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Buell Forum » THUMPer Forum » Buell Blast Thumper Knowledge Vault » Engine - all topics related to the Motor » Engine - Carburetion & Intake » Re-Jetted Bike Dies Above 12 MPH « Previous Next »

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P3pete
Posted on Thursday, October 11, 2007 - 07:39 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hey Guys, I re-jetted my '04 with a Pro Series intake & V&H exhaust. I've read through all related posts and links here, installed 48/175 jets, set the idle mixture screw 2.5 turns out and got the #6 washers (but haven't shimmed yet). Although the part #s for both jets match what's posted here (and so do the #s stamped onto the actual jets), the main jet does not seem to look or fit right. It seems way too small to thread properly, and does not have any length to it like the stock one, which seems wider overall.

On my test run, the bike started, idled and ran smoothly until about 12 mph or so. Opening the throttle any more caused the engine to bog and then die. I haven't opened the bottom of the carb again, but I have a feeling I'll see that main jet sitting at the bottom. The head and "hole" of the stock and new main jets seem identical, but the body/threads seems smaller around on the 175 than the stock. It didn't feel like the jet was large enough to thread, more like it stayed in there due to magnetic force. Anyone have a picture of a proper 175 jet or know what's wrong? Thanks for your help!!

-Pete
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Joey
Posted on Thursday, October 11, 2007 - 08:29 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Put the old and new jets next to each other and compare them. The only noticeable difference should be the size of the hole in the middle. If the threads don't match, something's amiss.
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Ezblast
Posted on Thursday, October 11, 2007 - 09:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Concur!
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P3pete
Posted on Friday, October 12, 2007 - 01:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thanks, guys. Both of the stock jets have a "tube" with holes in it that make them longer, which the new jets don't have. The 42 & 48 slow jets both are the same width in the threaded area. The 170 main jet is bigger than the 175 I got, which doesn't t have any tube extension after the threads. Also, the 175 head is recessed and the jet screws far into the carb, but the 170 head sticks out of its tube when installed. The part #s all match up & look right... What now? Thanks...
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Swampy
Posted on Friday, October 12, 2007 - 09:08 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

You probably got carb jets for a Mikuni carb, they are different thread pattern and head size. The Drag Specialties emulsion tube uses Mikuni jets so you have to be careful if you are using a Drag Specialties kit.

Also have you removed the diaphragm cover? If so check to see you do not have the diaphragm pinched.
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P3pete
Posted on Friday, October 12, 2007 - 11:13 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Swampy, thanks for the info. Both new jets have the same markings on the head as the stock ones (the jet size stamped on the lower half and some kind of symbol on the upper half). The part #s on the bag match what's listed on BadWeb. Do the Mikuni jets have the same part #s? I'll call the dealer & find out. Not sure where the diaphragm is... Is it in the top of the carb? I haven't opened that yet/ shimmed the needle. I DID move the float (I know that's a no-no). How bad is that to do?
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Xgecko
Posted on Friday, October 12, 2007 - 01:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

did you remove the stock jet from the tube and screw the new jet into the tube?
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Ezblast
Posted on Friday, October 12, 2007 - 01:45 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Also check your boot - das boot!
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Krid80
Posted on Friday, October 12, 2007 - 04:47 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

to me it sounds like you didn't install the jets onto the "holes in it" piece. the jets unscrew from that and the new ones go on.
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P3pete
Posted on Sunday, October 14, 2007 - 11:02 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Whoa, you guys might be onto something. Because I already installed a new boot and bought a spare (boot failure was what got me started on this path to rejet and not run so lean anymore). So the flute-like tube piece with holes in it is separate from BOTH stock jets?? I was wondering about that before, but the 2 stock jets have that kind of piece and looked like one solid part. Oh, man... if it's that simple and I overlooked it then I'm officially too stupid to ride a motorcycle and should turn in my license. Let me take another look... thanks, guys.
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P3pete
Posted on Monday, October 15, 2007 - 01:17 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Bike's running great, thanks! I separated the stock main jet from the 'tube' piece (whatever that's called) and re-attached the new jet. The confusing thing was that both the slow jets have those tube pieces fused permanently as one assembly. Thanks Krid80 & Xgecko for that info & thanks EZ for all the boot & rejet info and your individual email help. I appreciate it, guys.

Now to shim... I'm using good tools but it seems that the screws that are used all around the carb are prone to stripping at the head slots. Had that problem on the float bowl and it looks like it will happen if I try to remove the throttle plate assembly. How can I get to the top of the carb without removing any of these screws? Tilting isn't enough to get to all 4 screws.
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Ezblast
Posted on Monday, October 15, 2007 - 03:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

You might have to Dremel that screw holding the throttle cable holder to use a flathead screwdriver - I did for both and left it at that, however, the rest just come right off.
GT - JBOTDS! EZ
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Swampy
Posted on Tuesday, October 16, 2007 - 09:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Then replace them with commonly available allen head screws from your local hardware store.
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