Possible Bystarter?

[wentwest]

I've had lots of trouble with Honda bystarters. They are likely to fail to work properly and that leads to easy cold starts, good cold running, and poor warm running with falling fuel mileage. The bystarter is a type of needle valve that controls a secondary air/fuel circuit that runs around the main venturi, and adds a rich mixture while that circuit is open. As the engine runs, current flows through a tiny heater in the bystarter, which heats up some form of expanding material (maybe a wax pellet?) which forces the needle and ferrule at the end to move out, closing off the secondary circuit. If it does not work properly the circuit stays open and the mixture is too rich for a warm engine. You might notice that the pilot screw really has no effect on the idle speed when this happens.

Two things cause bystarter dysfunction that I know of. One is that the resistance in the heater goes out of spec, by wear and tear over time I guess, and the needle never extends. That can't be fixed and you have to replace the unit. You can do a test, which is in the service manual. The other is that the electric current does not flow properly to the bystarter. On some Hondas that current comes directly from the stator. If the wiring connections from the stator to the bystarter are bad, no power means no activity.

I live in a warm climate, so one one of my scooters I took the ferrule and needle off a bad bystarter, dropped them into the opening where the bystarter goes so they plugged the jet and the secondary circuit and created a solid, air tight plug to hold them down and in place, and secured it with a plate the was screwed down with the 2 screws that hold the bystarter bracket. That eliminated the whole circuit and the richer mixture. So far (2 years) I've had no trouble starting the engine at temps as low as 45. It runs very well.

I know I might be called out on some of this info, but this is what I've learned over several years. Good luck.

[GSX1400]

Just curiosity here but lets just say someone did activate the starter with the belt cover off, what would be the mechanical repercussions and recommended fixes?

I'd like to know more please.

[GSX1400]

[quote="thekingof7My scooter had no issues with pickup warm or cold until I started adding treatment to the fuel,[/quote]

What sort of treatment (and what for) did you put in your gas?

[motomech]

I've had lots of trouble with Honda bystarters. They are likely to fail to work properly and that leads to easy cold starts, good cold running, and poor warm running with falling fuel mileage. The bystarter is a type of needle valve that controls a secondary air/fuel circuit that runs around the main venturi, and adds a rich mixture while that circuit is open. As the engine runs, current flows through a tiny heater in the bystarter, which heats up some form of expanding material (maybe a wax pellet?) which forces the needle and ferrule at the end to move out, closing off the secondary circuit. If it does not work properly the circuit stays open and the mixture is too rich for a warm engine. You might notice that the pilot screw really has no effect on the idle speed when this happens.

Two things cause bystarter dysfunction that I know of. One is that the resistance in the heater goes out of spec, by wear and tear over time I guess, and the needle never extends. That can't be fixed and you have to replace the unit. You can do a test, which is in the service manual. The other is that the electric current does not flow properly to the bystarter. On some Hondas that current comes directly from the stator. If the wiring connections from the stator to the bystarter are bad, no power means no activity.

I live in a warm climate, so one one of my scooters I took the ferrule and needle off a bad bystarter, dropped them into the opening where the bystarter goes so they plugged the jet and the secondary circuit and created a solid, air tight plug to hold them down and in place, and secured it with a plate the was screwed down with the 2 screws that hold the bystarter bracket. That eliminated the whole circuit and the richer mixture. So far (2 years) I've had no trouble starting the engine at temps as low as 45. It runs very well.

I know I might be called out on some of this info, but this is what I've learned over several years. Good luck.

Interesting. I had a scooter shop back in the '80's for almost 10 years and they were hardly ever a problem. I guess it could be that they haven't aged well. perhaps the performance of the waxy material inside them deteriorates over time.
Thank for the feedback, I guess this old dog can still learn new tricks.

[Pancake Sauce]

Update on chinese bystarter: Well, it never came. The ebay seller said 1-2 days to process and ship. Then 15-21 work days to arrive. Even considering that + holidays, today was the maximum limit. I ordered it on august 7th and still not here on sept 6th. They will be getting some nasty feedback. People fly to the moon and back in less time. No excuse.
I might just splice my '85 stock bystarter and try that but I don't know if i can find a compatible connection plug for the conversion.

[GSX1400]

What's the sellers name or shop?

[thekingof7]

[quote="thekingof7My scooter had no issues with pickup warm or cold until I started adding treatment to the fuel,

What sort of treatment (and what for) did you put in your gas?[/quote]
The bystarter is a type of needle valve that controls a secondary air/fuel circuit that runs around the main venturi, and adds a rich mixture while that circuit is open.
At first some gumout, then a bit of seafoam.

This was over several weeks and many tanks mind you.

[thekingof7]

Honda auto-chokes are very reliable and usually only develop problems when people start messing with them. Also, It only acts on the starting circuit which functions only on the very bottom of the carb's metering range. Once the motor is up to temp, the auto choke has nothing to do with how the scooter runs.
The poster whose scooter looses power as it warms up should test the crank seals.

What I am starting to think is that several of the posters within this are all partially right.
Here is my theory

I do believe that the bystarter is functioning as it should, probably could a bit of degreasing though. What I am thinking is that as the bike warms, the auto bystarter applies the choke cutting the fuel in the mixture which leaves only the primary circuit supplying fuel, if my carb was beginning to become fouled up it would stand to reason that as soon as the enriched cold start mixture is cut off by the bystarter the only thing supplying the scooter is the primary circuit which likely has some fouling. Thus the scoot gets lower pickup due to less fuel being present after the bystarted engages.

How's that?

In addition to a different posters comment, I could believe that the fouling was exacerbated by the addition of the solvent ridden additives I used on the system which probably freed up some gunk somewhere along the line.
I have a spare carb from a parts bike, same model same year (best 90$ I ever spent on a scoot) I am throwing it a dunk bucket tomorrow and letting it have a nice soak before I attempt a swap. We shall see how things go from there. If things dont look up Ill be taking a spin over to the old mans house and doing some compression testing.
Thanks for all the input guys, slowly but surely I am learning and this scoot is improving.

Best Wishes,
John

[GSX1400]

In that case, see above explanation, your scoot would have much difficulties starting at very low temperatures then?
Indeed, (I'm assuming this) it starts ok at "normal" temperatures cause it doesn't have a striving need for choke and runs good until it starves for fuel when the choke is closed at "hot" temps.
Did you, or could you, do a test at very low temps when the choke should be essential? It should not start then not receiving enough gas through the first and choke circuit?

[Pancake Sauce]

Got my bystarter. Installed it. Then my throttle cable cashed out and got stuck full throttle 24/7. Replaced that yesterday with my '85 spree's cable. Bump sensitivity is GONE. Only slightly occurs immediately after starting cold and goes away within a minute or so. As for the power after warming up... I would say it improved slightly but even that might be wishful thinking.

I did, however, come up with an idea for why warm sprees lose power. I couldn't help but think that the function and efficiency of the aged driven face springs would change upon warming up. If they are somehow not holding the belt at a good climbing ratio then that would explain low "power". I could be totally wrong about this as I am no mechanic but it makes sense in my puny little brain. Isn't that giant spring in the clutch supposed to hold the climbing/takeoff ratio until you reach a certain rpm or something? Has anyone tested this possibility? I just wonder if the heat in the belt area causes some stuff to work off spec.