I have a 2006 Yamaha 90. We got it new, and was ride for 2 yrs. then was put up in storage. I changed the battery, air filter, spark plug and wire, cleaned the carb and put new jets in. Also cleaned gas tank and changed all fluids. It will start and idle fine. But as soon as I put it in gear and start to ride, it takes off fast steadily starts missing until it won't pull its own weight. Pull the plug and it looks to be flooding. But the floats are good, throttle isn't hanging, and the jet I am certain are the same size I took out. Anybody on here that might can help me out ?
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4 wheeler question because local shops don't have a clue !
- Thread starter gdf
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TBItoy
Well-Known Member
I'd buy a new carb.
Seems like all small engines I've messed with recently required a new carb (ie "rebulding" and cleaning them didnt' fix whatever was wrong with the carb internally)
Seems like all small engines I've messed with recently required a new carb (ie "rebulding" and cleaning them didnt' fix whatever was wrong with the carb internally)
untchabl
On the Rocks
Don't buy a cheap Chinese carb, spend the extra for an OEM carb. We've pretty much stopped rebuilding carbs at our shop, we just put new ones on.
Rjhoward32006
Well-Known Member
You will be lucky if the parts "carb" wasn't sourced out to overseas from the factory. But most likely that is your problem
d_daffron
Well-Known Member
If this is the yamaha 90cc engine I am thinking of you need to adjust the valves before you spend any money on anything! Look up the valve adjustment proceedure on Google and try that before you spend any money. The problem youre describing sounds exactly like its in need of this valve lash adjustment.
gottagofast
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Sounds like a bad coil to me
tommy450r
Well-Known Member
Fuel needle may have came loose check an make sure the little keeper under the return spring is in place
Rjhoward32006
Well-Known Member
x2 on the valves, I have run into that problem before also
sexxy
Well-Known Member
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X3 on valves. Make sure the throttle is screwed in properly at the carb. Check the fuel air mix screw. Should be about 1.75-2.5 to get it close enough to run. My sons 90 had the mix set to rich and would flood idling too long or if the throttle wasnt opened at least half throttle periodically.
Make sure the rubber seal is in good shape at the fuel mix screw too.
Make sure the rubber seal is in good shape at the fuel mix screw too.
ok thanks guys , yeah needle is good, I'll check valves and then just buy a new carb if that doesn't work !
I work on Jamaha's all day everyday. I've never had to replace a carb, unless a customer screwed it up somehow. Spray through every single passage with carb clean to verify it flows through ALL the passages. If the jets are stock sized, make sure the air box and all has not been molested. Make sure the oil doesn't smell like gas too...
To speed up your diagnosis, pull the choke or put your hand over the intake to change the fuel ratio and see if gets better or worse.
To speed up your diagnosis, pull the choke or put your hand over the intake to change the fuel ratio and see if gets better or worse.
gottagofast
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I'll say it again COIL...
Check your spark with an inline tester...
I suspect you'll see it die out when you get on it.
DON'T just throw parts at it and watch to see what sticks... Diagnose the problem...
You think it's flooding?... turn off the gas... If it doesn't come back then it's not flooding...
You suspect valve lash? .... only takes a few minutes to check it...
I still say coil tho... I've fixed LOTS of carburetors by putting a new coil on.
Check your spark with an inline tester...
I suspect you'll see it die out when you get on it.
DON'T just throw parts at it and watch to see what sticks... Diagnose the problem...
You think it's flooding?... turn off the gas... If it doesn't come back then it's not flooding...
You suspect valve lash? .... only takes a few minutes to check it...
I still say coil tho... I've fixed LOTS of carburetors by putting a new coil on.
Air box is good....cool is possible, has good spark. I'm having my brother look at it for proper valve clearance this weekend. He worked with Kawasaki race team for 10 yrs and ran a 4-wheeler shop before he took a plant job....I don't think we have three parts at it yet, that's what I am trying to keep from doing.
kmcminn
Well-Known Member
gdf said:
Be careful that 90 maybe a little big for you.
gottagofast
Well-Known Member
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Keep it simple! It's a Yamaha not a Taiwanese. I'll admit weird things do happen, but not very often. Fuel, spark, and compression is about all you "should" need to check for. If you have good compression and it sparks you still have a fuel/carb problem.
A compression test will tell you if the valves are tight. If you don't have a gauge put your finger over the spark plug hole and turn it over. If you can't hold your finger on the hole it's probably alright.
I would clean the original jets and put them back in. The aftermarket kits sometimes have different size jets with the stock number stamped on them. Poke them out with a strand of wire.
A compression test will tell you if the valves are tight. If you don't have a gauge put your finger over the spark plug hole and turn it over. If you can't hold your finger on the hole it's probably alright.
I would clean the original jets and put them back in. The aftermarket kits sometimes have different size jets with the stock number stamped on them. Poke them out with a strand of wire.
zukimaster
Hold my beer and watch this!
I have built a couple of small carbs, get a torch cleaning kit, those holes are so small in those carbs just any little thing at all will stop them up. And Yamaha makes the best carb cleaner, most shops keep in in stock, let it soak in it over night .
