Battle with My Riva 125

Looks like you have easy access to AVgas. My carb issues (not a Riva) were totally solved by buying non ethanol gas.
Before switching over to non ethanol, if my bike sat more than 3 days it had carb issues.
Tried Seafoam but that did not seem to help. After cleaning the carb for the third time I drained the tank and filled with non ethanol, no more carb issues. Bike has sat for 2 weeks and still cranks at push of button.
Non ethanol is about 10cents a gallon more expensive here, but well worth it.

I no longer use AVgas on my scoot. The regular gas from Costco is working fine now.

I truly believe the sticky stuff on the carb I had before was due to the use of MMO ( Marvel Mystery Oil) with breather tube connected. I ran scoot with AV gas and crankcase breather detached ( by mistake), and I didn't get any sticky stuff. Changed engine oil to an oil with no MMO added and breather tube connected, and I didn't get sticky stuff.

I now have the crankcase breather tube covered with a filter and is vented to outside. The hole on the air filter box is blocked with a plug. Added 3oz of MMO to engine oil as of yesterday. The scoot should be good for a while.

I have an easy access to AVgas but it is way too expensive. Using AVgas defy the purpose of riding the scoot.

I don't know where I can get non-ethanol gas in WPB area.

Glad you got things sorted out. If it's your daily driver it probably doesn't matter if you use ethanol. Looks like you don't have too many choices for non ethanol according to this.

Well I can say one thing. You are persistent. Most people would have given up long ago and hauled it to the landfill. It sounds like your scooter was not very well treated or maintained before you got it. I have a Yamaha Vino 125 that I bought new, which now has over 20,000 miles on it. It is still like new. I have never had a single problem with it, other than the fuel line and vacuum petcock. I have replaced the fuel line about 4 times, and have completely done away with the petcock. It was an inline design, in the fuel line between the tank and carb. I just ran a straight line from the tank to the carb. I can pinch it to shut off the fuel if I need to. Surprisingly the needle valve has not started leaking yet. Maybe it does not have a rubber tip on it like most of them.

Real gas is impossible to get around here. There is a marina about 20 miles away, but they only sell the 10% moonshine gas too. Local airport will not sell avgas unless you are putting it into an aircraft. The only source of real gas is the local dragstrip, and the stuff costs $9 a gallon, not an option. Ethanol gas is bad stuff. I am pretty sure it destroyed the plastic gas tanks on 2 honda dirt bikes. They developed cracks all over. It also turns rubber to mush. It will damage any rubber fuel line, vent line, and any rubber parts in the carb. It also tends to destroy the packing in manual petcocks and the diaphragm in vacuum petcocks. It melted the diaphragm in the fuel pump on my '72 Pinto.


If your scooter has any kind of emissions crap on it, I definitely recommend getting rid of that. The fuel tank should be vented directly to the atmosphere, no into a cannister. Make sure you carb float bowl vent is open. Make sure your crankcase vent is not restricted. Many bikes have a "separater" in the crankcase vent system, designed to separate liquid from vapor. There is usually a long tube with a plug on the end of it to catch the liquid, which is usually a combination of oil, gas, and water. It is commonly called a "puke tube" and needs to be drained every so often. Or you can just leave the plug off.

Unfortunately, motorcycles and scooters do not yet have positive crankcase ventilation systems like cars, they are usually vented to the airbox. Cars from 1962 on use actual engine vacuum to suck the vapors out of the crankcase. Don't know why this won't work with bikes. The Honda Met and Ruckus from 2002 through 2005 had a very poorly designed venting system, most of these engines did not make it past 10,000 miles. It was redesigned in 2006.

If the carb gets all gunked up again (it has to be engine oil, nothing else it could be. thats why I don't understand why spray carb cleaner would not dissolve it) try connecting a hose directly to the crankcase vent fitting, and leave the other end open. As was said, a single or 360 degree twin (which is basically a 2 cylinder single, both pistons rise and fall together) inhale and exhale through the crankcase vent. In a 180 degree twin, where one piston goes up while the other one goes down, they cancel each other out. They also don't vibrate as much. A more efficient design all around from an engineering perspective, but somewhat lacking in character.

Thank you for the link. According to that link, there's one gas station near to the airport I work at. I'm due for refill of a 5 gallon tank soon. I'll try the gas from that station, then.

Thank you for your post.

Nice that your lawnmower likes ethanol.
My KLR did too.
Unfortunately my SYM doesn't.
Could be some carbs are more sensitive to it.

The piston diaphragm had stretched so bad that it didn't fit any more on my Buell's carb. I had to buy new one. Could it be due to ethanol???

Maybe.

I'm day dreaming about having a disc brake on my Riva 125.

Which scooter has 10" wheel and disc brake so I could see on CL to source the front end?

The Vino 125 and Zuma 125 are both disc equipped. The Riva sure could use better brakes.

OK. Thank you.

Those two models are not so popular around here in So FL CL. But I'll keep looking.
Last thing I want to do is to go with Chinese clones even though they are dirt cheap.

The solenoid installed before was functioning intermittently. I had to knock to make it work sometimes. No wonder it was free from a shop. So I bought replacement solenoid from auto parts store for $13. Installed it without bench testing it, thinking it is new. What could be wrong? Right?

http://shop.advanceautoparts.com/we...oid-bwd_5972906-p?searchTerm=starter+solenoid#

Well, it didn't work. The coil is open, no continuity between the two small posts. I could returned it for another unit but I decided to have fun. Drilled out the rivets to open up the solenoid and found a problem. Soldered a wire to complete the coil. Re-assembled all back and it is working as it should on the bench. Installed it onto the scoot and still working.

Found some Vino 125 front end parts on eBay to entertain my idea of having disc brake on my Riva. But I think I have to let them go for now that I cannot afford them.

My Riva 125 with Sunrise this morning.



$13 automotive starter solenoid works every single time for start up. I was thinking of buying the OEM solenoid from Yamaha if this one doesn't work. But so far so good that I don't have to spend $65 plus shipping for that.

I have been wondering why I don't have ethanol problems. It's the rubber. My carburetor is an old Bing with no rubber parts except a rubber ring at the top, which doesn't touch fuel. And its octane requirements are low.

It well destory old fiberglass tanks but I feel when it come to the carb it would take years to effect the rubber. It all is a matter of age. The old the scooter the more likely it's going to damage it. Anything made in the last 10 years should be good but then I been wrong before. As my girlfrend I wrong about everything .

On last few rides, the starter motor engaged upon applying front brake. First I thought the starter cut-off relay or starter button is stuck closed. Removed the relay and pulled on brake, the starter turns over. And it was intermittent at that.

Checked wiring diagram and the scooter. And I found the problem was with the newly installed automotive-starter solenoid. The coil was finding a ground source through inner casing and mounting bracket. So, I made sure the solenoid is insulated.











Now, no more problem.

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Couple of days ago, I went to a gas station where supposed be selling ethanol free gas. There are faded flags at the station advertising it. Rode up to the pump with 5 gallon tank strapped. The pump has a placard saying it ha 10% of ethanol. ???? WTF. I should have gone inside and ask for detail. But I figured "well, regular gas has been OK so why change?". I left the station and went to Costco for less expensive gas.

Pirelli tires (SL26) were installed in July last year. Now the rear tire is bold. It has lasted for 2210 miles while front has a lot of tread left on it. Also, the rear tire picked up a wire or a nail. It has a slow leak. So, I had to buy a tire locally. The shop has very limited selections, 2, for the size. I picked Vee Rubber, VRM134. Made in Thailand. Have any one used this brand/tire? I have never heard of this brand. How well does it perform? I haven't ridden the scoot since the tire change because the exhaust pipe is in need of attention. See below.



The pipe is over at the welder being beefed up, shall be ready tomorrow.

Awesome thread. I'm clearly new here but I've been lurking this thread for a bit. I have a 2001 XC125 as well. I was having the hot start issue. I ordered the new starter clutch and idle gear assembly. I installed it just a few minutes ago. Here's the problem now.

It starts fine but it sounds like the starter motor is still running when started. It will not idle either.

Do you think the starter motor is actually running or is it possible that the idle gear is actually engaging the starter motor and spinning it?

I'm quite new to working on these, so excuse my ignorance

Again, awesome thread. I admire your determination.

I pulled it apart again and I'm thinking that maybe there is too much pressure on the starter clutch and that's not allowing the starter gear to disengage? Thus still spinning the starter gear while the engine is running. perhaps too much torque on the nut on the primary fixed sheave?

The new clutch assembly does not come with lube which is specified by Yamaha, molybdenum-disulphide oil.

I used 50/50 mix of STP and engine oil instead, and it has been trouble free.

Three rollers on clutch assembly should retract due to centrifugal force as the engine starts and run, dis-engaging clutch. Since you have new assembly it is hard to have wrong spring used to prevent rollers to retract.

If your starter motor continued to get voltage as my starter motor has had, you will hear faint mechanical sound. My engine continued to operate normally. It did not hinder idling.

Your idling issue may not be related to starter issue.

The lock nut torque for primary sheave is 40 ft-lb.