the thickness of one washer and it smoothed out quite nicely. I am running a K&N air filter in stock box, Kerker headers with 2.5 inch competition baffle and a Dyna-S ignition 120 mains On my 78 Supersport [F3].

Good Luck
Bido

[mlinder]

Also check your chain... how much play is there?

[keener]

my chain is just over 1 cm or just under 1/2 in. so its about right...little on the tight side but i dont think its enough to cause th problem

[MJL]

Uneven carb tuning can cause this, I think.  Have they been vacuum synced?

mystic_1

My thoughts as well.  Unsynced carbs will surge as they fight each other to control engine speed.

[Bido]

To add to my previous reply valve clearance,cam chain, timing, plug gap, carb sync, float height and clean carbs were done before I changed the needle height. I start with the easyest first.

Bido

[keener]

is it a big job to bring my carbs to honda to get them vacuumed synced since I dont have a vacuum to do so? how much would it cost about?

[upperlake04]

 Over the long term, buying your own manometer to synch your carbs yourself would be the most cost effective. A one time dealer synch versus the cost of buying are probably not much different. You would have the satisfaction of doing it yourself, as often as you please, as well as get familiar with your machine, and know that it has been done properly as well. And you'll have more friends.
   http://www.carbtune.co.uk/