# Honda HS621 engine speed



## YSHSfan (Jun 25, 2014)

I have an HS621 Service Manual on order, but looking at the owners manual under specifications it states 5.5hp at 4000rpm. Does it mean that the engine speed is set to 4000rpm? (I've seen most Honda gx engines set at 3600rpm).


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## JnC (Feb 21, 2014)

3700 +/- 150 according to Robert. I used mine the first time ever the other day, I felt like the engine rpm was a very low, checked the throttle lever under the cover and it was at full. The performance was underwhelming as well, I havent had a chance to hook up the tach and check/adjust the max RPMs just yet but I am hoping they need adjustment as I was not impressed with the performance the other day, which is sort of scary as I have completely loaded my fleet up with three HS621s, havent tried the other two just yet.


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## YSHSfan (Jun 25, 2014)

Thanks JnC.
Does any one know what the compression and valves adjustment spec would be on the HS621?
Thanks.


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## JnC (Feb 21, 2014)

0.15mm on the intake and 0.20mm on the exhaust valve.


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## YSHSfan (Jun 25, 2014)

Thanks JnC


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## YSHSfan (Jun 25, 2014)

I see that the engine speed on the HS621 can only be adjusted at the governor. Should it get done at engine operating temperature (10 min or so of run time) and under load or not?


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## YSHSfan (Jun 25, 2014)

Found this on a post from [email protected] (my only question remaining is _Should it be adjusted with a load or not?_ I noticed that there is a decrease in the engine speed of 125-200rpms when the auger is engaged).
_*
The HS621 shop manual says 3,700 ±150 rpm. Here's how to set it:*_


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## JnC (Feb 21, 2014)

Thats standard max rpm i.e. without load, the +/- 150 should compensate for the load, set it to 3800 rpm as thats what I'll be setting mine to as well.


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## YSHSfan (Jun 25, 2014)

Thanks JnC.
I actually adjusted it to its maxed of 3850rpm. I'll see how it performs when testing time comes.


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## JnC (Feb 21, 2014)

hsblowersfan said:


> Thanks JnC.
> I actually adjusted it to its maxed of 3850rpm. I'll see how it performs when testing time comes.


Were you able to adjust the rpm just by adjusting the throttle lever stop or did you have to mess around with the governor as well? 

I think I am going to do the same to my machines as well, just set it to 3850.


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## YSHSfan (Jun 25, 2014)

JnC said:


> Were you able to adjust the rpm just by adjusting the throttle lever stop or did you have to mess around with the governor as well? .


I tried the lever stop screw first, but realized that it was not doing anything as the throttle is wide open. Looked at it carefully + the info that Robert supplied before indicated that on this engine you can only change the max rpm speed by adjusting the governor and so I did.
What I learned from this is that it takes a very little movement of the governor shaft to increase/decrease 100-200rpm (my first attempt moved the speed over 4500rpm :icon-hgtg.


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