86 Spree By-Starter Warm Up Question

[cmybimmer]

Hello All, new member here! I recently purchased two ‘86 Sprees and one is currently running (black), and the previous owner used a few parts from the other (red) for the first one. He told me it’s more of a parts bike, but it’s like 90% complete and Id rather getting that back on the road (plus it only has like 2400 miles, half as many miles as the black one).

My main question is the one that runs is giving me a problem that I can’t quite fix. Initially it would start up fine, but bog while accelerating. I also noticed that the bystarter was loose and the wire was cut as well. Also, the air filter was some universal foam material that was barely sitting in there.

To make the long story short, i did/replaced the following:
- Took apart, cleaned, and reassembled the carb
- Took apart the engine cap, cleaned the piston and caps fins, and reassembled.
- Replaced air filter
- Replaced by starter and fastened it*

Now with all that, the scooter started up very nicely and actually drives amazing when its cold. Reached 28 mph with it.

The problem is when it warms up. I did a lot of reading about the bystarter and its function, which is what inspired me to buy a new one (ebay). Prior to buying, i noticed that when the engine is all warmed up and I give full throttle the engine hesitates. I take off the (back then) loose bystarter and plug the hole with my finger and as soon as i do that the scooter takes off effortlessly. I was like great, pretty clear sign that a new bystarter will do the trick and i can smash around in this scooter. New part comes in, i install it, drive around and the problem continues when hot. I’m not sure what can cause it to still hesitate when warm with a new bystarter.

My next thought was just to get a new manual choke carb that i can switch after it warms up so it functions properly but i wanted to keep it as original as possible.

Any ideas? Thanks in advanced!!

[motormike]

It is very difficult to diagnose a scooter problem when I can't be there with the bike.
One thing I can say, if the bystarter isn't closing off the enrichment circuit after the initial warm-up, it causes a "rich" condition, which in turn causes it to bog.
Another possibility that comes to mind is the condition of the emulsifier tube. All of the tiny holes must be open to perform properly...bogging is possible with this condition.
Just maybe, the mixture screw can be adjusted to eliminate the bog.
If you turn the mixture screw, and no difference is noticed, there is a possibility the passage controlled by that screw is not fully open, and requires some additional cleaning. It is not uncommon to need to clean a carburetor several times before actually getting it to properly tune.
When you discover the issue and get it fixed, please report back here, thanks.