717/ 720 Rotax complete rebuild recommendations

[chazmcgee12]

717 Rotax inner seals went and I am looking for recommendations for rebuild kits and parts. Hear some bad things about sbt and wsw but I’m having trouble finding oem parts. I want to rebuild the whole engine at this point so I need a crankshaft piston rigs rv shaft and gasket. 2002 gti so leaning on reliability… for the most part.

Swallowed a bolt from the carb plate and I think the brass rv shaft shredded and then just ate the seal.

Deleting oil injection and going with dual carbs

 

[mikidymac]

No reason to delete the oil injection or go dual carbs.

WSM parts are perfectly fine and better than SBT. You just need a reliable shop to bore the cylinders for the new pistons like Group K. Pro-X pistons are very good and probably the best aftermarket, just below OEM.

 

[Bacardi]

Get a new crank, new complete gasket kit, use 5 hole gasket on cylinders base, rebuild the carbs with OEM mikuni to factory specs or slightly enrichment on high speed screw, put Prox pistons, torque everything to spec, do not use loctite 518 on crank cases, instead use any good silicone sealant resistent to gas, use loctite 243 on the bolts that need it, check the clearence on the rotary valve (this is important).
Do not delete oil injection, put new hoses, and new clamps alignment the put correctly and use only a good Api Tc 2 Stroke oil, i use Castrol Power 1 Ultimate 2T (may not be available in your country, if not, Amsoil Interceptor.
On the first tank, you should add oil to the fuel, 50/60:1 is good if the runing the oil pump at the same time, this prevents the initial start, if the oil pump is not correctly bleeded.
You will have an engine good for many many hours.

Cylinder to piston wall, minimum is 0.10mm max is 0.20mm, set them to 0.12/0.13mm, they will be slightly "loose", but you will have a lot less chances of cold seizure, because marine engines are always on throttle and our engines run on open loop cooling the pistons will expand more than the cylinders.
Any doubts, just ask.

 

[chazmcgee12]

No reason to delete the oil injection or go dual carbs.

WSM parts are perfectly fine and better than SBT. You just need a reliable shop to bore the cylinders for the new pistons like Group K. Pro-X pistons are very good and probably the best aftermarket, just below OEM.

Yeah I emailed group k a couple weeks ago still haven’t heard anything. Heard they’re the best

 

[chazmcgee12]

Get a new crank, new complete gasket kit, use 5 hole gasket on cylinders base, rebuild the carbs with OEM mikuni to factory specs or slightly enrichment on high speed screw, put Prox pistons, torque everything to spec, do not use loctite 518 on crank cases, instead use any good silicone sealant resistent to gas, use loctite 243 on the bolts that need it, check the clearence on the rotary valve (this is important).
Do not delete oil injection, put new hoses, and new clamps alignment the put correctly and use only a good Api Tc 2 Stroke oil, i use Castrol Power 1 Ultimate 2T (may not be available in your country, if not, Amsoil Interceptor.
On the first tank, you should add oil to the fuel, 50/60:1 is good if the runing the oil pump at the same time, this prevents the initial start, if the oil pump is not correctly bleeded.
You will have an engine good for many many hours.

Cylinder to piston wall, minimum is 0.10mm max is 0.20mm, set them to 0.12/0.13mm, they will be slightly "loose", but you will have a lot less chances of cold seizure, because marine engines are always on throttle and our engines run on open loop cooling the pistons will expand more than the cylinders.
Any doubts, just ask.

Awesome thank you i appreciate it.

Get a new crank, new complete gasket kit, use 5 hole gasket on cylinders base, rebuild the carbs with OEM mikuni to factory specs or slightly enrichment on high speed screw, put Prox pistons, torque everything to spec, do not use loctite 518 on crank cases, instead use any good silicone sealant resistent to gas, use loctite 243 on the bolts that need it, check the clearence on the rotary valve (this is important).
Do not delete oil injection, put new hoses, and new clamps alignment the put correctly and use only a good Api Tc 2 Stroke oil, i use Castrol Power 1 Ultimate 2T (may not be available in your country, if not, Amsoil Interceptor.
On the first tank, you should add oil to the fuel, 50/60:1 is good if the runing the oil pump at the same time, this prevents the initial start, if the oil pump is not correctly bleeded.
You will have an engine good for many many hours.

Cylinder to piston wall, minimum is 0.10mm max is 0.20mm, set them to 0.12/0.13mm, they will be slightly "loose", but you will have a lot less chances of cold seizure, because marine engines are always on throttle and our engines run on open loop cooling the pistons will expand more than the cylinders.
Any doubts, just ask.

Awesome, thank you i appreciated it! Already rebuilt my carbs just trying to find the best guy to rebuild crank and bore cylinder

 

[chazmcgee12]

Just curious because I saw this on other forums too. Why are people against premix. I definitely would feel more comfortable blocking the oil pump off due to a blown mercury 200 that blew due to an oil line failure. I run pre mix in that and have no issues

 

[mikidymac]

On these you still have to supply the rotary gear with oil so you still need an oil tank or a connected hose to keep checking th eoil level on.
Also these oil pumps just don't fail. The only thing that can fail is the small 3/32" oil lines from the pump to the intake but they last 20+ years so just change them every 20 years to be safe.

These are also a variable rate oil injection pump that isn't related to rpm so at idle they provide almost no oil which is good to prevent fouling plugs and more than premix at wide open throttle so you will use less oil and get as good or better engine oil than premix.

I would call Group K, I haven't had much luck with email, they are old-school.