Elite 80 acceleration problems

[breaze]

Working on a 2003 Elite CH80. Current problem is that it will hold idle but any attempt to accelerate bogs down. Also, it seems to randomly accelerate on its own while idling.

Here are some of the checks I've made so far:

Went thru all of the electrical checks with the only thing out of range being the primary coil - it measured .4 resistance and is supposed to be between .1 and .3. The secondary coil readings were fine. The exciter coil reading was low but I pulled the flywheel, cleaned everything and it now is in range.

Checked the resistance on the by-starter and hooked it up to the battery for 10 minutes to make sure the needle extended about 1/8 inch, but I have not done the air pressure test to make sure it seals off the fuel flow of the choke circuit when warm.

Checked the timing and it seems to be advanced while at low idle (I don't have a tach but warmed up, with rear wheel barely moving, the timing is advanced).

I can imagine that a faulty by-starter allowing extra fuel thru would cause acceleration problems, but the advanced timing is what's throwing me. I'm thinking my next move will be to take a CDI and a coil off a working 81 Express SR I have and see if they make a difference.

Any suggestions? Could a bad coil advance the timing?

[Clivester]

I'd suspect the carb as most likely culprit first. If the timing really is off, that's going to be due to the setting of the timing chain requiring a partial top-end break-down.

Are the valve clearances OK?

Have you cleaned the carb yet? If not, I would do that first. Check especially for the diaphragm over the slide. If it has leaks like a pinprick/cracks or is not seated properly you will not be able to throttle-up.

[breaze]

Thanks - I set the valve clearance today which didn't seem to change anything. I cleaned the carb - used dip overnight but I haven't had experience with any carbs using the diaphragm before. I'll pull it back off and go over it a little more closely. I'm pretty sure I had it seated right, but I didn't check it closely for tiny holes, etc.

[breaze]

Didn't have much time yesterday, but I did clean all the grounds and checked connections. I had already adjusted the valves - it was a first for me and it took forever to get it right (at least I hope it was right) - was not able to get the feeler gage thru at all when I started but got it thru with a slight drag when finished on both intake and outtake.

I also pulled the top of the carb and checked out the diaphragm- its a 2003 and best I can tell the needle does not come out although there is a hole in the top plug that I hooked a wire in and tried to pull out - not with too much force. The diaphragm seems to have no tears or holes but does fold over easily at the top losing its cone shape. Not sure how it seats - there doesn't seem to be a groove to seat it in but it goes right to the edge of the wall and the top seems to sit down on it without pinching.

It cranks more reliably now with the battery holding charge and I was able to lower the idle to what seemed a smooth, low idle and the timing checked out right where it should be. It still will not accelerate though.

Today I plan to pull the carb along with another I have on a 97 Elite 80 parts bike and see if I missed something in the cleaning process - I'm hoping to see how the diaphragm is seated in the other one and compare.

Thanks for your suggestions.

[Wheelman-111]

Greetings:

It may not be this, but I suggest you have a look around from the airbox to the intake for any obvious possible vacuum leak. An old trick I've used is to take an UN-lit propane torch and just fume a bit of the gas near the suspected leak. A spray of carb cleaner can work too. If fumigation produces any repeatable change in the idle speed, you've found your issue.

The diaphragm carb design is shared by Harley-Davidson. I also adapted a VE24 Diaphragm carb to Flash II. Seating that infernal contraption will drive you nuts the first oh,... 10 times. Refrigeration, good molding skills, 3-D perceptual awareness, patience and occasionally Blind Faith will prevail. If there's a leak there, the engine will often behave erratically since vacuum is necessary to raise the secondary slide. Any grit or drag along the slide will do it too. Check for a bent needle.

[Clivester]

You're probably aware of this, so excuse me if it seems obvious, but hopefully the diaphragm (or any other rubber or plastic parts for that matter) was not soaked in the carb dip was it. That would cause it to expand and loose its elasticity.
------------------------end of dire warning and disaster disclaimer--------------------------

Although not a perfect test you can somewhat check for a decent diaphragm seal in a couple of ways.

TEST 1 - After assembly when you push up the slide it should move freely and smoothly with slight resistance. Push it all the way to the top and watch it drop - it should take about a second to drop due to resistance of the diaphragm.
TEST 2 - Place a vacuum cleaner hose over the manifold end of the carb. Look at the inlet side while slowly opening the butterfly. The slide should gradually rise - cool huh!

[breaze]

I took the carb off today, checked it all out - seemed clean. Looked at my other carb, diaphragm was seated the same way. Put it all back together and it accelerates fine - not sure what I did or if I did, and don't really care. Got the idle and mix screws set pretty close and went out for a test drive.

This scooter was apparently in some Mississippi flooding (Mississippi title with "flood damaged" brand). I did a lot of cleaning and electrical checking and probably over thought the whole electrical concern - I was convinced there was some major damage to some electrical components, but it always seems to come back to air and fuel.

Thanks for your help so far - a couple more things bothering me though:

I only have experience with small 2-stroke 50cc scoots - 2 Expresses and an old Suzuki Shuttle. With those, when I release the throttle, no matter how fast I am going, the engine goes down to idle. With this Elite 80, the engine speed seems tied to speed and doesn't go down to idle until almost stopped. Similar to not pushing in the clutch and using the engine to slow you down in a manual transmission car.

This can't be right - any thoughts?

[Clivester]

With this Elite 80, the engine speed seems tied to speed and doesn't go down to idle until almost stopped. Similar to not pushing in the clutch and using the engine to slow you down in a manual transmission car.

This can't be right - any thoughts?

Probably because your previous bikes did not have CVT transmissions. Also, the CV carb does not immediately drop the slide when the throttle is let off.

[CharlotteSpreeRider]

It has to do with how the clutch works. You cannot push start these bikes, because the rear wheel is attached to the clutch drum, which has the clutch weights inside it like shoes. No matter how fast you manage to get the outer part moving, the inner part will never engage on its own.

HOWEVER...if the motor has already spun up the clutch weights and got them in contact with the bell (drum), so long as the weights stay in contact with the bell, the rear wheel can keep the weights engaged, and can actually keep the motor running, until sufficiently acted upon by an outside, unbalanced force (friction).

Don't believe me? Take your bike out, run it at top speed, then turn off the engine for a second with the killswitch or key, and then turn it back on, and explain why the motor is running without you having to restart it with the starter or kickstarter.