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Guest Message by DevFuse
 

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Can't get my brat past 40mph


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28 replies to this topic

#1 DevoScoobyRoo

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Posted 22 July 2013 - 08:03 PM

We recently put a webber on my brat and got all vacuums plugged and such. Webber was re jetted and rebuilt specifically for the brat.

Problem is when I get to about 40mph it starts acting like its starving for gas. We've messed with the mixture screw and it doesn't make a difference for the main issue.

Any ideas?

#2 CWP8

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Posted 22 July 2013 - 08:08 PM

hmm... thats weird. I would suggest talking to ShawnW



#3 DevoScoobyRoo

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Posted 22 July 2013 - 08:23 PM

How might I get ahold of said person?

#4 MilesFox

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Posted 22 July 2013 - 10:39 PM

Changed fuel filters?



#5 DevoScoobyRoo

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Posted 22 July 2013 - 10:51 PM

I haven't changed them yet. The one in the engine bay looks ok as for the other idk.

It runs like a Kenyan as long as I'm not going 40+

#6 NorthWet

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Posted 22 July 2013 - 11:31 PM

+1 on the fuel filter (is the one in the engine compartment really just a vapor separator, like in the carb'd EA82s?)

 

A lesser possibility is that your secondary isn't opening.



#7 BoxerRebellion

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Posted 23 July 2013 - 10:49 AM

Sounds like a lean condition to me. Suppose it could be rich, but if you were to ask me, I'd take a look at the jetting. You can throw larger or smaller jets into a carb, but the resulting effect isn't always desired. You can purchase multiple jet sizes either way, for cheap. Trial and error. I've been there with motorcycles. Also, the car can only take in as much as it can put out. So when the jetting gets messed with, but the exhaust stays the same, that's where things can potentially get wonky. I'd trial and error with different jets. "Don't fix it if it ain't broke," sure... Though... I think that'd be the easiest way. Best of luck.



#8 NorthWet

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Posted 23 July 2013 - 11:10 AM

Jetting should not have such a dramatic effect, unless you go wildly one side or the other.



#9 djellum

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Posted 23 July 2013 - 11:20 AM

check your coolant.  you may be dribbling water in through the base gasket.

 

fuel filters should be replaced, just on principle, but you should also check your fuel pressure.  webers are sensitive to fuel pressure.

 

check your vacuum advance line, make sure its on ported vacuum.  ussually not a major problem at speed, but always a thing to double check.



#10 Dinky26

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Posted 23 July 2013 - 11:51 AM

Was this a brand new Weber?

Reason I am wondering is that I am waiting for my Weber to come in so I can install.

 

Any idea how much effect happens when it is specifically rebuilt for the Brat?

 

Also I just replaced the filter under the bed less then 6 months ago, should I replace again when installing the Weber?

 

Ordered from a shop close to me, I was told a complete kit with everything I need for $389, didn't think that was a bad price for the package.



#11 DevoScoobyRoo

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Posted 23 July 2013 - 12:17 PM

Thanks for all the ideas everyone!

I checked fuel pressure already and it was good.
The secondary seems to get gas but it doesn't seem to be near as much. But that's normal isn't it?
I already had a problem with coolant escaping by the base on the weber and I don't seem to be losing Any more fluid.

The webber was not brand new but running.
It was just a rebuild as any other carb

#12 ferox

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Posted 23 July 2013 - 01:11 PM

We recently put a webber on my brat and got all vacuums plugged and such. Webber was re jetted and rebuilt specifically for the brat.

Problem is when I get to about 40mph it starts acting like its starving for gas. We've messed with the mixture screw and it doesn't make a difference for the main issue.

Any ideas?

 

As others have mentioned, fuel filters, I have had the same effect you describe from clogged fuel filters on ea81s on several occassions.  It's the first thing to check.  I would just replace them anyway since they are cheap.

 

When you say the carb was jetted for a Brat, what where the jets?  Most specifically, the secondary idle jet.



#13 naru

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Posted 23 July 2013 - 01:15 PM

Thanks for all the ideas everyone!

I checked fuel pressure already and it was good.
 

 

Idle fuel pressure does not mean much in this case.

Tape your gauge to the outside of the windshield and check pressure while going 40+ and motor acting like it is starving for gas.

Sounds like a weak pump or plugged filters to me.



#14 NorthWet

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Posted 23 July 2013 - 01:27 PM

And, since this was a used carb, which model is it?  More specifically, is the secondary opened mechanically or is it it vacuum-operated (as in the vast majority of street applications for this style of Weber)?



#15 DevoScoobyRoo

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Posted 23 July 2013 - 02:16 PM

150 main 145 then air correctors are 170 160 idle jets are 50 and 55. It was doing this prior to the webber but I thought it was my carb in the first place

#16 naru

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Posted 23 July 2013 - 03:15 PM

 It was doing this prior to the webber but I thought it was my carb in the first place

 

Thought so.

This pretty much confirms it is not the carb



#17 DevoScoobyRoo

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Posted 23 July 2013 - 04:04 PM

So other then the carb we have fuel filters and what else?

#18 Dinky26

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Posted 23 July 2013 - 04:09 PM

Fuel Pump?

 

Or a hole in a line somewhere??


Edited by Dinky26, 23 July 2013 - 04:10 PM.


#19 MilesFox

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Posted 23 July 2013 - 04:22 PM

So other then the carb we have fuel filters and what else?

intake gaskets (lean condition, coolant ingestion)



#20 DevoScoobyRoo

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Posted 23 July 2013 - 05:39 PM

Intake gaskets are brand new. We were going to
Do a ea82 swap for the intake and use a 82carb also but decided weber was a better choice.

#21 ferox

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Posted 23 July 2013 - 07:23 PM

So other then the carb we have fuel filters and what else?

 

Are you asking because you have changed the filters and the problem persists?



#22 djellum

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Posted 23 July 2013 - 10:33 PM

I think you know, but just in case, theres a filter in the rear under the car by the passenger tire.

 

some more specific info would help.  will it stumble at that speed regardless of how deep in the throttle you are, or will it act up at certain rpms as well?  when you say starved for gas, do you mean bucking and sputtering, just vibrating hard, etc?



#23 DevoScoobyRoo

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Posted 23 July 2013 - 10:42 PM

I think you know, but just in case, theres a filter in the rear under the car by the passenger tire.

some more specific info would help. will it stumble at that speed regardless of how deep in the throttle you are, or will it act up at certain rpms as well? when you say starved for gas, do you mean bucking and sputtering, just vibrating hard, etc?


Around 37-40m

#24 DevoScoobyRoo

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Posted 23 July 2013 - 10:44 PM

I think you know, but just in case, theres a filter in the rear under the car by the passenger tire.

some more specific info would help. will it stumble at that speed regardless of how deep in the throttle you are, or will it act up at certain rpms as well? when you say starved for gas, do you mean bucking and sputtering, just vibrating hard, etc?


Around 37-40mPh regaurdless whether I'm flooring it lightly on the gas it does some medium bucks and sounds like its going to die
As for rpms my tac doesn't work lol

#25 DevoScoobyRoo

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Posted 23 July 2013 - 10:45 PM

I think you know, but just in case, theres a filter in the rear under the car by the passenger tire.

some more specific info would help. will it stumble at that speed regardless of how deep in the throttle you are, or will it act up at certain rpms as well? when you say starved for gas, do you mean bucking and sputtering, just vibrating hard, etc?


Around 37-40mPh regaurdless whether I'm flooring it lightly on the gas it does some medium bucks and sounds like its going to die
As for rpms my tac doesn't work lol




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