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Discussion Starter · #1 ·
Hello everyone. I recently took some heavily modified CAG nightmare on trade, I work on cars, so I dont know much about 2 strokes. Obviously I need input from experienced people to get it to run again. It was missing the pullstart but was supposed to run when I got it, only to find out after buying a pullstart that was a load of hooey.

Gonna mess with it some more tomorrow, thinking I have a vacuum leak.

Oh yeah, live near Myrtle Beach, 31 years old, love to get this thing running so I can move onto the mini quad.
 

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Welcome to the forum........

Id start at the basics,,,do a compression test on the cylinder to start.....If it has an aftermarket headkit on it chances are the rings could be trapped in the piston from severe scoring at the transfer port sides..put some gas down the cylinder to see if it will fire is another way to tell if itll run..

If it pops and runs you may have to rejet the carb and adjust the c-clip on the carb needle richer.......

Another area to look into is the plastic intake manifold...those crack way easy

If compression is above 80 and the intake is good and the engine wont fire,,you may need a coil...check to make sure the pickup to magneto has a proper airgap of .020"...If still no fire swap the coil with the pocket quad and see if that gets it running.....
 

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Discussion Starter · #3 ·
I had to remove the engine and take it to the local neighborhood small engine guy. Turns out whoever built the engine in the first place had the piston in backwards. Now to reassemble with new gaskets.

But yeah, I did the thumb over plug hole test for compression, tried putting gas straight down through the plug hole, checked and rechecked for spark, and it does, all to find out the dimwit that assembled the engine had the piston in backwards, marcelowhich I suspected, but I work on cars usually, so I wasnt sure.

That litlte quad I have is a 250 chinese banshee lookin thing, it was running when parked but that was like 5 years ago.
 

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LOL...I cant beleive people actually think the window faces the exhaust port.........Good to hear you found the problem but not on what the guy charged you to find that out.......
 

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Discussion Starter · #5 ·
Didnt have much time to bang my head against it today but I did put new gaskets in, and I picked up a new spark plug that I ahvent installed yet.

This thing has a ada racing aluminum intake and reed assembly, when I removed it I tried blowing from the carb side thru the reeds, got plenty of air thru, tried sucking back through and got a little, but not much at all. How airtight are the reeds suppsoed to be? Visually they look fine.
Starting to hate thins thing.
BTW, the engine guy I know luckily needed some pointers on some rustheap impala he has, so the diagnosis was free.
 

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Didnt have much time to bang my head against it today but I did put new gaskets in, and I picked up a new spark plug that I ahvent installed yet.

This thing has a ada racing aluminum intake and reed assembly, when I removed it I tried blowing from the carb side thru the reeds, got plenty of air thru, tried sucking back through and got a little, but not much at all. How airtight are the reeds suppsoed to be? Visually they look fine.
Starting to hate thins thing.
BTW, the engine guy I know luckily needed some pointers on some rustheap impala he has, so the diagnosis was free.
If you have a stock carb and have the ADA 4 petal redblock youre gonna have alot of tuning problems....Youre gonna need a jetpack assortment..Id get a hp pumper carb retrofit kit so tuning wont be so tedious and messy.........When I gently blow through my reeds it sounds like an out of tune harmonica................

Id install the head without a base gasket and yamabond it down and it will take a full 24 hours before you can put the engine to use....I JB Weld mine down and add extra pressure nuts on the base on the long through bolts for extra security and to prevent cylinder walk due to the fact that there are no alignment pins keeping the head stationary and alot of unecessary clearance to allow it to happen...................
 

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Do you have the billet alum 4 reed set up, and a 15mm Walbro WYK pumper carb? I modded mine to fit 16mm HDA 48D Walbro no return line back to the tank. Keep you eyes open for the Davesmotors Go Ped sale of the week, every once in a while they have the HDA carb for $30 or so, both me and Cam2 got some already. See photos. The last 2 photos are a different ADA manifold for stock reed set up.
 

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Do you have the billet alum 4 reed set up, and a 15mm Walbro WYK pumper carb? I modded mine to fit 16mm HDA 48D Walbro no return line back to the tank. Keep you eyes open for the Davesmotors Go Ped sale of the week, every once in a while they have the HDA carb for $30 or so, both me and Cam2 got some already. See photos. The last 2 photos are a different ADA manifold for stock reed set up.
It sounds like to me someone bought an ADA 4 petal reed kit and used the stock plastic intake with stock carb because theres no mention of having a pumper carb when I told him to look at the plastic intake for cracks.....................
 

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Discussion Starter · #9 ·
Ok, so today I grabbed another stock cAG engine that was SUPPOSED to run, good compression, had to swap my coil and pull onto it, its firing, put it on the bike, still wont even pop.

The engine that came on the bike has the ADA reed setup just like that photo, but the carb looks waaay different, looks identical to the one on the stock motor, and I dont see a pump anywhere on either. The modded engine has nothing plastic from carb to head, the stock one has a plastic intake.

SO I have two of the same carbs with the little sliding choke and what I call a "piston" throttle instead of a normal butterfly.

Neither engine will even pop from starting fluid.

I also replaced the plug in the modified engine this morning just to try my luck. Still nuttin but a case of carpal tunnel from yanking on this pull start.

To make matters worse, I just toook a 2.5 trxxas t maxx on trade that only wants to run about half the time. Frustration is rising...
 

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Ok, so today I grabbed another stock cAG engine that was SUPPOSED to run, good compression, had to swap my coil and pull onto it, its firing, put it on the bike, still wont even pop.

The engine that came on the bike has the ADA reed setup just like that photo, but the carb looks waaay different, looks identical to the one on the stock motor, and I dont see a pump anywhere on either. The modded engine has nothing plastic from carb to head, the stock one has a plastic intake.

SO I have two of the same carbs with the little sliding choke and what I call a "piston" throttle instead of a normal butterfly.

Neither engine will even pop from starting fluid.




I also replaced the plug in the modified engine this morning just to try my luck. Still nuttin but a case of carpal tunnel from yanking on this pull start.

To make matters worse, I just toook a 2.5 trxxas t maxx on trade that only wants to run about half the time. Frustration is rising...
Ok so you have a SHA 14/14 carb with spigot mount intake...Something tells me either your coils are both bad or your bike is in need of some jetting....

how did you set the airgap on the coil?

Put some gas down the sparkplug hole and see if you get a pop....If not get a new coil...

I have plenty of T-Maxxes...theyre one of my favorite monster trucks...LOL..I have almost every model made and all are modded to death....Theres mods and such you can do to yours...first thing Id do is seal the carb,mod the fuel output so it flows better,,replace the glowplug with an OS-8 ,,set the needles to stock settings and use fresh 20% nitro fuel....When nitro goes bad it doesnt burn too well......

If all else fails with tuning check for airleaks or dirt clogs at the needles,fuel banjo bolt and the slider dust boot...If there arent any airleaks present change the glowplug,get fresher fuel and start over with factory LSN and HSN carb needle settings

The stock factory LSN setting is 2 full turns out

The stock factory setting for the HSN is 4 full turns out




When I get a used r/c I never trust the previous owners words or abilities unless theyre proven to me through years of knowledge/ability but mostly after I do a quick teardown and clean-up to see how many stripped / bent / broken / mix-matched or missing bolts there are or if there are any busted parts in need of replacing...

I open up the mill to see the con-rod/piston and cylinder shape...I check out the tightness of the pinch to see if it needs a re-pinching and I reassemble the engine with sensor safe RTV to ensure a leak-free seal that just o-rings don't really seal up in these engines at full expansion...I check out the one way bearing plus backplate before reassembly

I also disassemble the carb and make sure the carb needles have their o-rings and are rubbery and good and not dry-rotted and cracked . I make sure the carbs clean and I seal the needles/fuel banjo bolt / throttle slider dust boot with green tire slime and set them both to factory settings.I also change the glowplug for a fresh one and wash out the fuel tank plus change the fuellines if needed and mod the output nipple.......The carb also gets sealed to the engine with sensor safe RTV to ensure a positive seal at all times..
 

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Discussion Starter · #11 ·
Ok so you have a SHA 14/14 carb with spigot mount intake...Something tells me either your coils are both bad or your bike is in need of some jetting....

how did you set the airgap on the coil?

Put some gas down the sparkplug hole and see if you get a pop....If not get a new coil...

Ok youre gonna hafta dumb it down for me. the carb looks like a bell top kei hin like on an old kawi but obviously waaay smaller, the coil does fire, but I get a gentle shock, not the **** myself shock I am used to from a car. I have a Holley "stripper" jet kit but I doubt thats gonna work.

I have plenty of T-Maxxes...theyre one of my favorite monster trucks...LOL..I have almost every model made and all are modded to death....Theres mods and such you can do to yours...first thing Id do is seal the carb,mod the fuel output so it flows better,,replace the glowplug with an OS-8 ,,set the needles to stock settings and use fresh 20% nitro fuel....When nitro goes bad it doesnt burn too well......

If all else fails with tuning check for airleaks or dirt clogs at the needles,fuel banjo bolt and the slider dust boot...If there arent any airleaks present change the glowplug,get fresher fuel and start over with factory LSN and HSN carb needle settings

The stock factory LSN setting is 2 full turns out

The stock factory setting for the HSN is 4 full turns out




When I get a used r/c I never trust the previous owners words or abilities unless theyre proven to me through years of knowledge/ability but mostly after I do a quick teardown and clean-up to see how many stripped / bent / broken / mix-matched or missing bolts there are or if there are any busted parts in need of replacing...

I open up the mill to see the con-rod/piston and cylinder shape...I check out the tightness of the pinch to see if it needs a re-pinching and I reassemble the engine with sensor safe RTV to ensure a leak-free seal that just o-rings don't really seal up in these engines at full expansion...I check out the one way bearing plus backplate before reassembly

I also disassemble the carb and make sure the carb needles have their o-rings and are rubbery and good and not dry-rotted and cracked . I make sure the carbs clean and I seal the needles/fuel banjo bolt / throttle slider dust boot with green tire slime and set them both to factory settings.I also change the glowplug for a fresh one and wash out the fuel tank plus change the fuellines if needed and mod the output nipple.......The carb also gets sealed to the engine with sensor safe RTV to ensure a positive seal at all times..

Ok this is a 2.5 tmaxx, there was pink goo in the tank, so i turned the truck on its side and hosed it out real good with carb cleaner, went to the hobby shop(buttheads charged me $9 for one glow plug and it already quit glowing)and I grabbed a fresh quart of 20% fuel. I pulled the one mixture screw I noticed and hosed out the carb while on the engine with carb cleaner, put the screw back in and backed it off about 2 turns from closed, blew through the exhaust to tank hose to prime the fuel system, and started cranking it over with the glow plug ignitor on it. This came with the accessory glow plug heater thing instead of just using the tv remote thing that starts it.

As long as I gave it a lil shot of ether and idled it up and left the ignitor on it, it runs. And it revs pretty good too. But it needs that shot of ether to fire off and it needs the ignitor crutch to run. Blows some oil spotting out of the header too. But at least its makin heat and noise.

Aside from this tmaxx being a greasy mess and the hummer body being trash, its never been ****ed with much. The wheels are rock ragged but thats about the worst of it. All the bolts are uniform and nothing seems to be loose.

The last r/c cars I had was a Tamiya Lunchbox and a Grasshopper, both secondhand, so I have been outta the loop for awhile, I am used to the white rc10 disc wheels or the "barrel" monster truck wheels, lousy electric motors, lousier 7.2 battery packs, and anything nitro being a rich mans toy. I used to fantasize about freakin Clodbusters, and pedaled a bicycle on a paper route to finance my r/c car addiction.

Of course I ran the crap out of and destroyed numerous Tyco and Nikko junk over the years, btw, Nikkos might come with a 540 motor, but dont try to upgrade to something fancier, the circuit board cant take it.:D
 

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Ok this is a 2.5 tmaxx, there was pink goo in the tank, so i turned the truck on its side and hosed it out real good with carb cleaner, went to the hobby shop(buttheads charged me $9 for one glow plug and it already quit glowing)and I grabbed a fresh quart of 20% fuel. I pulled the one mixture screw I noticed and hosed out the carb while on the engine with carb cleaner, put the screw back in and backed it off about 2 turns from closed, blew through the exhaust to tank hose to prime the fuel system, and started cranking it over with the glow plug ignitor on it. This came with the accessory glow plug heater thing instead of just using the tv remote thing that starts it.

As long as I gave it a lil shot of ether and idled it up and left the ignitor on it, it runs. And it revs pretty good too. But it needs that shot of ether to fire off and it needs the ignitor crutch to run. Blows some oil spotting out of the header too. But at least its makin heat and noise.

Aside from this tmaxx being a greasy mess and the hummer body being trash, its never been ****ed with much. The wheels are rock ragged but thats about the worst of it. All the bolts are uniform and nothing seems to be loose.

The last r/c cars I had was a Tamiya Lunchbox and a Grasshopper, both secondhand, so I have been outta the loop for awhile, I am used to the white rc10 disc wheels or the "barrel" monster truck wheels, lousy electric motors, lousier 7.2 battery packs, and anything nitro being a rich mans toy. I used to fantasize about freakin Clodbusters, and pedaled a bicycle on a paper route to finance my r/c car addiction.

Of course I ran the crap out of and destroyed numerous Tyco and Nikko junk over the years, btw, Nikkos might come with a 540 motor, but dont try to upgrade to something fancier, the circuit board cant take it.:D
Sounds like you should of totally disassembled the engine checked the pinch and cleaned it up if the pinch is good....Theres two neeedles on the carb...Look at the official T-Maxx website,,,go to the model you have and go through the online owners manual showing the needle placements and the factory settings,,,,,,,

Ive been actively into R/c since I was 10 and I still have most of the cars I had back then aswell except for my very first which wasnt really remote control...It was a Cox tether car VW buggy that was purple...Now I have 35 of them...

RC10 GT with OS18 CV in it...This thing is pretty fast and quite uncontrollable....LOL



My Tamiya Super Hornet with a 1/4 scale r/c buggy I built



 

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How did you set the airgap on the coil..../

Dont go by the sparking coming from the coil as being good...i have a whole box of chinese coils that spark but wont fire the engines they came out of...................
 

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So True. Cam2 I have wanted to ask you for a long time... What is in the little cans of fuel for the RC cars and planes??
 

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All that, wow. Do you run that fuel in alky Cag engine, I was thinking about trying that with a Walbro Alky carb,lol.
 

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All that, wow. Do you run that fuel in alky Cag engine, I was thinking about trying that with a Walbro Alky carb,lol.
No because the nitromethane makes the fuel sketchy enough to explode.......I use an alky/methanol mix for race karts[methyl alchohol]...........You gotta be careful using the stuff though,,prolonged contact with skin is dangerous and detrimental to mental stability...........same as r/c fuels

Alky should be jetted to the richer side of the spectrum of tuning it in and it takes almost twice the alky jetting over gasoline to get it tuned right...............Thats why almost all of my racing engines have twin carbs...........



 

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Can you delute the fuel with something else?? Plus you need high compression to make it work,right?
 

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Can you delute the fuel with something else?? Plus you need high compression to make it work,right?
No...If you dilute it with regular gas youll never get it tuned right at all........Alky has a way different density and pop than gas..........gas has a 14.1 specific gravity...alky has around 9.1 so you have to jet or tune in the needles 1.5 times higher than normal to run alky

You need a compression ratio of no less than 15:1 with advanced ignition timing to properly run alky but the power is so extreme its NUTZ when dialed-in correctly....My Evil Wasp cag was slapping the crap out of my Polini when I had it running on Alky..I had to de-tune it because even with the 4" stretch it still wanted to ride 12 oclock high
 

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Discussion Starter · #20 ·
How did you set the airgap on the coil..../

Dont go by the sparking coming from the coil as being good...i have a whole box of chinese coils that spark but wont fire the engines they came out of...................
I cut a long strip of a business card to use as a gap guage, I read somewhere that was the way to do it.
 
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