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Rebuilding a Bystarter

Posted: Tue May 03, 2011 9:41 pm
by RunAckRun
Hello, just bought a 1986 Honda Spree and it has had trouble cold starting. I am pretty sure it is the bystarter, I have read about them and this one is fully extended out, I hooked it up to a 12V source and it did not retract. I am pretty sure it should retract, is this correct?
Is there a way to rebuild these or am I better off just buying a replacement?
If I need a replacement, where is the best place to buy via internet? I have seen them available on Ebay, but i am a little leary of the quality of these.

Any help is appreciated,

Thanks,
Ack

Re: Rebuilding a Bystarter

Posted: Tue May 03, 2011 9:54 pm
by bradmeehan
You have it backwards. It should extend when you apply 12V.

I bought them from ebay before. Be sure to check the ends. The 85 has a different connector than 86.

Re: Rebuilding a Bystarter

Posted: Tue May 03, 2011 10:05 pm
by RunAckRun
It is fully extended out when cold, I assume that the bystarter is bad. If should be retracted when cold correct?

Re: Rebuilding a Bystarter

Posted: Tue May 03, 2011 10:06 pm
by bradmeehan
Yes. Retracted when cold. Like jumping in a cold pool.

Re: Rebuilding a Bystarter

Posted: Tue May 03, 2011 10:10 pm
by RunAckRun
Thanks Brad, I took the two screws hold it in place and lifted up slightly and fired up right away so I assume the carb is good. Runs great after about 10 minutes to warm up. It needs a new battery, but I jumped it easily off my Jeep earlier tonight.

Re: Rebuilding a Bystarter

Posted: Tue May 03, 2011 10:56 pm
by Bear45-70
RunAckRun wrote:Thanks Brad, I took the two screws hold it in place and lifted up slightly and fired up right away so I assume the carb is good. Runs great after about 10 minutes to warm up. It needs a new battery, but I jumped it easily off my Jeep earlier tonight.
Should not have started as the bystarter system does not supply fuel with the bystarter removed.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 8:56 am
by RunAckRun
Bear, please look at this link. This is what I did, seemed to work for me.

http://www.scootertherapy.com/nqchokepage.html

Is it my problem? To test, remove the screws that hold the unit into the carb, and lift the choke slightly out of the carb body while cranking the engine to manually choke it. If it starts, then the carb is ok, choke is not.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 1:03 pm
by Bear45-70
RunAckRun wrote:Bear, please look at this link. This is what I did, seemed to work for me.

http://www.scootertherapy.com/nqchokepage.html

Is it my problem? To test, remove the screws that hold the unit into the carb, and lift the choke slightly out of the carb body while cranking the engine to manually choke it. If it starts, then the carb is ok, choke is not.
They are full of crap. The only way the bystarter system can work is if the bystarter bowl has a vacuum on it to draw fuel out of the float bowl and without the bystarter installed, that can NOT happen.

Fuel is drawn up out of the float bowl into the bystarter bowl, then into the throttle bore, IF the bystarter needle is retracted. Once the bystarter is heated and the needle extends the vacuum source is cut off and no more fuel in drawn from the float bowl and hence into the intake system. So running the engine without the bystarter only creates a vacuum leak, a small one but still a vacuum leak.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 2:37 pm
by RunAckRun
I see your point, I set the bystarter back down into the carb within seconds after the engine fired. My bystarter is fully extended, which I guess stopped the vacumn effect. Needless to say I ordered a new bystarter and I am hoping that is the issue. I am sure I will let you know if something else comes with it.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 3:00 pm
by Bear45-70
RunAckRun wrote:I see your point, I set the bystarter back down into the carb within seconds after the engine fired. My bystarter is fully extended, which I guess stopped the vacumn effect. Needless to say I ordered a new bystarter and I am hoping that is the issue. I am sure I will let you know if something else comes with it.
If the needle is extended then you get no enrichment effect for cold starts. You need to make sure the fuel passage to the float bowl is clear and the vacuum passage to the throttle bore is also clear.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 3:14 pm
by RunAckRun
Will do, thanks.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 3:22 pm
by noiseguy
Bear45-70 wrote:
RunAckRun wrote:Thanks Brad, I took the two screws hold it in place and lifted up slightly and fired up right away so I assume the carb is good. Runs great after about 10 minutes to warm up. It needs a new battery, but I jumped it easily off my Jeep earlier tonight.
Should not have started as the bystarter system does not supply fuel with the bystarter removed.
Hold on there. If you lift out the bystarter 1/16" or so, keeping the bystarter sealed to carb, I don't see why this wouldn't work as a way of ruling out the bystarter *if* it's failed in the extended position... though I always thought these failed in the retracted position. Once it's warmed up, tighten it back up and away you go.

Bystarter removed, if it runs, you've got a massive air leak. Not a good way to run a bike.

I've never seen this picture of a bystarter before... I didn't realize that it could be taken apart by unscrewing the plastic barrel. Looks like the plastic body is swaged over the barrel, and once that's pulled back it can be taken apart. I've always heard they are full of wax inside, but I've never broken one down to verify.

Image

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 3:32 pm
by Bear45-70
The wax is inside the brass can attached to the needle.

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 8:31 pm
by josh700
Not to be a thread stealer, but after reading your post I decided to loosen mine, pull it out a bit and see what happens. And now the bike will run much longer and I can actually adjust the idle to the proper speed. However after about 5 minutes it gets nice and warm she shuts down again. Where you having this trouble also?

Re: Rebuilding a Bystarter

Posted: Wed May 04, 2011 8:45 pm
by Bear45-70
josh700 wrote:Not to be a thread stealer, but after reading your post I decided to loosen mine, pull it out a bit and see what happens. And now the bike will run much longer and I can actually adjust the idle to the proper speed. However after about 5 minutes it gets nice and warm she shuts down again. Where you having this trouble also?
Sounds like your idle circuit is plugged.