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Motor is very tight. Opinions please?

#1

S

southernkilowatt

Hi all,
I have a 23 HP B&S on a troy-bilt big red horse 50"cut machine. Since day one when it was new the motor has been very tight. It seems to be at TDC of the motor stroke, and to start it I normally have to raise the hood and manually turn the motor by hand to get it past the tight spot then it starts normally.

I change the oil faithfully at the beginning of each season, and I always go back with the same oil that came in the mower. (i cant remember exactly what it is as I type)

I am thinking about going back with some type of synthetic or "Slick 50" type of oil at the next change.

Opinions?

As always, Thank you in advance!

Dave


#2

W

webuyanymower.com

Hi
Could you post the Model Type and Code number of the engine it would be a great help.
Some B&S engines have an internal de-compressor to help with starting. It痴 a simple device that opens one of the exhaust valves. If this is not working you will be trying to start the engine at full compression.
There are a few other reasons why the engine would do this. Could be a bent crank shaft or the drive belt is too tight. Faulty starter motor or Faulty battery.
With the numbers off of the engine it would be possible to check the spec of your engine.


#3

S

southernkilowatt

Good point, I should have posted model and serial in the first post, sorry.

Here is what I can find, it is a;

INTEK V-TWIN 725cc 23.0 Gross HP from the family of 6BSXS.7242VF ---- 276480 with a serail number 061113YG26292


#4

W

walmel

On single cylinder engines, one of the first things to inspect may be valve lash. If it is incorrect the valve may not open enough to trigger decompression


#5

B

benski

southernkilowatt said:
Hi all,
I have a 23 HP B&S on a troy-bilt big red horse 50"cut machine. Since day one when it was new the motor has been very tight. It seems to be at TDC of the motor stroke, and to start it I normally have to raise the hood and manually turn the motor by hand to get it past the tight spot then it starts normally.

I change the oil faithfully at the beginning of each season, and I always go back with the same oil that came in the mower. (i cant remember exactly what it is as I type)

I am thinking about going back with some type of synthetic or "Slick 50" type of oil at the next change.

Opinions?

As always, Thank you in advance!


If you do change to a synthetic, DO NOT add slick 50 or any other oil additive to the oil. All the manufacturers that I know request no additives be added to their product. On that note, I don't think synthetic will be the answer to what you're experiencing. I'll go with the valve adjustment/full compression check for this problem as well.
Click to expand...


#6

W

webuyanymower.com

Odds are its valve adjustment that is not decompressing the engine at start up.
As far as the oil goes stick to the engine manufactures spec these are basic little engines and do not like hi tech synth oils. You could do more harm than good.

If you are not comfortable dismantling the top end of your engine I would take it to a dealer.


#7

K

KennyV

webuyanymower.com said:
..
As far as the oil goes stick to the engine manufactures spec these are basic little engines and do not like hi tech synth oils. You could do more harm than good.
...
Click to expand...

It's likely the decompression system is not functioning correctly...

But the statement about synthetic oil Needs a response... These type statements that are made and remembered is what gets Bad information believed to be true...
If you switch to synthetic oil your engine will not like it ... It will love it, especially if you go with a good diesel rated synthetic like Rotella T6...
These basic small Air Cooled engines will have the greatest benefit using a quality synthetic....
But like others have said, your problem is most likely from other problems, it only seems tight because there is good compression, Using a synthetic oil will help maintain that compression 20 years from now..... :smile:KennyV


#8

W

webuyanymower.com

Now I am just confused the mineral oil verses synth debate has been going on for many years and in the right place synth oil is fabulous and can offer far more protection than mineral oil but surely if an engine manufacturer recommends a specific type of oil then presumable they have spent time and money to research what gives the best results over the life of the engine and any advice that is given in a forum of this type should reflect the manufacturers recommendations.
In the final analysis we have the choice to use whatever oil we like but personally I would keep to the manufacturers recommendation it has worked for me for the last 35 years I see no reason to change now.


#9

B

benski

webuyanymower.com said:
Now I am just confused the mineral oil verses synth debate has been going on for many years and in the right place synth oil is fabulous and can offer far more protection than mineral oil but surely if an engine manufacturer recommends a specific type of oil then presumable they have spent time and money to research what gives the best results over the life of the engine and any advice that is given in a forum of this type should reflect the manufacturers recommendations.
In the final analysis we have the choice to use whatever oil we like but personally I would keep to the manufacturers recommendation it has worked for me for the last 35 years I see no reason to change now.
Click to expand...
You are certainly entitled to stick with what the manufacturer recommends for the specification of oil for their machinery. For me, the choice to use synthetic gear lubes, hydraulic oils, 2-cycle oils, and engine oils, etc. that exceed the factory minimum requirements is an easy one. The engine manufacturers are in business to sell engines and parts. I'm in business to see if I can beat the average lifespan of the equipment I buy, and synthetic lube, custom engineered for the demands of small engines, is the best way I've found so far.:biggrin:


#10

W

webuyanymower.com

I guess you are right I might have a jaundiced view coming from an equipment manufacture back ground I tend to go by the book.
But dont get me wrong I am not saying synth oil is bad because clearly its not and in fact I use it in my racing saws and could not get the RPM out of them on mineral oil. It just would not be my recommendation in this case.
Anyway we seem to be getting off the topic I still think it痴 the de-compressor not working properly.


#11

S

southernkilowatt

OP here, thanks for the replies so far. I did not mean to start a debate on synt/vs/mineral oil however I do appreciate the feedback on both. I too admit to sticking to the book when it comes to oils and have always stayed with manf. recomendations. However in this case I am still very much considering switching to an all synthetic oil to see if it will help my problem.
A couple of points I would like to raise on the valve lash and decompression ideas, One being that this motor has done this since BRAND NEW. Aside from the test run at the factory I am positive that I am the very first one to run this motor. It would seem to me that a factory would not release a motor that had a valve lash or decompression problem and know about it. Not saying of course that its impossible to get a "lemon" so to speak, I realize that its not impossible. But let me ask this, is it possible that perhaps a wire could be broken or a valve not energizing or de-energizing at just the right moment and not releasing the compression on the motor at start up? Does this engine even have that capability?
Please continue to share your thoughts about the motor and by all means please continue to share your thoughts about the oil as well. I am finding it very informative and very interesting as well.

As always, thanks
Dave


#12

B

benski

I hate to say this, but perhaps the engine wasn't adjusted correctly at the factory, or assembled with defective or incorrect parts.:eek:If this has done this since new, it seems like it might be possible. As for switching over to synthetic oil, I'd be shocked if it made a difference in what you're describing. I'd lean more to changing oil AFTER I got this particular issue rectified. :)


#13

D

Duffer72

Those and other briggs engines have a recurring problem with this condition, you just need to adjust the valves properly and it will clear up but don't be suprised if it happens again in a few months, I have a couple that I get called on that I have to do it every 6 months or so, but most people just give up and turn the motor over as you have stated you do and they start right up.


#14

S

southernkilowatt

If I just leave it alone and continue to start/crank it like I have all along, do I risk damaging the engine in any way?


#15

D

Duffer72

One of the mowers that the people have given up on has been like that for 3 or 4 years now, it doesn't seem to effect the running once it kicks over at all. it is just that the engines have been max'd out for HP rating that they have the compression release so tight of a spec that it is what causes it.


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