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7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 12:36 am: | 
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I posted this elsewhere, but then I realized it's probably more appropriate to post here.
This is in regard to an '03 Blast I recently sold someone, who has now unfortunately inherited problems I did not know he would be having. I'm trying to help the guy out so he can actually use the bike.
So, the '03 Blast is in the shop, being worked on/diagnosed by a 28-year experienced H-D tech. It won't go over 45mph. The boot is fine, he has cleaned the carb, put everything back together and it's still topping out. It has no power. I cleaned the carb myself earlier this summer and may have screwed something up because he is saying that "someone messed around with this" (not a good sign) and that it wasn't put back on correctly. He wants to completely replace the carburetor. Here's the thing: before I sold it, I was getting it up to 55mph without issues (except for one time when it just lost all power on the highway). Would a carb that seemed to be working after I cleaned it and put it back on be causing it to top out? Would the whole carb ever really need to be completely replaced (I know carbs have several replaceable parts)? It's going to cost $450. Could this be a gas issue?
Sorry for my ignorance. I really need some quick advice. I would like to help the guy out, but my budget is TIGHT (I'm a full-time student working a couple jobs to pay mostly for insurance and food, and I just found out the car I bought with the money I sold the bike for is having some bad issues with it as well), so I don't want to have to shelf out more than I need to. Your help would be much appreciated! |
Akbuell
| | Posted on Thursday, October 11, 2012 - 10:16 am: |
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As long as your carb cleaning did not involve big hammers and chisels, I don't think it needs replacing.
If it starts and runs fine otherwise, the problem is likely with accessory systems - fuel flow to the carb or flow of exhaust gases. A partially clogged gas cap vent or fuel line or fuel filter, if it has one. A collapsing or clogged air filter, or something blocking the air inlet. A loose internal baffle, or mouse nest,ect, in the muffler.
Hope this helps, Dave |
7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 11:58 am: |
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Thanks, Dave! This does help. I thought replacing the carburetor sounded really really fishy to me, especially since I rode with that carb fine (except for that one time, which may have bee a different issue) after I cleaned it myself.
I'm trying to grasp how all the things you listed might cause this issue. Fuel flow makes a lot of sense to me, and I even told the guy that there had been water in the gas tank and that it could use a flushing. A partially clogged gas cap vent would keep the gas from flowing well because it wouldn't let air into the tank, creating a vacuum, right? The air filter is new (K&N), so I think that's not the issue. What might be a good indication that there's something wrong in the muffler?
Thanks, Kevin |
Reepicheep
| | Posted on Thursday, October 11, 2012 - 12:31 pm: |
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Agreed, unless there is some sort of physical damage someone can point too, I don't see why replacement is justified.
Its easy enough to clean everything out, put everything back to stock, and start from that baseline.
Replacing the carb really ought to be a last resort (though if you have ready access to another carb off of a good bike, I can see swapping them for a bit just as a "spend 20 minutes and know for a fact if the problem is carb related or not" diagnostic step). |
7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 01:37 pm: |
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Reepicheep, thanks for your input!
I don't imagine they have another Buell Blast handy. Would any Harley carb work for testing whether the problem is carb related?
Dave,
The only time I used a hammer on the carburetor was when I tapped out the pin holding the float, which was fine and I was able to tap it right back in when I put it all back together. Maybe I should just buy the guy a carb rebuild kit and tell him have the mechanic replace all the components?
Thanks guys,
Kevin |
Andersonhdj
| | Posted on Thursday, October 11, 2012 - 03:02 pm: |
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My 5 cents.
Would'nt be the first time a diaphragm that looks good has caught me out, old Beemers, RS models, won't make more than a ton, replace the diaphragms on one or both carbs, hello 120mph.
Just also occured to me, run it hard,as fast as it will go for mile or two, pull the plug and check the color, if it is fuel starvation the plug will be tending to white on the porcelain insulator, and if you look very carefully deep into the insulator area inside the plug you will likely find greenish/yellow tinges.
(Message edited by andersonhdj on October 11, 2012) |
7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 03:23 pm: |
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Hi Anderson,
You know, it's funny. I was just about to post something about how the mechanic even took it apart himself, cleaned it, and put it back together. If he did all that, having seen all its components, it would make no sense why he would suddenly think the carburetor needs to be replaced because he would have seen some physical damage before even putting it back on and trying to get the bike up to speed again. But, if you're saying a diaphragm that looks fine (but isn't) could cause that, that may be it. Any idea where I could find a new diaphragm? Thanks. |
7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 03:26 pm: |
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Does anyone know if Reepicheep's suggestion (swapping out the carburetor temporarily for one on a good bike) would work on with any other good Harley bike? Would the carburetors on another bike be incompatible with the Buell Blast? |
Akbuell
| | Posted on Thursday, October 11, 2012 - 06:32 pm: |
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I was just being a smart-alec about the hammer and chisel; I really didn't think you would have bashed a carb bad enough to need replaced.
The carb swap should be like-for-like. Other carbs might work, or could be made to work, but not what you want for trouble shooting. And good call by Anderson re the diaphragm. Certainly worth confirming yours is good.
Try smacking the muffler in various places with the heel of your hand. Listen for rattles from inside the muffler caused by loose bits. No rattles is good. |
7heluvuvgodisgr8rfar
| | Posted on Thursday, October 11, 2012 - 07:33 pm: |
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Dave, I knew you were joking about the hammer and chisel  Thanks for the info on the carb-swapping and figuring out if it's an inside-the-muffler issue. Really appreciate it.
Do you guys know if after doing the spark plug test and finding out that it was in fact a fuel starvation problem if that can still be caused by something in the carburetor and not something non-carb related? |
Harleyelf
| | Posted on Friday, October 12, 2012 - 12:02 am: |
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Sure, if the coil is failing it might spark only at low speed. Your timing may have slipped, check it with a light. Your intake manifold may have a crack. That would still give you the lean-glaze on the plug.
A too-big carburetor, if you have a good one to swap in, will get you over 45 mph.
What it will not do is let you run wide open throttle. Feather the throttle in as the motor accepts it. This is just a trouble shooting tool to see if you can ever go over 45 - if you try to use it long term you will run rich and foul plugs.
Have you drained the tank and watched the fuel flow through the petcock and fuel line? If it has a breathing issue, this will find it as good as any hill. |
Andersonhdj
| | Posted on Saturday, October 13, 2012 - 11:12 am: |
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Hey fella, do the run first and establish whether it's getting enough fuel. That's your base starting point, you could fiddle endlessly and speculate all day but you need definitive diagnosis.
As to the diaphragm unfortunately no, I am not working from a point of view that i know the machine, this is just general diagnostic stuff i use on any machine irrespective.
What make of carb is it? If it's a "Mikuni" then it may be possible to get a diaphragm from a "Solex" carb parts supplier.
Solex sold the manufacturing rights to their carbs to Mikuni in the late 60's/70's if i remember correctly.
Incidentally thats where i source BMW diaphragms from as well as jet's etc.
If you have weak spark it will show at the plug.
There is one other scenario i see quite frequently, typically an ignition coil on a bike draws more as the duty cycle goes up, ie, the faster the engine speed, the more current is reqd, quite often i see partially broken conductors in the loom that limit current delivery to the coil, however this is often accompanied by " hoes,proes en snork" or in english coughing, spluttering and backfiring!!
Confirm fuel delivery first!! |
Andersonhdj
| | Posted on Saturday, October 13, 2012 - 04:22 pm: |
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Another thought occurred, in view of my previous post, you should perhaps do 2 tests,
first ride at 35ish for a good bit, stop. check the plug and note it's color, THEN , drill it hard for a a coupla clicks then check the plug again.
If the plug is a nice tan color at 35ish, normal suburban limit,whatever that might be in your part of the world, and then becomes black at max,it's likely to be power issue, if of course it goes whiteish with the afore mentioned greenish /yellow tinges, it's a fuel issue.
If you blip the throttle at standstill and the rev's don't drop immediately you shut the throttle, you could have a vacuum leak/bad mounting flange gasket. |
Akbuell
| | Posted on Saturday, October 13, 2012 - 07:54 pm: |
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All good stuff; I learn a lot from these discussions. And re Andersons plug checks: When it is time, snap the throttle shut and turn the stop/run switch to off while pulling in the clutch and coasting to a stop. Gives you the 'cleanest' results.
And please don't let me lead you astray with various problems and solutions. Your situation could be the result of something like a misrouted or not seated throttle cable or return cable, causing the throttle control to not be able to open completely. Don't ask how I know that ....Dave
(Message edited by Akbuell on October 13, 2012) |
Britchri10
| | Posted on Sunday, October 14, 2012 - 07:29 am: |
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RE: Possible fuel starvation. How does it run if you switch the tank to reserve?
It could be crap in the petcock restricting fuel flow.
Chris C |
7heluvuvgodisgr8rfar
| | Posted on Sunday, October 14, 2012 - 07:46 pm: |
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Hey guys, thank you all for your input! This is cool stuff. Unfortunately, because I don't have the bike with me (the guy who bought it, and who currently has the bike, is about a 1.5 hour drive away) I can't do all these tests to figure out what's going on. So, I apologize for not answering some of your questions when it comes to the color of the plug, behavior of the revs, etc. I gave the guy a link to this forum, so hopefully he's able to do the tests that you're suggesting, and I'll wait to hear from him about his findings. So, right now, the ball is in his court, so to speak. I find it to be very fishy that he has yet to give me the name and number of the mechanic he brought it to (and who is saying that he needs to completely replace the carburetor), but, anyway ... I appreciate all your help. Thanks! |
Harleyelf
| | Posted on Sunday, October 14, 2012 - 09:19 pm: |
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I like the throttle cable thought. If it starts fine and runs fine until it hits the speed limit, perhaps something is preventing the throttle cable from asking for more than half throttle. Does the handle rotate a full half turn above idle? |
Andersonhdj
| | Posted on Monday, October 15, 2012 - 03:33 pm: |
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That does seem fishy, my guess is he's hoping to take you on a trip! And i've known some "specialised" mechanics! Nuff sed!! |
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Please help! Won't go over 45mph and I don't think it's the boot.