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Collection, Preservation and Display of Old Lawn Mowers

Suffolk 98g14 1a "throttle lag"

Hi all

I wonder if someone could share some wisdom please. I have a couple of Suffolk Punch mowers (see thread in General forum for pics) - not sure how old they are but certainly older than me, probably by a decade or more.

On one of them the engine runs very well but has a complete dislike of choke - any choke at all even when cold starting and it won't run. Apart from that, the engine runs well - should I be concerned, is there anything to check, or do I stick with "it aint broke so don't fix it".

The other starts with choke but has a kind of "throttle lag" when you open the throttle from idle, it thinks about it for a second, splutters and then picks up speed. Same question again - is there a most likely cause? 

Both are used for mowing the lawn, about a fifth of an acre in all. I'm not afraid of stripping them down but am entirely self taught so far. I have stripped and cleaned the carb on the first one but left both the jets screwed in as my experience with adjusting the main jet only caused problems. I guess I don't understand cause and effect of all the other bits :)

Any sage words are appreciated



wristpin Wed, 15/04/2015

Can we establish which carbs you have. I'm thinking the Zenith  up draught carbs fitted to the early 75 and 98cc cast iron block engines and  the early 98cc aluminium block one. An image would be useful  - unable to find the one that you refer to.!

Starting without choke suggests too high a fuel level ot partially blocked air cleaner and spluttering on acceleration a weak mixture, incorrect slow running jet adjustment or partial blockage of the idle/progression drillings/jet; but could even be an ignition issue..

steveb Wed, 15/04/2015


near top thread in the General forum, pics are here…

carbs are Zenith 13 TCA-2

re the choke starter, I did replace the foam air filter last night as it was fairly nasty, that may have some effect but it was late so I didn't try to wake the neighbourhood! I replaced it with an offcut of some packing material that looks very much like the filters in my house ventillation system (a inch thick white wooly/nylon/stranded sheet that can be cut with scissors), Not sure how fussy these machines are about the exact composition of these filters, hopefully not !

By "too high fuel level" assume you are talking about the main jet mixture, or is the level of fuel in the float a possible concern? I have played with the mixture, mainly with ill effects! but not adjusted the carb float


Re the splutter on acceleration I have played with the mixture so I don't think it's weak (but no real way to tell).I didn't realise that the idle could impact main running so I left it well alone - I will have a look at that, and if that fails strip the carb and give it a good clean

Thanks for the advice



wristpin Wed, 15/04/2015

Seems that a "google account" is needed to view the pics but Zenith is enough.

The high fuel level that I had in mind was the level in the float chamber- faulty float or needle not cutting off the fuel when at the correct level. 

the correct air filter material is "open cell foam" . Closed cell foam as used in packaging is too restrictive. Try starting it with no air filter and see if it still starts without choke.

The Zenith is fairly crude without much of a progression system but a bit of juggling between the idle and main jets should sort the problem From memory a basic setting for the idle screw is about three quarters of a turn from fully closed. For the main jet just unscrew it until the engine sounds heavy and slows down, then back in till it stalls, counting the turns and then halve it.

On an old machine that may be dragging in air from around a worn throttle shaft you will need to play with the settings regardless of what the book says.


steveb Thu, 16/04/2015

Thanks. It should let you see the images without a google account - did you click on the link, or copy and paste the URL? If the latter, it may be that the forum has truncated the URL. The full one is below:

The packing foam I used for the filter is nothing like normal packing material, it is a very lightweight, almost see though mesh - more similar to the G3 filters in my house ventilation system - you can breathe through it with no real difficulty - I guess the closest comparable is like a very fine plastic wire wool and would act as a course filter. 

I will look at the mower over the weekend and report back. 


wristpin Thu, 16/04/2015

Clicking on the link and it goes straight to a request to sign in or create a Google account!

Anyway your air filter material should be fine. We'll se what happens!

steveb Mon, 20/04/2015

Thanks. Worked on one mower this weekend, fresh SAE30 oil and the old sponge air filter replaced with the home-made mesh one, that did seem to make a difference - it started on (half) choke, moved to no choke and cut the lawn beautifully. I think because the air filter hangs downwards I never thought to look at it - sometimes it it the simple stuff!

I have moved some pics from google to here for your info. This is the one that didn't like choke. note the front rollers I had to turn up as the original ones had rotted through




This is the one that won't accelerate cleanly from idle :



I'll have a go at that next weekend

Thanks again


wristpin Mon, 20/04/2015

Good old bit of solid engineering, no frills and fit for purpose. Takes me back to when we would have a workshop full of them awaiting service every winter. Not much went wrong with them and when it did it was easy to fix. Nice that you have one with the cast alloy rear roller rather than the plain steel one. Same goes for your home turned front rollers; nicer period touch than the later plastic ones!

steveb Mon, 20/04/2015

I have 2 near-identical ones (both were pictured above - one is brighter orange and has original rollers). Do you have a guess at the age - I am guessing early 60's - would that be about right - the engines are both 98g14 model 1a

As an aside, I have managed to purchase a whole bunch of piston rings labelled "suffolk" - sets of three , some 2" and others 2.25" - not sure if any is suitable for this engine , but I seem to have about 10 lifetimes supply, so if someone can make good use of a set I will happily post them. Some are branded Cords, others Westor.


wristpin Mon, 20/04/2015

I would think that you are probably about right on the age of your machines. if my memory is correct the last of that design were a "muddier" green and branded Qualcast. Someone on this forum has possibly got a brochure and can give you chapter and verse.

Cords piston rings were designed to "rescue" worn, oil burning engines without the need for a proper re-bore and reconditioning job. In fact the brand is still around but their major business now is making original equipment rings for some of the well known and respected engine manufacturers. They do still have some stocks of their "oil saver" rings and I recently bought a set for a Kubota Mag and you will see a listing for Suffolk/Qualcast rings near the end of the attached brochure. The biggest issue was tracking down someone in their organisation who knew about them!

Westor was an after market or pattern brand that became part of Central Spares of Wimbourne who are still very much alive. I have a copy of their 1996 catalogue which lists 75cc Suffolk rings for the cast iron block enginr, their pt no 10804, original L03514/5/6. for the 98cc c/i  their pt 10812, original L08219/20/21 and for the A98 aluminium block pt no 10815.

The 10804 75cc c/i set are still listed in their 2015 catalogue so I guess that they held or inherited big stocks as well!

steveb Mon, 20/04/2015

ha, you are a fountain of knowledge. so, totting up it seems that I have

5 sets of Cords "912s" - labelled Suffolk 2".For the 75cc iron according to the PDF you uploaded 

7 sets of Westor 10812 - so for 98cc iron

1 or 2 sets of (not westor but labelled with their part no 10815 and handwritten "suffolk 98cc aluminium")

Now considering that at most I would use a couple of sets for the 98cc iron, (and they are showing no sign of needing them soon) I find myself long lots of rings, If anyone wants a set then just ask, I seem to have enough for 10 lifetimes..



arnk Sun, 26/04/2015


I could give a good home to a set of 75cc rings for my old Suffolk 17 Dual Drive.
Will you be going to the Milton Keynes rally?  I was thinking of bringing mine to the rally this year.  I tuned mine up with a ColourTune, which seemed to work quite well.


steveb Mon, 27/04/2015

yes, sure - is there some way to get your address to me (does this site have private message facility..?) , if so I'll stick them in the post

Unlikely to make it to the rally - I have a fresh new baby now which seems to be absorbing all my leisure time. Barely have time to cut the lawn these days!


olcadmin Mon, 27/04/2015

The site does have a private messaging feature, as follows.

Anyone registered on the site and logged on can click on the user name of a forum participant (top left of the post's panel) to view their profile and contact them directly (click the "Contact" tab).

wristpin Tue, 28/04/2015

I've always used the "send email" tab below the posters details , top left of a post. Other than it discloses my email address is there any reason not to? I also  thought that there was no PM  facility on the forum.

olcadmin Tue, 28/04/2015

Wristpin, that link achieves the same as the way I described in the previous link and opens same page. Neither works if you're not logged in. It's private so serves the same function as a PM facility. Keith.

wristpin Tue, 28/04/2015


steveb Tue, 05/05/2015

HI Alistair - I sent a private message to you asking for your address to send the piston rings to - let me know if you didn't get it


steveb Mon, 25/05/2015

Update on the mower that wouldn't accelerate cleanly from idle - I ended up stripping and cleaning the carb and finding a use for the wire mesh that is used to surround a nice bottle of rioja to poke out the fine drillings and once it got put back together the engine runs a lot better than before - it picks up revs quite cleanly now so that is good.

One the bad side, it's exposed another problem with the centrifugal clutch. I shall open another thread to avoid cluttering this one!

Thanks for your help so far


wristpin Mon, 25/05/2015

Open another bottle and add a drop to your  fuel tank , the machine may seem to run better.