Carb Diaphrams. Replace one or all?

Tom P

Tom P

Joined
Sep 5, 2006
Messages
143
Location
Vista, CA
Bike
2004 ST1300
I just pulled the carburetors to solve a cut out in the 1800-2200 rpm range and found a cracked diaphragm in one. Any advise on if I should replace all of them? Bike is 1999 and has 160,000 miles on it. If so is the only viable source Honda? Saw them at Service Honda for about $93.00. I guess that is for just one and not all four? Ouch!
:confused:

The rubber boots from engine to carbs looked good and are pliable. The lower clamps, though screwed tight, seem a little loose though. Don't know if that is an issue as the boots are on solid and I can probably tweak the clamps to tighten them (or new clamps)?
 
Not sure on the diaphragms, but based on the mileage and how difficult it is to get to the carbs., I would recommend replacing the boots for sure, and while you are there you may want to consider the coolant hoses and clamps as well. With age, they will begin to weep. Nothing worse than fixing one problem and having another show up after you get it all back together.
 
I would just replace the torn one. Might be able to fix it if its not bad. If it is bad there was a link to a company on here some where that would refurb it. Think it was like 35 bucks.
Isolators/insulators/rubber things, whatever they are called are still pretty cheap. 40 bucks for all four. Just replace em. Look for coolant leaks under the carbs and fix those.
Congrats on 160K btw. Makes me feel good when I hear of mileage like that. Maybe I'll get there some day.

Shalom
Michael
 
For the $279 difference I would replace only one new or try to come up with a used set of carbs. Thay way I would have a bunch of replacement carb parts if needed.
 
AZ711 said:
Not sure on the diaphragms, but based on the mileage and how difficult it is to get to the carbs., I would recommend replacing the boots for sure, and while you are there you may want to consider the coolant hoses and clamps as well. With age, they will begin to weep. Nothing worse than fixing one problem and having another show up after you get it all back together.
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Yeah, doing the coolant hoses and probably the boots... the Hard one to swallow is the diaphragms. Have emailed the place in England to see total cost and time to get here. Like Pepe says, I might buy the carb set on E-bay for couple hundred.
 
I'd say it depends on how much work you think it was to get to the carbs. If you think it wasn't bad then you do only one (I just replaced the 2 radiator elbows below the carbs so I know what I think! :)).

I like Pepe's idea of buying a used set!
 
Rick77 said:
Kind of like when I do any plumbing job at home.
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(Not so) Funny you should mention that, just got back from STrayCatt's in-laws, replacing the kitchen faucet: Six Hours! The faucet was a piece of pie, the kitchen sink drain (not mentioned in the original bid) and the bi-fold closet door (also not mentioned) ate up the majority of the time. :D

On the diaphragms, there's a not from me on the board somewhere for an alternate source. Company in England. I found it at My-MC, st-1100 board. PoSTed the contact info here about 2 months ago. Search Diaphragm, something should show up.

I've always replaced just the torn one, but about 2 years ago HAD to replace all four. I still blame Iowa gas.
 
George said:
(Not so) Funny you should mention that, just got back from STrayCatt's in-laws, replacing the kitchen faucet: Six Hours! The faucet was a piece of pie, the kitchen sink drain (not mentioned in the original bid) and the bi-fold closet door (also not mentioned) ate up the majority of the time. :D

On the diaphragms, there's a not from me on the board somewhere for an alternate source. Company in England. I found it at My-MC, st-1100 board. PoSTed the contact info here about 2 months ago. Search Diaphragm, something should show up.

I've always replaced just the torn one, but about 2 years ago HAD to replace all four. I still blame Iowa gas.
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That's the outfit I emailed about the diaphragms but I did not receive a response (only one day) and I want my bike back....After all the good advice I decided to buy just one. The others still look in good shape. Thought about doing a patch as I have read about some others
doing but I think the rips are just to big. After all when you think of 93.00 verses having to pull again if it doesn't hold and then still having to spend the money. Don't think so. Thought about buying the whole carb set but every time I buy more than I need
it all just seems to set there. I am looking forward with excitement to having the old girl running good again. She has always been such a dream to ride and the hi cupping caused by this has been really annoying. Cleaning the slow speed jets I think will help alot also.
Doing a valve adjust also plus water hose replacement. Everything else looks pretty good for being an old gal.
Oh, and getting the carbs off really wasn't bad. I banged them a little and then a large screw driver prying at all four corners a little and they came right off. Hope they go on as easy. Waited until I had popped them off to remove throttle cables and the hose underneath.
Hardest thing was that front breather hose. It must really get the heat. It was fried on and I really had to wok to get it off. Crap, forgot to include a new one in my order to Service Honda.
 
As a mechanic, I would definitely consider doing all 4, especially if you ride very far from home (and at that mileage, I'm guessing you do). And adding up the cost of 4, I would sure look on ebay for a used set. Look for the newest set you can find, combined with the lowest mileage. I had carb issues with my '95 and I scoped out ebay, and found whole sets for $100 quite often.

Its all about the balance- cost, time it takes to repair the carbs vs. just replacing the set; and how much it will affect you if you guess wrong and have further issues while on the road.

Jim
 
I bought a set of undesireable carbs from Don Cortez. The carbs had been severely exposed to the weather and are in really ruff shape BUT the diaphragms were good. The d's now reside in a zip lock in my closet, awaiting the next tear on either of my bikes. Might try to collect another set as further insurance.

STraycatt has done similar, spare set in his garage.
 
I found THIS site yesterday while poking around. Seems they make some "replacement" diaphragms for various carbs for $19.50 each (just the diaphragms, not the slides). I don't know if they have one available for the 1100, but it would be worth looking in to.

George, if you get a few minutes, could you check the measurements (as shown HERE) to see if they have a cross??

**Disclaimer: I have NO affiliation with this company, I've never made contact with them, just thought I would share what I've found**
 
Here is the reply from England. I think it sounds like a good way to go but for now because of time constraint I just ordered one from Honda. I am not worried about failure of another while on a trip. I have been riding it all over with the hic up syndrome and it never caused any major problems. If it happens again though I think this route woud be a good way to go.

We take payment at https:// www.PAYPAL.com
We also take all major Credit / Debit Cards [Visa/Mastercard/Amex/Solo/Maestro]
Don't know the EXCHANGE RATE?
Check it out at http://www.XE.com/ucc

NRP Carbs and Diaphragms
Unit 2,
Station Approach,
Victoria Station,
Manchester,
ENGLAND,
M3-1NY

Tel/Fax: +44 (0)161 832 8646
Out of hours answerphone

Hi Thomas ,
Thank you for your enquiry Re: ST1100 diaphragms
Yes we have diaphragms in stock for your model, we now make these in
completely synthetic Viton rubber, completely inert and resilient to modern
fuel containing 10% and more alcohol [Ethanol].
Our material is certainly as good as, if not better than original Honda
The Viton material is slightly denser than OEM, and we have reduced the thickness marinally
We normally supply diaphragms re-fitted to your original slides [so you
would send your slides over to us]
That is the ?fitted? price listed, this service is a tried and tested
method we have used for 15 years. All original rings re-used, and the
finish is exactly as original.
GB ?34.00 each X 4 = ?136.00 Priority return Airmail GB ?10.00= ?146.00
Just remove needle from base of slide and send them to us

WRAP SLIDES INDIVIDUALLY TO AVOID DAMAGE TO EACH OTHER

Turaround would be 2-4 days from receipt
If you need other parts please advise
Float bowl seal GB ?6.00 each
Needle valve and seat GB ?10.00
Air cut-off diaphragm [on side of carb] GB?12.00 each with spring/o-ring

We are increasingly being asked to supply loose diaphragms.
If you feel this option is for you, it would save some time/cost
Dis-assembly of the slide is NOT necassary [or recommended]

If you want loose diaphragms we can supply these at -15% [self-fit discount]
So, GB ?34.00 -15% = ?28.90 X 4 = ?115.60
Priority Trackable Airmail GB ?8.50 Total GB?124.10
I can send you fitting hints/tips, it is not too difficult
Dis-assembly of the slides is not necassary
It re-fits back in between the plastic rings like the original

Please advise which offer you would like to take
I can send you a Paypal payment request if you wish
Credit cards also no problem
Regards
Andy
PS. GB?1.0 = USD$1.55 approx
Loose diaphragms are shipped within 48 hrs of payment
 
I have noticed, in addition to not-so-great fuel economy that it does seem my 1100 is not pulling as hard as it used to. It still pulls in 5th at 75mph (indicated) when I roll on the throttle, but it doesn't seem to pull as hard.... I'm gonna have to get into the carbs and check out the diaphragms, aren't I? :/
 
sirepair said:
I found THIS site yesterday while poking around. Seems they make some "replacement" diaphragms for various carbs for $19.50 each (just the diaphragms, not the slides). I don't know if they have one available for the 1100, but it would be worth looking in to.

George, if you get a few minutes, could you check the measurements (as shown HERE) to see if they have a cross??

**Disclaimer: I have NO affiliation with this company, I've never made contact with them, just thought I would share what I've found**
Click to expand...


Nobody's checked measurements to see if they have something that will work? $20 a pop ($80 total) is sure a heck of a lot better than Honda prices.
 
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