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Buell Forum » THUMPer Forum » Buell Blast Thumper Knowledge Vault » Engine - all topics related to the Motor » Engine - Carburetion & Intake » Rejetting question... » Archive through July 30, 2007 « Previous Next »

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Jackbequick
Posted on Sunday, March 05, 2006 - 02:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Dave,

I'm retired, I get seven Saturdays every week.

I'm at the top of Alton Ave off of Bayside if you can find that. It would be a left across from Lenny's Automotive coming from the island, and the mail box numbers will be reading just under 600.

I should get my new tires mounted and on during the week next week. Then I just have to wait out the winter a little more. As much as I want to ride on a nice day, the terror of all the gravel and new potholes on the roads gives me a little more patience.

Jack
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Manomako
Posted on Friday, March 17, 2006 - 09:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

ok, here goes...I just rejetted my 2000 blast with stock exhaust with #45 and #170 jets. at first i couldnt get the damn thing to rev past idle,it sounded like it would flood out. but then i realized i needed to cover the hole on the upper left side of the carb that creates the vacuum. when i did this it would rev to higher rpms, but now it pops. i call it a pop, i dont believe its a backfire because its coming out of the carb not the exhaust. i tried adjusting the idle mixture screw and it helped a little but it is still popping.
is it ok to adjust the carb w/o the air filter on and just plugging that vacuum hole with your finger? what did i do wrong? what should i do now?
thanks in advance.
d in maine
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Swampy
Posted on Friday, March 17, 2006 - 09:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Are you using the stock air box?

Did you get the gasket in the wrong place for the air box?

Did you take the carb off to do the work?
is the rubber intake boot still in good shape? Torn, over tightened, in place??

Did you bend the float when reinstalling the float bowl?

You probably didn't get something reinstalled correctly, with the finger over the vent making the RPMs to go up I would think the carb boot is leaking, torn, or damaged, because that would build vacuum in the slide chamber raising the slide.
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Manomako
Posted on Friday, March 17, 2006 - 09:51 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

thanks for getting back to me so quick...yea, the its the stock air box. got the gasket in the right place, but again, ive got the whole airbox off while i'm trying to adjust it. yup, i took the whole carb off to clean it. the intake boot seems to be in good shape. how can it be overtightened?
float bowl flexes freely, you can hear it when you shake the carb.
are they the right jets? i thought so, but maybe i read the archives wrong.
thanks again,dave
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Manomako
Posted on Friday, March 17, 2006 - 09:56 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

i did notice that the slide didnt seem to be sliding up, even tho when i push on it it slides freely.
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Swampy
Posted on Friday, March 17, 2006 - 10:03 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Did you take off the diaphram cover?
and not get the diaphram pushed back in the groove?
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Ezblast
Posted on Friday, March 17, 2006 - 11:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Good and replace the boot- its old and they are cheep.
GT - JBOTDS! EZ
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Manomako
Posted on Saturday, March 18, 2006 - 06:29 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

yep, took off the diaphram cover and reseated it, pretty sure i got it right. is it ok to run w/o the airbox?
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Manomako
Posted on Saturday, March 18, 2006 - 06:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

by the way, with the idle mixture screw, does unscrewing make it richer or leaner?
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Manomako
Posted on Saturday, March 18, 2006 - 11:50 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

ok, so i just got back from the harley dealer and got a new intake boot and while i was there they let me look at the parts manual and i noticed that the needle goes UNDER the wierd white plastic "spider" that the spring goes on. I had the needle going thru the spider from the top, thus never allowing it to go all the way down...Eureka! i havent fixed it yet but i think that is the culprit, i'll let you know, but thanks for all the input!
dave
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Swampy
Posted on Saturday, March 18, 2006 - 02:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Yes you can run it without the air box installed.
The idle mixture screw from a light bottoming, back it out 2 1/2 turns. Yes, unscrewing it makes it looser, Ha!
Yes, Unscrewing it makes it richer.

Did you remove the alumimummmmmm plug to get to the idle mixture screw?

(Message edited by swampy on March 18, 2006)
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Manomako
Posted on Saturday, March 18, 2006 - 04:04 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

ok ok, you guys can call me numb...its official, i put the needle back the way it was supposed to be and SHAZAM! it works. go figure... in fact the new jets got rid of all the popping! it running excellent! thanks swampy and EZ for coming to my rescue, and chalk this one up if you have some other dumba$$ have the same symptoms!
Its 34 degrees here in maine and i just got back from my longest ride, 3 hours around the island(mount desert island) and it was awesome. supposed to get into the 40's next week, shorts weather!!
thanks again, you are the wind beneath my wings...HAHAHAHAHHAHAHAHA
dave in bar harbor
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Swampy
Posted on Saturday, March 18, 2006 - 05:21 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

See....
Them singles like those larger jets!

Makes run like they was supposed to!

So are you ready to come to Michigan to ride to Iron Mountain, and meet up with the Buy and Ride Deal that Daves is having on the weekend of May 5th?
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Cecil1
Posted on Friday, October 13, 2006 - 08:54 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I have a quick question on jetting.
How do I tell if our Blast has been rejetted? We bought it about 3 months ago from the second owner. He bought it with a K&N filter and Vance and Hines pipe on it but did not know if it had a jetting kit in it. Are the jets labeled or color coded?I looked at it the other day and the cap on the mixture screw has not been removed yet if that helps. The blast runs good but needs a little more go to it.

Tim
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Ezblast
Posted on Friday, October 13, 2006 - 10:31 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

No - not done!
GT - JBOTDS! EZ
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Gearheaderiko
Posted on Friday, October 13, 2006 - 10:56 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The jets have the numbers on them
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Cecil1
Posted on Friday, October 13, 2006 - 11:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thanks for the fast replies.
Guess thats the next mod.

Tim
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Mabueller
Posted on Sunday, November 12, 2006 - 05:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

In reviewing http://www.nightrider.com/biketech/hd_cv_mods.htm they suggest drilling out the vacuum port and I have also read about changing the piston spring. Are these mods suggested?

I bought my bike used with a V&H exhaust on it. I didn't think it had been re-jetted but since the fuel/air screw has been opened I now suspect something has been done. I have 45 & 175 jets, shims and a recommended needle for a '88 1200 on its way. I am not sure what I will find once I open up the carb, but I guess I'll soon find out.
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Swampy
Posted on Sunday, November 12, 2006 - 11:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I have opened my vacuum port hole to .100 on both Blasts. Stock they were .085 or so.

I have not noticed any ill effects from doing so. In other sites they recommend .125, but thats for the twins.

I wonder what size a stock carb vacuum port is on a twin. Anybody know?

My Sportster is a Drag Specialties modified CV, so it is probably already drilled out.
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Gearheaderiko
Posted on Tuesday, November 14, 2006 - 09:03 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

My Opinion: I dont recommend doing anything that is irreversible to your carb unless you really know what you're doing, really know how to tune in carbs, have extra money to spend.
It's doubtful that these mods are the 'magic bullet' to unleash great performance and if they cause a problem, then you've got to buy new parts.
Yes, they may solve a particular problem or improve an area of carb related performance, but if you dont know what your trying to accomplish, you're just shooting in the dark.
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Swampy
Posted on Tuesday, November 14, 2006 - 10:53 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Yes you are right. I think that the larger the vacuum hole the faster the slide opens up, that can be good and bad....

The beauty of the CV is that the total amound of carb opening is controlled by throttle position and engine load(vacuum). That keeps you from bogging the engine and over-fueling it when you open the throttle hard.
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Stevy
Posted on Sunday, July 08, 2007 - 11:40 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I just ordered a D&D exhaust. Do I really need to rejet? I don't care about performance so much. Just looks and sound.
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Xgecko
Posted on Sunday, July 08, 2007 - 12:09 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

do you need to???? no especially if you haven't done any intake work but you will notice a difference and considering the cost ($30 max if you do the needle and shims) vs change it's worth doing regardless
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Gearheaderiko
Posted on Sunday, July 08, 2007 - 02:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Concur! I've done it!
Though just the jets alone are under $10 and if you start to experience knock & ping I'd change jets asap. You should definitely drill out the plug on the air mixture screw and adjust that.
If you find it hesitating(bogging) on acceleration, thats a hint to change jetting also.
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Sking1973
Posted on Wednesday, July 18, 2007 - 09:14 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

If you change the jets do you have to change the needle and shims? I've seen posts and websites that say replace both and some that say just the jets. A full Dynojet kit has everything, but costs $100. If I just get the jets I've got 10 or 12 bucks invested. Hmmmmm.
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Ezblast
Posted on Wednesday, July 18, 2007 - 11:30 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

two #6 washers - shimming the stock needle will do the trick;0)
GT - JBOTDS! EZ
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Gearheaderiko
Posted on Wednesday, July 18, 2007 - 12:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Jets first, then the needle shims. Yeah $15 bucks total and you can at least compare jetting with most others. $100 for a jet kit and you're basically on your own!
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Xgecko
Posted on Wednesday, July 18, 2007 - 04:11 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

For me, 2 jets, needle and 3 #2 wide ID washers total cost $19...the washers were the hardest thing to find. Take the needle to a good hardware store and find washers that fit. If they have a Micrometer then you can even measure how many washers you need
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Buuueller
Posted on Monday, July 30, 2007 - 06:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Ummm, Im sure Im just a dope but I havent read anything specific on how to shim the needle. Im quite a wrench turner but I just cant picture what is meant by shimming?
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Swampy
Posted on Monday, July 30, 2007 - 07:25 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

First, Welcome the the Badweb Buuueller!

The vacuum operated slide in the CV carb has a needle that controls mid range fuel delivery. Some needles have extra grooves and a "C" clip that is used to adjust needle higth. The stock Blast needle is non-adjustable. So to adjust it you need to shim it with appropriate sized washers. The total thickness that works best is between .050 and .10, stacked shims(washers) The washers can be found at hardware stores or some cycle shops may hve them in carb parts boxes.

Also read up on the slide diaphragm and make sure you put it back together properly without pinching the diaphragm which is easy to do if you are not careful.

Good luck, post back what you find.
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