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

The pin in the ring gap is to keep the rings from rotating on the piston.  You have to look closely at the ring ends, the cut out on the ring is to one side with a bit of a protrusion on the other side to fit slightly under the pin.  The reason for keeping the rings from rotating on the piston is so that the ring end doesn't end up catching on a port opening. 

Something has to be intrinsically wrong with the engine/crank to shear the key again.  That's not a common occurrence.  Got to wonder if the original crank might not be true.  If that were the case, you'd probably see some serious vibration prior to the flywheel breaking the the shear pin.  What shape are the main bearings in?  I know the engine is virtually new but something somewhere is out of whack.  It will be very interesting to find out what the problem was.

Did you count the needle bearings?     I looked up the part no. 801290 for the bearing strip but it doesn't indicate the number of needles.  I looked at the image and counted 32. 

http://www.ereplacementparts.com/rollerstrip-p-685842.html

JRT:

I found this link over at the other small engine forum.  They have the manuals!!

http://www.perr.com/phpBB3/viewtopic.php?f=15&t=8002

Note:  On page 32 of the R-tek engine manual, it states:  " NOTE: Replace crankshaft and/or flywheel if keyway is distorted or cracked in any way." 

Can't say for sure, but looking at the photo of the two cranks one above the other, the left counterweight on newer crank doesn't look right.  Maybe it's just the picture???

jrtrebor et al.

Trust you guys are doing this as a hobby and main passion but not a primary source of income.  You guys put so much love and passion to your snowblower project, it is painful to watch when you run into a problem such as this.  If you can't fix it then no one can.  I enjoy restoring bicycles (not the motorized kind) so I know how much fun it can be as well as a pain in the neck on an occasion.

borat - After I saw the pins I figured they were to keep the rings from spinning and getting caught.  But I was a little surprised that they were both in the same location on the piston. 
Lining up both the ring gaps.  I would have thought that they would put them on opposite sides of the piston.

The lobe does look a little tweaked.  But it could be lenses distortion from being so close.  I may take it by a machinist friend and have him put it on lathe and see if that shows anything.
The main bearings felt and looked fine.  I did not count the bearings.  But will tomorrow.

But I agree I think that crank just isn't right.  The close up below shows better how the casting and machining was not even on the one side of the counter weight lobe. 
There were also strange marks on the edges of the lobes.   No evidence on the piston skirt or anywhere in the crankcase of the lobes rubbing or hitting.
I'm also beginning to wonder if the taper angle on the crank end is incorrect.  Not allowing full contact of the flywheel hub with the crank taper surface.
That would not only allow the flywheel to slip or spin on the crank.  But it might also allow it to wobble.  At this point I think the engine had a defective crank from the factory.
Bad machining.
This engine could not have been run very long.  There is no carbon or heat discoloration anywhere in the engine, none, even the plug looks hardy used.

MN_Runner wrote:
I do it as a source of additional income.  But mostly because I just enjoy it.  I also like the challenge of solving some of the problems.  And trying to determine the causes. 
Building a better mouse trap is always a theme as well.  Finding a better way to do something.  And of course, I love tools.

To check the fit of the old flywheel to the new engine you could using something like bluing. Put it on the crankshaft's taper, say, then put the flywheel on. Maybe rotate the flywheel a bit against the crank. Then take it off and see if the blue from the crankshaft is covering the entire taper of the flywheel. I'm sure there's some way to accomplish the same thing (checking for contact) without having to actually buy a specific product just for this.

http://en.wikipedia.org/wiki/Engineer%27s_blue

Jrtrebor,

   Opened up my first two stroke a couple of months ago to get familiar with them and did snapped the ring in the same way not noticing the groove position hump. 

    I looked up all CCR models using the 141cc across a few years of each model run and all have drawings list the same 801220 crank. 

   Your finding the physically different lob indicates that the drawings are not correct and for a model run there may be unaccounted for differences at lest with the online parts lists. 

   Other than this mysterious crank it looks like Toro is getting it’s hp bumps from rpm bumps.   For the HSK850 it gets a bit more fuzzy as many different makers used that engine from 4 to 7hp.  There are a lot of pulley arrangements which cause crank bumps of the part numbers so hard track across engines.  There is variation in the governor spring so overall it looks for Tecumseh HSK850’s the changes from 4-7hp are probably only rpm changes also with different governor springs.

   On the 141cc it looks like the vane and spring are the same from early 4hp 2400’s up to your 2010 6.5hp.  They’re probably just spec’ing the governor spring arm to be bent for the rpm boost.

The rpm hp progression:

R*Tec

CCR2400   3950 4hp

CCR2450   4050 4.5hp

CCR3000   4150 6hp

CCR3650   4250 6.5hp

HSK850

CCR2400 3850 4hp

CCR2500 3850 5hp

SS722EC  3950 7hp (Ariens value but not a min-max like the others and probably +- 150 bringing the 7hp to possible 4200 which makes sense).

  In the past I thought that mufflers, carbs, possibly heads, ports, bores, pistons and rings were the cause of hp bumps.  It’s looking like on the 141cc and 139cc engines over the years it’s basically adjusting the rpms for the boost. 

   It would be interesting to know just how much weight difference there was between your cranks.  For a while I was weighting 8hp, 7hp and 5hp cranks on rebuilds.  I found differences in similarly hp engines.  Some differences were due to 3/4 vs 1 inch cranks but some were lob differences.  The lighter cranks were in lesser maker engines (all Tecumseh) so I thought it might be do cost cutting but never sure.

MNRunner: 

I've been a motorhead all of my life.  I've never charged anyone a cent for fixing something for them.  I do it because, as JRT says, we enjoy the challenge of fixing something, especially at no cost to either myself or the owner.  More often than not, I can.  Occasionally money might be spent but judiciously. 

I recall fixing a non-starting snow blower for a friend's sister.  It was a very old Craftsman from the early 70's not in the greatest shape.  It was the first snow storm of the year.   My buddy and I drove over to the sister's house and on the way, he was explaining to me that HE had recommended a "friend of the family" mechanic to go over the snow blower for her only a month or so earlier.   So I fix it in a few minutes (dirt in float bowl and auger shear pins broken).   As we were driving home, he told me that he was very disappointed that we had to fix the snow blower because his sister had just shelled out ........  $480.00 for repairs!!!!   I was dumbfounded.   I told him the machine isn't worth $150.00, why would she pay him that much to fix it?   "Friend of the family", pay the bill.  That's absolute b.s.  If he were a friend, he wouldn't be sticking it to the guy's sister.  Would he?  And, it's not like she's got tons of money being a single mom working a low paying, menial job. 

It's rewarding  to help people, usually friends and relatives, to save them a few bucks and often a lot of bucks.  As we are all aware, 90% of stuff that doesn't work needs a very simple fix.  Usually fuel related, which is often caused by negligence. 

JRT: 

I agree, that the ring  retainer pins should be offset at least an inch or so.  You'd think that having both joints in the same location would allow a bit of blow-by.   Obviously hardly enough to matter.   The pins on my Yamaha pistons are spread a good inch and a half apart. 

It's hard to tell by looking at pictures but, that crank has to be defective.  Spinning it up on a lathe should show imbalance.  I'd also check it with a dial indicator to see if it's warped.  I suspect that the new crank will solve the problem.  Too bad about the broken ring.  I hate when a $2.00 part holds up a project.

Can you spin up a crank on a lathe to check for imbalance, though? I'd expect the crank, by itself, *should* not be balanced, since isn't it also trying to help reduce the imbalance due to the connecting rod and piston going back and forth? If the crank itself were balanced, then there's nothing to help counteract the conrod & piston. I would agree on using a dial indicator to check for runout, at least.

Now I'm curious- would you consider buying a new crank for the engine? If I could confirm that the crank is *definitely* bad, then I might consider that. But it also needs a flywheel. Barring some really cheap source for those, I will admit I, personally, might consider the engine too far gone (but I've also never had to do that kind of major surgery on an engine). Based on what I saw for Tecumseh crank pricing, a new one could be ~$70 or so, plus a flywheel, maybe at a similar price? I wouldn't pay those prices to try and resurrect it, unless I could be sure those would do it, and I could definitely sell the machine for more. But that's just me. Of course, a similar, inexpensive machine that got backed into, but still has a good engine, could be a nice source for parts.

Thus far I've primarily just fixed machines for me. Some for family. Not 'cause I'm unwilling to do it for friends, just haven't really been asked. I've fixed plenty of computers for friends & family. There is something fun about getting a device working properly again. And it's nice when it turns out to be just bad gas or something similarly straightforward.

trouts2 - I agree, Bumping up the RPM on these engines does seem to be the only difference I've been able to find that explains the increase in HP. 
And as borat's video clearly showed.  Higher RPM does make a difference the blowers performance.  Glad to hear I'm not the only one who has made the
mistake with the ring.  Bugs me when I do things like that, but sometimes that's how you learn.  Trial and error.  Don't mind the trials, don't like the errors.

borat - I always amazes me what some people end up paying for repairs.  As you said most problems are fuel / carb. related and not a big deal.
Other issues are simple part swap fixes.  I love being able to fix things for someone and feel fortunate to have the knowledge and ability to be able to do so.
Been working on all kinds of things for many years.  Guess that is why I kind of enjoy trying to figuring out things like the problems with this engine.
It's a challenge, unlike a lot of other no-brainer repairs.

I just ran across an ad on CL where a guy is selling his Toro 3650 because it needs a new flywheel.  Hmmmm,  Maybe there is a problem Toro isn't talking
much about.  Thought this was curious as well.  Note:  On page 32 of the R-tek engine manual, it states:  " NOTE: Replace crankshaft and/or flywheel if keyway is distorted or cracked in any way." 

I looked and the B&S engine manual link you posted (thank you).  Read that the crank / rod needle bearing count is 33.  You were close.
I know, it's usually not the cost of the part it's the delay.  Although the rings are going to cost me about $20.00 unless I can find a junk engine somewhere.
Either way, it's money well spent if I can get things running correctly again, the blowers in great shape.