Motorcycle Repair/1975 GT 750


Can you help me and my mechanic friend ?  my bike is at his shop and he is concerned about leaning bike back too far to stop excessive oil smoke on 2 of the cylinders.  I have owned this bike since new and want to get her back into like new shape again

thanks Eric

Really I'd need a bit more information to be able to offer a definitive answer- which two cylinders ? Smokes only at start-up and first couple of miles, or heavily all the time ? If the smoke is from the right side, then most probably the crankshaft seals are gone and will need to be replaced. If mainly at start-up and then clearing after a couple of miles, then the most common problem is leaking check valves in the oil injection lines at the base of the cylinders. To tell the difference:

- drain the oil from the cylinders via the SRIS valves and check to see if its injector or transmission oil - if its injector oil, then its likely the check valves on the oil injector system - you may be able to flush the valves - do not use blow them out using air pressure as you will ruin them completely - otherwise replace
- take the side cover off the oil tank, and mark the level and let the bike stand over night - check the level after 24 hours and if it has dropped, then its most probably a check valve problem - flush or replace

If its transmission oil then continue

- drain the transmission oil and check for contamination - indicates oil seal issue
- check for oil leak from breather - in cases where the seals is really bad, the transmission will be pressurised and push oil out the breather

- requires full engine tear down and crank rebuild

If none of the above - is the injection rate set correctly ?

Good luck !

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Ian R. Sandy


I can answer restoration questions specifically about the Suzuki GT750 Water Buffalo/Kettle/Water Bottle which was made between 1972 and 1977. I may also be able to assist with some restoration questions on the Suzuki T500 made between 1968 and 1977. I will not answer questions about other makes or models. I focus on restorations - I not especially interested in 'non-stock' restorations or rebuilds.


I wrote the on-line reference manual on the Suzuki GT750 called 'A Field Guide to the Suzuki GT750 Le Mans' which is available at no charge on line. I currently own six Suzuki GT750's - a 1972 (scheduled to be restored in 2013), a 1973, a 1975, two 1976 models and a 1977. I also operate and maintain the on-line reference site 'Suzuki T/GT Resources' as well as the Old Japanese Bikes web site.

I am a member of the VJMC, the AMCA and of the CVMG.

'A Field Guide to the Suzuki GT750 Le Mans' 'Notes from the Corner' - the OJB blog 'The Suzuki T/GT Resource Pages'

Graduate of Sheridan College in Instrumentation Technology, which is interesting but not really germane to this discussion - I owned my first GT750 new in 1974 and have owned and ridden at least one now for very nearly 40 years.

Awards and Honors
My 1973 GT750 was featured as the 'March' bike in the recent CVMG-RMS section calendar.

Past/Present Clients
I am the web-admin for the CVMG, and also for the CVMG-RMS section. I am also a moderator on the Sundial 2 stroke board.

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