Honda modification

sailorhuete

New Member
Oct 31, 2011
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Jacksonville
My GX35 would not turn over today after after 88.3 hours. I took off the valve cover to inspect the belt. The centrifugal decompression cam lobe, not the whole lever it's self, broke off and out of the plastic cam belt gear. When it did it took some of the cam gear with it but it still had all of its outer teeth some how. I poured out the oil and saw some large pieces of black plastic from one of the gears that were large enough to not come out through the fill and drain hole. I took it to the certified Honda shop 2 blocks away from my house and they said that they will see about rebuilding it with the decompression system removed from the upper cam gear. The mechanic said that it looked like the decompression system on the gear was pressed in so it may come out easy enough for them to do the modification. There was also no charge for any on the repairs as needed since it is under warranty from Honda.
 

silvaire

New Member
Jan 25, 2009
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North of the Golden Gate
If this were my issue...

I wouldn't accept a warranty repair that left my GX35 without its factory engineered decompression feature.
Are there other know examples of this particular failure mode out there?

Without the decompression system in place the engine will be much more difficult to pull start and will kick back. If you had a means of "bump starting" the engine before, you will probably no longer be able to do so.

Only if this issue was a know deficiency of the GX35 would I then consider removing it. Honda didn't go to the expense of engineering and producing the decompression system for this engine "just for the heck of it".

I think it was Charles Kettering who said something like: "Unnecessary parts cost nothing to produce and cause no service problems". Just something to think about.
 
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sailorhuete

New Member
Oct 31, 2011
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Jacksonville
I have had in the garage at my house a cb 250, crf 70, xr 80 xr 100, cr 80, cr 125, and 3 cr 250 hondas. None of them had any unnecessary parts and they never broke. They were ridden and always started with ease. None of the xr's had decompression levers.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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Ridin' inSane Diego, CA.
My take on this situation would be to let Honda fix it without the compression release. It is only 35cc and should start easier without it anyway.....GXH 50cc engines don't use them a they fire right up.

I've thought about removing them on my GX160, Predator 212cc and such for fear of them failing as yours had, but it does help on the larger engines with pull-starting them.

Only the larger Honda XR's have ever come with compression releases (250cc - 650cc) and yes it does make them much easier to start as the fairly high-compression and a large piston is more difficult to kick start without one.

dnut
 

silvaire

New Member
Jan 25, 2009
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North of the Golden Gate
I have had in the garage at my house a cb 250, crf 70, xr 80 xr 100, cr 80, cr 125, and 3 cr 250 hondas. None of them had any unnecessary parts and they never broke. They were ridden and always started with ease. None of the xr's had decompression levers.
I too have owned a slew of small Honda bikes over the years, and yes, none of them had compression releases - manual or automatic. You will probably be just fine without the compression release on your GX35. It WILL be harder starting, but maybe not enough so to make a significant difference.

If, for instance, you are using this GX35 on a friction drive setup with no clutch and use bump starting, it may then be considerably more difficult to do so. The same would go for a recumbent (or anything else) using a rope and pulley starter system.

As this engine came with a decompression system - and assuming the failure of yours was a fluke - if it were being fixed under warranty I would want the benefits of having it as original if possible (resale and such). You can always take it off later.


Edit:
What sort of drive system are you using your GX35 with?
Also, please let us know how your engine works out without the compression release.
 
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scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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I too have owned a slew of small Honda bikes over the years, and yes, none of them had compression releases - manual or automatic. You will probably be just fine without the compression release on your GX35. It WILL be harder starting, but maybe not enough so to make a significant difference.

If, for instance, you are using this GX35 on a friction drive setup with no clutch and use bump starting, it may then be considerably more difficult to do so. The same would go for a recumbent (or anything else) using a rope and pulley starter system.

As this engine came with a decompression system - and assuming the failure of yours was a fluke - if it were being fixed under warranty I would want the benefits of having it as original if possible (resale and such). You can always take it off later.


Edit:
What sort of drive system are you using your GX35 with?
Also, please let us know how your engine works out without the compression release.
Moot point.......Compression release, de-compression system has been an option (manual or automatic) since the 1960's anyways.......you can certainly live without it .......can't you???

dnut
 

silvaire

New Member
Jan 25, 2009
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North of the Golden Gate
.....GXH 50cc engines don't use them a they fire right up.
Actually, the Honda GXH50 engine does use an automatic compression release - as does every other single cylinder Honda general purpose engine that I know of. So do the Subaru 25 cc and 35 cc 4-stroke engines.

Sailorhuete's engine will be probably be just fine without an auto compression release on it. My point is that if it were my engine being fixed under warranty though, I'd just want it to be the same as it was originally built by Honda.
 
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Dagwood

New Member
Aug 4, 2011
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ilinois
I feel the need to chime in here..only to bring up a point..the need for a compression release on a product is generally determined by 2 things..first of course is the market the product is sold to, and the percieved need for a "easy pull"..well the GX35 is a string trimmer emgine, and an easy pull is very highly desired...2nd in the engineering phase..the size of the recoil pulley is considered, and on this product it is pretty small..so there is little mechanical advantage..IF I were to run this engine without the CR, I would onitor/examine the recoil pulley carefully, as it may or may not be durable enough to stand the extra force. And on another subject..Silvaire...your Handle is one close to my heart..for I restored and own a 1947 model 8A...truely a craft ahead of its time!
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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Actually, the Honda GXH50 engine does use an automatic compression release - as does every other single cylinder Honda general purpose engine that I know of. So do the Subaru 25 cc and 35 cc 4-stroke engines.

Sailorhuete's engine will be probably be just fine without an auto compression release on it. My point is that if it were my engine being fixed under warranty though, I'd just want it to be the same as it was originally built by Honda.
I've yet to see a compession release on a Honda GXH50 or the HS clone



dnut
 

Dagwood

New Member
Aug 4, 2011
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ilinois
And its a valid point....any modifications to the engine and Honda reserves the right to in-validate warranty..of course..since absoultely NO Honda General purpose engines are approved to sell on bikes..go-karts..minibikes , or anything similiar..you cannot reveal that if any warranty repairs are attempted.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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And its a valid point....any modifications to the engine and Honda reserves the right to in-validate warranty..of course..since absoultely NO Honda General purpose engines are approved to sell on bikes..go-karts..minibikes , or anything similiar..you cannot reveal that if any warranty repairs are attempted.
Did you by chance happen to read the first post in this thread? He is getting the work done by an authorized Honda shop and it's being repaired for free under the Honda warranty.

dnut
 

Dagwood

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Aug 4, 2011
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ilinois
Yes I did.., And I really dont want to take any issues with that statement...its my opinion..and thats all...that since there are a couple of things that are kind of..out of sync here, that the dealer is doing this work and one or more of a couple of things are happening...and I dont want to know...
1: the dealer is standing the repair himself for whatever reason..good customer..nice guy..whatever, because WE at American Honda Motors would never approve a warranty payment to a dealer who repairs an engine, and does not put back in the exact way we built it.period. PArticularly this CR issue.
2; The dealer is fooling around with the paperwork for his re-imbursement, to get it to go thru, so we are paying for it, or paying for some of it. And dont know the correct story or application the engine is on.
 
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silvaire

New Member
Jan 25, 2009
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North of the Golden Gate
I've yet to see a compession release on a Honda GXH50 or the HS clone
Here is a link to the Honda website page regarding the GXH50 engine.

http://engines.honda.com/models/model-detail/gxh50

It shows the the compression release system of the GXH50 in considerable detail.

I believe you are correct regarding the Chinese copies of the GXH50 not having an auto compression release though.
 
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Erich_870

New Member
Dec 4, 2009
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Alaska
Here is a link to the Honda website page regarding the GXH50 engine.

http://engines.honda.com/models/model-detail/gxh50

It shows the the compression release system of the GXH50 in considerable detail.

I believe you are correct regarding the Chinese copies of the GXH50 not having an auto compression release though.
Sorry, but that is not a GXH50 Cam.



Scotto posted the right cam information, showing that there is no decompression on a GXH50.

Erich
 

silvaire

New Member
Jan 25, 2009
36
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North of the Golden Gate
Erich,

The picture you posted from the Honda website may be a generic example of an automatic compression release - not one specific to the GXH50 engine.

I do not have personal knowledge of the GXH50. The page from the Honda website quite specifically states that the GXH50 is equipped with an automatic compression release - and this is a feature I have found in every other modern Honda general purpose engine I have encountered.

Bottom line on an auto compression release is that it requires less of a pull to start and that it lessens the loads on the starter system components. More than once I have had a starter handle snapped from my hand (once it shattered the handle when it whipped around and hit the engine) or had the starter rope break from a kick back. In addition to the benefit of easier starting, including an ACR allows the starter components to be made considerably lighter (and with a longer expected life), more than offsetting the cost and complexity of the ACR.
 
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Dagwood

New Member
Aug 4, 2011
70
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0
ilinois
Gents, ON the Honda website that photo is in fact a generic representation. The GX50 is the only model of Honda's "diagonally split blocks" engine family WITHOUT an overhead camshaft. The GX100, GC120, GC160, and GC190 are the engines built in this manner with a belt driven OHC, the GXH50 has an internal cam, with pushrods. THE GXH50 is the last of this design with the others long ago discontinued. IN the 19 years I have worked for this company, I can not remember Honda offering an engine into the US powered equipment market without an ACR, but I admittedly dont remember everything! (thx scotto!).
 
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scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,508
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38
Ridin' inSane Diego, CA.
Gents, ON the Honda website that photo is in fact a generic representation. The GX50 is of the family of Honda's "diagonally split blocks" with an overhead camshaft. The GX50, GX100, GC120, GC160, and GC190 are the engines built in this manner. Amoung a couple of others long ago discontinued. IN the 19 years I have worked for this company, we have never offered an engine into the US powered equipment market without an ACR.
The GXH50 does not have an overhead cam but does have overhead valves and I've still yet to see an ACR on this model.

dnut
 

Dagwood

New Member
Aug 4, 2011
70
0
0
ilinois
Re: Honda modification..pass the salt and pepper

ahemm..boy this crow tastes bad without salt and pepper!

So just to clear up this cam issue..I thought I better look it up to prove my statement..now I see I must edit my statement! thx for the correction scotto!
Here are both IPL's from the GX50 and the GX100 engines, straight for the official parts book. One can clearly see the GX50 engines internal cam and pushrods, and the GX100's more modern belt driven OHC ..at least I hope they are big enough to see!, I had to scan them in and reduce the image to post here. Now about the ACR..
Scotto..this image shows a small "cam lobe on the cam lobe" on the GX50cam. This appears to be the rocker for the ACR, and All my sales information says the GX50 has the ACR feature. BUT...I have seen mistakes before, and due to the fact there are no GX50s in our warehouse at the moment due to the production disaster we faced this past summer..I cant go and get one. I even went thru the warranty junk to see if there was an old one in the pile, but nothing. This is not suprising, due to the fact that this is the lowest sales volume engine in Honda offers. Anyway..according to the info, it is supposed to have an ACR...But now you have me doubting myself! Its not like changes in production dont get by me sometimes, or mistakes are never made in our info..So to keep from having to make gravy from my fried crow..I will defer a definitive statement till I get my hands on one! Thanks for the help..and I edited the post so the archives wont have mis-information for future readers.
 

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