# CCR3650 Briggs Engine



## Cinci5 (Jan 18, 2016)

Ok it’s been a while since I posted but I have a question. Just playing around on a spare R Tek for a 3650, ported and polished, I know why, but like I said just playing. Does anybody know why the intake on engine is rectangular but manifold is round.
Makes no sense to me but the only thing I can figure is that they planned on using a different carb but it didn’t pan out.
:icon_scratch::icon_scratch::icon_scratch:


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## RedOctobyr (Mar 2, 2014)

Cool! It would be interesting to hear more about the work you did to it. I just got my first R-Tek, I've been trying to learn more about them. I like the machine's performance so far, but we've only had little storms. 

As I understand it, this basic engine layout is based on the Lawn Boy Duraforce engine. Perhaps, when they tilted the engine to fit it under the blower's cover, the round angled manifold was only available/practical shape? 

Do you know if the cylinder bores are aluminum, or are they cast-iron bores? I'm guessing aluminum, but I don't know. I wonder whether I should try and remove the muffler to remove carbon from the exhaust port & muffler. I don't know whether that's an issue with these, and I don't know how much the previous owners used it. I haven't had a "big" 2-stroke in a long time.


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## Cinci5 (Jan 18, 2016)

Cast iron or steel. Yes take it off cause there is a small hole drilled in exhaust port above the port that starts the flow before port opens. If thats not clear it effects performance. I widened the ports and cleaned up the transfer ports. Polished the exhaust port and piston head and milled about .020 off head. Got it all back together but can’t find the governor so had to order kit.


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## RedOctobyr (Mar 2, 2014)

Nice, thanks for the info! That sounds pretty cool, I'd love to hear to how it performs. Maybe I'll try taking it apart once the season is over. I'm paranoid about stuff like breaking off a muffler bolt. 

"Cleaning up" the ports, meaning like smoothing them out with sandpaper, etc? Or something else? Milling the head is presumably to increase the compression ratio? 

I'd love to know how fast these can spin safely. It seems that Toro controls the power rating by changing the RPMs. The highest I saw in the R-Tek service manual was 4000 +/- 300, for the 3650 and Snow Commander. I have mine set to 4000-4100 at the moment, but I could raise that a bit and still be in-spec. 

It could be fun to have a cheap R-Tek blower that I wasn't really attached to, for experimentation. Things like trying a port modification, or ramping it up to 4600 RPM, etc. On another forum, a user was a big fan of the 2-stroke Tecumsehs (HSK850, I think), and had his running at up to 5000-6000 RPM, without issues. But I have no idea if the R-Tek can handle going beyond 4300.


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## Cinci5 (Jan 18, 2016)

Smoothing meaning getting rid of rough casting marks and blending all rough edges. Polished with dremel and sanding disks. Also diamond bits from Harbor Freight.
Always looking on C-list for bargains. I repair them and others for local landscaper’s who plow in winter. They like the little powerlites for quick cleanups. I like the 2 strokes been doing this stuff for years on the side. Do chainsaws also. EPA ruined the 2 stroke era.


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## Cinci5 (Jan 18, 2016)

You can see aluminum casting on left and how much mismatch there is.


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## RedOctobyr (Mar 2, 2014)

Thanks! Any chance you have before/after pics, for comparison?


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## Cinci5 (Jan 18, 2016)

Well finally got it up and running getting ready for winter. Its a beast idles at 4610 smooth. Advanced the timing a few degrees by slotting the coil.
Hopefully under load all is well gotta get some snow to fine tune. Gotta get new belt chirps when engaged that’s my way of doing a burnout. 😂


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