# HS928 Out of Time ?



## orangputeh (Nov 24, 2016)

last summer i got a 928 from a guy that told me the dealer told him the engine was out of time. they said maybe the key was sheared on the flywheel. I took off the flywheel and the key is fine. the valve adjustment is fine. the compression is high. there is fuel and spark.

someone suggested taking crankcase cover off to check timing marks on gears? do you think this is right? 

the compression is around 120 which i have never seen on a Honda snowblower engine. usually it's around 100 or so. I am going to check the valve adjustment again.

what could be wrong if I open up the crankcase? anyone have experience with this kind of problem?


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## paulm12 (May 22, 2015)

I don't see how timing can increase compression (it could decrease it). Both valves are closed at the peak of compression. What is the symptom that lead to the "timing is off" diagnosis? And yes, it is very easy to mismatch the camshaft to the crankshaft and mess up timing. There is usually a mark on both the crank gear and cam gear that have to match up (on Tecumseh engines is very visible). Removing the crankcase cover will show if they are matched. Downside is you will probably have to replace the gasket, and maybe the oil seal on the crankshaft.


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## orangputeh (Nov 24, 2016)

paulm12 said:


> I don't see how timing can increase compression (it could decrease it). Both valves are closed at the peak of compression. What is the symptom that lead to the "timing is off" diagnosis? And yes, it is very easy to mismatch the camshaft to the crankshaft and mess up timing. There is usually a mark on both the crank gear and cam gear that have to match up (on Tecumseh engines is very visible). Removing the crankcase cover will show if they are matched. Downside is you will probably have to replace the gasket, and maybe the oil seal on the crankshaft.


double checked valve adjustment and it is right on the money. not sure why they said timing is off. after spending hours on it can not get it started. previous owner had same problem and had dealer check it and they could not get it to start either. the owner did not want to spend any more money on it. 

the only thing i can think of is a tooth broke inside the crankcase since as far as I know it has never been taken apart before.


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## paulm12 (May 22, 2015)

hmm. I'm guessing you have checked these already:

- are you sure there is spark at the plug, not just tested the coil?
- try another plug?
- tried starting with starter fluid?

Here is the Tecumseh L-head timing marks:


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## vinnycom (Nov 6, 2017)

orangputeh said:


> ..... after spending hours on it can not get it started. ......


ok, but exactly what did u do for those hours to fix a no start problem.

carb adjust and/or clean?
fuel delivery check?
spark check?
use starter fluid to test?
manifold leak test?
etc etc


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## RedOctobyr (Mar 2, 2014)

orangputeh said:


> the only thing i can think of is a tooth broke inside the crankcase since as far as I know it has never been taken apart before.



Sounds like it may be worth taking the engine cover off, only if everything else has already been checked out. 

But depending on the # of teeth on the gears, I'd expect that you might need to break several gears, before the timing could slip. Looking at paulm12's picture, it would take more than 1 broken tooth. 

Does the timing "look" reasonable? When each valve opens, does it seem logical, based on the piston position? 

Are you getting air drawn in through the carb, and out from the exhaust? I know that sounds stupid, but if one valve wasn't actually opening, for whatever reason, you *could* have compression, but it would not run, since no fresh fuel mixture would actually be flowing in & through the engine.


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## orangputeh (Nov 24, 2016)

paulm12 said:


> hmm. I'm guessing you have checked these already:
> 
> - are you sure there is spark at the plug, not just tested the coil?
> - try another plug?
> ...


yes.



vinnycom said:


> ok, but exactly what did u do for those hours to fix a no start problem.
> 
> carb adjust and/or clean?
> fuel delivery check?
> ...


yes.


RedOctobyr said:


> Sounds like it may be worth taking the engine cover off, only if everything else has already been checked out.
> 
> But depending on the # of teeth on the gears, I'd expect that you might need to break several gears, before the timing could slip. Looking at paulm12's picture, it would take more than 1 broken tooth.
> 
> ...


i will check. thanks. i checked everything listed above but am going to check all this again before I pull the crankcase cover.


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## paulm12 (May 22, 2015)

If you have another machine with similar engine, can you look through the spark plug holes and kind of tell if the timing is correct? On the Tecumseh engines you can see (barely) the valves opening and closing, and compare to the position of the piston. Or maybe through the valve covers. 

I understand your confusion/frustration, it seems the problem should be obvious.


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## orangputeh (Nov 24, 2016)

i feel that I and the honda mechanic is missing something basic so i already re-installed the flywheel and then i will put the flywheel cover back on and start from scratch as if i am looking at this problem for the first time.
will check back.


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## contender (Jan 18, 2018)

orang, unless I miss reading, if this is a Honda HS928, my manual shows compression 85.3 to 120.9 at 600rpm. A 2nd manual shows the same.

Is the plug wet??


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## orangputeh (Nov 24, 2016)

contender said:


> orang, unless I miss reading, if this is a Honda HS928, my manual shows compression 85.3 to 120.9 at 600rpm. A 2nd manual shows the same.
> 
> Is the plug wet??


i'll check back in 2 days. thanks. ya the compression was around 120 and i thought that was too high as most Honda's test out at around 100-105. my tester is very old so I got a new one.


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## ST1100A (Feb 7, 2015)

Generally when you are pull starting the engine the automatic decompression release will activate and your compression will be much lower than 100-120 psi. When the engine fires and reaches over 600 rpm's the decompression release will deactivate. I have seen the little decompression mechanism on the camshaft go bad already, and it wont open the exhaust valve to decompress when it should, giving high test readings, or if a valve is way out of adjustment, like the exhaust valve too loose from not being set right, or the rocker arm stud loosening up in the head. I have seen that already and that will give high test readings, but it would still start, or at least try.
I have seen people install the ignition module backwards on engines before, some wont fire, others will be out of time on the spark timing. Also check the armature module air gap to flywheel because that will change the ignition timing a little bit.


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## orangputeh (Nov 24, 2016)

ST1100A said:


> Generally when you are pull starting the engine the automatic decompression release will activate and your compression will be much lower than 100-120 psi. When the engine fires and reaches over 600 rpm's the decompression release will deactivate. I have seen the little decompression mechanism on the camshaft go bad already, and it wont open the exhaust valve to decompress when it should, giving high test readings, or if a valve is way out of adjustment, like the exhaust valve too loose from not being set right, or the rocker arm stud loosening up in the head. I have seen that already and that will give high test readings, but it would still start, or at least try.
> I have seen people install the ignition module backwards on engines before, some wont fire, others will be out of time on the spark timing. Also check the armature module air gap to flywheel because that will change the ignition timing a little bit.


update.

installed flywheel and coil. observed ex. valve with muffler off and felt pressure. strong spark. it STARTED right up. this is confusing me since i put in hours on this before removing the flywheel/coil and did not even get an almost start with all 3 components ( compression/spark/fuel )

the only thing i did different from last time was remove flywheel to check key and coil. had spark before. had fuel before . clean carb before.

so don't understand what the difference was. it started first pull. glad i dont have to take crankcase off to inspect timing marks and decompressor mechanism. 

could this have been a coil problem even though I had spark before? I had compression, spark, and fuel both times so am trying to understand what was different this time in case I run into this problem in the future.


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## nwcove (Mar 2, 2015)

maybe a bad ground ? what are you using for a spark tester ?


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## orangputeh (Nov 24, 2016)

nwcove said:


> maybe a bad ground ? what are you using for a spark tester ?


inline spark tester. had spark before but can not remember how strong it was as I did all this before winter andjust now came back to it. perhaps it was a bad or weak ground.

thanks.


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## nwcove (Mar 2, 2015)

orangputeh said:


> inline spark tester. had spark before but can not remember how strong it was as I did all this before winter andjust now came back to it. perhaps it was a bad or weak ground.
> 
> thanks.


is it an " open air " adjustable tester as opposed to the neon light type ?


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## paulm12 (May 22, 2015)

glad it is running, but I agree would be nice to know what changed. I think a bad connection or ground may be it.


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## contender (Jan 18, 2018)

My guess/experience, it was flooded... why I asked about the plug being wet....


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## orangputeh (Nov 24, 2016)

contender said:


> My guess/experience, it was flooded... why I asked about the plug being wet....


wish it would have been that simple.


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## ST1100A (Feb 7, 2015)

orangputeh said:


> update.
> 
> installed flywheel and coil. observed ex. valve with muffler off and felt pressure. strong spark. it STARTED right up. this is confusing me since i put in hours on this before removing the flywheel/coil and did not even get an almost start with all 3 components ( compression/spark/fuel )
> 
> ...


To see if the decompression release is functioning you would see the exhaust rocker move to open and close the exhaust valve quickly when it is just before TDC on the compression stroke. If the vavle rocker and valve doesn't move, then you know you have a problem there.
If you removed the flywheel, you probably removed the ignition module/coil first. Then when you reinstalled it and set the proper clearance, you could have set the ignition timing properly. If the coil clearance was out of spec before you removed it, that will change the ignition timing a bit, and it could be out enough to cause hard starting. A possibility.
Good luck with it and hope everything will work well for you now.


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## ST1100A (Feb 7, 2015)

orangputeh said:


> i'll check back in 2 days. thanks. ya the compression was around 120 and i thought that was too high as most Honda's test out at around 100-105. my tester is very old so I got a new one.


The compression would be around 85 at pull starting speeds, a lot of times below 600 rpm's, when above 600 rpm's you would get up around 120psi because the automatic decompression release would de-activate.
Another thing that will effect the compression readings would be valve clearance. Those readings are taken at the proper valve clearance. If the valves were set too tight on the intake, it would be a bit lower, a loose intake will raise it a bit. A tight exhaust would lower it a bit from the decompression cam, a loose valve would raise it a bit from the decompression not activating when and as long as it should.
If you pull the engine over slowly, it will turn over easier than it would if you pulled it over very fast because of the way the automatic decompression works, as long as the valve clearance is set to factory specs.


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## ST1100A (Feb 7, 2015)

contender said:


> orang, unless I miss reading, if this is a Honda HS928, my manual shows compression 85.3 to 120.9 at 600rpm. A 2nd manual shows the same.
> 
> Is the plug wet??


The compression would be around 85 at pull starting speeds, a lot of times below 600 rpm's, when above 600 rpm's you would get up around 120psi because the automatic decompression release would de-activate.
Another thing that will effect the compression readings would be valve clearance. Those readings are taken at the proper valve clearance. If the valves were set too tight on the intake, it would be a bit lower, a loose intake will raise it a bit. A tight exhaust would lower it a bit from the decompression cam, a loose valve would raise it a bit from the decompression not activating when and as long as it should.
If you pull the engine over slowly, it will turn over easier than it would if you pulled it over very fast because of the way the automatic decompression works, as long as the valve clearance is set to factory specs.


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## ST1100A (Feb 7, 2015)

A way to check Honda compression on most of their small engines with the automatic decompression release is to loosen the exhaust valve clearance by more that .010 above the recomended clearance, I.E. if they call for .011" on the exhaust, loosen it to .025" just to be safe, then test the compression reading. That way you are bypassing the automatic decompression release. Don't forget to reset the valve clearance back to factory specs after testing.


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## RedOctobyr (Mar 2, 2014)

I'd expect this testing approach would work on most small engines, not just Hondas?


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## ST1100A (Feb 7, 2015)

RedOctobyr said:


> I'd expect this testing approach would work on most small engines, not just Hondas?


Yes, the ones with an automatic decompression release on the exhaust valve lobe of the camshaft.


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## orangputeh (Nov 24, 2016)

ST1100A said:


> To see if the decompression release is functioning you would see the exhaust rocker move to open and close the exhaust valve quickly when it is just before TDC on the compression stroke. If the vavle rocker and valve doesn't move, then you know you have a problem there.
> If you removed the flywheel, you probably removed the ignition module/coil first. Then when you reinstalled it and set the proper clearance, you could have set the ignition timing properly. If the coil clearance was out of spec before you removed it, that will change the ignition timing a bit, and it could be out enough to cause hard starting. A possibility.
> Good luck with it and hope everything will work well for you now.


thanks for the tip about the compression release. did not know that. was thinking the same thing about the coil . hoping that was it. learning something new everyday.


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## groomerz (Feb 7, 2015)

Never seen Honda out of time most never get taken apart. Can’t jump teeth without human intervention Great imaginations


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