Hutzl MS660 failure ~ 20h

[weimedog]

So....the Cross Top I had end has (had) bore alignment issues, and it ate another bottom end (crank) before I figured it out. Damn. A lot of time spent as a result. Thought it was pretty cool when it survived the (first) rod bearing failure. Assumed it was the crank at fault. Take two..another crank that I had checked. (in a fixture & dial indicators for stub alignment and for "spread" between the halves) Ate it in three tanks. Common denominator? Brand name of the bottom end parts....and...the Cross Top end I moved from wreck 1 to the now wreck 2. SO I started measuring (Why didn't I do that first tine out?? Because I was so certain the cranks were NG.....but I was wrong. Cranks were probably fine.) And the cylinder's base flange thickness varied about .005-.008 from one side to the other. Explained that away with castings (rationalizing?)...then from flange base to squish band. A 010-.015 difference from one side to the other. Realized thats a trend. Put it on an arbor...and sure enough. SO its now in the town trash transfer station's bin ..tossed with anger. I'm pretty sure it's the exception not the rule, but I guess the bottom line is if you waste a rod bearing, might be a good idea to check ALL the components before moving them to another case.. My frustration can be your knowledge I hope. No video. Don't want to vent in that venue.

 

[Mac&Homelite]

I understand your frustration. That is where I am with my 361 kit saw and it refusing to hold a tune. I suspected the carb, so I bought a used oem carb which will hopefully solve the problem. Despite not wanting to vent about it, I would have liked to hear you discuss about the component failures on yt. I got most of what you said in the post, but the visuals are helpful to see, at least for me.

 

[weimedog]

I guess I'm Leary about calling out brands....I kinda shot my mouth off on the first blow up blaming it on the cranks. Which I now realize wasn't an issue at all. For that matter Nothing from FT was the reason for two crank failures. So I have to unwind that perception....but I'll show a little in the next video. And try not to be too negative on the brand that manufactured the top end that cost me two weekends of wrenching when I needed to be doing home related things. Does bring up a valid discussion of hobby vs. real. OEM vs. AM. And whats your time worth? (Yeah, I'm still annoyed)

I guess the other reason I don't want to "trumpet" names of the brand is some of the saws built with the same "brand" part in the area are running fine. My situation is the anomaly not the norm. Had I been more focused I probably would have figured it out before creating another hand grenade by moving the offending part from blow up one....to the next victim. SO I have to accept that reality as well...can't just blame the part for two blow-ups.

 

[Bedford T]

So....the Cross Top I had end has (had) bore alignment issues, and it ate another bottom end (crank) before I figured it out. Damn. A lot of time spent as a result. Thought it was pretty cool when it survived the (first) rod bearing failure. Assumed it was the crank at fault. Take two..another crank that I had checked. (in a fixture & dial indicators for stub alignment and for "spread" between the halves) Ate it in three tanks. Common denominator? Brand name of the bottom end parts....and...the Cross Top end I moved from wreck 1 to the now wreck 2. SO I started measuring (Why didn't I do that first tine out?? Because I was so certain the cranks were NG.....but I was wrong. Cranks were probably fine.) And the cylinder's base flange thickness varied about .005-.008 from one side to the other. Explained that away with castings (rationalizing?)...then from flange base to squish band. A 010-.015 difference from one side to the other. Realized thats a trend. Put it on an arbor...and sure enough. SO its now in the town trash transfer station's bin ..tossed with anger. I'm pretty sure it's the exception not the rule, but I guess the bottom line is if you waste a rod bearing, might be a good idea to check ALL the components before moving them to another case.. My frustration can be your knowledge I hope. No video. Don't want to vent in that venue.

how long have you had the cylinder? was it a recent run?

 

[Cobalt78]

Not sure as I don't have a tach, but tried to make it rich. I'm changing muffler today, as this one has been opened right up, past any gains and all noise. Will be going through another couple of tanks before giving it to its owner..so will be trying again to get it 4 stroking at WOT. Has genuine Walbro carb, the chinese one was horrible, when trying to seat the needles they felt really spongy. The owner of it I'm trying to push into a 661, but he is building a new house currently so no chance..plus a 661 is $2500 here, and this thing is probably at $500. But agree it sounds rich and too fast, but the H screw is out a fair way, any more and it dies when idling, despite adjusting L and idle screw. Its no Stihl to tune, thats for sure. Once I've got it better I'll try to post another vid, its good having other peoples ideas for tuning..cheers

I’m not an expert but did have a very similar problem with my FT 660. Turns out I had a blown crankcase seal on the clutch side