Carb issue

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Diablotin

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I cleaned the carbs last week and have been running with some seafoam for more than 60 miles but my issue remains. Carbs are already sync too.

The bike have an hard time to take the throttle between 1 and 3k rpm. The problem is less with choke or when warm. Also I notice some backfire at low rpm.

I have been looking for air leak but it doesnt seem to be the issue.

Tnx

Michael

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The plugs look fine. Neither too lean or too reach. Although I had a very poor mileage on the first full tank.

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I think peashooter and shotgun are in order. Search those terms. Also, I'm gonna go out on a limb and say that you might have a pilot jet problem since it's 1-3k. I've had my carbs apart three times and have a set from Dannymax on my bike right now. It's also possible that you have an a/f screw problem. Good luck. You'll get lots of good help here.
 
Peashooter done already. Thats the first thing I did. Plugs did look lean at first with previous A/F setting. All of them. Running at 4 turns they looked fine. I believe its too much since the bike is use to run well at 3.5 with a slight reach condition.

Not sure what but something leans the carbs. I will check the wet levels and manifolds boots tomorrow.

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This is usually caused by the low speed jets. It does require complete dismantling and cleaning. I usually have to use oxy-acetylene torch tip cleaners to ream out the jet orifices because they get so clogged that cleaners often don't clean them out. Some of the jets are so small they are really hard to clean. You can buy the tip cleaners at most any tool store for less than $10.
 
mine has done the same thing, to a lesser extent, for a while now. shotgun clears it up but eventually i'll have to dig in.
 
Today I noticed something weird. Carbs are perfectly sync at 1.5k RPM but when I put down the idle at 1k, I notice that the left side has higher values than the right. I brought it back to 1.5k and they are perfectly sync at 24 on the carbtune.
Any reason?

I'm planning to do a shotgun but I'll need to find a compressor first.
 
Carbs should be synched at, or below normal idle speeds.

Have you checked your voltage at idle lately? Missing at those RPM's could also be your black box stuttering from low voltage.
 
Not sure where I read it, but I saw it was advised to sync at 1500 rpm.
Weird when in carbtune's manual, They say at idle.

I tried at idle, then my 1.5k will be unbalanced.

I used to have a good voltage, but yeah didn't check it lately. I will do that asap.
 
just some updates...

I spent some time over the WE to make a full check. That was like a practice session after reading all the stuff here lol


I did a shotgun (not fully since I had to use air spray can) and noticed that the mixture screws where holding some rust due to missing washers and o-ring. Springs are also in a bad shape due to the rust. I'll check for replacing those asap. For now, it's clean but I had to put it back without missing parts and with the bad springs.

Drain holes were clogged.

Vboost was stuck in open position due to the adjustment screw being too tight.

My float level were off, they are now set to 1.115. On top of that, the float was not positioned properly with the needle spring. My wet level look fine now (16 mm) but I still need to do it again more accurately. I'll do it again when repla:bang head:cing the mixture screws.

After correcting all those, I can already see huge improvement.
I'm still too rich, I can still smell the gas from the exhaust but the bike is running much better now. It's still hesitating at low rpm, it doesn't accept a full throttle smoothly. I might try to target 1.125 for the float and 17 mm for the wet level depending on what I read next time.

I have measuring it with a home made setup that way I don't need to put back the carbs on the bike to check the level.
I was thinking about setting up something live an IV bad or bottle to supply the carbs in gas and suspended high enough to maintain enough pressure. I did it with a plastic bottle and hoses feeding directly the carbs, it works but it's an hassle :rofl_200:

Still it takes less time than assembling and disassembling the rack over and over :bang head:


I usually let somebody messing up with the carbs since until now I was a bit worried about doing it myself.
I always felt knowledgeable after all the time spent here but I used to be afraid of moving from theory to practice.

But at the end, the moral of the story is sometimes better to deal with your own shit yourself, even if it takes you forever. At least you know what and how it is done :p

Big thanks to your guys who are writing those sticky post :punk:

If somebody has a better idea than my IV, I'll appreciate :)
 
Hey Michael,

have you gone as far as disassembling the carbs (in pairs is enough) so far in order to remove the jet blocks? I guess if you got into the float chambers you must have..

Anyway, reason I'm asking is because most of the time, if there's any shit in there, the one place that will get clogged is those tiny pilot jets in the jet blocks - you need to remove the blocks and the rubber plugs to get to them.
I reckon it's most likely that these are causing your low revs probs...

cheers
 
Had same problem had take carbs apart clean idle jet flushed tank new filter runs fine now.
 
Hey Michael,

have you gone as far as disassembling the carbs (in pairs is enough) so far in order to remove the jet blocks? I guess if you got into the float chambers you must have..

Anyway, reason I'm asking is because most of the time, if there's any shit in there, the one place that will get clogged is those tiny pilot jets in the jet blocks - you need to remove the blocks and the rubber plugs to get to them.
I reckon it's most likely that these are causing your low revs probs...

cheers

No I didnt get as I was lacking of time for a full cleaning.

You might be right though. I'm still planning to dismantle the carbs soon so I'll clean everything myself this time.

No need to say how ur sticky posts were helpful this WE ;)



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I still need a lot of choke when starting the bike until it warms up. Low RPM are still rough but now at least it doesnt choke anymore.
I guess the deep cleaning is really needed if I want to get somewhere :)

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I still need a lot of choke when starting the bike until it warms up. Low RPM are still rough but now at least it doesnt choke anymore.
I guess the deep cleaning is really needed if I want to get somewhere :)

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If you can get the carb cleaner in a paint can with a basket, do it. I let my jet blocks minus rubber parts sit over night to help ensure they get cleaned.
 
Yep that's exactly what I had in mind :)

My issue is always time since I work like a slave and use the bike to commute.

I'm a bit slow I guess but I should be able to do it over a WE soon.

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If you can get the carb cleaner in a paint can with a basket, do it. I let my jet blocks minus rubber parts sit over night to help ensure they get cleaned.

Check the directions on the stuff you use....GUNK Carb-Medic says to remove parts after 20 min. It's pretty strong, and will gobble up pot metal. I don't believe there is any in oem VMax carbs but some aftermarket parts could be different. :confused2:
 
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