Engine cuts out at full throttle????

dczys

New Member
Sep 5, 2010
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I did a search but couldn't find a good answer, for my situation. Blaster will cut out at the end of the first 4 gears at full throttle. Will run fine though up until mid-top end of those gears then bog down. once i get into the last two gears it will rip through all the way and run fine without cutting out.

Any ideas?

-TORS removed
-CPW carb
 
I would do a plug chop to check your main jet. Make sure you have good fuel flow from tank to carb. Check your float level to make sure it's set to the correct spec. Make sure ail filter is clean.
 
Check tank vent and carb vents.

CPW sells lots of carbs, can you be more specific? Size and make? Is this a new set-up or existing that just started running bad? If new list ALL settings/jets, and ALL mods.
 
I just pulled of the plastics and removed the aluminum air box / and tubing to the carb. Then pulled the carb and took off the bowl and pulled the main jet. Now that i put it back together i cant remember what that jet size was. I am thinking it was 120 but i am not positive. I then put the carb back on and took it for a spin without airbox or airfilter, and it ran perfect with out cutting out. So i figured either i knocked off some crap while in the carb or it was the dirty airfilter. Next i put the tubing / air box without the airfilter and ran it.. and again it bogged down.. I took that all off agian so i was running straight of the carb and in ran perfect again.. I am thinking i am running too rich???

CPW 30 carb
G Force or G3 something like that reeds and reed cage
Port and Polished top end
FMF powercore exhaust
 
Plug chop.

Warm up motor to operating temp.

Fit new B8ES plug, ride through the gears and hold WOT in 5th or 6th gear for 10 seconds, or as long as you can safely.

Switch of the motor and pull in the clutch, roll to a stop.

Take the plug out and replace the old one for the ride home.

Carefully cut the threaded end off the plug to expose the insulator.

There should be a smoke ring of a cardboard or biscuit colour around the insulator.

If it is non existant or a very light colour, you are lean and require a larger main jet.

If it is a lot darker you are rich and may go down a size in main.

I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace of mind that I won't need a rebuild so soon.
 
Plug chop.

Warm up motor to operating temp.

Fit new B8ES plug, ride through the gears and hold WOT in 5th or 6th gear for 10 seconds, or as long as you can safely.

Switch of the motor and pull in the clutch, roll to a stop.

Take the plug out and replace the old one for the ride home.

Carefully cut the threaded end off the plug to expose the insulator.

There should be a smoke ring of a cardboard or biscuit colour around the insulator.

If it is non existant or a very light colour, you are lean and require a larger main jet.

If it is a lot darker you are rich and may go down a size in main.

I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace of mind that I won't need a rebuild so soon.

I know a lot of you will disagree, but I was talking to my friend yesterday (Ford Mechanic, has 4 four wheelers--Suzu 500 (aka Quadzilla), 400, 80 and another I can't remember, drags 1/4 mile Ford F-150 (that is a sweet machine), dirt track inspector..etc, etc), he has been riding sno-mos and 2-Stroke quads his entire life and never once blown a motor. When I was telling him I was looking for a place big enough to do a plug chop, he said 4th gear is enough, hit top speed, cut the engine and pull the clutch. You don't need to hit 5th or 6th gear WFO for 10 seconds...you just need WFO until top speed. That is all it needs.
 
I think it's also relative to tires/gearing too. The object is to pull as hard and as long as you can. Fuel demands are highest at heaviest load.:o

I have actually never "cut" a plug, I'm like Blaaster, I'll leave a horse or two in the barn, thank you I:I, the ONLY thing that cools the piston is the incomeing fuel/air charge. As long as it runs good and doesn't foul plugs it's lean enough. Properly tuned the exhaust temp about 6" from piston face is about 1200*f, aluminum melts at about 750*f, hhmmmmm, you do the math :D Worst thing is that power doesn't drop off much at all when you go from "perfect" to lean, that's why no one notices it and melts down.X(
 
I think it's also relative to tires/gearing too. The object is to pull as hard and as long as you can. Fuel demands are highest at heaviest load.:o

I have actually never "cut" a plug, I'm like Blaaster, I'll leave a horse or two in the barn, thank you I:I, the ONLY thing that cools the piston is the incomeing fuel/air charge. As long as it runs good and doesn't foul plugs it's lean enough. Properly tuned the exhaust temp about 6" from piston face is about 1200*f, aluminum melts at about 750*f, hhmmmmm, you do the math :D Worst thing is that power doesn't drop off much at all when you go from "perfect" to lean, that's why no one notices it and melts down.X(

Are we talking Blasters or trying to make a few on here blush???

I almost agree with what you say, but lubrication cools the piston too. It is a dangerous game to play though, 1200*f versus atmospheric temp mixed with gas and oil...the 1200*f keeps it hot much longer than the mix hitting it can cool it...that's why you gotta keep an eye on the plug chop. I think the important thing that a lot of people miss, is when they have that nice cardboard/biscuit color, that is the fine line, they would be smart to bump up 1 main size, to ere on the side of safety and finances. ;)
 
Are we talking Blasters or trying to make a few on here blush???

I almost agree with what you say, but lubrication cools the piston too. It is a dangerous game to play though, 1200*f versus atmospheric temp mixed with gas and oil...the 1200*f keeps it hot much longer than the mix hitting it can cool it...that's why you gotta keep an eye on the plug chop. I think the important thing that a lot of people miss, is when they have that nice cardboard/biscuit color, that is the fine line, they would be smart to bump up 1 main size, to ere on the side of safety and finances. ;)

The cardboard/ biscuit colour will give you maxium performance without it being on the too lean side, but if you are going to thrash the motor, or want peace of mind, bump it up one size.

You will hardly notice the power drop.

The way lubrication cools the piston is by reducing friction!

I was always under the impression that going from perfect jetting to just a little lean, gave a slight increase in power, with the chance of mild (un heard and un noticed) detonation. Like fools gold, looks good but useless.
 
The cardboard/ biscuit colour will give you maxium performance without it being on the too lean side, but if you are going to thrash the motor, or want peace of mind, bump it up one size.

You will hardly notice the power drop.

The way lubrication cools the piston is by reducing friction!

I was always under the impression that going from perfect jetting to just a little lean, gave a slight increase in power, with the chance of mild (un heard and un noticed) detonation. Like fools gold, looks good but useless.

Absolutely, I agree 100%....something my friends don't think I ever do. :D And yes, lubrication reduces friction...but, also, has a slower boiling point too, so it tends to stay "cooler" longer. Being a machinist at one brief point in my life, that was why we flooded parts with coolant/lubricator, to keep the inserts from dulling and breaking from heat of the cutting. No matter what, I would prefer to be rich and riding for a long time, than lean and always worrying...even it if was slightly lean.
 
What oil gas ratio should i be using? Currently i have 32:1 in there.. Should i be up more to like 40:1 or higher with these mods?