Suffolk Punch Dual Drive Mower

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Timboy
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Suffolk Punch Dual Drive Mower

Postby Timboy » Wed Apr 15, 2009 6:31 pm

I have just got hold of a suffolk punch dual drive mower. It will not spark , checked carb,plug, points any ideas? Type 75G 14 Model 13A Engine No 518391 many thanks Tim
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Clive.
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Wed Apr 15, 2009 8:08 pm

Hello Timboy,

If the spark remains missing then it may be worth another look at the contact set (points)..they really do need to be Immaculate Clean and Dry....even grime from feeler gauges can upset things. I have sometimes used a fine carborundum paper pulled through the contacts as a method of fine cleaning. With a final clean up once set with a bit of clean dry card pulled through the contacts to finally rid any grime....or I have used a corner of a Cotton handkerchief in lieu of card..but don't tell mother. :oops: :wink:

Check that the contacts do move correctly as it is possible for a set to stick open if things have got corroded...and also that the faces are true and flat togther once closed.
The setting for contacts is 18 thou of an inch and the spark plug 20 thou or 25 thou which was recomended later on.

The older set of points that I think your engine will have.??..like a long elongated horizontal S shape held by a spring wire clip with thin washer behind...are no longer available, as far as I am aware..(more recent totally different type are available for later engines) So do look after the set you have..they were quite sturdy type of set so will usually clean up.

The suppressor clip that joins HT cable to spark plug has a length of carbon rod within it and can fail. Also if the supressor has been removed too many times then it may be that it is only screwing into insulation rather than HT wire.!
....And never dismiss the spark plug...they can go on for years but equally if oil impregnated can fail.

Coils (and condensor to an extent) could be tested....certainly could anyway when I was working in the mower world c.18 years ago.
It would be taken in still mounted on the stator plate with contact and all...BUT do mark with a scribed line the position of the plate before removal or else the timing will be upset and need working out again.

Do take care with your repair work...if in any doubt, although it is an older machine, they were made in massive quantities and an older long established service agent would still be familiar with them.

All the best,
Clive.
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Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Thu Apr 16, 2009 8:45 am

Thanks Clive I am going to take plate off and take it to my local dealer any ideas where I might find a manual for a complete rebuild ? many thanks Tim.
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Thu Apr 16, 2009 5:54 pm

Hello Tim,
Do note the reference I made to marking the location of the stator plate before you remove it...it is on slotted holes and needs a scribe mark from backplate to the stator plate so that you can put it back in exactly the same positon.
I hope you get on ok..I do fear that some will look and say obsolete and not be too keen to check it...hence my reference to older long established agent similar to our local agent who I would hope may be able to at least test the set up.
To be fair to agents... parts wise these models, except for where the newer model used parts from the older type, would have been deemed obsolete by c.1980.

From experience quite a large proportion of the ones that used to get brought to the counter where I used to work needed a more thorough clean up of contact set..hence my thoughts to double check this.....but then these machines are 18 years older than when I last stood behind a mower agent counter. :oops: :wink: .....and a break down of coil or condensor could have occured.

Operating manuals tend to appear in all the usual places, car boot sales through e-auction sites..to specialist collectors of such paraphernalia...

With the age of the mower I would suspect that the operating manual whilst not a full service repair manual would have more engine service info than a manufacturer would put in such a document these days.!!

All the best,
Clive.
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Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Thu Apr 16, 2009 6:09 pm

Hi Clive I took it in they said to heat the coil on a radiator so i used a hair dryer on gentle heat , put it all back together hey presto I have a spark do you know the plug gap? It will only run when I push the tickle button in as soon as I let it go it runs for a few seconds then cuts out. I have checked fuel flow and this seems ok. I stripped the carb down and cleaned it when is the choke on in vertical or horizontal position?. Many thanks Tim.
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Thu Apr 16, 2009 6:51 pm

That's good then....

I reckon the plug gap was 20 thou at first then later models increased to 25 thou inch.

Choke lever is..Up, horizontal to choke for start..then Down, for normal run.

Rust sediment can settle in the carb bowl over time and white corrosion too and have got into the feed to main fuel jet.

A regular one was the brass idle air tube, that is set vertical in the carb bowl, getting blocked...it has a very fine jet hole and whilst it is involved with slow run it will upset full speed running if blocked up

On the later carb type with a copper? fuel pipe direct into carb top the idle air tube will pull up and out of the carb bowl for cleaning...but on the older type that has a bolt on banjo type fuel inlet the idle air tube was a screw in type and tended to be stuck.! ..and often best cleaned in situ.

I have also seen a crust of rust form above the float needle seating so make sure you have a good flow at that point.

Check for vent at petrol cap.

It may just need to be set richer on the main jet screw..??. they would be set just on the rich side to allow good pick up to drive.

**As usual I will add...to always run the machine outside....never in shed/garage etc due to exhaust fume danger...
**Do be aware that being a centrifugal clutch machine take up to drive the cutting cylinder is immediate on increase of engine revs..and do not trust the dual drive lever lever not to jump into drive and the whole thing set off forward :shock:

I think there was facility on some to uncouple drive by moving a sliding section (when switched off) near the clutch drum..but again be wary of it..as there may still be a follow through of drive to blades simply due to momentum of associated shafts.

All the best,
Clive.
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Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Sat Apr 18, 2009 9:22 am

Hi clive it runs thanks cleaned out carb again when i move throttle the engine does not chane speed much i suppose i need to tweek the carb a little. I took off one side cover to see why blades will not turn and found there was only 2 chains. the bottom left gog needs to come off how do i remove it. Should there be 3 chains and should the bottom left cog turn with the blades? Thanks Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Sat Apr 18, 2009 6:32 pm

Hello Tim
I believe the Suffolk Punch 14" and 17" dual drive had 3 chains.
1st from top shaft to cutting cylinder, 2nd from cutting cylinder to an intermediate sprocket, 3rd from intermediate to roller sprocket.
14" had a knob to engage roller drive, 17" had a lever to do similar.
(Colt 12" had 2 chains...ie; no intermediate sprocket.)

I recall that the Punch 17" had a nut to retain the sprocket on the cutting cylinder end...and then the sprocket was on a parallel shaft with a key.
I also recall that the sprocket used to come lose in which case the key, keyway and sprocket would suffer burring damage. I can't recall if 14" used the same basic fitting idea..it was a similar chassis style but not fully identical.
Which width of cut mower do you have.??

(Colt 12" had a pin through the cylinder shaft rather than a key..it used to get worn and drop out.!)

** Check chain operation whilst static...
As spinning chains in open chaincases can snag clothing, remove fingers......

Reference the revs..do you think that the governor linkage is all ok.??... The throttle cable operates a lever arm on top of the inlet tube...from this lever arm a governor spring links to a loop in a rod. The rod at one end attaches to the thin tin vane above the flywheel and the other end to the actual throttle arm of the carb.
The action is such that as the handlebar throttle lever is moved to rev up the governor spring is tensioned and the engine revs increase. The tension is matched by the air blow from flywheel onto governor vane and an equilibrium? is reached so the revs arrive at and are maintained at the desired set speed....then as load in mowing is applied the engine would start to slow and the blow to air vane would diminish..thus causing the spring to pull open the carb spindle a fraction more to compensate and maintain revs at the desired set speed..this should all happen constantly.

I wonder if the engine is only running light and not under load that the change in engine revs is not really very noticable.?? It should be really I would have thought though as the engine should be able to tickover slowly and steadily such that the centrifugal clutch disengages. Perhaps the tickover is set high on the throttle stop screw.??

A bit more to ponder on.!! :wink:
Clive.

Hopefully this time whe I click "submit" this will post ok....this morning having been typing all I got was page not found.!!...I was not so happy.!!
and abandoned the job to go shopping and to the local Daffodil show..
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Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Sun Apr 19, 2009 9:34 am

Hi Clive mine is 17inch. I have taken the chain to the blade sprocket off and there was a key in the sprocket which I pulled out with a pair of pointed plyers very worn. How do I remove the sprocket, do i need to? because when i turn the blade by hand the shaft that the sprockets on turns but the sprocket does not move, if i turn the sprocket the shaft does not move, is it something to do with key? thanks Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Sun Apr 19, 2009 10:00 am

Hello Tim,
The key on the 17" was a woodruff semi circular key that fitted into a machined slot in the cylinder shaft...certainly on the later ones that I had dealings with.
The slot in the sprocket would locate over the part of the key protruding from the shaft and this would be the way drive was transmitted. http://en.wikipedia.org/wiki/Woodruff_key

If you have not actually removed the cutting cylinder sprocket then I feel it must be only part of the key that has come out.??....as it it has sheared off.?? leaving part key in the shaft and part in the slot of the sprocket. OR.. it could be that older machines had a straight key.??...or it has had a repair with a bit of straight key wedged in.?? It was weak point in the machine.

With end nut removed I think the the sprocket should just pull off.??..perhaps just is not the word.!! I think it was on a parallel shaft but then any burring and damage might add to the fun.
There is often not enough room to get a leg type puller in...often mower establishments have some nifty angled levers to get in behind such sprockets and use on bearing blocks too...one each side to give an even lever off.

Clive.
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Timboy
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Sun Apr 19, 2009 10:39 pm

Hello Clive still can not get engine to go fast enough to rotate blades any ideas? Tim.
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Mon Apr 20, 2009 7:48 am

Clive how free shoud the bades turn they seem quite stiff to turn by hand is does this seem right? Tim
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Re: Suffolk Punch Dual Drive Mower

Postby Clive. » Mon Apr 20, 2009 5:39 pm

Hello Tim,

The cylinder blades should just be in very light contact with the fixed bottom blade....the usual analogy is to liken them to a pair of scissors.

If a pair of scissors are slack they will not cut...but if too tight they are too difficult to open/close...

It could be then, if set very tight, that the engine just can't get the cylinder underway.??..

Did you get the sprocket/key sorted.??

Clive.
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Re: Suffolk Punch Dual Drive Mower

Postby Timboy » Thu Apr 23, 2009 9:42 am

Hi Clive I checked the blade clearence seems ok not touching bottom blade but blade is quite stiff to turn by hand. I could not get the cog off so I got another key tapped it in and that seems to have done the trick. Tim
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