Mikuni carburetor cr 250 in my blaster

[andres]

Hello, I'm new to the forum.
this is my first post.
I am from Argentina and I own an old 1994 model blaster.
mmi blaster, owns carburetor honda cr 250) mikuni). the problem is difficult to start.
also has GYTR air filter and flappera VFORCE 3 with carbon sheets.
which may be the problem??

 

[Awk08]

most carbs from dirtbikes are jetted way too rich for our blasters

the keihin 34mm i run required a leaner needle, pilot and main jets.
some have had to change the slide also.

for your modifications, the stock 26mm carb will work best, no need for that big carb.

nice blaster !
and welcome to BF

 

[jus_me]

Welcome,, what does you're plug look like after a few kicks?

 

[Blaaster]

You mentioned that the reeds may be a problem, I would check them for gaps, frays or chips.

Reeds and low compression are high on the list for non starting issues.

Nice looking ride, and welcome.

I am curious, what breed of dog is helping the lady hang the washing out?

 

[Wifesblaster]

Couple thing I see in the pics that could cause you some problems down the road. Is that flex duct your using to go from carb the filter? Your chain looks really loose too.

Like AWK said if that cylinder isn't ported and the head isn't cut the carb is to big. Has it ever ran good since you put that carb on?

Most common issues associated with hard starting is broken reeds, reeds aren't sealing shut, no spark or weak spark, and air leak.

 

[Wifesblaster]

You mentioned that the reeds may be a problem, I would check them for gaps, frays or chips.

Reeds and low compression are high on the list for non starting issues.

Nice looking ride, and welcome.

I am curious, what breed of dog is helping the lady hang the washing out?

I forgot about low compression. It's been a long day at work!

 

[Awk08]

I am curious, what breed of dog is helping the lady hang the washing out?

i'm guessing a fairly good sized doberman ?
quite muscular but a little too tall to be a rottweiler

 

[Blaaster]

Couple thing I see in the pics that could cause you some problems down the road. Is that flex duct your using to go from carb the filter? Your chain looks really loose too.

Like AWK said if that cylinder isn't ported and the head isn't cut the carb is to big. Has it ever ran good since you put that carb on?

Most common issues associated with hard starting is broken reeds, reeds aren't sealing shut, no spark or weak spark, and air leak.

I know flex duct as "Donkey Doodle" here in Aussie.

I second the motion that the carby is way too big, you will be loosing a lot of velocity and creating awful eddy currents with the Doodle.

It would be a nightmare to get the jetting correct.

 

[andres]

You mentioned that the reeds may be a problem, I would check them for gaps, frays or chips.

Reeds and low compression are high on the list for non starting issues.

Nice looking ride, and welcome.

I am curious, what breed of dog is helping the lady hang the washing out?

thanks for the help.

is a dobermann

 

[andres]

el blaster una vez en marcha funciona bien a altas velocidades, pero en baja, falla.
mi consulta es, alguien tiene este carburador en su blaster?? que chicleres tiene colocados???

 

[Awk08]

No comprende

 

[andres]

the blaster once started works well at high speeds, but low, it fails.
my question is, anyone have this in your blaster carburetor? which is placed chicleres??

 

[Wifesblaster]

That carb is to big! Get the cylinder ported or put the stock carb back on.

 

[andres]

that's the problem, I bought the quad and so I do not have the original carburetor.
I'm looking for ways to carburarlo, to work well.

 

[Blaaster]

the blaster once started works well at high speeds, but low, it fails.
my question is, anyone have this in your blaster carburetor? which is placed chicleres??

The problem lies with the big bore carby.

At low revs the speed of the incoming air is not adequate to draw fuel into the venturi.

At high revs the speed of the air is increased, therefore making it easier to draw fuel through the jets.

Reducing the bore size of the carby will solve the problem.

The hose which comes from the air cleaner to the carby is also creating a problem, the uneven internal surface will be creating havoc with the air flow.

Trying to jet such a large carb will leave you without much hair, you will be pulling it out often.

I am not saying that it cannot be done, but you may need to experiment with lots of jets, jet needles, needle jets, maybe pilot jets, slides and float level settings, plug chopping at each change.

If you are going to try, firstly remove the corrugated feed from the air filter and replace it with a smooth surfaced one.

 

[andres]

gracias Blaster!

I will change the air flow hose as a first step.
2nd'll try different chicleres
3 ° change the position of the needle.

thank you again!

 

[Blaaster]

gracias Blaster!

I will change the air flow hose as a first step.
2nd'll try different chicleres
3 ° change the position of the needle.

thank you again!

Remember that you should plug chop after every change to air or fuel flow.