Blaster murders plugs and spudders at full throttle

[Blaaster]

Have to say a stock 26mm carb will work fine try with a 240 main jet first

/\ /\ /\ /\ /\ Not real good advice!!!!!

fmf SST, VF4reeds,KOR aggressive trail port and rechambered head,32:1 premix.

Not sure on the SST as I have never jetted one but I am pretty sure it would like a #270 - #280.

32:1 will bring it up one size so #290.

Hard to say on the porting and the head mod as I found that my head required a smaller main.

If you go with a 26mm then I would be plug chopping a #300 first.

 

[79 bronco]

I had a strange spark plug problem! I would get about 1/2 of a day on a spark plug and then my motor would start breaking up past 3/4 throttle, then i'd put a new plug in and it would run great. ALL MY USED PLUGS LOOKED GREAT! It did this for over a year, then it started breaking up past 3/4 throttle ALL the time. I thought it was jetting problems, i try'ed main jets in my 36PWK from 172 to 140, and they all did the same thing!

THEN i called CT racing, and they told me that a had a common problem. I probably have a WEAK SPARK and the flame is extinguishing at 3/4 throttle, something is going bad in my IGNITION SYSTEM. They told me to tighten my spark plug gap between .20-.18 and if it makes a difference then weak spark is the problem. ONLY RUN A TIGHT GAP FOR TESTING!!!!!!!!!!

I tighten my plug gap to .20 and it made a BIG difference! I had a bad CDI!

 

[Blaaster]

/\ /\ /\ /\ That is a real possibility if the spark becomes weak it may not have enough oomph to fire under the greater pressures at WOT.

 

[motoman159]

Hey guys thanks, also I have an amr monster coil and open airbox, thanks bronco, ill try that

 

[Blaaster]

If you have no lid on the airbox the main should be upped 2 more sizes!

 

[motoman159]

If you have no lid on the airbox the main should be upped 2 more sizes!

I know I know. But im not going to run a stock carb. Its out of the question. Not trying to be rude,I just dont want to

 

[79 bronco]

I know I know. But im not going to run a stock carb. Its out of the question. Not trying to be rude,I just dont want to

The carb size is probably NOT the problem!

If the cylinder is ported by KOR then i would give him a call and ask if he has a idea of what jets you should be around for your size carb and mods.

Jetting may NOT be your problem, you may have a IGNITION, WEAK SPARK problem.

I spent a lot of $$$$$$ on jets when a WEAK SPARK was my problem! I almost spent more $$$ on a smaller carb!

I got every main jet from 130 to 172 and every pilot jet from 35 to 70 for my 36mm PWK Keihin carb and could not get it jetted right because of a bad CDI box. What a wast of $$$$$$$ in jets! lol :-[

 

[motoman159]

The carb size is probably NOT the problem!

If the cylinder is ported by KOR then i would give him a call and ask if he has a idea of what jets you should be around for your size carb and mods.

Jetting may NOT be your problem, you may have a IGNITION, WEAK SPARK problem.

I spent a lot of $$$$$$ on jets when a WEAK SPARK was my problem! I almost spent more $$$ on a smaller carb!

I got every main jet from 130 to 172 and every pilot jet from 35 to 70 for my 36mm PWK Keihin carb and could not get it jetted right because of a bad CDI box. What a wast of $$$$$$$ in jets! lol :-[

In the winter I had my jetting spot on confirmed by a plug chop... I know what jets my carb should be running... it was rich because it was jetted for winter therefore I bumped the main down one size.... im going to test my motor with a tight gap tomorrow and ill let you know, thank you...

 

[Blaaster]

I know I know. But im not going to run a stock carb. Its out of the question. Not trying to be rude,I just dont want to

I apologise for rabbiting on, but I have a dead set aversion to 30mm OKO carbs, they are responsible for many a major jetting headache.


An old trick to run a motor with a weak spark, especially useful if a motor is continually fouling plugs. Works great on a 4 poke that is burning lots of oil.

Use a stranded copper HT lead and insert a small button as depicted with about 1/8" between the holes.

Of course it is no substitute for a healthy ignition system, but it has filled a gap for me a few times.

 

[motoman159]

I apologise for rabbiting on, but I have a dead set aversion to 30mm OKO carbs, they are responsible for many a major jetting headache.


An old trick to run a motor with a weak spark, especially useful if a motor is continually fouling plugs. Works great on a 4 poke that is burning lots of oil.

Use a stranded copper HT lead and insert a small button as depicted with about 1/8" between the holes.

Of course it is no substitute for a healthy ignition system, but it has filled a gap for me a few times.

Ive got a brand new amr coil that I dont want to cut up

 

[motoman159]

I tightend my gap to .24 (smallest I have) and still the same thing....

 

[Wifesblaster]

I tightend my gap to .24 (smallest I have) and still the same thing....

Pm member "Just me." He uses a 30mm OKO carb and may have some helpful info for you.

 

[motoman159]

Pm member "Just me." He uses a 30mm OKO carb and may have some helpful info for you.

Jetting is not at fault here.im not trying to be rude but im leaving to go to west virginia and im looking to take the blaster and if I need parts I need to order them now. Haha

 

[Blaaster]

Ive got a brand new amr coil that I dont want to cut up

I don't blame you, I only posted the button idea as a stop gap method when all else fails.

Under some conditions a larger spark gap can create a better firing.

If the tight gap does not make any difference, open it wider than specs and try it.

Beware though that running a gap out of specs can cause combustion issues which may lead to detonation.

 

[motoman159]

I don't blame you, I only posted the button idea as a stop gap method when all else fails.

Under some conditions a larger spark gap can create a better firing.

If the tight gap does not make any difference, open it wider than specs and try it.

Beware though that running a gap out of specs can cause combustion issues which may lead to detonation.

It did detonate like hell when I started it with the small gap

 

[Blaaster]

It did detonate like hell when I started it with the small gap

PM sent .

 

[motoman159]

God I hate the piece of sh*t its been nothing but problems since the day I bought it

 

[79 bronco]

I tightend my gap to .24 (smallest I have) and still the same thing....

Correct me if i wrong, but doesn't the NGK b8es come out of the box with a .025-.024 gap?

I run my gap all the time at .025 to .024, and i was running bad. Then i tested it at .020 gap and WOW WEAK SPARK.

CT racing told me to do the test i had to gap it between .020-.018.

This is the plug gaping tool i have and it goes down to .020. Buy K Tool International Spark Plug Gap Gauge Tool KTI73701 at Advance Auto Parts

 

[motoman159]

Correct me if i wrong, but doesn't the NGK b8es come out of the box with a .025-.024 gap?

I run my gap all the time at .025 to .024, and i was running bad. Then i tested it at .020 gap and WOW WEAK SPARK.

CT racing told me to do the test i had to gap it between .020-.018.

This is the plug gaping tool i have and it goes down to .020. Buy K Tool International Spark Plug Gap Gauge Tool KTI73701 at Advance Auto Parts

Alright, I took at brand new b8es plug out of the box (it was at .28 from the box) borrowed my brothers gapper, gapped it at .20and it ran like sh*t

 

[Larry's Shee]

What does the spark look like? Color? Have you ohmed the stator? Coil (I know it's new, so what)? Tried another cdi? Has this ever ran right with the OKO ( http://www.blasterforum.com/engine-13/oko-no-go-41056/ )?
ALL wire connections clean and tight, maybe add dielectric grease, coil mount clean, bare metal, ohmed switches?

Consider running seperate ground from coil directly back to engine.