I need jetting help

[Tbrock77]

The main jet will not be giving you any problems until you get above 3/4, throttle, it has no say in the mix until then, that is why a too big main jet is recommended, to avoid the chance of a full throttle melt down.

The problem is either in the pilot circuit or the fuel enrichment circuit.( choke )

Needing the air screw so many turns out points at a pilot jet that is too large, or a float level that allows too much fuel into the carby.

Does the carby seep fuel at all?

The large issue of smoke is possibly a build up of oil in the header pipe being burnt off, and of course a richer than optimum mixture at idle will compound the matter.

It doesn't over flow and as far as I remember it has a stock pilot. I took the pipe off and tilted the quad to check if the oil injection had caused the bottom end to fill with oil, it happened before.

I'm going to take the carb apart tonight and give it a througoh cleaning. I noticed the vent tubes are missing, would that cause a problem?

 

[Blaaster]

Missing tubes should not cause problems but they should be fitted.

How was the float level?

 

[Tbrock77]

The float level was right but I'm going to double check.

I mentioned the tube because I thought maybe if they were plugged it would cause venting issues

 

[Tbrock77]

I took this video after adjusting the air screw properly. I don't know if it'll help but I figured it couldn't hurt.

 

[speedyslyder]

i want to see pic of your carb??
you should be able to hold pilot jet up to a light and see through it
clogged pilot jets/broken chipped reeds/reeds not sitting flat/low compression fuel flow/air =hard starting
whoever ported cylinder might be causing a problem?
also get a different color duct tape for the seat

 

[Tbrock77]

i want to see pic of your carb??
you should be able to hold pilot jet up to a light and see through it
clogged pilot jets/broken chipped reeds/reeds not sitting flat/low compression fuel flow/air =hard starting
whoever ported cylinder might be causing a problem?
also get a different color duct tape for the seat

I plan on tackling everything tomorrow. I can definitely rule out low compression. I just put the reeds in so I doubt they'll be chip or broken but I will check them out.

 

[Tbrock77]

Cleaned the carb, checked float level, checked jets 32.5 and 290, checked reeds, added vent lines. The spark seems a bit weak to me but I'm not exactly sure what a blaster spark should look like so I took a video.

 

[Tbrock77]

This thing is driving me nuts. I've got it in to about 1.5 turns on the air screw because it was running lean (the plug was burnt) now it seems to hang up before coming back to idle which is a sign of an air leak but spraying around the typical leak spots with carb cleaner doesn't change the rpm at all. I'm at a loss with this thing. I'd really like to get this sorted out so my girlfriend can get some riding time on it.

 

[Awk08]

sign of an air leak but spraying around the typical leak spots with carb cleaner doesn't change the rpm at all

that is not the correct way to find airleaks,
this is............
http://www.blasterforum.com/threads/leakdown-testers.55015/

 

[Tbrock77]

that is not the correct way to find airleaks,
this is............
http://www.blasterforum.com/threads/leakdown-testers.55015/

*Shameless plug* You'll have a pm

Is there anything else you suggest? The leakdown test was going to be my next step but I just wanna know if there's anything else I should check. Did you take a look at the spark video? I don't know what regular blaster spark should look like.

 

[Awk08]

*Shameless plug* You'll have a pm

Is there anything else you suggest? The leakdown test was going to be my next step but I just wanna know if there's anything else I should check. Did you take a look at the spark video? I don't know what regular blaster spark should look like.

the spark does look a little weak in the vid, should be more blue than the yellow-ish it is....
check all connections, clean with brake clean if dirty, check black wire ground
@ coil for good clean connection to bare frame.
unscrew plug boot, replace is the best option to rule it out, most any auto store should have the screw on NGK boots for around $5.
cut 1/2" from wire end before screwing new boot on.
do the ignition troubleshooting to find any problems with the coil and stator

you can turn the airscrew in to 1 turn or even 1/2 turn out to richen the pilot circut, nothing wrong with that at all.
if under a 1/2 turn produces highest idle, that suggest you need a leaner pilot jet, which in a stock carb is very unlikely.
turn the airscrew 1/2 turns or less at a time, allow 20+ seconds for engine to respond to the new air/fuel mixture, until you find the spot that produce the highest idle, this should be done with the idle speed set slightly higher than normal. return rpm's to normal after finding airscrew setting that produces highest idle.
fine tune with 1/8th turns till it revs clean and returns to idle without hanging.


no tuning can be done successfully until it is proven leak proof, with a proper leakdown tester

 

[Tbrock77]

the spark does look a little weak in the vid, should be more blue than the yellow-ish it is....
check all connections, clean with brake clean if dirty, check black wire ground
@ coil for good clean connection to bare frame.
unscrew plug boot, replace is the best option to rule it out, most any auto store should have the screw on NGK boots for around $5.
cut 1/2" from wire end before screwing new boot on.
do the ignition troubleshooting to find any problems with the coil and stator

you can turn the airscrew in to 1 turn or even 1/2 turn out to richen the pilot circut, nothing wrong with that at all.
if under a 1/2 turn produces highest idle, that suggest you need a leaner pilot jet, which in a stock carb is very unlikely.
turn the airscrew 1/2 turns or less at a time, allow 20+ seconds for engine to respond to the new air/fuel mixture, until you find the spot that produce the highest idle, this should be done with the idle speed set slightly higher than normal. return rpm's to normal after finding airscrew setting that produces highest idle.
fine tune with 1/8th turns till it revs clean and returns to idle without hanging.


no tuning can be done successfully until it is proven leak proof, with a proper leakdown tester

I should have a leak down tester being shipped Monday but if the spark looks weak to you I will try a different coil, I have 2 parts blasters atm. I didn't want to try it before because I wasn't sure if I was just going to be wasting time.

 

[Tbrock77]

So I was going to swap out the coil but it seems someone messed with it. This doesn't match a regular blaster coil and they cut the spade connector so I can't swap a normal one on. Any ideas what this coil is to?

Also checked stator resistance. I'm at 160 between the black and black/red which is low. And 20 between the black and white/red. Could that low resistance be causing a problem?

 

[Tbrock77]

Well that'll do it. Bad stator. Tossed in a new one that ohmed properly and it fired right up cold.

 

[Awk08]

Well that'll do it. Bad stator. Tossed in a new one that ohmed properly and it fired right up cold.

glad ya got that part of the equation sorted, leak free will give you piece of mind to get the jetting correct

 

[Tbrock77]

glad ya got that part of the equation sorted, leak free will give you piece of mind to get the jetting correct

I still have to get the jetting right but I think it'll be a lot easier now. If I still can't get it good I'll wait til I get that tester and see if I have a problem somewhere.

and apparently the coil is from a moto4. If it works I guess I'll leave it alone. If I have any future problems I'll replace it will a stock blaster coil.