-MXD-

i installed the 88 tak kit last weekend. i finally had some time to sit down and tune it and i cant get it right.


i have tried the 92 & 85 main jet with the clip position in all and the middle seems to be the best so far.

it only has problems in the top end. i can tell if its too rich or too lean. it almost seems like its reving out too fast, but i know its not. sometimes it will pop real loud too. do i need a bigger main jet or a smaller one?

ive checked the timing and that seems ok. there is a very light knock too, not real loud, but noticable, not sure if this is normal for the 88 kits. any help is appreciated, ive already read all the other 88 threads and all the other info too. the 85 main and middle clip is what i have now, but i still cant top out the bike in any gear and 1st is by far the worst

RuntStunts

Sounds lean man. Never installed one though. Go bigger

f4stunna

do you have a rev box? if not get one. and i would strongly suggest HD valve springs becuase it will float the valves on a stock head before it rev's out. but other than that tuning it right is a trail and error effort and you will get it sooner or later so keep at it.

turboglenn

on my 88 i run the 85 jet and middle position for a stock bike , you really need about an 82 jet or so cause on a stock bike the 85 is enough to have it runnning as rich as 10:1 A/F, you want to be around 13.2:1 ideally.

look for the post called another 88cc question (carb related) in this same forum, we just went through all of this same chit.

-MXD-

i printed and read that thread like ten times while i was tuning it. im in cali so i figured that may be why the dif in main and clip position. i was told it was running too lean and that i may need to get a main as big as a 107 but i think i runs better with the 85 than the 92 so im not sure

ive never done carbs before, but i have the idea down, just cant tell if its running lean or rich so i dont really know which way to adjust. is there any major signs that will help me?

it pops like mad

draggsxr2000

here is a simple suggestion Run the hell out of. Clean the plug real well. Now go run it where you are having problems. WHile its having problems. KIll the motor pull out your plug and look at it. Ya gotta kill it like cut the ing off and slam on the brakes. Sooner the more acc the plug reading. And go from there. IF its wet to rich. White too lean. Thats how i tune my drag bike. Easy

COWFIDDY

most of those kits run rich, and surge at high rpm. seems like its hitting rev limiter but its not. ive built 4 of these kits and owned 2, and they run rich. lean them out and they will run great. if your running top end high rpm when it starts surging reach down and pull up the choke a little (this will richen the mixture) if its surges worse then your to rich. wide open throttle mixture is set by mainjet not needle clip position. so you need to change mainjets for wide open throttle problems. go a little leaner.

-MXD-

all those that said it was still running too rich...THANKS A TON. i had to put a 75 main jet and it fixed the problem. the kit is mean, i love it now

RuntStunts

Really, glad to hear you got it goin. Once again, experience pays

Z50NATIONALS

sometimes less is more huh.
the reason a smaller jet worked is, im sure like the rest, you
took the air box off and are just running a air filter bolted to the back of the carb and a little short intake manifold.not good for air velocity
you dont have enough velocity of air to match what the carb can put out
if you want to make these things really scream you have to have some velocity
of air passing through the carb to atomize the fuel properly and charge the combustion chamber to its capacity. other wise the best head in the world wont do diddley.

Fuscat

In your instance Z what can be done to add more velocity for those that have gone to the bolt on filter? It would apply to stock carbs w/ bolt on filters too?

Z50NATIONALS

for a stock carb fuse, put the stock air box back on, if you dont have that you can add a piece of hose(radiator hose) the same size as the back of the carb between the airfilter and carb, the one one my stocker its about 2 3/4 inches long thats with a 70 carb so you may want to go shorter look at the stock airbox boot and double it.stock airbox is best, i know that sounds very gay but that carbs cfm isnt very high and thats why it is restricted.
on my stocker i use a stock xr70 intake and carb then for a filter i have a k&n with a built in vellocity stack,this thing screams for a stocker and thats other people saying it not me. more fuel is the key and to get more fuel you have to have more air and it has to move at the same rate as the carb flows fuel other wise your fuel air mixture isnt right,your combustion chamber isnt filled to capacity result your not making all the power that you can.
rule of thumb to go by short plenum top end (which everyone runs) long plenum bottom end(no one hardly runs) for instance look under the hood of a street car then look under the hood of a nascar now you will realize what i mean
look how far the throttle body is away from the actual intake port itself(its a long way away) look at the nascar and the carb sits right on top of the port
plenum length is 1/8th the distance from carb to port, now look behind the the carb or throttle body, the difference there is the throttle body has a long tube running to the air box ,nascar the air filter is right on the carb.
the more tube the more velocity .
i would recomend a 70 carb and intake runing stock airbox and pipe and that thing will rip

Z50NATIONALS

check out the different sizes of holes in the intakes one is a fiddy one a 70
the one on the left is the fiddy intake and you cant get your pinky into it the 70 intake you can stick your thumb into almost up to the second knuckle

Fuscat

HMMMMM big *** difference! hahah

I'm currently running the TB light 88kit. Does the same advice apply? You say stock pipe & airbox with 70 carb is that for a stock motor 50? Would changing to a 70 carb with the light 88 (cyl & piston only) require a pipe change anything else need to be changed with this configuration? What about running the bolt on air filter with the 88light and the 70 carb & intake and stock 50 pipe? I can't go back to stock airbox because of frame mods, my key is now in the way. I don't want to change pipes due to noise level and cost. I was thinking this could be an option to not change much or spend much but gain a pinch ?

Just when I say I am about done modding, I always seem to find away to need to spend a buck or two hahahah

fab5fiddy

leave it be. never change the stock pipe unless you change the head. and for the price of a 70 carb, i could send you a 20mm carb. leave well enough alone. it should run just fine.

Z50NATIONALS

yeah fuse it still apply's, it applys to any 4 stroke
most of the guys say leave the stock pipe for the 88 i would agree unless your running the head too. carburation is the cheapest and easiest hp gain, if you want it to pull, give it some velocity , even if you just add some tube to the back will help some.

-MXD-

yeah i run an air filter that goes directly on the carb. it came with the kit, but i planned on getting the K & N next. i also got a fiveo exhaust, is this a bad thing? should i just run the stock exhaust too?

when i do get the K & N will i have to get a bigger main jet?

Z50NATIONALS

usually you do have to jet up with a pod style filter
if your running a stock head i would use the stock pipe

bikefrk

very good advice

50mob

I just put my 88 in today and it is doing the same thing(popping noises and revs out quickly) Some said it could be running rich but I checked my plug and it's white which would indicate too lean. so I don't know what to do. I would guess the timing is off, although I thought I set it perfect. Any other suggestions??