Gyro - general thread

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catch22!
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Re: Gyro - general thread

Post by catch22! »

Checked the fuel valve. All clean and flowing. I did note that when in the reserve position it leaks around the valve. From the design and that they riveted the holding plate on, I take it this is a common problem. When in the ON position the fuel flows through the filter tube directly to the base. When in the reserve position, the fuel flows around the valve to the base. Anyone know if these are repairable? Thinking of taking the rivets out and threading the holes, then lapping the valve seat. Any replacements out there?

Next, I rechecked the Bystarter. 8.6 oms resistance, good conductivity across the leads and when I hook it to a 12 v power supply, the valve slowly comes out. I sprayed carb cleaner in the enrichment port and also through the air fuel needle. Reset the air/fuel needle to 2.25 turns out. Bike started up, but again, runs for about 2 minutes and then stalls. WIll not immediately restart, but after about 5 minutes it starts fine.

I have a clear fuel filter on the fuel line and can see that it is full. I also opened the screw on the base of the carb just after it stalls. The bowl has fuel in it. I am thinking I have a plugged primary fuel circuit and it is running with the bystarter open and then dying when the bystarter closes.

Does that sound correct?
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motormike
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Re: Gyro - general thread

Post by motormike »

Yes catch22!...what you say above all sounds correct.
My '85 shares exactly the same symptoms, except that when it dies the first time after start-up from cold, it will restart after 10 seconds, and from that point on, runs WOT just fine. That tells me the Main circuit is fully open, is my opinion.
I believe the air filter box and correct density filter foam plays a strong part in the tedious tuning of the Gyro carburetor. Recently, after a filter change, I have been required to place two fingers over the airbox inlet sometimes during a restart.... :urban:
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vintagegarage
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Re: Gyro - general thread

Post by vintagegarage »

Catch22,
This isn't completely relevant to your problem, but I'll post it here to document some of what I found when having fuel valve/carb problems on my 86 Gyro S a few months ago. First of all, the carb and the short throttle cable leading from the carb to the cable junction box were the only parts missing on my Gryo when I got it, and the engine hadn't been running in perhaps 10 years. It did come with a new-in-the-box eBay "fits Gyro S Carb". The carb was this one:

http://www.ebay.com/itm/1985-1986-HONDA ... UK&vxp=mtr

I also ordered the missing piece of throttle cable used off ebay. When the throttle cable came in, I started to install the new carb and throttle cable, and immediately found that the "fits Gyro S" carb didn't fit. The fuel input pipe on the replacement carb faces to the rear instead of to the left side, and fouls in the plastic shroud that brings cooling air from the fan area into the cylinder shroud. It took me a couple of hours to modify the fuel input pipe to go sraight up so I could mount the replacement carb. The replacement carb also came with an un-numbered main jet, so I put in a new #75 main jet (still available new) just for general principles.

I also found that my fuel petcock was plugged up. Unlike yours, it wasn't leaking. It took me some hours of work and a couple of days of soaking in carb cleaner to get mine working. The reserve circuit was the easiest to get working. All of the sediment and rust from the fuel tank had settled into the reserve circuit, and I cleaned much of it out with a toothpick and air gun. I used a guitar wire to gradually clean out the tall tube leading to the main circuit, and it took many cleaning cycles to get the main circuit to flow as rapidly as the reserve circuit.

I finally got the main petcock circuit clean enough to keep the carb full of fuel at extended WOT. but found that the reserve circuit was pretty much always on, as fuel was leaking past the o-ring on the fuel filter that is supposed to keep fuel out of the reserve circuit. In otherwords, with the petcock set to on, the engine would continue to run until the tank was out of gasoline, meaning that essentially, I had no reserve. I walked home a couple of times until I decided to test the petcock in the shop with a catch bucket. I ended up buying a new fuel filter with o-ring and getting the sealing right between the filter and the petcock, and finally got the reserve to be a reserve.

In the end, I got the gyro running perfectly. Started first time from cold, idled perfectly when cold, through the bystarter transition, and when hot. Throttle response was excellent, with no hesitation when going downhill from off throttle to full throttle.

Not willing to leave it good enough, I finally located a correct original used carb with original bystarter on eBay and bought it for $100. After cleaning it very well, and testing it, I replaced the new Chinese replacement carb with my Rube Goldberg fuel inlet pipe with embarrassingly poor workmanship. with the cleaned up original carb.

Now the Gryo starts instantly when cold, idles perfectly through the bystarter transition period, and perfectly when hot, and never dies after being started. It runs perfectly at WOT all day. The only problem is a slight hesitation when going from throttle off down a hill to full throttle at the bottom of the hill. I tried many adjustments to eliminate the hesitation with no success. Rather than revert back to the Chinese carb, I decided to keep the original carb and have just learned to live with the hesitation.
catch22!
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Re: Gyro - general thread

Post by catch22! »

Good point to check RR. I will pull the Air Cleaner and check the filter. I remember reading on an earlier post that someone had filters that work for the Gyro. Do you have information on that?

Also, I want to build a cover for the carb . I know a few of the members have done this. Anyone have pictures of what they built?
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Re: Gyro - general thread

Post by motormike »

catch22! wrote: I remember reading on an earlier post that someone had filters that work for the Gyro. Do you have information on that?
Yes, noiseguy has the air filter foam...buy two and support the board. :thumbwink:
Click the Link below... :urban:
viewtopic.php?f=1&t=12045
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Re: Gyro - general thread

Post by catch22! »

Got the new filters in today. Thanks for the recommendation, The old filter was made by the PO. It was a green scrubby. I took the bike for its first longer run today. It went about a mile and died, they restarted after a few minutes and took me home. So, I am still sorting out the issues.

I did note that the bike is throwing out a good amount of oil out of the exhaust. Checked the injector valve with the throttle open and it is right on the indicator pointer. Is there a way of adjusting the pump volume? I did not see anything in the manual or in a search of the web.

Other question would be if there is any potential transmission oil is getting into the engine?
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Re: Gyro - general thread

Post by vintagegarage »

There is no adjustment to the oil pump volume, and the oil smoke will very likely disappear if you go for a good long ride that lets the muffler get fully hot. Once you have had one or two good long rides, my guess is that you will probably have good smoke for the first hundred yards or so every time you start it from cold, but then no or very little smoke for the rest of the ride. Mine do anyway.. Smoke disappears after the engine warms up. I assume my oil pumps leak a tiny bit.
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Re: Gyro - general thread

Post by motormike »

catch22! wrote:is any potential transmission oil is getting into the engine?
Probably not, but a VERY good idea to drain and refill the gearbox.
Remove bolt on backside, behind right, rear wheel.
Raise front wheel slightly off ground, drain for few minutes until stops dripping.
Return to level and fill with 6.4 oz. of 10W40 oil.
This should be enough oil to fill gearbox up to the drain-fill hole and just start running out a little.
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Re: Gyro - general thread

Post by catch22! »

Thanks RR. This pump was not hooked up when I got the bike, the tank was cracked, so I figure that is why they disconnected it. I picked up a tank and put the system back in operation. Compression on the bike is 130, but it does have 3000 miles on the Odometer.

Is it normal that you get actual oil out the tail pipe? I get black splatter of wet oil on the rear fender.
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Re: Gyro - general thread

Post by motormike »

catch22! wrote:Thanks RR.

Is it normal that you get actual oil out the tail pipe?
I get black splatter of wet oil on the rear fender.
The "RR" you call me is just fine, as i see you are getting that from my signature...however, my username is "motormike"... :urban:

The spatter of oil you see coming from the exhaust indicates oil has drained into the pipe and is still being blown out
when engine runs. Will diminish over time, with frequent running, but can be baked out with fire.
Re-paint with high-temp spray found at any home improvement store, sold as "Grill Paint" (BBQ grill, that is)... :wink:
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Re: Gyro - general thread

Post by catch22! »

Thanks Motormike. I think there is still oil in the fuel from when I first started it. That would add to the smoke. Going for some rides and will see if the issues work out.

BTW. What type of road speed should I expect? I am getting 25 mph per the speedo on flat streets.
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Re: Gyro - general thread

Post by motormike »

catch22! wrote: What type of road speed should I expect? I am getting 25 mph per the speedo on flat streets.
Depending on tire size and rider weight, 30mph is about the top end of speed you will see for Gyro.
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Re: Gyro - general thread

Post by catch22! »

Thanks Motormike. I am up there on weight for this bike (210), so it is probably appropriate. Took it out for another run today and it stalled out and this time did not restart after setting for 2 hours. Back to the drawing board. I did find another original carb, so I will wait till that comes in and go over it again.
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Re: Gyro - general thread

Post by catch22! »

Any thoughts on the aftermarket bystarters on Ebay? Any good?
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Re: Gyro - general thread

Post by motormike »

Have been riding the Gyro around east Nashville lately.
Nearly lost my mind when it hit 37mph, albeit on a steep decline.
I can feel some gasping of the carb on top end.
Putting a clean and reed inspection on the list.
Something is pulling the fuel through even when rolled off,
as you might expect with a vacuum leak.
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