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kennylibido
PostPosted: Tue Aug 26, 2008 8:07 am  Reply with quote
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Okay,

I have a 1972 Honda CB175 in need of smaller Main Jets - after having the carbs overhauled and the timing corrected, the plug are still fouling. The bike is clearly running rich. I'm convinced that the main jet needs replacing.

Here's the issue, however. I see on the Keihin carbs (twins) that the basket is secured with a spring device which makes accessing the basket very easy - I'm having a very difficult time determining what the model of the carb is but I believe it's an older PE. When I look at service manuals, there is no section which addresses simply removing the main jet. Instead, it appears as if I have to remove the entire carb. I'm not convinced this is the case, though.

Is anyone famliar with the carb? If so, am I able to simly pull the basket and unscrew the Main Jet or is there more to it than that? If so, any guidance or advice would be well appreciated by me. Hell, I might even buy you a beer if you give good help!

Cheers,

Joe.


Last edited by kennylibido on Thu Sep 04, 2008 7:38 am; edited 1 time in total
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Matty
PostPosted: Tue Aug 26, 2008 3:36 pm  Reply with quote
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fine be that way.

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-++-you can't spell jackass with out JKSC-++-
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ron
PostPosted: Tue Aug 26, 2008 6:19 pm  Reply with quote
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Location: santo paulo

you're really going to ask for opinions on this board and then leave an emty post?

You're REALLY asking for it...

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yup
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kennylibido
PostPosted: Tue Aug 26, 2008 8:36 pm  Reply with quote
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I asked a question and then determined the answer was that I was being a pussy - a little self-searching showed me the way.

I was aggravated about a service issue with a motorcycle and posted for advice - when I read what I wrote, I had fear and loathing and then manned-up.

So, really.

Disregard.

Turn away, I'm hideous.

Really.

Nothing to see here.

Nope.

Nothing.
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Spikehead
PostPosted: Wed Aug 27, 2008 3:22 pm  Reply with quote
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Location: N.W. corner pocket of Mpls.

1) They all do that.
2) You bought the extended warranty, right?
3) What surging? There's no surging!
4) If you have to ask, you wouldn't understand.
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Brooke
PostPosted: Wed Aug 27, 2008 8:07 pm  Reply with quote
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Spikehead wrote:
1) They all do that.
2) You bought the extended warranty, right?
3) What surging? There's no surging!
4) If you have to ask, you wouldn't understand.


To add to that, a wise man once posed this question to me, "Why buy the gas when you can get the macadamia nuts for free?"
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Spikehead
PostPosted: Tue Sep 02, 2008 11:20 pm  Reply with quote
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Brooke wrote:

To add to that, a wise man once posed this question to me, "Why buy the gas when you can get the macadamia nuts for free?"


Wow. When did you meet President Bush?
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kennylibido
PostPosted: Thu Sep 04, 2008 7:49 am  Reply with quote
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Okay,

I have a 1972 Honda CB175 in need of smaller Main Jets - after having the carbs overhauled and the timing corrected, the plug are still fouling. The bike is clearly running rich. I'm convinced that the main jet needs replacing.

Here's the issue, however. I see on the Keihin carbs (twins) that the basket is secured with a spring device which makes accessing the basket very easy - I'm having a very difficult time determining what the model of the carb is but I believe it's an older PE. When I look at service manuals, there is no section which addresses simply removing the main jet. Instead, it appears as if I have to remove the entire carb. I'm not convinced this is the case, though.

Is anyone famliar with the carb? If so, am I able to simly pull the basket and unscrew the Main Jet or is there more to it than that? If so, any guidance or advice would be well appreciated by me. Hell, I might even buy you a beer if you give good help!

Cheers,

Joe.
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Brooke
PostPosted: Thu Sep 04, 2008 9:02 am  Reply with quote
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On a PE the jet is inside the float bowl. Take that off, spill gas all over yourself, unscrew the jet. That's it.

BUT WAIT! I don't think you are running rich. Unless someone has been tinkering in the carbs the stock main jet size should be fine. It's not likely that that factory jet enlarged over time and is allowing more fuel in. Exceptions would be that some 'mechanic' used a coarse wire to clean the jet and it was reamed out far too large. Or that the exhaust is so clogged up that there is very little exhaust actually getting out. In either case, changing jet size is like fixing a broken leg by buying a bicycle. On a 4 stroke, if the plug is oily and fouled, then the rings or valve guide seals are not holding back the crank case oil. This more likely to be the case in my opinion.
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Derrick
PostPosted: Thu Sep 04, 2008 10:05 am  Reply with quote
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First of all this is impossible to figure out on line without the bike so I'm an idiot for responding but I disagree with Brooke. Surprise!

Who knows what has been done to this bike? It is a 1972! It would be easy to check the main jet sizes and rule that out. DO IT. But do you even know what stock main jet size is? It might even be impossable to tell if the main jets have been reamed with out a new jet to compare. Is the engine stock? Why are you convinced its running rich? Is the plug oily or dry carboned? If it is oily Brooke is right there are other issues with the engine. If it is a flat black carbon build up on the plugs then I believe it is too rich but not necessarily because the main jet size. It could be that the floats messed up or the idle jets have been reamed or many other things. I doubt a blocked exhaust would foul plugs. Maybe a dirty or blocked air filter.

The mechanic should have checked all that. Sounds like you need a new mechanic.
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kennylibido
PostPosted: Thu Sep 04, 2008 11:08 am  Reply with quote
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I haven't pulled the Jet yet (the reason for this post in the first place) but the pipes are custom on the bike - it was a rebuild. I assume that the Main Jet is not stock (#98). The mechanic I spoke with agrees that the issues the bike is having are likely related to the Main Jet because of performance issues from 1/2 to full throttle. The bike was tuned and cleaned professionally.

Anyway, the issue was mostly about how to get the Jet out so I can determine if it is part of the problem - I suspect the guy who rebuilt it probably went too large on the Jet and I need to bring it down a notch or two.

I'll certainly post if the Jet is stock because there's some 'splainin' to do if that isn't the issue from jump.

The plugs are both exactly alike after running the bike about 50 miles - sooty black - no oil. The pipes are fine. Carbs are fine except for slight leakage from the right side.
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Derrick
PostPosted: Thu Sep 04, 2008 11:41 am  Reply with quote
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I'm not sure what a professional tune up is if the jetting is still wrong...

You might want to get a few jets. Start a couple sizes above stock to see what the custom pipes are doing. Then bump down step by step until the plugs stay clean and stop. The engine should run a lot smoother and faster if it was fouling the plugs that quick before.
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kennylibido
PostPosted: Thu Sep 04, 2008 11:55 am  Reply with quote
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I may well be garbling the language - the carbs were overhauled and the timing was corrected - apparently the timing was way off. They asked me to drive it and then report back the condition of the plugs.

Believe me, I am praying that the Jet is bigger than stock because this is pain in the ass mostly because I want to work on the bike to get it where I want it but am having trouble plugging it into the schedule of my mundane life.

I know more about Jets now than I ever thought I would.
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Derrick
PostPosted: Thu Sep 04, 2008 11:57 am  Reply with quote
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Well the scariest thing is that it was rebuilt and it seems by someone who didn't know what they were doing.

Good luck.
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some_dude
PostPosted: Thu Sep 04, 2008 2:22 pm  Reply with quote
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kennylibido wrote:
I know more about Jets now than I ever thought I would.

When you're a Jet,
You're a Jet all the way
From your first cigarette
To your last dyin' day.

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