converting GT750 to premix, what is involved?

[MikeD]

R cylinder is seized, in thinking about it the seller said he'd used starting fluid, makes sense that a right handed person would squirt it into the R carb... Tucking this bit of knowledge away for next time. Wish I would have known, would have dropped the price down.

So looks like I need to move up to the next bore, but I've never trusted autolube pumps, even on my RZ350. So since the barrel is off I might as well split the cases since there is 25k or so on the odometer and get the crank serviced too and convert to premix.

What mods do I need to do on the crank/bearings to run premix? Do the mods, once in place, prevent me from running the oil pump in the future? Who does good Suzuki crank service on the left coast?

[dyrberg123]

Hi.

I did my gt 750 crank last year, and thought about the same, so i brought it up here but was recommended from many to go the other way checking the oil lines and checkvalves etc.

The Suzuki oil pumps are retty reliable units - i have never had a failure with one.

But if you want to do so you have to have the crank modified as it now have some flingerplates fitted to prevent the air/fuel mix washing out the lube from your mains.

Cheers

[MikeD]

Modified how exactly?

[Alan H]

The slingers on the crankshaft get oil away from the bearings not to them, and the engine is designed to use the CCI pump which is very reliable.
The autolube system was completely different.
It might be an idea to revise that idea for long term reliability.
Depends how much you like spending money and stripping/rebuilding engines, I suppose.

[Drewski]

The only major failure I've seen on any two stroke with a mechanical oil pump was the failure of the owner to keep an eye on the oil tank level

I'd stick with the pump too but as above, search "oil line check valves" for info about possible problems and remedies.

[tz375]

On a Yamaha, the oiling system injects oil into the inlet tract and from that point on, it's more or less the same as pre-mix.

Sukuki used a different system. They have two feeds per cylinder - one to the inlet port fr the piston/barrels and one to the main bearings. Oil is pressure fed to the main bearings and from there it is collected via an oil linger plate on the crank and a matching lip on the main bearing. Form there, the oil is centrifugally fed to the big ends the same way that Honda twins with roller cranks are fed oil.

To change to premix both slinger parts need to be modified or removed and that along precludes the possibility of reversing the process cost effectively.

On a Yamaha there are oil feed holes at the base of the transfer ports to feed oil mist to the mains. No such feed holes exist on a GT750.

For a drag race bike, pre-mix is OK but the factory TR racers used premix plus the pump.

[old racer]

I ran my drag bike on premix for years,
With no crank modification.
But i would not entertain running a road bike without a pump.

[MikeD]

ok, that makes some sense

who is good for crank service on the west coast?