Victa Professional 550 self propelled parts question

[MrBedford]

Hi,
A friend of mine owned a Victa Professional 550 self propelled mower, which had no spark and hadn't run for a long time. He got sick of trying to start it, so he gave it to me for nix. I fitted a new G4 carby kit and Decompression valve, I then solved the no spark problem by removing the magneto coil and ignition module, and by cleaning them and all the electrical terminals. After replacing these components I reset the Magneto air gap and now have excellent spark. The mower starts first pull now, and runs fine, except there is no idle, it just runs flat out all the time so I still need to sort out that issue, although I'm fairly certain it's not caused by a vacuum leak.

My reason for starting this new thread is because the self propelled mechanism makes the mower take off like a rocket and you almost have to run to keep up with it. The Victa workshop manual for the 550 says the mower is fitted with a 105mm drive pulley above the gearbox which gives a travel speed of 5.2km/h, and that a slower speed can be achieved by fitting a 120mmm pulley which changes the travel speed to 4.7km/h. A "Slow Speed Kit" can be purchased for this purpose, the kit containing a 120mm pulley, a new drive belt, and a tube of Loctite. Searching the internet I only found one of these Victa Slow Speed Kits available, but the asking price is almost 200 Australian dollars!

So my question then is, does anyone on this forum know where I can get one of these Slow Speed Kits cheaper? $200 is a lot of money to fork out for a pulley. Even just a second hand 120mm pulley by itself might do, if anyone knows where I can find one?

Thanks.

 

[bertsmobile1]

From the top
Your no idle problem is most likely the governor diaphragm
If you try to refit the cap with the center plug & spring in place the new thinner diaphragm will slip out of place so not make a seal
The simple check is to put a longer length of tube on the governor section of the carb then blow & suck
If the diaphram is working it will go faster when you blow & slower when you suck
When you fit the governor diaphragm, slip a LITTLE rubber grease around the end
Push the cap on strait till it clicks & double check it is home all the way round
Then slip the long spring in and the final cap .

Now for the hard bit
B &S discontinued all of the old Victa parts when they took over and AFAIK sent them all to be destroyed so there is no support for any Victa other than the new Briggs on a bowl model
However AllMowers list it Victa slow pulley but they list a lot of stuff that they can not get to drag you to their web site and it is a pay first , then get told "we can't get it" 6 months latter situation.
The best source would be Bruce at Outdoor King they do not list either the pulley or belt but he is genuine & knows mowers
Other than that you can just go to an engineering supply company and buy a M pulley blank
Stenco used to make an excellent range of aluminium pulleys although I have not bought one since before everything HAS to be imported from China
Pay the $ 5 and join the Outdoor King forum if you have no luck
There is a large number of very good old school tech on there who have a lot of old spares
Next best alternative would be to go to Vintage Mowers which is an Australian based web forum ( this one is mostly US ) and has a dedicated Victa section plus there are a large number of Victa enthusiasts there who should be able to sort your problem out
It is also a PAY to join forum which prevents web bots & spammers from signing on so it is very safe & very helpful

 

[MrBedford]

Thanks for the informative reply. I am aware that high revving issues can be caused by vacuum leaks, or an ill fitting carby diaphragm, and/or a poor fitting "O" ring on the engine crankcase. I'm pretty sure I've eliminated those possible causes but the problem still exists. As you probably know there is a plastic button fitted inside the very bottom of the crankcase which has a tube protruding through the crankcase to which the vacuum hose to the carby is fitted. According to my Victa Service Manual it's called a "Vacuum Nozzle" and is designed to govern the speed of the engine. The manual says the nozzle position is pre-set at the factory but by turning it in either direction the engine revs can be increased or decreased. I considered doing this but even though it might decrease the revs I'm pretty sure it's not going to give me the option of dropping back to idle speed when using the control lever on the handle. Thanks for the advice about the diaphragm, I've checked it several times and I'm certain that is not the issue. I'm going to have to give the situation more thought.

Regarding the drive pulley. Thanks for the heads up about AllMowerspares. I've noted your comments about the Outdoor King forum and will give it a try.

Thanks again for the advice.

Cheers.

​

 

[bertsmobile1]

I would recommend you ring Bruce first ( OutdoorKing ) at his Concord shop for an honest heads up before sending cash & credit card details to AllMowers
If you buy from AllMowers the do not use a credit or debit card , use a third party system like PayPal because I have serious doubts about their standard of data security and fear thy are just using stock off the shelf Microsloth business platform, it feels vey much like NAVS which has security holes big enough to drive a double decker bus through .

Before you play with the Nozzle do the blow suck test
If the carb fails the blow suck then the problem is in the carb
I do about 20 or so a year & have never needed to touch a nozzle other than to replace a broken one
If you have no throttle response then double check the cable is in the valve cam and not in front or behind the hole for the nipple they can be tricky some time to get in position properly.
Better than 90% of run away engines I have come across has been caused by the edges of the diaphragm edges not fully secured all the way round so leaks at the edge .
Fine speed adjustments used to be done with different strength springs which were colour coded and I do the same now days by using calibrated old springs as currently there is only one spring available and that spring is discontinued so when they are all gone we will have to get them made

 

[StarTech]

Bert thanks for giving the heads up about the vendor to a fellow user. It like Bailey's here where a lot of got our credit credit details over 5 yrs ago when a key logging program got installed on their system. I tend to PayPal for vendors just to insulate my credit card now.

 

[lbrac]

Going from a 105 mm drive pulley to a 120 mm drive pulley would speed up the travel speed by ~14.3% to ~5.9 km/hr, not reduce it. If you meant the driven pulley instead, the speed would be reduced by 12.5% to ~4.6 km/hr, which is in the ballpark.

If the other recommendations fail, an industrial bearings and drives distributor should be able to supply a suitable pulley and belt if you remove the parts from your mower and carry them in. They can measure and match the belt, shaft and key sizes. If you measure the center to center distance between the drive and driven shafts, and the diameter of the other pulley, they should be able to calculate the correct belt length.

 

[bertsmobile1]

Going from a 105 mm drive pulley to a 120 mm drive pulley would speed up the travel speed by ~14.3% to ~5.9 km/hr, not reduce it. If you meant the driven pulley instead, the speed would be reduced by 12.5% to ~4.6 km/hr, which is in the ballpark.

If the other recommendations fail, an industrial bearings and drives distributor should be able to supply a suitable pulley and belt if you remove the parts from your mower and carry them in. They can measure and match the belt, shaft and key sizes. If you measure the center to center distance between the drive and driven shafts, and the diameter of the other pulley, they should be able to calculate the correct belt length.

It is the driven pulley we are talking about

 

[MrBedford]

Before you play with the Nozzle do the blow suck test

Ok, I tried the blow/suck test as suggested and the diaphram seems to be seated ok and working. Sucking on the hose caused the engine speed to come back to idle and blowing increased the revs.

After that, I did a re-check for other causes of a vacuum leak and found that the hose connection to the vacuum nozzle at the bottom of the crankcase was a possible source. The end of the hose look somewhat stretched in diameter, so I cut the end off and also applied some Hylomar gasket compound around the vacuum nozzle nipple and re-fitted the hose. It appears to have made a difference. The mower now responds to the throttle lever and reduces it's revs. It's not quite dropping back to the correct idle speed, but it's a vast improvement. Tomorrow I'll use the gasket compound on all the hose connection to see if I can improve it further.

I would recommend you ring Bruce first ( OutdoorKing ) at his Concord shop for an honest heads up before sending cash & credit card details to AllMowers
If you buy from AllMowers the do not use a credit or debit card , use a third party system like PayPal because I have serious doubts about their standard of data security and fear thy are just using stock off the shelf Microsloth business platform, it feels vey much like NAVS which has security holes big enough to drive a double decker bus through .

Yes, I will give Bruce a ring, thanks. That's good advice about online shopping. For many years I've done my online shopping via Paypal, and on the odd occasion where I need to use a credit card I'd setup one with a minimal credit limit so if I do get scammed they won't profit much by it.

Thanks once again for your help.

Going from a 105 mm drive pulley to a 120 mm drive pulley would speed up the travel speed by ~14.3% to ~5.9 km/hr, not reduce it. If you meant the driven pulley instead, the speed would be reduced by 12.5% to ~4.6 km/hr, which is in the ballpark.

It is the driven pulley we are talking about

My apologies. I should have been clearer regarding which pulley. The actual drive pulley is a smaller one on the engine shaft. The pulley I'd like to change is the "gearbox drive pulley", it sits directly above the gearbox and is connected to it by a shaft. There is also a belt tensioner pulley between the two. Relevant pages from the Victa service manual showing the pulley can be seen at the links below.

https://imgur.com/lFsqyQR

https://imgur.com/OclHcwP

If the other recommendations fail, an industrial bearings and drives distributor should be able to supply a suitable pulley and belt if you remove the parts from your mower and carry them in.

Thanks for that advice. There are such distributors in my area.

 

[bertsmobile1]

There should be no need for sealant if the hose is still in a servicable condition
It is nothing fancy just 3/16" PVC
I think they went with it so there would be something that needs replacing
When it gets old & hard it leaks around the spiggots for the decompressor & the governor
You can use any fairly hard hose that will not collapse under vacuum
I have used Tygon on the occasions when I ran out .
even the heavy walled size was a bit soft so the governed response was a bit slow
If it is fast overall then you probably need to add a shim washer to the carb cam
Supposedly the limit is 3 but I have stuck 5 in there on more than one occasion
Each one drops the speed about 200 rpm at idle and near double that at full speed

 

[MrBedford]

There should be no need for sealant if the hose is still in a servicable condition

I think the nozzle tube on this mower has had some rough treatment by a previous owner which causes it to leak.

you probably need to add a shim washer to the carb cam

It already had one washer fitted, I will try another.

The Victa manual gives good instructions on how to make a homemade water device for testing the amount of vacuum produced in the crankcase. It says "The difference between the upper and lower level of the water should be 1.33mm-1.50mm. The lower level means insufficient vacuum".

It would be interesting to see what level this mower produces.