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PostPosted: Sat Sep 01, 2012 9:53 am 
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Hey guys i haven't posted on here in a while bc i had to sell my buggy a couple of years ago...dang economy...anyways i was able to make a series of trades and ended up with a decent street legal buggy! So im back in the game now! When i first picked it up and drove it around it was back firing pretty bad and had to be pull started. I took it home and gave it some love...fresh tune up, new battery, timing corrected, new points distributer, plugs, wires, alternator conversion, new fuel pump for the alt conv. (mechanical not electric). After all of that i was still getting a little bit of back fire so I went and picked up a couple of rebuild kits for my webbers. One side was REALLY bad! Got them all cleaned up and poof back fire gone as well as a smoother idle! I was elated! Jumped in and took off down the road...This is where the fun begins...acceleration and shifting felt fine in 1st-the bottom of 3rd. after shifting into 3rd at about 30mph i continued to accelerate to about 45mph but really wan't getting much more so I shifted to 4th. RPM dropped as it should however i maintained 45mph and couldn't accelerate past that. RPM stayed the same. Im not sure if it not dropping enough gas or what. My guess was some sort of fuel problem, and thought that maybe the stock mechanical pump couldn't handle my webbers. After further research, i found it "should" be able to handle it. Anyone have any ideas of what it could be? Sorry for the long post, i just wanted to get as much info as i could to you guys...
Thanks for the help!
Brandon

heres a couple of pics of what it looks like right now...This is right in the middle of my carb rebuild...
http://i544.photobucket.com/albums/hh34 ... xhaust.jpg
http://i544.photobucket.com/albums/hh34 ... ebuggy.jpg


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PostPosted: Sat Sep 01, 2012 10:36 am 
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make sure your getting about 30 degrees full advance and since you did everything else you might as well change that coil made a world of difference in how mine ran.

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PostPosted: Sat Sep 01, 2012 10:55 am 
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hpfreak wrote:
make sure your getting about 30 degrees full advance and since you did everything else you might as well change that coil made a world of difference in how mine ran.


I didn't do the timing...There's a guy in town here thats been working on bugs for quite a while and did all the tune up and timing stuff. He keeps pretty much anything i could need in stock...Are you talking about the ignition coil? It starts up just fine every time!


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PostPosted: Sat Sep 01, 2012 2:40 pm 
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just a thought but check to make sure your accelerator cable is pulled tight so that when you floor it , it is opening up the throttle plates all the way! good luck and let us know what it was!

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PostPosted: Sat Sep 01, 2012 2:53 pm 
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diamonddav wrote:
just a thought but check to make sure your accelerator cable is pulled tight so that when you floor it , it is opening up the throttle plates all the way! good luck and let us know what it was!


I had the same concern...the cable was a little loose so I pulled it tighter but it still does the same thing...I'm really not sure what's going on. I'm going to replace all the fuel lines, filters, and coil to see if that helps. May have to figure out how to check the timing. I'm just tired of bangin my head against the wall trying to figure it out...thanks guys for all the help!


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PostPosted: Sat Sep 01, 2012 3:51 pm 
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what size motor and carbs is it? could be a jetting issue.


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PostPosted: Sat Sep 01, 2012 4:38 pm 
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kevin f wrote:
what size motor and carbs is it? could be a jetting issue.


I was told it is a 1835cc. I've only had it 2 weeks now...carbs are dual webber 44's. Very well could be the jets. They were cleaned but not replaced. Im not even sure what size i would need. After rejetting do you need to syncronize carbs again?


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PostPosted: Sat Sep 01, 2012 5:09 pm 
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What kind of trans do you have. It looks like it might be a swing axle. I would jack it up and make sure you are not getting any extra resistance in 4th gear.

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PostPosted: Sat Sep 01, 2012 6:02 pm 
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MickeyMouse wrote:
What kind of trans do you have. It looks like it might be a swing axle. I would jack it up and make sure you are not getting any extra resistance in 4th gear.


Theres no unnecessary resistance...I cant get the rpms to raise again after shifting into 4th. In that situation the rpms would increase but speed would remain constant. I really feel it is a lack of fuel issue. The way i see it is when im in the lower gears i have enough gas for a certain amount of momentum I can shift gears through out all of that untili hit the threshold where i need more gas to increase momentum. That threshold just so happens to be top of 3rd or bottom of 4th. Larger jets mean more fuel which makes since. I was really thinking that the fuel pump wasn't large enough for the carbs but was advised otherwise. I may go get a gauge to see exactly what it pushing through it. I really appreciate all the help! The last couple of days i have literally lost sleep over this.

-Brandon


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PostPosted: Sat Sep 01, 2012 9:23 pm 
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Maybe 3rd and fourth gears are slipping on their shafts?


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PostPosted: Sat Sep 01, 2012 9:55 pm 
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Ibanidiot2 wrote:
Maybe 3rd and fourth gears are slipping on their shafts?


Could be. Would this make a squealing noise or something coming from the trans or would it just float around the shaft? I guess it would get progressivly worse as time goes on huh? more wear=less power...I dont know. Im still leaning towards fuel. When i first got it back from getting the timing and tune up done, i drove it down the road and it was doing the very same thing only in 1st and 2nd! Thats when i decided to do the carb rebuilds. This fixed my idle, a little bit of back firing and i thought my main problem. However, no luck after the test ride. Just moved to top of 3rd/bottom of 4th...Im off work monday so we'll see how much i can get done. No parts to play with this weekend. :(


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PostPosted: Sun Sep 02, 2012 2:21 am 
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look down the throat of the carbs and see what size the venturis are stamped somebody may have changed them but, a stock 44 carb has 36mm venturis, and personally i think that is too big, 40's are better suited for a 1835 imo and they come with 28mm venturis

the problem this may cause is a loss of torque (slow/lazy air speed/flow) which would be felt most in 4th and maybe even 3rd especially with a stock geared car tranny

also too big a header will cause a loss of torque (not enough back pressure)

another issue i came across once was not having a good free flow from the tank to the pump due to crimped lines and trash built up in the valve on the bottom of the tank restricting flow

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PostPosted: Mon Sep 03, 2012 12:50 pm 
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ridenrace6 wrote:
look down the throat of the carbs and see what size the venturis are stamped somebody may have changed them but, a stock 44 carb has 36mm venturis, and personally i think that is too big, 40's are better suited for a 1835 imo and they come with 28mm venturis

the problem this may cause is a loss of torque (slow/lazy air speed/flow) which would be felt most in 4th and maybe even 3rd especially with a stock geared car tranny

also too big a header will cause a loss of torque (not enough back pressure)

another issue i came across once was not having a good free flow from the tank to the pump due to crimped lines and trash built up in the valve on the bottom of the tank restricting flow

Thanks for the help Ill check into this just as soon as i can! I just changed all my fuel lines and filters with no change in the problem...oh well they were looking pretty beat up. Have a good labor day everyone!


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PostPosted: Thu Sep 06, 2012 2:38 pm 
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ridenrace6 wrote:
look down the throat of the carbs and see what size the venturis are stamped somebody may have changed them but, a stock 44 carb has 36mm venturis, and personally i think that is too big, 40's are better suited for a 1835 imo and they come with 28mm venturis

the problem this may cause is a loss of torque (slow/lazy air speed/flow) which would be felt most in 4th and maybe even 3rd especially with a stock geared car tranny

also too big a header will cause a loss of torque (not enough back pressure)

another issue i came across once was not having a good free flow from the tank to the pump due to crimped lines and trash built up in the valve on the bottom of the tank restricting flow


The venturis are 28 and I'm running 115 main jets. Its still acting like its not getting enough fuel to the carbs...


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PostPosted: Thu Sep 06, 2012 4:41 pm 
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what size are the idle and air jets also which emulsion tubes?

f11 tubes seems to be the most commonly used but have run across a few f7 tubes

also it somewhat depends on the other jets but a 115 main seems a little small, i would try a 130 or 135 and see what does

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PostPosted: Thu Sep 06, 2012 9:18 pm 
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ridenrace6 wrote:
what size are the idle and air jets also which emulsion tubes?

f11 tubes seems to be the most commonly used but have run across a few f7 tubes

also it somewhat depends on the other jets but a 115 main seems a little small, i would try a 130 or 135 and see what does


Ill check the other jets in the morning. I was thinking the same thing about the main jet. Im pretty sure emulsion tubes are f11. I tried to stop by my local shop today but it was during lunch so no one was around. Ill swing by in the morning and pick up some bigger jets. What size idle and air should i be running? Thanks for the help!


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PostPosted: Thu Sep 06, 2012 10:50 pm 
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200 is a good starting point on the air jet till you get the idle and mains figured out

as for idle im just guessing but something in the 55 or 60 range should be close

how many rounds out are the idle mixture screws, i try to adjust the idle jets to so the mixtrue screws are as close to 1 1/2 rounds out as possible but anything between 1/2 and 2 1/2 should work till you everything else pretty close and as long as you end up between 1 - 2 rounds it run out just fine as far as idle jets

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PostPosted: Sat Sep 08, 2012 7:06 pm 
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Changed the main jets to 135 added an electronic "booster"pump for the fuel. It's running smoother but still bogging down. Looks like it may be passed what i can do in the garage. Ill probably take it down to the local shop again next week to check timing/re sync carbs/ general diagnosis of the problem... :( so much for riding tomorrow...


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PostPosted: Thu Sep 13, 2012 2:19 pm 
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UPDATE:

I got the dune buggy fixed!!!!!!!!! Turns out the float in the passenger side carb needed to be adjusted better. I took it out for a test ride and noticed a complete 180 in the performance! I am literally still shaking from the rush of the first test ride! Thanks for all the help guys! I wish i lived closer to you all, but if anyone is ever in texas let me know! Id love to go for a ride!

-Brandon


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