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post #1 of 48 (permalink) Old 11-07-2018 Thread Starter
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pocket down on power after performance mods

Hey guys,

i currently have a 43cc pb and only mod was a big bore kit and the bike went pretty good. I purchased a 19mm performance carby and installed some triple stage carbon fibre reeds but after the install the bike feels like its lacking top end power now and with the stock carby and reeds the bike felt like it went harder then.

on the 19mm carby i checked what size it is but it doesnt have it written on it at all and im not sure if i can adjust it to be richer or leaner.

What seems to be the problem that im having as i thought the new carby and reeds will make a big difference. Is it a jetting issue i need to fix up as im contemplating on installing the stock carby back on.

thank you
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post #2 of 48 (permalink) Old 11-07-2018
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Re: pocket down on power after performance mods

Welcome to the forum....

I hate to say it but you bought the wrong carb....19mm is way too big for a tool based engine thats 1.6hp stock and more for the 39cc Chinese watercooled machines..................


The right carb that actually adds performance is a WYK192 or WT603T pumper carb retrofit kit..They dont need rejetting and if the engine requires a tuning change its easier to do by adjusting some screws instead of guessing the jet size to use........


You can use the Del Rep 14/14 too but they require re-jetting...

Right now it would be best to upgrade the fuelline and fuel filter to 1/4" perform whats called the petcock mod then adding a 1/4" inline fuel shutoff to replace the problemsome petcock on the stock carb...

Good Luck

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post #3 of 48 (permalink) Old 11-07-2018 Thread Starter
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Thanks for the information mate. Do y oiu have a link for the proper carby?

If I do the petcock mod and leave my cf reeds in, the bike still run a bit better?
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post #4 of 48 (permalink) Old 11-07-2018
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Re: pocket down on power after performance mods

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Originally Posted by johnni View Post
Thanks for the information mate. Do y oiu have a link for the proper carby?

If I do the petcock mod and leave my cf reeds in, the bike still run a bit better?
It will run a lil better but it has a fixed mainjet that only delivers so much fuel....theres an adjustable needle and you can adjustthe float leaner but its trial and error type stuff where the weather plays a huge factor in how it runs....

When you buy the carb kit Id get a fuelline retrofit kit for it too...

https://www.ebay.com/itm/Racing-Carb...mGCR:rk:3:pf:0

https://www.ebay.com/itm/Gas-Fuel-Li...gfL:rk:22:pf:0

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Last edited by CAM2; 11-07-2018 at 04:05 PM.
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post #5 of 48 (permalink) Old 11-11-2018 Thread Starter
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Re: pocket down on power after performance mods

i bought this carby in the link below mate

https://www.ebay.com.au/itm/RACING-C...Ma8:rk:19:pf:0

but i see this carby for sale and people buy them.

if i buy a kit with different jets and test to see which jet is better, can i gain my top end back ? as this carby doesnt have a adjustable needle, only i can change the jets around
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post #6 of 48 (permalink) Old 11-11-2018
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Re: pocket down on power after performance mods

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Originally Posted by johnni View Post
i bought this carby in the link below mate

https://www.ebay.com.au/itm/RACING-C...Ma8:rk:19:pf:0

but i see this carby for sale and people buy them.

if i buy a kit with different jets and test to see which jet is better, can i gain my top end back ? as this carby doesnt have a adjustable needle, only i can change the jets around
If you like riding hit n miss type stuff where one day it runs good and the next its running like crapolla due to the change in seasons, weather temps,air pressure etc..Youre golden then....

If you do research that type carb has an slider assortment pack aswell as a needle assortment pack too to further adjust that carb and its sold through DelOrtto......


Heres a thread for you to checkout so you can figure for yourself if you want to waste $$ on that 14/14 carb....This member had those same thoughts about that very same carb and beleived it was the best carb for his build.....

Theres vids in there too to compare to but just know in the end he finally broke and bought the right carb just as the coldness of winter started chasing him indoors...Hes from Canada.......

https://www.pocketbikeplanet.com/167...-head-kit.html

Almost every member I tell to never lose scope that these are tool based engines but its funny when they fail to remember or realize why I say that until they've learned the error of not heading the advice of those who've been there and tried that...... LOL

Good Luck....
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Last edited by CAM2; 11-11-2018 at 10:43 AM.
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post #7 of 48 (permalink) Old 11-11-2018
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the stock carb is better you can raise up the needle and mod it the del rep carbs all you can really do is chang the jet or buy a slide kit that is more expensive then just getting a pumper retrofit kit...

Faster then a speeding E Revo
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post #8 of 48 (permalink) Old 12-12-2018 Thread Starter
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Re: pocket down on power after performance mods

thanks for all the help guys

ill use this thread of instead of making another one for 2 more questions i have.

1. Im thinking of drilling out my stock carb and ive been reading a few threads but im struggling to find what size drill bit to use on the forum, ive read maybe a 9/16 ? if not what size ? and do i drill the intake half way then rotate and do the other side of the carby that connects to the manifold the same size ?

2. once that is done to rejet the carby im buying a jet kit of 0.640.670.700.75. Do i start testing each jet to see what is good with me while leaving the c clip on the needle on the same position ? or do i need to test each position ?

current mods on my cag are triple stage reeds, petcock mod, big bore and modded stock exhaust.

thanks
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post #9 of 48 (permalink) Old 12-12-2018
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Take the measure of the carburetor slide/piston, this is max. drillsize, think should be 14mm, drill in more steps 12,5-13-13,5-14 and from evere side(airintake and gas outtake). Can alsow use a dremel for that work, than you can go a little bit up(1-1,5mm).

Little help for seting a carb(sorry have only in german)

A= airscreew
B= low jet and gasvalvecut
C= needl and pulverisator
D= mainjet

Mainjet calc= carb diameter x 5 + 5%
14mm x 5 + 5% = 73,5

So you can start with a 0,74mm mainjet, set clip to the middle.
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Last edited by Chrisi; 12-12-2018 at 09:49 AM.
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Re: pocket down on power after performance mods

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Originally Posted by johnni View Post
thanks for all the help guys

ill use this thread of instead of making another one for 2 more questions i have.

1. Im thinking of drilling out my stock carb and ive been reading a few threads but im struggling to find what size drill bit to use on the forum, ive read maybe a 9/16 ? if not what size ? and do i drill the intake half way then rotate and do the other side of the carby that connects to the manifold the same size ?

2. once that is done to rejet the carby im buying a jet kit of 0.640.670.700.75. Do i start testing each jet to see what is good with me while leaving the c clip on the needle on the same position ? or do i need to test each position ?

current mods on my cag are triple stage reeds, petcock mod, big bore and modded stock exhaust.

thanks
If you do the 9/16" drillbit mod chances are youll be wasting your time....Drilling a 2 stroke carb straight through doesnt enhance performance;-it diminishes velocity which doesnt make any more power than it did stock.Alls it will do is cause a tuning nitemare.


Ive modded the stock carbs in all sorts of ways and found the best mod for them is taperporting them and instead of making the venturi area totally round and losing barrel seal on the sides throwing off tune by adding too much air at idle is giving the venturi a raised oval shape which enhances velocity aswell as performance plus if done right will give you more range of throttle too when the venturi roof is raised higher.....

The barrel can be modded too.....

I said it before and Ill say it again though....Nothing beats a WYK192/WT603T or WT813 pumper carb for these tool based engines....

Good Luck
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Last edited by CAM2; 12-12-2018 at 02:55 PM.
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don't wast time and make the same mistakes others have put the stock reeds back in and go get yourself a pumper carb retrofit kit bolt it on tune and enjoy

the fibreglass reeds work good to but they don't last to long...

Faster then a speeding E Revo
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post #12 of 48 (permalink) Old 12-13-2018 Thread Starter
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I decided not to port the carby but installed my triple stage reeds. What's happening now it's not bogging out at wot but once you let go of the throttle and give it throttle again after a few seconds it dies.

The needle is set on the 2nd from the top but thinking to move it down one spot and try that ?
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the triple stage works good on a stock engine with a rocket key but flutters like crazy on a engine that has a two peace head kit

Faster then a speeding E Revo
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Re: pocket down on power after performance mods

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Originally Posted by johnni View Post
I decided not to port the carby but installed my triple stage reeds. What's happening now it's not bogging out at wot but once you let go of the throttle and give it throttle again after a few seconds it dies.

The needle is set on the 2nd from the top but thinking to move it down one spot and try that ?
Pull the sparkplug....note the color of the tip....White or tan = lean black = rich and butterscotch brown = optimal

When in doubt always refer to the condition of the sparkplug.It tells you how to adjust your tune aswell as refer back to post #6.........

Good Luck

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Last edited by CAM2; 12-13-2018 at 11:32 AM.
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post #15 of 48 (permalink) Old 12-13-2018 Thread Starter
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Re: pocket down on power after performance mods

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Originally Posted by MrKitty View Post
the triple stage works good on a stock engine with a rocket key but flutters like crazy on a engine that has a two peace head kit
I thought the whole point of triple stage reeds were to stop the flutter at wot. Which reeds will stop the flutter that I should use on my engine with a head kit ?


ill check the spark plug tonight and see what colour it is and adjust my tune correctly.
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Re: pocket down on power after performance mods

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I thought the whole point of triple stage reeds were to stop the flutter at wot. Which reeds will stop the flutter that I should use on my engine with a head kit ?


ill check the spark plug tonight and see what colour it is and adjust my tune correctly.
Triple stage reeds are hit n miss improvements aswell..If youre using the same stock exhaust it may answer some stuff....Theres EPA restrictors in them things that cause problems and may be the reason why youre having so many problems and don't get me started about those so-called hp exhausts they sell too because 99% are a joke on anything pushing over 2hp...LOL....

When you build your engine theres things you need to know after you build it seeings you can build two identical looking engines and both engines wont even be close to being the same...Thats the riddle embedded with-in chinese made stuff.

Knowing how to build the engine right is the key..Its real easy to overlook the simplest things like replacing the crank seals or orienting the copper washer that seals the head wrong.

Then theres the process of proving out what you built by doing a leakdown test to first ensure the mill has no leaks at the base,cap,crankcase or crank seals.

Knowing what you built after its built by doing a squish calculation aswell as a compression test tells you the kind of fuel you should be running and gives you an idea on the strength capability and to choose proper induction.


After alls said and done its up to you to find what works and doesnt work for what you built as far as reed selection and carb selection/jetting, sparkplug choice,sparkplug gap etc seeings its a tool based chinese made engine and not a CR/KX/YZ or RM japanese made 2 stroke..


Its typical to beleive what you have can be improved by spending $$ and bolting things on to enhance performance and it will just magically work..If it was true then how come the chinese DONT have a high performance build manual or give instructions how to hop up a 2 stroke and youre here looking for answers?

Heres some quick first start-up vids of some of my builds...

This ones a 1pc 40mm build..Its the same exact engine that came on the bike,,a lil blueprinting , modifying of stock parts and some power porting of the same old cylinder plus piston and this bike became pretty intense also quite insane..The Only bolt-on mod is a pumper carb...LOL

https://flic.kr/p/24bMkE7

This ones a 2pc 40mm performance cylinder thats blueprinted and built to party......

https://www.flickr.com/gp/[email protected]/Lg7766


And...A basic before and after..Two different bikes but same size 40mm 1pc engines..

Bone stock....

https://flic.kr/p/25gyPxX

modified....


https://www.flickr.com/gp/[email protected]/M6c5R0
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Last edited by CAM2; 12-13-2018 at 08:19 PM.
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post #17 of 48 (permalink) Old 12-13-2018 Thread Starter
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Re: pocket down on power after performance mods

your absolutely right ill find what works for me as I already bought my cag with the head on it and it ran great then I did the petcock mod and the exhaust mod.

ill get some cf reeds and give them a shot as maybe stiffer reeds will help my bike as my bike was a champ before it started bogging down and then I did the petcock mod and exhaust mod
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go with fiberglass reeds or stock some of the C.F. reeds suck and some of them are actually good it depends on the manufacturer but nobody really knows who the manufacturer is because everything's made in China more than likely the guy you bought it from had it tuned for the parts that were on it as soon as you change anything you also change the tune with the carburetor you have that means rejetting then playing with the needle height...

Faster then a speeding E Revo

Last edited by MrKitty; 12-14-2018 at 10:45 AM.
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Re: pocket down on power after performance mods

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your absolutely right ill find what works for me as I already bought my cag with the head on it and it ran great then I did the petcock mod and the exhaust mod.

ill get some cf reeds and give them a shot as maybe stiffer reeds will help my bike as my bike was a champ before it started bogging down and then I did the petcock mod and exhaust mod

Absolutely..youre getting the idea.When in doubt go back to what you had regroup and go from there.

What type of mod was done to the exhaust?

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Last edited by CAM2; 12-14-2018 at 11:42 AM.
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post #20 of 48 (permalink) Old 12-14-2018 Thread Starter
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I've done the mod by adding in a extra belly in the middle of the exhaust. I'll put back my stock reeds and see how I go from there as hopefully the petcock mod has stopped the bogging down at wot
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