97 Blaster Runs and Idles but Wont Rev without stalling

t0aD740

t0aD740

Member
Apr 30, 2015
10
1
34
Ohio Valley
In 15 years of owning them, (this is #3) I've never been as stumped as I am with this 97 Blaster. Ran like a champ the last 3 years but now only Idles and won't Rev up, it just stalls out when going past 1/4 throttle.. if that. Seems to idle fine otherwise. I thought I knew my stuff and I've been reading everything on here for the past month but im still stumped.

Engine Details/mods:

  • FMF Fatty Moto and Power Core II silencer, clear and clean of obstructions. (New gasket and copper permatex after leak tests.)
  • Open air box w/ clean k&n filter and Outerwears over the airbox.
  • Rebuilt stock Mikuni carb (Needle is in the middle clip postion. 300 main w/ brass washer & plastic thing, new a/f screw 1 1/2 turn out, 32.5 stock pilot, new float and float seat/needle + retaining clip & screw.) Oil injection nipple is plugged off.
  • New Boyseen Power Reeds
  • Numerous new NGK B8ES spark plugs
  • New crank seals
  • Stock timing (used to run +4) and woodruff key is good. Flywheel seems ok
  • Tried new coils, stators and CDI boxes already.. hasn't really changed anything. Stock OEM stator is back in it.
  • Wiring harness was checked, w/ good grounds and continuity. Only headlight and kill switch is used.
  • TORS brick is still on top of carb but isn't wired up, the rest has been deleted. No parking break sensors, etc.
  • Oil injection is blocked off.. I run premix @ 32:1 with 93 gas
I run Blendzall #460 "Green Label" 2-Cycle Racing Castor and have done so for years (they're local :cool:)
I occasionally use 2oz. of Blendzall #490 Power Booster mixed in with everything as well

Elevation is about 1200 ft.

Performed leak-down test and passed, compression test is @ 120+

Idles low and stalls soon as I give gas, turn fuel off and RPMs rise.. turned gas back on, engine slows and Idles a bit then stalls. Too much gas it seems.. Hopefully I can try another carb altogether.
I can't even ride it to do any kind of plug chop.. ugh.

I dont get it... Tired of dumping money into parts, I need some other opinions because im at my wits end with it at the moment. I'm ready to ride already!
Cheers-
 
Last edited:
Forgot to mention that there is good fuel flow.. Petcock has been removed and cleaned, along with the tank.
When float bowl screw is cracked open, fuel flows out. Carb doesn't overflow otherwise. I have a small inline fuel filter but I haven't had any problems it.

Seems like the carb is giving it too much gas and it bogs out if i push the throttle at idle, RPM's don't go up and it stalls. Fires right back up usually but sometimes I gotta kick it a few times to clear out the flooding..if that is in fact what it's doing. When I pull the plug, its wet. After idling on and off for a few minutes, sometimes the plug looks kinda fouled. I never have to use the choke to start the bike cold, maybe in the winter time if i recall but thats about it.
 
sounds like you have tried everything from the moon and back.
dont got much for yah lol and im sure all this is irrelevant but whack the heck...

gas cap is ventilating properly?
tried removing in line fuel filter?
the tors brain is in fact unplugged underneath front nose?
flywheel magnets are in good shape?
case bearing/or main bearings are spinning freely?
did you ever see any metal shaving's in the top or lower end?

positive that no one put a newer cdi on it with tors built in?
i would think if it is flooding you could at least get it to rev up at least 1 time lol
i have rode for like 1-2 min before not realizing the gas was turned off:eek:

got pics? we love pics
 
I'll have to double check the float height, its a new yamaha float so it cant be too far out.

Air filter was cleaned and oiled, good to go there.

Ill go back to a 280 main but i dont think it makes much of a difference at this point, it wont rev that far at the moment..

Gas cap vents fine, i'll try removing the inline filter. I'll get some more fresh 93 gas and mix up a new batch

TORS brain has been gone since before i got the bike 3 years ago

Flywheel/magnets have seen better days but they aren't rusted up bad, i scuffed off the magnets but i'd like to get another (lightened) flywheel

Bearings seem fine, no play and everything spins freely. Engine runs great but it just doesnt want to take gas without stalling out, especially in gear. Although when i changed the gearbox oil, there were some fine metal shavings sticking to my magnetic drain plug. It was refilled with Belray Gearsaver

I ordered a new TORS box, its the right year 88-02.. same as my OEM one but its aftermarket. I tried both, no difference.

It'll rev up when i shut the gas off on the petcock but soon as i turn gas back on, idle drops down and usually stalls.

I have just about tried everything to the moon and back.. its crazy! I'll get you guys some pics in a little bit :)
 
Last edited:
t0aD740 said:
I'll have to double check the float height, its a new yamaha float so it cant be too far off

It'll rev up when i shut the gas off on the petcock but soon as i turn gas back on, idle drops down and usually stalls.
Click to expand...

That really sounds like your ticket. As the fuel level in the bowl gets used down to the normal height setting it runs. When you put the pressure in the line and add more fuel in the bowl it bogs out.
 
First, if it ran fine before, it's not your main jet, don't change it.

Take a length of clear hose that fits bowl drain. Attach to drain nipple, hold other end next to cab body with end higher than gasket surface of float bowl. Open drain screw, fuel will rise to level, which should be no higher than gasket surface. Just because float is brand new doesn't mean it's adjusted properly. You only have 1.5mm (.060 " ) adjustment range, pretty precise.


Make sure emulsion tube/main jet holder is fully seated and idle jet is still tight. If you still have old air screw compare it to new one. Check that slide cap gasket is good, cap is tight.

Slide alignment pin still in carb?
 
seeing how what yur saying is true?
i think summin is dragging like a bearing/or you got weak spark.
and the obvious ''carb problem"s
kinda like applying both brakes and trying to move on a 4 wheeler car whatever,
but this is online advice soooooo dont quote me lol:D
after chasing eveything you can and coming out short
im sure im dead wrong but just trying to get your thinking perhaps outside the box seeing how you are very well familiar with the blaster:oops:
 
Hey guys,
First, thanks to everybody for their opinions on what may be wrong with the bike.
I had to take a little break from it for my own sanity but I worked on it today and found out a little more..

I soaked the carb in chem-dip overnight and everything is about as clean as its going to get. I changed the main jet back to 270 where I had it before. I also experimented with the float height and it doesnt seem to be flooding like before but it still wont rev up without bogging and slowing the rpms to where it usually stalls out.

Someone mentioned that the stator may be going out. I have an oem one still in it and also a new, aftermarket one from caltric with the adjustable timing plate. I ohmed them out and everything seems to be in spec but from what i've read, there could still be the stators going bad.. with the spark not strong enough to allow it to run like it should.
That's the only thing I can think of at this point.

So..my next question is where is good place to get an oem stator parts, where do you guys get your stators at?

I'm thinking I could buy just an oem pulser and charging coil, then solder them on. I'm not worried about the lighting coil, the current one seems to work fine and my headlight is functional.

Thanks
 
Bump

Sourcing parts: new OEM Yamaha complete Stator or just Coils .. Cheapest recommend place to purchase from or if anybody on here has one for sale, please pm me.

Thanks!
 
Cool! if its a confirmed tested/working stator, I'm game at this point. I could just ground out the extra wire, no biggie..

Shoot me a pm, I'm definitely interested!
 
hello ,did any of you guys ever figure out the problem with the bike not revving up, I am having exact same problem, stator went out, replace with New one now will not revv up, idle only, everything on the bike is year old and was running great before stator went out
 
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