Noob needs help

[aaronsoccer4]

I just bought a 98 blaster bored 40 over, ported and polished with a pro circuit exhaust and it goes pretty good but when I really wind it up and get high in the rpms it cuts out and backfires, does it in all gears. his mix is 32 to 1 amsoil, he said the guys who did the work said upgrade the carb, the stock carb is still on it he threw in a cr 85 carb for me to throw on, is it the mix or is the carb to small or does the carb need to be cleaned or jetted please help i'm kinda bummed

 

[Luni]

Its not the mix. 32:1 is fine.

Sounds to me like your main jet is too lean. Usually cutting out and backfiring is a symptom of too lean. Bogging and just not going anywhere is a symptom of too rich.

The carb isnt too small, although you would get more power out of a bigger carb (somewhere in the 28-30 mil range). Id say your main jet is too lean. You really should take the carb out and pull out the main jet, and read it and see what the guys on here think you should start at.

What kind of carb is the CR85 one? Is it a Keihin or a Mikuni? If its a Keihin I can help you with the jetting, if its a Mikuni, youll need one of the other guys to help you (Ive only ever had a Keihin on mine. Its all I know).

 

[acezeesawtooth]

what is your jetting like? did you jet it after the port and polish or the new pipe? if you answer no to either of those you need to rejet. im thinking probably a 270-280 with the airbox lid on and about 300 with it off... but you need to learn how to jet and how to do plug chops if you're gonna mod

 

[aaronsoccer4]

the spare I have is a keihin and I'm guessing the kid who had it before who just had the work done last week didn't rejet it ill pull it apart tomorrow morning and figure out what jets are in it and which ones are in the stock carb, btw the carb I got is 28 mill and will the open lid airbox give me any performance?

 

[99LRDblaster]

Depends on the year, but the CR 85 typically runs a Mikuni 28mm carb. That carb may or may not be a bit small depending on how aggressive the porting is. As far as jetting......I'd start with a 330 main just to play it safe and work your way down after plug chopping. What size main is in it right now?

EDIT: Just looked it up.......some years used a 28mm PWK Keihin carb, so be weary of that as well as the main jet sizes are different between Mikuni and Keihin.

Just take the float bowl off the carb and look at the main jet and see what number it is.

 

[Larry's Shee]

Removing lid will give some increase. The cr carb will also give some. Seeing you have to rejet no matter what, decide which carb you want to use before so you're not buying jets twice and jetting twice.

 

[bonesZ33]

ive heard 50:1 is best for amsoil

 

[Luni]

Yeah, so have I, but I dont think Id be ballsy enough to run my machine at 50:1

And oil is oil, ratio is ratio, his oil ratio isnt causing him to break up.

 

[Awk08]

Yeah, so have I, but I dont think Id be ballsy enough to run my machine at 50:1

And oil is oil, ratio is ratio, his oil ratio isnt causing him to break up.

not to be a dick, but that is wrong info, oil isnt oil, and i have an email straight from amsoil telling me to run the dominator at 50:1 as it is designed with extra lubricants to be run at that mix, drove me nuts for weeks at 32:1 before i emailed them, and the bottle also says 50:1 right on it
they also make another oil to be run at 100:1
thats why i stick with my tried and true maxima super m at 32:1

check them jets and let us know

 

[aaronsoccer4]

the jet was a 230, I moved my needle around a little bit and removed my airbox lid and it seemed to make it better by putting the metal clip on the needle 3 slot down from the top it was 2 down and then I put my airbox lid back on and it ripped, not as powerful but no back fires then i get down the street and i lose power and it backfires and stalls so i took the walk of shame home check everyhing put the needle back where it was and nothing filled it up with gas and I have determined that I have no spark and the thick orange wire has no power please help I just got this thing yesterday and now it wont start

 

[aaronsoccer4]

so I have spark now but I cant get it to start it just keeps backfiring and almost starting

The problem was when I took off my stator cover the bolt holding it on was loose I spun it a little before i tightened it that wouldnt affect the timing or anything else would it? this is driving me nuts

 

[99LRDblaster]

so I have spark now but I cant get it to start it just keeps backfiring and almost starting

The problem was when I took off my stator cover the bolt holding it on was loose I spun it a little before i tightened it that wouldnt affect the timing or anything else would it? this is driving me nuts

If the flywheel nut comes loose, nothing is holding the flywheel on to the crank other than the woodruff key in the crank and it will sheer off causing the flywheel to spin freely and yes the engine will run like absolute crap.

If you have a Mikuni carb and have a 230 main with your mods, you need to STOP.......RIGHT NOW.......go throw your keys in the woods, and order a larger main jet ASAP. You are running absurdly lean.

 

[aaronsoccer4]

hahaha ok so I shouldn't drive it untill I get the right main jets? what do you reccomend? I'm ported and polished bored 40 over pro circuit pipe and I am gonna take my airbox lid off what jet should I go with? oh yeah and I'm gonna do the timing advance diy eventually

and as for the timing what should I do, undo the bolt spin and try to get it close? or is there an easier way?

 

[hudack]

i would try a 310 and go from there if you have the stock carb on right now
also just an fyi a .040 over bore doesnt nothing for power just cleanes up the cylinder from what the last pistion dammaged good luck to ya

 

[aaronsoccer4]

I bought a 280 and a 300 jet and the 280 is to rich my plug was wet and it bogged up top and exhuast smeeled like unburned fuel does that sound right, I cant idle now ntw

 

[Luni]

AWK I didnt mean by saying "oil is oil" that all oils are the same. However density of oil particles in suspension of gasoline isnt going to vary much between different brands of 2 stroke oil.

Ive personally ran the Amsoil 50:1 stuff mixed in at 32:1 to solve a dispute of this very nature I had on another messageboard at the time about a year ago after I got my jetting dialed in.

My bike didnt run any different with the amsoil in it than it does with yamalube R oil at 32:1. When I said oil is oil, as long as you have your jetting for your oil ratio down, changing from Amsoil to Klotz, to Yamalube, to Maxima shouldnt (at least in MY experience) affect your jetting or the way your engine runs. In addition to that, Ive met plenty of people who run Amsoil Interceptor at 32:1 and some even as low as 25:1 with no issues. However, they jet according to their oil/fuel mixture (the more oil you run in your gas, the more main jet you will need to run because the oil leans the a/f mixture out slightly).

Likewise, if you want to run Amsoil at 50:1 you may need to rejet. You may need to go down a size on your main, because at 50:1 theres almost half (a little more) the amount of oil suspended in the fuel mixture, and as a result youre actually getting more fuel and you run a smidgeon richer.

In addition to running the Amsoil at 32:1 I also sucked some premix I made from Amsoil and Yamalube (seperately of course LOL) up into a hydrometer (measures specific gravity of a fluid), and the gravity of both mixtures were pretty much the same.

Thats what I meant by "oil is oil and ratio is ratio". I didnt mean to run crappy oil in your Blaster. Now in your case of the Amsoil, Im truly not sure what caused your engine to bog with it in there, but thats definately not what happend when I ran it.

 

[PikledBeats]

so I have spark now but I cant get it to start it just keeps backfiring and almost starting

The problem was when I took off my stator cover the bolt holding it on was loose I spun it a little before i tightened it that wouldnt affect the timing or anything else would it? this is driving me nuts

I can almost say with 90% certainty that you ran it lean and burnt up the top end.

 

[aaronsoccer4]

I dont think i burnt up my top end because i fixed it and it runs good but its still not jetted right i tried 260 and gears 4,5,6 it ran beautiful but 123 were bogging like it was to rich there was a lot of smoke to

 

[PMitchell08]

I'm running a 270 main in the stock carb,, stock pilot, stock needle position, airscrew at stock position 1.5 turns from bottom. Motor runs just right, not too rich not too lean.

Mods are: FMF Gold series pipe w/shorty silencer, modded airbox lid (hole cut, prefilter installed, and removed snorkel), pro design intake manifold, billet reed spacer, TORS removed, oil injection removed, 32:1 mix.

Stock Porting, Stock bore, stock timing, stock reeds.

Have you checked the airscrew on the bike since you've owned it? Some people mess with them without knowing what they're doing. If you're not sure about it, turn it all the way in, then back it out 1.5 turns, then adjust from there. Turning the screw out (counter clockwise) leans the mix, turning the screw in (clockwise) richens the mix, if it runs best with the screw all the way in, go to a bigger (richer) jet and re-adjust.

My only other suggestion at this point besides getting the right jetting is tear down the carb and be sure it is spotless. A small obstruction in the pilot jet or the main nozzle, though not likely the cause of your problem, may be a contributing factor.

Good luck.

 

[Racer51]

Get rid of the Reed spacer imediatly thats your problem it's choking it off keep your jets at 270 or whatever it was at first also try a 36:1 mix to transhion it. while changing jets.