Author Topic: CHOKE PLUNGERS  (Read 2726 times)

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Offline stevo21

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CHOKE PLUNGERS
« on: November 02, 2020, 09:32:53 PM »
Hi all,there have been a few threads about missfiring on one cylender and running rough,these have been due to choke plungers leaking and causing problems , running rich ect. riders are fitting different jets altering neddles to compensate for the rich mixture and rough running.( Lots of unnecessarywork ). I have recently had my plunger fitted with a new seal, this was done by a person advertising on e bay (motorcycle parts) who can reseal choke plungers. I have recived the plunger back and have fitted it, taken my ds7 for a good run ,on my return i have removed my spark plugs to check the colour and have noticed a change ,they were slightly lighter than before,( A better colour) and i am happy with the perfomance of my bike.So before you change jets and neddles its worth having your choke plunger seal replaced,So dont throw away your faulty carbs. Anyone who can repair parts for these old bikes gets a thumbs up from me.I hope this thread can help any one with choke plunger problems. It did mine

Offline CBM

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Re: CHOKE PLUNGERS
« Reply #1 on: November 03, 2020, 10:37:20 AM »
I know someone that had a set done for a Suzuki GS and is delighted with them. The Guys Ebay ID is Zed1015

Offline Barnett

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Re: CHOKE PLUNGERS
« Reply #2 on: November 03, 2020, 10:47:04 AM »
Hi all,there have been a few threads about missfiring on one cylender and running rough,these have been due to choke plungers leaking and causing problems , running rich ect. riders are fitting different jets altering neddles to compensate for the rich mixture and rough running.( Lots of unnecessarywork ). I have recently had my plunger fitted with a new seal, this was done by a person advertising on e bay (motorcycle parts) who can reseal choke plungers. I have recived the plunger back and have fitted it, taken my ds7 for a good run ,on my return i have removed my spark plugs to check the colour and have noticed a change ,they were slightly lighter than before,( A better colour) and i am happy with the perfomance of my bike.So before you change jets and neddles its worth having your choke plunger seal replaced,So dont throw away your faulty carbs. Anyone who can repair parts for these old bikes gets a thumbs up from me.I hope this thread can help any one with choke plunger problems. It did mine

Very sage advice.

Offline c50

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Re: CHOKE PLUNGERS
« Reply #3 on: November 03, 2020, 10:59:03 AM »
You're bang on. It's frustrating to read many posts on here where there is a never ending list of remote and often costly possibilities when the solution is often simple and easy to check. I always point out the choke (seals and pick up jet) and main jet washers leaking, how easy it is to check the air jets are clear etc etc mostly to be ignored or at least no confirmation they have been checked buts that's forums. Then they often spend wasted hours messing with pilot jets, cleaning out more jets for the 9th time, stupidly changing the size of jets (on a standard bike) or replacing jets for no reason and replacing coils and ignition parts without any need.

The worse thing you can ever do is modify the engine when you have a fault, ie modify the carbs, especially the primary conversion, fit an electronic ignition etc. Always find the fault before you modify anything because put simply, the bike should run very well standard, if it doesn't its not the set up. Swapping or modifying the settings can introduce more issues on top of what you already had making it a complicated mess and any improvement is just masking the fault.  A rule of thumb is, a healthy engine will tolerate quite large adjustments from standard without changing the way it runs much. eg  Needle adjustment and Pilot air adjustment, very little noticeable difference within a couple of notches or a  turn or so, only the E models have a slight noticeable difference to pilot adjustment as they refined the set up a little,  earlier versions almost unnoticeable. Set it to spec and leave it. Same for timing, you can be  1mm + out (not recommended!) and the bike will still seems to run normally. If a small adjustment of something makes a marked difference, there is another problem lying underneath.  Sometimes it is a combustion problem due to worn out or badly rebored cylinders, new rings in a knackered bore, but nobody wants to accept its the bores and would rather spend days and weeks messing with unnecessary stuff. Fear of undoing a few bolts and taking the barrels off is often the reason, but does them no favours. Then I also sympathise as most will take them to a rebore shop who will probably push them into fitting the wrong pistons claiming they have fitted them to 100's without issue. Well yes they fit in hole ok and won't seize usually, thats, the negatives, not getting into that! they are the "experts"  :D

Enough of that, whatever makes the world go around is a bonus currently.

Offline Paulrs

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Re: CHOKE PLUNGERS
« Reply #4 on: November 03, 2020, 11:32:32 AM »
Agree with all the above comments.  The only thing I would add is check with Motocarb or Allens first to see what genuine mikuni parts are available. 

Obviously they may stock less for the older models but for my 250C Steve at Motocarb seemed to have a source for most bits (although some parts came in Suzuki bags  :o)   

For example, Motocarb stocked an entire choke assembly to fit the Mikuni VM series on the 250C.  Considering this included the operating lever and plunger with the seals it was a bargain at £23 inc vat.  The only down side was it had a rubber thumb pad moulded on the operating lever.  Didn't need it as my choke was working OK, just needed the lever replating.  But it was an interesting collection of parts for the price.




Offline c50

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Re: CHOKE PLUNGERS
« Reply #5 on: November 03, 2020, 12:04:12 PM »
Agree with all the above comments.  The only thing I would add is check with Motocarb or Allens first to see what genuine mikuni parts are available. 

Obviously they may stock less for the older models but for my 250C Steve at Motocarb seemed to have a source for most bits (although some parts came in Suzuki bags  :o)   

For example, Motocarb stocked an entire choke assembly to fit the Mikuni VM series on the 250C.  Considering this included the operating lever and plunger with the seals it was a bargain at £23 inc vat.  The only down side was it had a rubber thumb pad moulded on the operating lever.  Didn't need it as my choke was working OK, just needed the lever replating.  But it was an interesting collection of parts for the price.

Might see if I can get a couple of those. I have seen quite a few R5's with the rubber lever pad. Must have been standard on some of those. Had the Indian  parts from PJM etc years ago, were absolute junk like most of the parts I bought, went in the bin. It's worth changing the plunger seals regardless if they seem ok. When under extreme vacuum they could easily leak. I honestly believe this leak is common and causing a lot of poor running.


Online zed1015

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Re: CHOKE PLUNGERS
« Reply #6 on: November 03, 2020, 01:19:43 PM »
Hi, I'm Rob - zed1015, the geezer doing the choke seat refurbs.

I would have posted a proper ad on here but that's not allowed for non paid up club members
.
Although currently into building Kwak Z9/1000 specials I'm still a mad RD - TZ fan and have owned 41 various RD's, YR5's, DS7's etc until I was lured away from strokers when I bought an FZR600 back in 93 and as far as I know the first person in the UK in 1980 to monoshock and watercool a horizontal split Yam aircooled twin ( YDS7) with new 350LC barrels, swingarm , a TZ350 water pump and Swarbrick pipes etc  (let's forget the red nylon coated frame of the pre powdered polyester days that went pink in the sun after a few years though  :-X   ;D)

What I will say is that if you are running the original plunger seats there's no doubt that they ARE leaking to some degree and will be the cause of all sorts of elusive fueling and running issues if you don't know what you are looking for and the key here is that I use ethanol resistant VITON which the originals didn't and most likely any pattern ones don't either. 

The plungers or their seats are the first thing you should replace or renew BEFORE digging deeper into your carbs as this may save you chasing your tail and needlessly replacing internals or being fooled into thinking your carbs are worn out which they almost never are.

I'm able to do almost any Mikuni plunger ( except the permanently moulded on pull knob type yet ) not just RD's etc so if anyone needs this done for any bike just PM for details.

Price direct is cheaper (£12.50 + £3 p&p to UK via P/P Friends/Family) than going through the Ebay listing (https://www.ebay.co.uk/itm/254751405186?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649) and less than any decent pattern replacement and you need to send just the bare plunger with the spring etc removed.

I'm not a business, just a bloke in a shed doing this as a beer/retirement fund gig which was initially started for the Z1 Owners Club where the plungers for the early Mikunis are obsolete and choke seat wear causes major issues.
 
Email me at - zed.1015@yahoo.co.uk

Cheers. Rob.

Offline Gr8uncleal

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Re: CHOKE PLUNGERS
« Reply #7 on: November 03, 2020, 03:25:46 PM »
Welcome Rob.

It's well worth the few quid it costs to join the club - I get most of mine back in unfranked stamps on the newsletter envelope!  :D
Yam RD200DX (Gr8auntiepat's)
Yam FZX700 Fazer
Yam RD400C slowly getting back to standard
Yam RD350B rough
Yam RT2 almost finished
Yam DT360A almost finished
Suzi GT550J just started
Suzi 1250 Bandit regular rider
Yam RD125(A?) in the kitchen being reassembled
Yam RD250E just started
Yam DT3 just in

Offline Barnett

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Re: CHOKE PLUNGERS
« Reply #8 on: November 03, 2020, 05:16:58 PM »
Welcome Rob.

It's well worth the few quid it costs to join the club - I get most of mine back in unfranked stamps on the newsletter envelope!  :D

Cheepskate! :o :D :D I thought it was only me that did that! Christmas is my fav. time, loads get missed  :D

Offline Motty

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Re: CHOKE PLUNGERS
« Reply #9 on: November 03, 2020, 06:51:28 PM »

Welcome to the Forum Rob  8)
“...inside every old person is a young person wondering what the f*@k happened.”
Terry Pratchett

Offline betty foRD

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Re: CHOKE PLUNGERS
« Reply #10 on: November 03, 2020, 08:08:41 PM »
Welcome Rob.

It's well worth the few quid it costs to join the club - I get most of mine back in unfranked stamps on the newsletter envelope!  :D

Cheepskate! :o :D :D I thought it was only me that did that! Christmas is my fav. time, loads get missed  :D

Yep, even with that anti tampering thing it’s no match for a seasoned RD tinkerer!
Last one I ‘up-cycled’ was used to send Jock a kick start spring... there’s nothing quite like a Scotsman’s face when he finds out he’s getting free postage  :D :D :D
Rev 'em till they rattle

Offline psoidon

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Re: CHOKE PLUNGERS
« Reply #11 on: November 26, 2020, 09:41:17 AM »
Just had my plunger back from Rob, great job and great service.

Looks like new now :-)

Ian
1978 CD175 (Unstarted project)
1974 RD350
1980 Z650 C3
2001 Vmax

Offline johnA

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Re: CHOKE PLUNGERS
« Reply #12 on: November 26, 2020, 03:47:07 PM »
can vouch for Rob's work myself he's helped me out in the past on a few things not carb related though a very clever and knowledgeable man when it comes down to anything engineering.

Offline Tailchaser

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Re: CHOKE PLUNGERS
« Reply #13 on: December 16, 2020, 10:01:24 AM »
Just got mine back from Rob and it looks like a job very well done and quick turnaround as well (Royal Mail aside!). Can't provide feedback on running, etc as bike is undergoing the annual 'winter jobs' at the moment.

As an aside, I had a chat with Steve @ MotoCarb about a suitable replacement for the VM28SS carbs that are used on the 250/400 C/D/E and this was his reply:

"The plunger I stock is a slightly different design to the OEM version. It will only fit if the other parts (lever, spring, nut and boot) are also fitted as an assembly.
The lever has a rubber cover where you push it down (photo)
 
VM Starter assembly complete   £18.00 inc + post"

96716-0

Hope this may help anyone who's looking for one.

Cheers,

Jeff
RD250E

Offline vectisitch

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Re: CHOKE PLUNGERS
« Reply #14 on: February 06, 2021, 01:36:32 PM »
Had Rob do my choke pluger and it's a top job. Very quick turnaround too. Thanks very much