throttle problems

[whooez]

OK first off I have been reading a lot of good stuff on this forum. The info has helped a lot in my projects.

So here is what is going on, i bought two 1985s one was in running condition the other not so much i have added the air pods and also jets, shimmed the needle and blocked off air flow. i can get the bike to start and idle just fine no problems there, but when i twist the throttle the bike falls right on its face and dies.....?

I have adjusted the carbs every way that i can think of....I need some insight please help...

[zekkfett]

Is your float height set to 17mm? Getting proper vacuum to the petcock? Any vacuum leaks?

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[Blaine]

Apr 24, 2013 9:51:01 GMT -6 whooez said:

OK first off I have been reading a lot of good stuff on this forum. The info has helped a lot in my projects.

So here is what is going on, i bought two 1985s one was in running condition the other not so much i have added the air pods and also jets, shimmed the needle and blocked off air flow. i can get the bike to start and idle just fine no problems there, but when i twist the throttle the bike falls right on its face and dies.....?

I have adjusted the carbs every way that i can think of....I need some insight please help...

Welcome.Make sure that the slide diaphrams are sealing properly so the slides open & make sure that the vent tube (upper "t") is open not kinked.

[whooez]

Zekkfett how would i check the float hight...?
I do have zacuum lines hooked up properly and the do have vacuum....
One other thing i dont know about is next to the starter there is a cap with a bolt on the top with a small hose in the shape of "?" Mark. Do i need to cap that off..??

[Blaine]

Apr 24, 2013 12:54:19 GMT -6 whooez said:

Zekkfett how would i check the float hight...?
I do have zacuum lines hooked up properly and the do have vacuum....
One other thing i dont know about is next to the starter there is a cap with a bolt on the top with a small hose in the shape of "?" Mark. Do i need to cap that off..??

No that is a breather for the crankcase & must have a small filter on it when using pods.Normally it gets filtered air from the airbox.You Set the float hight by measuring with the bowls removed,

[zekkfett]

I'll post an alternative solution (Carbs still on the bike) here in a bit, when I leave work.

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[zekkfett]

Without taking the carbs back off, this is the easiest solution. If the carbs are on the bike, the bike will need to either be on the center stand, or standing upright to get an accurate reading.

[whooez]

Thanks for the info i will get on this tomorrow and let you guys know how things turn out... ;D

[whooez]

So i did the little tube trick but have to way to measure with graduated marked tube...the fuel level in both carbs are right at the seal line....is this correct...

Also what is the best starting point to tune my carbs???

[zekkfett]

According to the manual, if you do the test exactly as stated, the fuel level should be 0.5mm below the zero line.

If anything, your bowl fuel level is a little high, which can cause flooding into the carbs and airbox.

Also, it's important that you start with your test tube high, then lower it (SLOWLY). If you start low and raise it, the fuel in the tube can't defy gravity, and go back into the bowl.

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[beegz]

I love reading all the post in the forum!

so I am having the same kind of problem.. bike fires right up and ildles perfect. i can rev it to about 4k RPM and then it starts bogging out around 4.5 and will die if I don't get off the gas. I check the level of the fuel In the carbs, sitting perfect. am I not getting proper vacuum? could a seal be bad in the petcock? it almost feels like it's not getting enough gas to keep it at high rpm.
thanks got the help

[Blaine]

May 28, 2013 21:17:15 GMT -6 beegz said:

I love reading all the post in the forum!

so I am having the same kind of problem.. bike fires right up and ildles perfect. i can rev it to about 4k RPM and then it starts bogging out around 4.5 and will die if I don't get off the gas. I check the level of the fuel In the carbs, sitting perfect. am I not getting proper vacuum? could a seal be bad in the petcock? it almost feels like it's not getting enough gas to keep it at high rpm.
thanks for the help

I would start by disconnecting your fuel line & checking fuel flo from the petcock.You may have some dirt plugging the screens on the petcock.Also make sure that the vent tube (on upper T) is clear & not blocked or kinked.

[eaglerider]

Adjust your valves.....sounds like they are too tight.....that prevents the engine from revving and running right.

[kpaiva]

I keep reading about upper t not being pinched or blocked.i thought you were supposed to attach both carb vacuum lines to the upper t line to the pet cock

[Blaine]

Dec 5, 2016 21:02:16 GMT -6 kpaiva said:

I keep reading about upper t not being pinched or blocked.i thought you were supposed to attach both carb vacuum lines to the upper t line to the pet cock

Nope.It remains open.....You can "T" both vacuum nipples on the carbs together & than to the petcock......But the easiest is to just block off the vacuum nipple on the right carb & just run a straight hose from left carb up to petcock.

[blackmaxx]

Or you have a plugged jet in the carb. My 2011 Yamaha quad had that exact problem. It would fire up and idle but as soon as I touched the throttle, the motor died. Took off the carb and inspected the jets and found the intermediate jet plugged. Cleaned it out, inspected the rest and re-assembled. Runs like a top now. BTW, this quad is still like new with less that 80 kms on it. So this carb issue was basically from factory. No idea how it happened but now there is an inline fuel filter installed too.

Cheers