Lawn Boy Duraforce Gas/Oil Mixture Recommendation

[Cujet]

Originally Posted By: Hokiefyd
The Duraforce engines used bushings, yes.


Yes they do. And they don't hold up at lean oil ratio's. 32 to 1 will be just fine.

 

[boraticus]

Got to wonder why LB would go with bushings in a two cycle engine? Cost savings?

Anyway, that's good to know. Thank you.

 

[Lewis9]

Mix at 32 to 1, these engines were designed fairly recently when high quality oil was being produced. Like stated in other post that the internals need 32 to 1 oil mixture to maintain proper lubrication. I use a ashless and smokeless oil, only smokes a little when I first start the mower. Definitely drill the main and idle jet one size bigger. Here is a video on how to do that.
https://www.youtube.com/watch?v=08ee478t-LE

 

[Lewis9]

Originally Posted By: boraticus
Got to wonder why LB would go with bushings in a two cycle engine? Cost savings?

Anyway, that's good to know. Thank you.


Not sure where the bushings are because I had a dura-force throw a connecting rod (bought it from a dealer where it was stored outside for a number of years, rusted connecting rod bearing) and there are roller bearing on the crank and needle bearing on the connecting rod and piston. The 1960 LB had brass bushing and those need to run at 16 to 1 ratio. Might be some miss-information here. Fast forward to 2:18 of video.

https://www.youtube.com/watch?v=-U5LPNDogRs

 

[Hokiefyd]

Originally Posted By: boraticus
Got to wonder why LB would go with bushings in a two cycle engine? Cost savings?


Cost savings, probably. This is one of those anti-Cinderella stories where a second party got involved and, to the dismay of many, really changed what was going on. Toro bought Lawn-Boy in the late 1980s. One of the things Toro did was try to update Lawn-Boy's F engine. The V engine (a real piece of work) was the result. The V engine design morphed into the E engine (Duraforce). It was generally a good engine, but there were some compromises made on a number of fronts. One of the most apparent is the super lean jetting -- many find satisfaction in re-jetting or drilling it out. There were other things, too...like the bushings in the connecting rod big end rather than the needle bearings from before. I personally don't care for the plastic carburetors common from that era, though I don't know if those were exclusively after Toro bought the brand or not.

Many Lawn-Boy fans feel that Toro bought Lawn-Boy for their 2-stroke technology for Toro's snowblower line (the Toro R-tek is basically a Duraforce engine) and then junked the rest of the brand. It didn't happen overnight, but the death of the staggered wheel deck was the death of the brand to Lawn-Boy fans. Today's Lawn-Boys, with stamped steel decks with plastic front axles and Chinese Kohlers, are a real contrast to Lawn-Boy quality of the past.

 

[Lewis9]

Originally Posted By: Hokiefyd
Originally Posted By: boraticus
Got to wonder why LB would go with bushings in a two cycle engine? Cost savings?


Cost savings, probably. This is one of those anti-Cinderella stories where a second party got involved and, to the dismay of many, really changed what was going on. Toro bought Lawn-Boy in the late 1980s. One of the things Toro did was try to update Lawn-Boy's F engine. The V engine (a real piece of work) was the result. The V engine design morphed into the E engine (Duraforce). It was generally a good engine, but there were some compromises made on a number of fronts. One of the most apparent is the super lean jetting -- many find satisfaction in re-jetting or drilling it out. There were other things, too...like the bushings in the connecting rod big end rather than the needle bearings from before. I personally don't care for the plastic carburetors common from that era, though I don't know if those were exclusively after Toro bought the brand or not.

Many Lawn-Boy fans feel that Toro bought Lawn-Boy for their 2-stroke technology for Toro's snowblower line (the Toro R-tek is basically a Duraforce engine) and then junked the rest of the brand. It didn't happen overnight, but the death of the staggered wheel deck was the death of the brand to Lawn-Boy fans. Today's Lawn-Boys, with stamped steel decks with plastic front axles and Chinese Kohlers, are a real contrast to Lawn-Boy quality of the past.


Where are these bushings? I had dura-force apart and there are needle bearings on the connecting rod. Go to 2:18 of the video link above.

 

[Hokiefyd]

The bushings are in the connecting rod big end. It's possible that some engines used needle bearings while some used bushings. Here's an example of one with bushings:

http://www.ebay.ca/itm/95-7629-611207-La...=item1a02d927d5

For what it's worth, bushings in a connecting rod big end are not unprecedented. Some of the earlier Lawn-Boy engines (C or D) used bushings there, too.

 

[Lewis9]

Well the one I had apart definitely had needle bearings on the connecting rod. I really doubt that some might have come with needle bearing and some without, 16 to 1 ratio was for the bushing OMC motors from the 60's. 32 to 1 is going to have bearings, if the dura-force has bushings on the connecting rod the spec would be 16 to 1 to lubricate the bushing enough. I posted a video of what the motor looks like when I took it apart. Those little pins are needle bearings from the connecting rod.

 

[Hokiefyd]

This thread...

http://forums2.gardenweb.com/discussions...-lb-d400-series

...indicates that the fuel/oil requirement was not driven on bearing vs. bushing on the connecting rod big end. That does correlate with what we know to be true: at least some Duraforces had bushings in the big end, and the D600 engines used bushings in the big end, and they spec'd 32:1.

 

[dlundblad]

Awesome mower. I bought one of these bad boys last fall for $20. Just needed a new primer bulb.

 

[Lewis9]

Found a service manual of a 6.5 duraforce. Needle bearing on all duraforce LB's

duraforce

 

[Cujet]

Originally Posted By: Lewis9
Found a service manual of a 6.5 duraforce. Needle bearing on all duraforce LB's


Do you mean these needle bearings?????????

 

[Hokiefyd]

Originally Posted By: Lewis9
Found a service manual of a 6.5 duraforce. Needle bearing on all duraforce LB's


Some, not all.

 

[Lewis9]

http://www.biodsl.com/fsm/Duraforce_Service_Manual.pdf

There is no foot note on different wrist pin or connecting needle bearings, Yes there is a bushing/bearing that makes contact with the needle bearings and is designed to hold them in place. Show me a parts break down where its a bushing with no needle bearings?

https://lookup3.toro.com/partdex/index.cfm?xCaller=Toro&lang=us_en

I did find a connecting rod that utilizes brass bushing on both ends 1959 5250 that was ran at 16 to 1, Most who restore these older mowers up date to needle bearings.

http://www.ebay.com/itm/Lawn-Boy-Mower-P...=item1a03881cba

 

[Lewis9]

Originally Posted By: Cujet
Originally Posted By: Lewis9
Found a service manual of a 6.5 duraforce. Needle bearing on all duraforce LB's


Do you mean these needle bearings?????????

random connecting rod, what is the part number?

 

[Cujet]

Originally Posted By: Lewis9
Originally Posted By: Cujet
Originally Posted By: Lewis9
Found a service manual of a 6.5 duraforce. Needle bearing on all duraforce LB's


Do you mean these needle bearings?????????

random connecting rod, what is the part number?


Not a random pic, that was pulled from a DuraForce Siver 6.5. There may be needle bearings placed between those bearings and the crank. But they are not shown in my diagram. In which case, the bearings would have to be loose and placed individually. If that's the case, I apologize for any inaccuracy. My manual does not show any needle bearings.

 

[ragtoplvr]

There ARE needle bearings between the liner and the crank. You will have a count. Easy to lose one. Use Vaseline to hold in place when assembling.

Rod