Topic: need to see if Im on the right track with timing (throttle hang up cured)

[Mortum]

I did a search and read a ton of post on static timing. Here is where Im at.

The bike was hanging up at around 3000 rpm's after riding for awhile. After reading many post and talking to a local guy I went ahead and pulled the points and point plate to check the mechanical advance.

It was a little sticky so I cleaned it and the lubed it with a light coat of lithium grease.

I put everything back together and set the points to where they were just opening at the fire marks on 1-4 and 2-3. Bike started with the choke but ran bad.  Came back in searched some more then adjusted points gap the right way.

I then took a 12v bulb ground one wire then clipped the other to the points for 1-4. Turned around to fire mark for 1-4 then rotated plate a little till the light just came on.

Did the same for 2-3 except I moved the "sub plate for 2-3 just till the light came on.

Tried to start the bike and nothing. turns over but will not start with or with out choke.

I pulled the the plug wires and checked each one and I have fire on all four.

Went back and checked the static timing again and it didnt move. Its set to where the light just comes on and stays on at the F mark for 1-4 and 2-3. Its not set where is flickering the light is on at this point still no start.

Am I doing something wrong or am I missing a step?

Thanks guys.

[OldSchool_IsCool]

Let's double check your reassembly.  Make sure you have the plugs down tight and that the correct wire is on the correct plug.  While you're at it, take the plug caps off the wires and look for any corrosion in there.  If you see green, clean up the spike in the cap and clip about a quarter inch off the wire (back to clean copper). 

[Mortum]

your going to love this. My buddy that works with me on bikes here and there thought it would be funny to drain all the gas out of the tank while I was gone.  So even if you knew you had gas and know your carbs are clean make sure a buddy hasnt stolen your gas. 

[OldSchool_IsCool]

 

[Mortum]

seems that I still have the hanging rpm problem. Anyone have any ideas. I have read alot of post on it when I did my search but no one has come back and posted if and what fixed there problems.

[bwaller]

If you have access to a timing light, check the timing at full advance too.

 Make sure you have a little free play in the pull throttle cable, do the slides snap shut when you release the throttle? If not try rerouting your cables so they do. Maybe the cables are in rough shape,or dry or both. This will have to be addressed sooner than later anyway.

Is the idle screw set too high? You may need to synch your carbs too, this can also hold rpms up there

[Mortum]

cables are new and lubed. Throttle is snapping back to stop every time. When I  start it up cold with the choke it idles up to about 3000 rpms with out the choke it dies. I will have to find a manual and make sure the choke is set right.

I read in a few post that with the choke it should be around 2000?

Also right now if I blip the throttle up to 4000 it will drop slowly then hang up at 2000 then if I just barely blip it she drops right down to 1300 or so.


If Im out riding after about 20 mins the idle will go up to 4000 and hang there. If I turn the idle adjustment down to around 1300 then the next light it will drop to near 0 and die.

Got me pulling my hair out.  I sprayed wd40 around the intake boots to see if that made a diffrence and I didnt notice any at all.

[TwoTired]

What bike?

Have the carb been vacuum synch'ed?

[bryanj]

nowhere do you say you set the points gap at 14 thou BEFORE setting the static timing

[markjenn]

AFAIK, there is no "fast idle" circuit on our old-style choked carbs, so you have to give them throttle during starting and to keep them running after they start.  At least I have to when I start mine.  I use full choke briefly to get it to fire, then immediately back off a bit to keep it running.  Within 20 seconds or so, I can back off the choke completely although it won't idle reliably for another minute or two.  These things are a world apart from a modern computer-controlled FI system on car.

On the hanging idle problem there can be a lot of causes:  intake leaks, throttle hangup issues, severe carb missync, mis-adjusted carb slides, etc.  I'd start by making sure you have throttle cable free play and that there is nothing physically preventing the carb linkages from lowering the sildes all the way.  If your intake boots are in bad shape, I'd just replace them - any 35-yo bike probably needs new ones.

On mine I was having the problem and replacing boots didn't help it, but I'm still glad I put new ones on.  What it ended up being was that some previous ham-fisted mechanic had adjusted the slide rods way too high in the linkage - the service manual has a spec for the clearance between the top of the carb and the bottom of the linkage.  Mine were way out of spec.  Adjusted them all down to spec and I regained idle control with the throttle stop screw.  Had to re-sync afterwards, of course.

- Mark

[brianzenk]

With the bikes electrical system off use an ohm meter with the same hook up as the light bulb connections. If you get the set up right you can rotated the back plate until the points open exactly at the F point 1-4 then 2 - 3. The meter is the better way to go to see where the points open because the digits change. Use the timing light to see the results. Getting the gap correct takes a little time by trial and error. I must have turned the crank shaft around 50 times to find the top most point where they open to set the gap.

[Mortum]

well well well... The throttle hangup is cured. After having the carbs on and off umpteen times I replaced the accel pump this morning. While I was doing that I decieded to synch the carbs. I bought some vacum gauges last week and got to it this morning.

Well the screws that hold the slides to throttle linkage had come loose and that was my problem.  Took her for a ride and she runs like a champ  now. Now that I finally figured this out I am back on track with my cafe  build and not selling her. LOL.