| Author |
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Marksblast
| | Posted on Wednesday, October 26, 2016 - 08:53 am: | 
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Call or mail Dan. He is 'da man'.
Best parts and service.
http://buellridersonline.com/forum/showthread.php? t=7730&s=346cd59afa359b586b9382c68910f751 |
Jetlee
| | Posted on Wednesday, October 26, 2016 - 09:53 am: |
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Any Harley dealer should have that o-ring. Go buy that first before searching for a new manifold. |
Modrummer
| | Posted on Wednesday, October 26, 2016 - 11:48 am: |
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Good call on Dan. Just got a 170 main jet from him!
I'll pick up one of those O-rings ASAP.
Thanks! |
Modrummer
| | Posted on Friday, October 28, 2016 - 03:57 pm: |
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Ok so still having issues. I replaced both the o-ring and the intake manifold itself and I"m still not getting enough vacuum for the carb piston to lift on it's own. I sprayed some carb cleaner around the intake manifold to head seal and the bike still tries to die like there's a leak, which makes no sense...
I took a video to show you the problem. First I show the bike with throttle revving to show the cylinder isn't going up. Second I spray carb cleaner around the intake manifold and you can hear the bike almost die.
Any ideas? I'm pulling my hair out.
https://youtu.be/hNiFC23uA30 |
Gearheaderiko
| | Posted on Friday, October 28, 2016 - 05:30 pm: |
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Did the 170 jet fit?
To eliminate the "leak" take the manifold of and seal it with gas resistant silicone and make sure it's dry (ditch the o ring for now. That has to seal it and it may only be a short term fix just so you can diagnose. I have the same thing happen to me with the test.
Make sure that vacuum nipple in the carb is capped.
I think an intake leak to stop the slide from fully opening would make your bike almost if not completely unrideable.
To be sure you're not looking for a problem that doesn't exist: how does the bike run and accelerate?
Will it do 30mph in 1st gear? Will it hit the rev limiter in 2nd and 3rd gear? 4th should top out at 80mph.
While I questioned Jet Lee's inquiry about the timing, it could be possible if the timing is off to not hit max rpm. (It sounds fine in your video). You have to remember that the piston only opens up with vacuum. If you're not getting full "suction", you won't get full lift from the piston.
Sometimes the point is missed that it only has 30hp and it must be revved out to redline to get the most out of the engine. It's not a twin where you rarely have to go past 4000rpm to get decent useful everyday acceleration. |
Gearheaderiko
| | Posted on Friday, October 28, 2016 - 05:31 pm: |
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By Full "suction" I mean 6500rpm under load. |
Modrummer
| | Posted on Friday, October 28, 2016 - 08:31 pm: |
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I have a 170 jet on the way from Dan. Running a 165 at the moment.
I installed a new seal and put some high heat gasket maker on it a few hours ago, just letting that dry over night to see if it fixes it.
The bike is barely rideable, it's insanely slow though (like 50cc scooter slow). If I have a ton of room it will eventually get to about 55 or 60, but it can't reach WOT. I've ridden a stock Blast before and it's at least 3 times more powerful than this. Also, with the airbox off I can turn it all the way to full throttle and reach down and push the piston up with my hand and it suddenly accelerates hard like it should, so definitely a vacuum issue where the piston just isn't getting enough to go up on it's own. It moves freely by hand so nothing binding it or anything.
It will hit 30 in first eventually, just takes a bit, and after a while it will redline second, but it can't get to redline in 3rd unless I"m going downhill haha. |
Gearheaderiko
| | Posted on Friday, October 28, 2016 - 10:57 pm: |
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Thanks, just checking!
I really want to see if the new 170 main fits, that will tell us if it's stock jetting.
I have a suspicion the piston/slide spring was replaced with something else.
As it doesn't seem to lack the power you know it should have (when you manually push the slide up) I doubt it's anything mechanical. |
Modrummer
| | Posted on Friday, October 28, 2016 - 11:26 pm: |
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I should have the new jet tomorrow so I'll let you know!
I'm thinking the same thing as you. Seeing as the carb is now running a Superboot and a new intake manifold and gasket.
If my gasket maker fix doesn't end up working, I'll probably try finding a new piston/diaphragm. Will any piston made for a Harley CV carb work? Or is there a specific one for the buell?
Thanks again for all your input! |
Modrummer
| | Posted on Saturday, October 29, 2016 - 03:55 pm: |
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I figured it out! And you're gonna hate me cause it's something I already checked...
I decided to take the carb completely apart again and look at everything as close as possible to make sure I wasn't missing something stupid. Starting feeling all around the diaphragm and found a really tiny little cut in it, it's not even visible unless you're handling the diaphragm honestly. I put a piece of electrical tape over the cut to test it (on the upper side of the carb so it couldn't get into the engine of course), put everything back together and... bam! Blast suddenly has power! It's literally 3 times faster than it was before haha.
I think the cut was so small that it let the carb SORTA opperate normally, but as soon as it got to higher rpms with higher vacuum, it would all escape through that slit. Just ordered a new slide/diaphragm.
Thanks again for all the help, coudln't have done it without you! |
Gearheaderiko
| | Posted on Saturday, October 29, 2016 - 05:04 pm: |
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You were right there anyway, just about to order the correct replacement parts. It just always helps to have support, even though you really did all the work 
I'm pretty sure the diaphragms and Pistons are the same in all the Blast/HD carbs. |
Gearheaderiko
| | Posted on Saturday, October 29, 2016 - 05:09 pm: |
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27585-88 vacuum piston.
"-88" means they've been using the part since 1988 and its a Harley part number. |
Modrummer
| | Posted on Sunday, October 30, 2016 - 09:54 am: |
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Perfect, that's the one I ordered!
Man I wish I would have seen that little cut earlier, would have saved me some time and hassle. Oh well, live and learn. At least now I know I've got everything in the carb set up right and don't have to wonder what else the previous owner did to it!
The new 170 jet from Dan fit by the way, so it looks like I have the stock Emulsion tube. |
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