Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

    The results of Borats Craftman seem pretty good even in comparison to the newer Toro's with 141cc engines and curved paddles runing stock rpm.  I gave up on MTD straight paddles a few years ago so stopped buying them. BUT given the good showing of Borats machine decided to give an HSK850 a fling for which a cheap MTD or Murray is a good candidate.

   This morning I picked up an MTD 5.5 in excellent shape, (mostly) for $100.   The body is excellent, no rust no scratches but the inside of the bucked has the paint scrapped.  The guys 3 car lot was sand and gravel with mounds and holes.  It's electric start, 4-5 years old but only used for two seasons due the owners heart condition. 

    It came with a line cord and for some reason three brand new belts, a bottle of Sta-Bil and a gallon and a half can of gas half full.  His son gave it to him with a bottle of Sta-Bil which he thought was the mix required.   He only ran it with Sta-Bil, no oil and from what he tells me only ran about slightly less than a gallon of gas through it since he got it.  He claimed that one can of gas half full he gave me was the only fuel he ever bought for it.  

   It fired up on the first pull and seemed to run strong so I ignored the no oil part and bought it.  It gets 95psi compression on three rope pulls and 115 on electric start so seems ok. 

Borat,

    I'd like to compare the flat paddle section of this one to yours.  If you can please measure your mid-paddle section flats.  What's the L and W of one section and what's the distance front to back?  The MTD is (2) 1 3/4 x 4 1/4 sections and the front to back span is 8 1/4.  If they match then the MTD should compare your Murray with booted RPM.  I've got an excellent condition Toro 3650 I'm using this year so have a good machine to compare with.

Borat,

   Thank you for the measurements.  I thought your machine might have a bigger paddle output section or more velocity with a bigger diameter.  There’s no excuse for this thing to not output and be useful other than weight.  Never thought of that. 

   We’ll see if it can be muscled down.  That might not be a problem for younger professional clearers.  The first purpose of doing this was to muck around but it occurred to me that a beefed up machine could be of use to pro snow clearers.  Every year a couple come by to pickup machines.  They can race through light snow jobs with an SS’s saving scads of time over a two stages.   Having a beefed up clunker would be better deal than burning up an expensive Toro.

    Got string through a screw hole in the side of the cover right at the position of the top of the governor arm.  It works out the string is easy to work the governor and not a lot of friction on the string coming out of the case. 

    Your MTD probably has the open bottom like this one so a filter and shutoff were installed.  On draining the gas it was dark, slightly bluish unlike the gas in his refill tank which was slightly yellow amber.  He might have started out with a tank full of oiled gas and been diluting it over time.  Or possibly his son put in some oil and he forgot about it. It seems to run fine and doesn’t smoke so probably fine.  It snaps up very quickly to high revs. 

    Obviously there was a belt or tossing issue at some point and the reason for all the extra belts.  Belts of the wrong type for the electric start version.  The belt that’s on there now is a ½ x 35 ribbed so I suspect it had slipping problems and someone decided to use a ribbed belt.  The factory ½ x 35 is not ribbed.  

    Lots of people sold off their SS’s after last year’s big snows.  They probably expected too much.  Possibly the MTD's owner  owner had problems, suspected the belt and was given the wrong belt a few times. Very easy to do with this model.

   So it’s a done deal and now snow is needed to test.  No snow here through Feb 6 at the earliest. 

   Do you think it would be useful to stick in a cooler plug given the almost 30% increase in firing time?

   

Can't recall right now what's in mine but what heat range plug do you have in yours?   Personally, I don't think heat will be that much of an issue due to on/off the throttle operation.  If it were pegged full throttle for several minutes at a time, I might be pulling the plug to see how it looks. 

Otherwise, if the carb is running correctly and no indications of a lean condition, I wouldn't be too concerned about the plug.  Pretty sure my HSK850 machines are running on original plugs and no signs of any problems.  I'm thinking of cutting a hole in the plastic cowling to access the spark plug on my machines.  Lot of screws to pull to take the cover/chute off otherwise.  

What oil to fuel ratio you running Trouts?   I'm running mine around 32:1.  It's more oil than the recommended ratio but I like the idea of more oil if the engines are running at higher rpms and working harder. 

>>>Can't recall right now what's in mine but what heat range plug do you have in yours?  

RCJ8Y.  The concern was not for plug life.  It was for head, bore top and rings.  The extra temp from rpm boot would provide more residual heat that a cooler plug might help to dump.  ??  Not sure if would have any meaningful effect.

>>>I'm thinking of cutting a hole in the plastic cowling to access the spark plug on my machines.  Lot of screws to pull to take the cover/chute off otherwise.  

   Absolutely, it’s a bother to go in there.  Today I got the belt cover off and screws for the top undone but could not slip the cover over the chute because of the chute control handle.  The chute assembly is bolted on with 4 bolts accesed from below.  Two are hard to get at and one doubles as a motor mount.  I gave up and worked with the few inches gained by a loose cover.

    The sparkplug can be accesed by the hole in the cover right above the plug.  It’s covered with a removable plug so easy access. >>> MTD<<<, another first in innovation over Toro, Ariens the one the angles use – Honda.  You know who uses Yamaha.

>>>What oil to fuel ratio you running Trouts?  

   For all snow machines 50:1 even if less is spec’d.  For the booted machine I’ll probably run a tighter ratio.

   I guess I’ll have to go through the frame also and see what might happen with that.  The first take is the motor seems to be more solidly planted in there than the Powerlite type mounts with the hokey angled piece screwed into the recoil.  This is an experimental so if it rips itself apart it’s ok.  BTW: last week I gave away 3 very good condition HSSK50’s just to get rid of clutter, two with starters.  It never fails, I’m regretting it now.

(Is there a way to adjust text size in a post?)

Sounds nice, trouts2! Yeah, the extensive covers on SS's strike me as kind of a pain. It looks tidy (no "ugly" engine staring you in the face ), but it sure is more trouble to access anything. That's pretty cool that the MTD gives you a way to access the plug. I have no such access port, just a mystery hole in the back, facing the operator. The best use I can figure out for it is that maybe you could use it to spray starting fluid towards the carb's intake (even that isn't a straight shot). I don't have a tach/hour meter that I want to dedicate to this machine (I just have 1, and it gets moved around as needed). And because the plug wire is inaccessible, I can't just pop it on to quickly check the RPM's, if I start fooling with the governor. That's really lucky if your machine survived a brush with being straight gassed!

By the way: boratify- (v) to enhance the performance and value of an engine for very little money, by increasing RPM's, esp. by means of a string on the governor. Usage- "My snowthrower was OK, but kind of underpowered. But then I boratified it, and now it's awesome!"

We may need to submit it to Urban Dictionary.

I've been looking at the spark plug heat ranges for HSK850 engine.  The Champion RCJ8Y is the equivalent to the NGK BPMR4A.  Number 4 on the NGK scale sounds kind of hot to me.  Most machines I operate run in th 6 to 8 range.  They're generally air cooled two stroke motorcycle engines with no fan cooling.  I'd say that if the engine is going to be run hard and long, I'd probably lean toward a NGK plug in the 6 range.   If it weren't for all the effort it takes to get at the spark plug, I'd pull the one on  the Craftsman to see how it looks.  

It's safer to run a cooler plug than a hotter plug.  One thing we have to remember is that with the added RPMs, there's also added fan speed which produces more air across the cylinder head and around the cylinder.  With relatively cold air keeping things cooler, the engine might be fine with the stock plug.   Maybe tomorrow I'll cut a flap/hole over the engine head to access the spark plug.  Might as well cut a hole big enough to get my whole hand down in there.  I can see dropping the plug sooner or later and having to fish it out of the belly pan.   Going to be a pain in the butt to get the location right unless I pull the lid off of it and I really don't want to do that.  Especially in the cold.  

Damn you and your foresight Trouts!!  I never thought of the spark plug heat range issue on the hopped up machine.  Now I have to know!

Edited this morning....

I found this chart published by Champion that cross references heat ranges between different brands of spark plugs.  According to the chart, the "8" series Champions are equivalent to the "7" series NGKs.  if that's the case, the RCJ8Y should be alright.  It's not all that hot of a plug.  The BPMR4A is a fairly hot plug as rated by NGK.  Which leads me to another quandary,  if there is that much of a difference in heat range between the two brands, how does an NGK BPMR4A qualify as a replacement plug for the RCJ8Y?   Something doesn't sound right.   Comment?

I edited the above post to include more information concerning spark plug heat ranges in the HSK850 engine.

Looking for additional input and comments concerning the differences between the Champion and NGK brand heat range comparisons.

Did a bit more research.  It seems that the RCJ8Y is a common plug used in grass trimmers, chainsaws and other small, high revving two cycle engines that will be run in hot ambient temperatures.   With this recent acknowledgement, I'm not as concerned about the stock spark plug being used in a higher revving HSK850.  After all, the Tecumseh will not likely be spinning past 6500 rpm and usually working in cool conditions.  Many of the chainsaws using the same plug do twice that and much hotter conditions.   

I was looking around a month or so ago, trying to figure out NGK equivalents for the Champion plugs in my "new" machines. I'd been seeing comments that people prefer NGK to Champion, so figured I'd give NGK a shot. I was looking around to replace an RCY8Y, I think it was, and I was finding suggestions for either the BMPR4A or the BMPR6A. But I couldn't find a consistent answer (and I did not have your multi-brand cross reference, borat), so I was worried I might end up making things worse if I picked the wrong heat range. Finally just gave up and bought the suggested Champion plugs. I've never really had a problem with them, so I figured why potentially foul the plug or whatever because I picked the wrong substitute?

Your chart would fairly clearly make it sound like the 6A plug would have been a better match. But I wasn't sure. They don't go out of their way to make it easy to figure out a replacement.

Edit: These are two cross-reference documents I found while reading up on this previously. Maybe they'll help someone. As a point of reference, for NGK replacements for an RCJ8Y, the first link shows BPMR6A. The second link shows BPMR6A, BPMR4A, and BP6ES.

http://www.sparkplugs.co.uk/pages/technical/Champion-to-NGK-cross-ref.htm

http://www.jsesc.com/mfg_docs/ste/Spark_Plug_Interchange.pdf

For some reason, the information that I've been gathering leave me a bit unsettled regarding the comparative heat ranges.  The information on chart, although published by Champion is quite a bit different than proposed cross-equivalent plugs between NGK and Champion.  Three heat ranges difference "7" on the chart and "4" on the recommended NGK plug doesn't appeal very well to my logic.  Regardless, as per my edited message above, I've come to the conclusion the the RCJ8Y is likely cool/hot enough to work well in the HSK850. 

I've got several hours of hard work on my Craftsman with no signs of problems.  It just keeps on keeping on.  The only time it slows down or stops is when it runs out of fuel.


edit...

An NGK 6 makes much more sense.  Why some vendors recommend the NGK 4 is beyond me unless the actual heat  variance between a 4 and a 6 is not that great operationally. 

Regardless, I'm satisfied enough not to bother pulling the Craftsman apart.   When the temperatures warm up, I still think I'll make an access door in the cover to make spark plug maintenance easier. 

RedOctobyr: a mystery hole in the back, facing the operator

   Often there’s an empty opening for models sold without optional electric start.

 

RedOctobyr: I can't just pop it on to quickly check the RPM'

   Last year 4 machines were setup with wires on the plugs running to the handlebars.  That end had a quick connect and the mate on a short wire on the RPM meter.  It worked out OK for static readings but underway snowblowing the machines are changing speeds rapidly.  The small variations in load cause the RP M meter to re-compute which takes a few seconds and it presents fuzzy readings until the machine gets more stable.  I was looking monitor engine sagging and that usually happened too fast and unsteady for the meter’s response time.  That was on two stages which are much more stable than single stage machines.  On the riding mower things are more stable and the meters readout well but for those a few readings with a vibratech and you know what’s going on so a fixed meter there is not so worth the effort.

 

boratify- (v) to enhance the performance and value of an engine for very little money, by increasing RPM's, esp. by means of a string on the governor. Usage- "My snowthrower was OK, but kind of underpowered. But then I boratified it, and now it's awesome!"

 

Great definition.  Can that expand?  To borat…..When borating…..When finally borated…..

 

Borat and RedOctobyr:

  

    I had poked around last week because the dealer sold me a Honda BR4HS and my machines call for 6 and 8’s.  ??  Not sure why but I’m going to get the spec’d plugs.

 

   For all the reading I did what I’ve come up with on plugs is use what’s spec’d unless there’s a consistent plug condition that indicates going up or down would help.

 

   My asking about plug temp was for overall chamber temp.  It looks like the dissipation on a plug is so local that it won’t have any effect on the chamber.  So that’s out.

 

    For raised temps getting lowered by running a cooler plug.  ??  All I got from looking into that was confused.  Getting to know for sure requires equipment and test procedures I can’t do.  The only view into this is probably noting when the engine explodes, melts or throws a rod.  Better than that would be as you suggest, monitor the plug occasionally.  That’s easy, telling enough and probably all that’s required.

 

   An interesting point Borat made was that some OPE that scream and use 6 and 8’s at least by Champion charts.  Using an 8 in a pushed HSK850 will probably be fine.

 

   In some of the heat range stuff they talk about fitting a plug into a 500 to 800 degree range.  The heat ranges are big and broad so picking a plug you don’t really know about other than by 4, 6 or 8 indicating a temp range you don’t know for internal temps you don’t know is too much to deal with.  I give up.  The result of all that whatever is knowable by pulling the plug and having a look.  If something is suspected and another range might help then the charts are somewhat helpful for a ball-parking another range. 

 

  After mucking with the boratified machines 4000 seems like slow motion. 

 

"After mucking with the boratified machines 4000 seems like slow motion."

No kidding. 

I can't get my head around why single stage snow blowers were never manufactured with a throttle similar to a chainsaw?   What could possibly be the reason not to do it?  Just don't make sense to me.   Since modifying the Craftsman and seeing how soooo much better it is, I'm even more bewildered.

Maybe too much of a good thing.  With SS machine performance like that, they might not sell as many dual stage machines.  Who knows?