My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

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MisterActorMan
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My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

Hello everybody!

I am brand freaking noob to all this stuff.
To skip my lovely story about getting my bike and go straight to my current problem, scroll down to the last few paragraphs.

My brother hooked me up with a cheap as-is Yamaha Riva off of craigslist where he lives (San Luis Obispo). Cost me 120 to buy the thing and get it transported to my place. Last registration was August 2006. At the DMV I caught someone in a good mood who took off the fees and registration cost me 284 (versus 503 with fees).

I rode the bike around for a while thinking scooters were actually scooters, meaning things that didn't need to be registered/licensed/insured, etc, and got a ticket for old registration and parking violations. Fun!
(For anyone who doesn't know [though this might just be redundant for y'all experienced folk] scooters are tiny engine things made to be stood upon that sometimes have a seat and need no license, registration, etc; motorcycles are two wheeled vehicles with engines larger than 150cc and within certain weight/speed limits; those two wheeled vehicles with engines smaller than 150cc are neither scooters nor motorcycles...they are motorIZED cycles, and have every single requirement of a full sized motorcycle: M1 licensing, insurance, and current registration. Mopeds are two wheeled vehicles that can be fully propelled by their attached pedals and fit certain speed/weight requirements; require an M2 license and a one-time registration fee. see: http://www.dmv.ca.gov/motorcycles/motorcycles.htm)

Anyway, even with the fees, I spent about 400 dollars getting the vehicle, and then of course there were licensing and the safety class fees, which totaled 180. Then there are the needed repairs, which currently ran me about 25 dollars for tools/oil/etc, and 120 for a carburetor from ebay that has a return policy I trust...so, all in all, this little guy has cost me 725. A lot more than the original 100 I invested in it...yeesh.
Point being, I went whole hog and am now able to ride a full-sized motorcycle and I think it's a good life investment, and this bike seems great to start on and I plan on keeping it up and enjoying it.

That being said, my current problem is one with the carburetor.
When I got it, it hadn't been run for a while, and it was cold out; the guy said it had starting issues, and I brought starting fluid. After about ten minutes of spraying starter fluid, pumping the gas, and having it allllmost turn over, it did, and ran steady.
Currently, I need to use starting fluid every time I start it cold (including, say, when it's 80 degrees out; anytime the engine hasn't been run). The idle and acceleration is weak for five minutes/until it warms up; sometimes after revving it hard the carb will falter. Once it died on me, after driving steeply uphill for a while and then letting off the gas.

Other forums/searching indicated that what I had was a clogged/weak main delivery valve insiet he carburetor. I took it to a general motorcycle repair shop and he pointed out to a place on the carb, behind the throttle adjustment screw, where it looked like there should be something bolted on, and said that was where the choke should be; aka, my carb was missing its choke. That explained the problem with cold starting, etc.

So, I found a part on ebay that seemed appropriate and said it included all parts, was from a working cycle, etc. However, the same apparently vacant place exists on the replacement carb as with the current carb. I've attached an image with the area circled. Can someone please tell me whether this is indeed the place for the choke to go, and I bought a bum part? Or, if not, what is supposed to go there/why it looks empty? I haven't had time to install/test the part yet, but plan to soon (like, this coming weekend, Feb 20th, or the next).

Image

An additional problem I have is a wobble/pulse on the rear wheel only when I brake. If this was a car, I would predict a warp brake rotor or drum. However, the same repair guy looked at my wheel and said it looked bent. Which I understand, but wouldn't I get wheel wobble at any slow speed, not just when I use the rear brake?

When I install the carb I plan to take as much of this apart and inspect as much of it as possible, including the wheel. If it's the wheel or the brakes, what is harder to fix and what should I expect to spend?

Thanks so much. Peace. Tim.
Attachments
Pic of 1988 Yamaha Riva used replacement carburetor; questionable area circled in red.
Pic of 1988 Yamaha Riva used replacement carburetor; questionable area circled in red.
125.jpg (154.02 KiB) Viewed 23851 times
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donny
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by donny »

you may have to find some diagrams of fuel system there may be a bi metal switch for warm up that has a reputation for being a problem. you have a newer model of that style and that is good the ones b4 had a really bad over complicated system they where trying to get away from. until you see the whole system laid out you will have problems trouble shooting. but i do not think this may be to bad for you to fix.

i have a 84 riva 180 that looks like new i picked up for 300$ but the few attempts i have made to get it running have failed, it has a night mare of 10 vac and positive pressure hoses and the bi metal switch and a funky gas heating up gismo to pre heat when cold rather than a choke, great ideas but finicky. relies on a really good battery too to power all that shit and start it, i plan to completely change it.

well for here in Canada a plate and license and insurance of some standard is required for all motorized 2 wheeled vehicles. but in the U/S you have some states with no license under 49.9cc a maybe not even insurance. but every state is different but you must compile to your registered states laws and ounce outside your home state is is up to how aware the cop is about current laws, he could be an pain if he felt like it but most do not hassle the little guys they are no threat but to themselves :lol:
presently enjoy riding a Ruckus and a Super 9. Tinkering with a Riva 180 and a couple of old Puch SV's. In the off season I enjoy a 1999 Polaris Indy 600 XLT Touring and a 2014 Artic Cat Prowler side by side
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

Oh yeah! Everything I said pertains only to CA DMV requirements.



So, that's handy to know that this carb is not as tricky as older ones. I've looked at some exploded parts diagrams (see: http://www.cmsnl.com/yamaha-xc125tc-riv ... partslist/ ) and that part is just not labeled. So I wonder if the diagram is for the wrong year or something, or if its just...some weird empty space on the carb? What about the picture and the possibly weird/missing part? Thoughts?
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by GVH »

On Bikebandit.com part number 23 and 8 seem to be the cold start device. Have you done a good cleaning of the carb yet. If it was sitting that long it will need a cleaning.

http://www.bikebandit.com/assets/schema ... 959_08.gif

As for the bent rim. If the rim is bent it should show up when driving. It will show up more at higher speeds but the hub with the brake shoes attached it solidly mounted. When you apply the brakes it will pass the pulse from the bent rim throught the brakes into the scooter. Much like a warped rotor on a car shows up in the pedal under braking. The big difference is the rear drum is the center of the wheel and will effect the axle and the whole scooter feels it.
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by GVH »

Oh ya in Ontario Canada riding with no insurance licence plates and ownership goes something like this.

No insurance $5000 fine, 6 month to 3 year license supension and possible 90 days in jail. Fines and jail time double each offence until you reach 4. Then it's a life time ban on driving plus they tow the vehicle and impound it each time.

No plates and sticker. $160 ish plus they tow the vehicle and impound it.

No licence is up to $1000 depending how many times you have been caught before. plus they tow the vehicle and impound it.

No ownership up to $300 fine plus they tow the vehicle and impound it until you can show proof of ownership.
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by Dan Durston »

Welcome to the site 8-)

The rear wheel wobble/pulsing seems to be mostly a warped/bent drum combined with a bit of play on the axle. If the drum is out of round then when you apply the brakes it will cause a wobble if there is any play on the rear axle, which there usually is. Since the drum is part of the wheel, you'd need to replace the rim. You can find these on eBay but it's hard to know if the new rim is going to be any better. Unless it's dangerously bad, I would probably just leave this for now. It may even sort itself out as things wear.

Regarding the starting problem, it sounds like there is clearly a problem with your choke or jets. Since that other eBay carb is missing this part too, it probably was never there. This carb was likely just used on other bikes with different choke systems so those bikes had this part. It could be that a manual choke fits on here. I would start by tearing apart the carb and inspecting your jets. The smaller 'idle' or 'pilot' jet is the one to watch as that is the one that supplies the fuel when the throttle isn't open. Basically you want to remove the bottom of the carb and then you'll see the brass jets which should just unscrew with a flat bladed screw driver. Hold them up to the light and make sure you can see a pin hole of light through them. If this all checks out, then the problem should be with your auto choke system. If you buy the service manual (eBay) that should explain the process to check the choke system using an multimeter device. Alternatively, you could just throw parts at this and buy some a new bystarter as that's often the problem.
Scooters Owned: 2003 Ruckus, 2006 Ruckus, 1983 Yamaha Beluga 80, 2007 Vespa LX 150, 2009 Yamaha BWS 125, 2008 Ruckus
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

Thanks so much guys. As soon as I get a chance to install it this weekend or the next, I will leave feedback about whatever progress I make.
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by donny »

well had any luck? with the carb?
presently enjoy riding a Ruckus and a Super 9. Tinkering with a Riva 180 and a couple of old Puch SV's. In the off season I enjoy a 1999 Polaris Indy 600 XLT Touring and a 2014 Artic Cat Prowler side by side
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

still waiting to install! I just moved to a new place. I'm either doing it this weekend or the one after...SPRING BREAK!! I'll still post when I've done it. Thanks for checking :D
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by donny »

yeah i got too get at my riva i have bike fever bad this year and broke so try too fix what i got
presently enjoy riding a Ruckus and a Super 9. Tinkering with a Riva 180 and a couple of old Puch SV's. In the off season I enjoy a 1999 Polaris Indy 600 XLT Touring and a 2014 Artic Cat Prowler side by side
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by Dan Durston »

You can do it! It's so close to starting...
Scooters Owned: 2003 Ruckus, 2006 Ruckus, 1983 Yamaha Beluga 80, 2007 Vespa LX 150, 2009 Yamaha BWS 125, 2008 Ruckus
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

I'm actually in the process of swapping out / fixing the carb starter issue--my hands still smell like gasoline as I type this!

I thought it would be fund to see if anyone responds quick enough for it to be any use during the install, as well as fun to look back on this later.

I've been using starter fluid to get my scooter to start when it's cold (when it's warm, never an issue) and so I presumed there was clogged/gunky jets in the carb...and I bought a carb off ebay and was going to put it in (right now!). However, I bought carb cleaner today and have let both the carbs (old and new) just sit with the cleaner in them while I did other tune-up stuff to the scooter.

I decided to put the old one back on and see if just running carb cleaner through it fixes it / unclogs the jets. Worth a shot, right? If not, I'll do as I planned and put on the new carb (and pray it works well...it was off ebay, after all).

I'm wondering what the difference between starter fluid and carb cleaner is, really--or is there not a difference? Both are just really high octane fuel? I've just sprayed carb cleaner into the old carb once I stuck it back on there, and it started and ran and died...a lot like what might happen with the starter fluid. It's got me wondering...!

Peace...(and wish me luck!) :D
Attachments
bike parts/tools. note the carb cleaner and starter fluid!
bike parts/tools. note the carb cleaner and starter fluid!
PICT0284.JPG (454.67 KiB) Viewed 23056 times
the bike with the old carb back on and attempting to start/clean
the bike with the old carb back on and attempting to start/clean
PICT0283.JPG (372.88 KiB) Viewed 23076 times
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

Damn, sorry for the big pics
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by MisterActorMan »

Okeedokee, SO! The new(er) carb does the same thing as the old carb.

With starter fluid, it starts up and, if I hold throttle on, it will keep running.

With carb cleaner, it starts up for about 2 seconds and then dies.

With no fluids sprayed into the air intake on the carb, the scooter tries to turn over, giving a nice unh unh unh unh unh almost turning over sound. Both carbs cause the bike to sound this way, although the newer carb sounds like it turns over a little slower, as if it were straining more--this may be because the battery hasn't charged all day and I've been cranking it off and on a lot.

So both carbs presumably have clogs inside and need disassembling and cleaning.

My question concerns the choke--it seems that every forum/Q&A of mine says that trouble starting is clogged jets, the pilot and the main, or something like that. What about the choke? It seems logical that since the problem is only when the bike's cold the problem lies with the cold start device, aka, the choke. Is there a way to specifically clean only the choke?

Anyway, I'm off with my exploded parts diagram and a lot of patience to disassemble the old carb and clean that sucker...thanks for the replies!
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Re: My Yamaha Riva 125 (1988): Starting/Carb Issues & Questions

Post by donny »

probably a clog but i think you also have a bi-metal switch for choke control? they have a habit of failure

in the stuff i have read you need a good and charged battery for these scooters, some sites on rivas i have read are for bigger batteries in them to help starting.

hope you have compressed air on hand to blow out carb.
presently enjoy riding a Ruckus and a Super 9. Tinkering with a Riva 180 and a couple of old Puch SV's. In the off season I enjoy a 1999 Polaris Indy 600 XLT Touring and a 2014 Artic Cat Prowler side by side
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