It's not GY6...can you help? Yamaha Razz Riva By FACE PLANT FOR LIFE (Read 6,402 times)

[FACE PLANT FOR LIFE]

Okay, so my friend has a 2000 Yamaha Razz Riva 50cc scooter. It's been in a few accidents, but it still ran before all this. Last year it was running, but it had a few issues with running. So we took the carb off, took it apart, cleaned it, and put it back together just as we took it apart. After that, it never ran again..We've tried and tried, but it's just not working. The carb bowl IS filling up with fuel (we've taken it apart tons of times), there IS vacuum. When we kick it (we don't have a battery), the oil light comes on (would that stop it from running?). If we spray starting fluid into the spark plug hole, it will eventually (after at least 15-20 kicks) make a sputter or two, but that's it. Irregardless of whether the airbox is on, it just won't run..What could be the issue here? It's a 2 Stroke, by the way.

[tvnacman]

did you compression test it ?

John

[FACE PLANT FOR LIFE]

We do not have a compression tester, unfortunately. That is one thing we were unable to do. But it ran before we cleaned the carb for the first time.

[tvnacman]

ok get a spray bottle , put the carb back on squrt some premix in the intake side and kick it see what you get . Are you getting spark ?

John

[jvino]

Does the kick feel like it has compression or does the kick starter go down real easy? Let me know other than that if you don't have enough compression you might be able to just put rings on it. If you take it that far down you will be able to see the cylinder walls and if there damaged. If you end up getting rings remember when you put it back together use oil so you don't scratch the cylinder walls. Keep us posted.

[Alleyoop]

Ok lets find out if lack of fuel or to much or spark plug not fireing.
Crank it like you do say 5 times and then take the Spark plug out and see if it is wet or dry.

Since it did not fire ONCE, IF it is wet the spark plug is not firing. If it is Dry then no gas is being suck in.

Now since you have the spark plug out STICK your finger in the hold and hold it nice and snug and HOLD THE THROTTLE WIDE OPEN and kick the sucker over a few times. IF it lifts your finger off the hole you have descent compression. If you just feel a little pressure you have very low compression.


Now also with the spark plug out stick it back into the BOOT CAP and HOLD IT ON THE MOTOR not the frame and crank it and see if it is sparking a nice BLUE FLAME.
Get back on the tests.
Alleyoop

[FACE PLANT FOR LIFE]

The spark plug fires nicely, but quickly gets SOAKED in premix. The kickstarter is EXTREMELY easy to push (no effort needed), but he says it's always been like that. When cranked with the spark plug out and my thumb on the hole, it just barely pushes and pulls on my finger. Also these bikes have about 71 PSI for an optimum compression.

[Deleted]

if it soaks the plug i have to ask: did you put the needle back in the slide right?
did you tighten the main jet?

the needle should have the eclip in the 3rd slot up from the bottom.

also, be careful with the carb. my razz is from 88 and it has a carb marked TK. stands for taishen keishong or something similar. very expensive carb. $250 from yamaha. you might be able to make a $40 2t one from scrappy work. need the manual enricher.

[FACE PLANT FOR LIFE]

I do not think it has an adjustment on the needle like the GY6 carb's do? I could be wrong, but I didn't see one. Then again, I didn't even know about the needle adjustment on the GY6 carb until today. And mine doesn't even have an adjustment, it's just set, unfortunately.

[Alleyoop]

Apr 18, 2014 21:09:36 GMT -6 FACE PLANT FOR LIFE said:

The spark plug fires nicely, but quickly gets SOAKED in premix. The kickstarter is EXTREMELY easy to push (no effort needed), but he says it's always been like that. When cranked with the spark plug out and my thumb on the hole, it just barely pushes and pulls on my finger. Also these bikes have about 71 PSI for an optimum compression.

Were in the world did you get the 71 for optimum compression? Most scoots will NOT run if they are under 100PSI and if they do they hardly have any power to move the weight of the scoot. Kick starter EXTREMELY easy to push no effort needed is a compression problem. Every pull on a pull start on a lawnmover or snowblower.
Alleyoop

[FACE PLANT FOR LIFE]

Apr 18, 2014 23:39:37 GMT -6 Alleyoop said:

Apr 18, 2014 21:09:36 GMT -6 FACE PLANT FOR LIFE said:

The spark plug fires nicely, but quickly gets SOAKED in premix. The kickstarter is EXTREMELY easy to push (no effort needed), but he says it's always been like that. When cranked with the spark plug out and my thumb on the hole, it just barely pushes and pulls on my finger. Also these bikes have about 71 PSI for an optimum compression.

Were in the world did you get the 71 for optimum compression? Most scoots will NOT run if they are under 100PSI and if they do they hardly have any power to move the weight of the scoot. Kick starter EXTREMELY easy to push no effort needed is a compression problem. Every pull on a pull start on a lawnmover or snowblower.
Alleyoop

I ran the VIN number to get the exact model and year for the Yamaha Razz. That is just what turned up. It seemed kind of odd..so we're dealing with low compression then? How odd for it to fail so conveniently when we cleaned the carb to make us THINK it was the carb. This thing has over 4000 miles on it. Probably needs a rebuild.



This forum also says it.

[Deleted]

Apr 18, 2014 23:00:51 GMT -6 FACE PLANT FOR LIFE said:

I do not think it has an adjustment on the needle like the GY6 carb's do? I could be wrong, but I didn't see one. Then again, I didn't even know about the needle adjustment on the GY6 carb until today. And mine doesn't even have an adjustment, it's just set, unfortunately.

theres an adjustment. its a clip that holds the needle in position in the carb and its like any other slide carb, also just like an adjustable gy6 carb.


and 71psi is right in the service manual. its a low comp engine. it has a ratio of 6.3:1.

[JR]

2T carb adjustment by one of the best in the scooter world. 90Gtvert aka Brent.

Can you say Reed Valve?

[90gtvert]

Howdy fellas. JR asked me to pop in if I had any ideas.

It could just be flooded? Have you tried holding the throttle wide open while you crank it over? If a 2T gets flooded sometimes the fuel will puddle in the crankcase. In that case you can remove all fuel supply and the plug will still come out wet when you turn the engine over. Either have to dump it out or siphon it out. Can't rely on it evaporating if there's much in there.

I really don't have experience with the Razz, but 71psi sounds too low to ever be a healthy runner. 6.3:1 could be a corrected compression ratio, not the compression ratio most of us think of. 71psi may be the correct spec, but I find it somewhat hard to believe that a chain drive scoot with 71psi compression test reading will ever run very well.

I would definitely check the reeds. Easy check is holding them up to light and seeing if any shines through. You may be able to get away with flipping the reed petals over. Maybe not, but it's worth a try for a quick fix. I've had engines running poorly and backfire and blow the reeds apart.

If the float level is set too high it could flood, but fuel will often overflow from the carb.

If you take the exhaust off and look up into the port with a light you may be able to get a look at the rings. They sometimes get stuck from buildup on 2Ts.

You can have a spark, but a weak spark may not ignite the mixture... especially if the mixture is not ideal to begin with.

Since it happened after cleaning the carburetor, never hurts to scrutinize your work there.

[FACE PLANT FOR LIFE]

All of this is great advice. I am going to try to get him to come back here so we can try a few things. I'll keep you updated.