Honda HRM215HXA scalps lawn

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  #1  
Old 07-29-08, 01:28 PM
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Honda HRM215HXA scalps lawn

Looking for some assistance with my 11 year old Honda HRM215HXA. Overall, the mower has performed well. Have never taken it for service. I change the oil every year, clean out and check the plug gap or replace it, if needed. Idle speed always adjusted to spec, ~2100 RPM. This provides a Full Throttle speed of ~3400 RPM, same with the blade engaged, but without a load. The engine starts up with one pull and sounds smooth in idle or full throttle. The blade is sharpened regularly. The foam and paper filter are clean. I mow every 4-6 days so as not to let the grass get too tall.

Issue: in the last 2-3 weeks, I have been experiencing a loss in RPM when bagging my Hybrid Bermuda grass, which is causing scalping. At times, I need to travel very, very slowly in order to prevent the engine from dying. I can, most likely, increase the mower height to compensate, but wish to maintain the grass at this height. The wheels are set at the 3rd setting, which is ~2 in. height. However, what is consistent year after year, is that when I scalp the grass at the beginning of the season, even while maintaining a sharp blade, I experience the exact same issue as I drop the mower height one notch at a time.

Questions:
1. What is the engines HP for this model?
2. Is is possible that this engine simply cannot handle the load I am placing on it (e.g. scalping conditions with hard stem grass or trying to maintain a low height where a large portion of the grass is the thicker and harder to cut sheath)? I notice that most of the modern mower motors today are utilizing 6.5 or 6.75 HP engines.
3. How can I determine if the governor is properly increasing the RPM under load? As stated above, there is no surging at idle or during operation, simply a drop in RPM when a load is placed on it.
4. There are 3 hole in the governor arm that the spring can attach to. The spring is in the middle hole. Why 3 holes and what effect can I expect by moving the spring from one hole to another?
5. Can the carburetor and/or fuel path have enough build-up to allow for this issue yet run excellent in idle, full throttle, or light load?

Thanks in advance,
Kazzy
 
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  #2  
Old 07-29-08, 10:06 PM
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According to the service manual, it's a 5 HP engine. I suspect the engine is getting tired after eleven years, even though it's been properly maintained.

I doubt that build up of deposits is the cause of your problem, but you might take a look at the muffler to see if there's anything clogging it. That would reduce performance under heavy loads, but the engine would run normally otherwise.

You might try taking narrower cuts to reduce the load on the engine.

The placement of the spring in the three holes determines how much the throttle is advanced when the governor senses a drop in engine speed. I'd experiment with it to see what difference it makes. About the worst thing that could happen is the engine will surge or "hunt" for the correct speed for the throttle setting or not be able to maintain the selected speed as well under load.

About the only way to check the engine speed is with a tachometer. You can get one to work with a magneto, but you have to hook it up to the grounding lead that goes to the terminal near the governor that kills the engine when you move the throttle to STOP. The RPM shown will be twice the actual speed, since the plug fires on every revolution of the mower engine.

I don't know of any place on the mower you could safely use an optical tachometer like they use for model plane engines with exposed propellers.
 
  #3  
Old 07-30-08, 07:06 AM
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There is an inductive pickup tachometer available for use with lawn equipment. They run around $40.00 and are widely available on the web and many small engine / lawn mower shops

http://www.tinytach.com/tinytach/index.php
 
  #4  
Old 07-30-08, 08:17 AM
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Thanks for your replies. I do have an nice inductive tach that I simply hold it up next to the spark plug. It is made for lawn equipment. As stated in my original posting, I run at 2100 RPM at idle and 3300-3400 RPM at full throttle with or without the blade engaged and all without load. There is a severe drop in RPM under load. This is based solely on audible diagnostics and the scalping results. Areas of the lawn that have more green leaf do not scalp - just the areas with more sheath than leaf. I know, maybe it's time to raise the mower height.....

Here's where I am at currently as I went to the local Honda dealership to obtain some parts and discuss my situation. I would appreciate your evaluation of what was discussed with me as follows:

Feedback from dealer rep:
1. Since I have a lush dense hybrid bermuda lawn (Tiff 419) and am attempting to keep it at 2" with a rotary mower, this will put too much load on ANY mower. Options include switching to a reel mower or increasing the mower height (just as the lawn services do in the area) so that I am only cutting the upper portion of the soft grass blade.
2. The rep claims that the new mowers rated for 6+ HP is marketing only and that I would see the same load issue even on these models when trying to cut a dense hybrid lawn.
3. They do not see build-up in the Honda mufflers and would not suspect this as an issue.
4. Weak governor spring should produce surging even in idle mode. Moving the spring to a hole that adds tightness to the spring will increase RPM; moving it to a hole that loosens it will decrease RPM. Wrong adjustment could lead to surging.
5. They recommend cleaning the carb jets as a proactive measure in order to ensure max fuel flow.

Here is what I purchased (had no issue since I have spent little on this mower in the past):
1. New muffler and gaskets
2. New air filter
3. New NGK spark plug
4. New carb gaskets
5. New governor spring

Thanks again and I welcome your inputs.
 
  #5  
Old 07-30-08, 05:21 PM
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Update:

All parts listed below were replaced:
1. New muffler and gaskets
Note: old muffler had black buildup inside , but nothing
that would exhibit blockage.
2. New air filter
Note: old filter was still relatively clean
3. New NGK spark plug
Note: old plug was 1-2 years old, but recently cleaned
4. New carb gaskets
Note: have removed the carb before for cleaning, but have
never replaced the gaskets.
5. New governor spring
Note: old spring was just slightly more relaxed than the new
one.

I also cleaned out the carburetor and jets, but did not see any form of residue at all before cleaning. Before firing her back up, I checked the compression through the spark plug hole. I have never performed this before. Per the manual I pulled from the web for a GXV140 engine (per my Owner's manual, my engine model is actually a GXV140K1 - not sure what the differences are). The GXV140 manual states that the compression should be in the range of 589-834 kPa and I measured 510-525, repeating the test multiple times with the same results. Is this anything to be concerned about? What are the symptoms of low compression?


Started the mower up after 2-3 pulls and adjusted the idle speed to 2100 RPM and the full throttle to ~3100 RPM. I noted while checking the RPM with my inductive tach that the RPM would fluctuate every few seconds in a non-repeatable fashion by about 100 RPM. It was a drop then back to setpoint.

I have yet to put a load on the mower and will do so within the next couple of days. I am capable of performing general maintenance, but anything beyond that (servicing valves, pistons, crankshaft, etc. is something that I have not tackled before.

Thanks to those taking the time to read my detailed efforts and very much appreciate your responses.
 
  #6  
Old 07-31-08, 12:16 AM
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I'd say your engine is pretty tired. The symptoms of low compression are low power and being easy to start (as long as there's enough compression for it to run). That's right on the mark.

The new governor spring may help a little with the engine under load, but I'm not expecting much from an engine that's 10% under the minimum compression spec.

Reworking the engine isn't all that hard or expensive, and some people actually enjoy doing that sort of stuff. But you'll still have an eleven-year-old mower when you're done, along with dirt under your nails, oil-stained hands, and hopefully a satisfied smile on your face.

You'll get back some of your lost power by grinding the valves and replacing the piston rings, but going beyond that to get like-new performance probably isn't cost-effective.
 
  #7  
Old 07-31-08, 03:57 AM
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how often to you mow ? bermuda should be mowed no more than 1/3 the current hight. you can "train" it lower over time.
when you say "scalp" are you talking about the brown spots or are you actually hitting the soil ? as you lower the hight over time the brown will go away.
 
  #8  
Old 07-31-08, 07:59 AM
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IMHO;
You don't have enough mower for the job "now". Over the years your lawn has grown stronger(more dense) and your mower has grown weaker. You need to upgrade your mower to a small commercial type walk behind or downgrade your preferred quality of cut. Have a good one. Geo
 
  #9  
Old 08-01-08, 04:11 PM
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All, thanks for chiming in!

Rogerfiles, thanks for your feedback and I agree that age has set in. Have not yet tried the mower with a load on it, but will do so tomorrow. Plan to go ahead and raise the mower height as the heat in the Dallas area has been 100+ for a while and will help with water conservation as well.

Flopshot, I mow every 5-7 days and rarely cut more than 1/3 off. I water deep every 3 days (about 0.5" per watering cycle). This minimizes the top growth while keeping the lawn healthy. By scalp, I mean the brown rotation spots that occur from cutting at a lower RPM. I am very interested in your comments about "training" the lawn. From what I have read, you don't want to cut into the sheath. But, if I were to lower my setting, I will be cutting into the sheath. Kindly explain.

Geogrubb, I am in full agreement with you and was simply looking to the "PROS" for some guidance and explanation of my observations. I like the cut of a reel mower, but do not want to spend the money for a nice one. I like the convenience of a rotary mower and have really enjoyed the features of my Honda, primarily the ability to adjust the transmission's speed control and the ability to release the clutch and eave the engine running, empty the bag, and quickly get back to mowing. What recommendations do you have for an economic commercial mower that has similar features?

Thanks again to everyone's inputs.
 
  #10  
Old 08-02-08, 04:59 AM
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Originally Posted by Kazzy View Post

Flopshot, I mow every 5-7 days and rarely cut more than 1/3 off. I water deep every 3 days (about 0.5" per watering cycle). This minimizes the top growth while keeping the lawn healthy. By scalp, I mean the brown rotation spots that occur from cutting at a lower RPM. I am very interested in your comments about "training" the lawn. From what I have read, you don't want to cut into the sheath. But, if I were to lower my setting, I will be cutting into the sheath. Kindly explain.


Thanks again to everyone's inputs.

i thought you may have been reffering to the sheath when you said scalping. by 'training' i mean bringing the lawn to a height where that amount removed will not reach the sheath and you are at the desired height. this is done by cutting gradually lower each time to reach your height untill the sheath has lowered. to a degree the sheath is a proportion of the total height. consider the fact that on a golf course bermuda varieties are maintained at much lower levels and still remain green. your optimal height would be determined by the variety, season, and growing conditions. turfgrasses have perameters but your location and conditions may require adjustments to your proceedures. you might also talk to a pro about growth inhibtors. i think you'll find that your mowing shcedule will be more like every four to five days.
 
  #11  
Old 08-02-08, 11:39 AM
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Flopshot, thanks for your post. I did not realize that once the sheath increases in height that it could be lowered without cutting a portion of it. Can you elaborate on this a bit more please? Since my Honda adjusts in 1/2" increments, it may not be conducive for performing the "training" you describe. And, since I have a large yard (not large enough for a riding mower), I am reluctant to mow more frequently, which may alone, as you stated, be keeping me for maintaining the sheath and leaf at a desired height. Thus the need to raise the mower height.

As I have reviewed the many comments provided to me by you and others, I have concluded that I either need to convert to a reel mower for ultimate satisfaction and finer height control or live with raising the mowing height during the season with a rotary mower. My loss of compression has, most likely, reduced my overall sustaining power especially as the grass density thickens during the season and I will probably be looking for a new mower next season and need to research my options. Honda or Briggs-based engine, Hmmm...........

Many thanks to all.
 
  #12  
Old 08-03-08, 06:09 AM
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your main problem stems from too much time between cutting.
your mower can't handle the mass, and when you do get the height you want you have removed too much blade. think of it this way... even if you had a v8 powered mower zipping through the lawn at 60 mph you will still have the problem of the browning caused by the percentage of blade removed.
the traing process is mearly a path to lower mowing height and will not be solved by a reel mower. also, reel mowers hate tall grass. they're great at not leaving a torn tip on a blade of grass and don't mind mowing wet grass. many think the reel is the way to go because they see them on the golf course but you aren't a golf course. try the four day cycle for one month dropping your mower one setting each time untill you're at the height you want. set your front wheels one setting lower than the back and make sure your blade is sharp.
watch your fertilizer applications and check into the growth retarder.
i'm not a turf pro but living in a county with over forty gof courses and selling power equipment to landscapers i've picked up a few tips on turf along the way. its why i have centepede grass and pinestraw.
 
  #13  
Old 08-03-08, 07:12 AM
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Flopshot, thanks for the informative assessment and recommendations. For additional clarification on the "training method", is this something you would advocate:

1. Start with dropping front wheels one setting
2. Then follow 4 days later with rear wheels
3. Drop front wheels again 4 days later
4. Then follow 4 days later with rear wheels
5. Repeat until I achieve desired height

Now some questions:
1. If I drop my mower height, I will be cutting into the sheath and stress out or brown the entire lawn. Once I cut into the sheath, 4 days later, can I really expect it to recover and grow the green leaf? My concern is that with my current mower situation where the RPM drops due to the load and stress or browning occurs, I still have brown areas, 6-7 days later before attempting to mow again. It does not always recover.

2. Since we are experiencing greater than 100 F weather in the Dallas area, is this something I should really attempt at this time?

3. I fear that with my current mower situation, lower than minimum compression, that my RPM's simply won't keep up and it will take me hours at a very slow speed to mow into the sheath.

4. Will my watering cycle need to change to compensate for the lower cut and sheath exposure? Currently at watering every 3 days, 1/2" per watering - approximately 1" per week as recommended by local experts. Started this last year and seems to do well.

5. I am fertilizing once every 1 to 1.5 months during the growing season. Is this OK? I will have to research the retardant product you commented on, as I am not familiar with it.

6. Once I achieve desired height, can I mulch instead of bad every 4 days to reduce my overall mowing time or will I experience a thatch buildup over time (recall I have Tiff 419 - fairway grass).

Thanks again for the valuable information and I've certainly learned a lot. I did not realize that a reel mower does not handle tall grass very well. As you stated, I am accustomed to seeing them used on those short manicured golf courses and assume that they are mowed daily.
 
  #14  
Old 08-03-08, 09:23 AM
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Had a great mowing experience this morning

Mowed for the first time this morning since the wholesale changes/repairs I made. It's been 1 week since the last mowing. Last night, I also took the liberty to put a nice edge on the blade. Continued to use the gas in my plastic container that been in there for the last 2 months( I always use additive to eliminate water buildup). Decided to raise the rear wheels one notch (2 1/2 inches) while maintaining the front wheels the same (2 inches).

Wow, I have not experiences such smooth performance in at least the last 2 years. Observations:

1. The engine speed did not drop (from audible assessment) during the whole mowing (about 5200 ft2 of lawn) even with a lower full throttle RPM (was 3300-3400, now 3100-3200). Even though there were some challenging areas of thicker grass, you would not know there was a load on the engine.

2. The engine some smooth. For lack of a better explanation, it sound like a smooth mini bike. Could this be the muffle change out couple with a lower RPM?

3. I believe that this is the sharpest that I've had my blade in a while since it sounded like a scissor was cutting the grass with a whipping sound.

4. Since I raised the back wheels and coupled with the high temperatures this past week, the amount of grass I bagged was significantly less than last week. My lawn bags are 16" x 12" x 35" (tall) and I filled only 1 this week vs. 3 1/2 last week.

5. Engine started on 1st pull, but usually has in the past during the season.

Thanks to everyone for their inputs and we'll see how long this 11 year old mower carries me.
 
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