998cc Gearbox knocking when cold - could it be the oil?

[Marek]

There is a distinct knocking sound in the gearbox when starting. After the engine warms up and starting, there is no more knocking. I recently changed the oil to a thicker one because I was driving in a hot climate. Do you think it has anything to do with the oil?

 

[Peter Aawen]

Yes, if your oil SAE Rating was high enough & didn't have a low enough W rating to start with, then that knocking could definitely be because you've used an oil that doesn't flow too well when it's not 'hot'; and depending upon exactly what the rating the oil you've been using is, you may have already damaged your gearbox AND/OR your engine because of that!! :banghead:

Don't forget that the engine and gearbox on these Rotax power plants share the same oil; and that you really NEED to use something close to the specified rating of oil in these Spyder things, especially since your ST's engine is a 998cc V-Twin, cos they are very susceptible to incorrect oil level &/or rating issues! :gaah:

I can't remember exactly which is the correct SAE rating without going and looking, but off the top of my head, any good quality oil with a rating of 5W40 should work pretty well in ambient temperatures ranging from about -30°C right up to about +40°C; while a 10W40 should readily handle temps from about -20°C up to about +40°C!! How hot was it where you were riding that warranted a higher rated oil?

So, what oil have you been using?? :dontknow:

 

[bikerbillone]

My 2020 RTL has the distinct 'bump' going into reverse or going into first gear on early start, after that smooth. From that I glean that an oil warm up before 'gearing' is a good thing. I also read that that the cold start is normal.

 

[Marek]

I drive on Motul 7100 oil. Before leaving for southern Europe, where the temperature reached 45 degrees Celsius this year, I poured in 10W50. Now I intend to go back to 10W40, which is what I used to use as a standard.

My 2020 RTL has the distinct 'bump' going into reverse or going into first gear on early start, after that smooth. From that I glean that an oil warm up before 'gearing' is a good thing. I also read that that the cold start is normal.

Yes, loudly shifting into first gear and reverse is as normal as shifting into first gear on a Harley. However, shifting from reverse to first (and vice versa) by holding the switch for a longer time does not cause a knock. However, I wrote about knocking from the gearbox when starting drive with a cold engine...

 

[Mikey]

I would say get that 50W out of there, first thing; and if you think you don't trust your 40W, maybe go through one of your hot spells, then have your oil analyzed to see how well it's keeping up! If it's breaking down, then go from there.

 

[BajaRon]

On the one hand. Since the oil is a 10w at cold startup, I am surprised that it is giving you issues. Since 10w is a great cold start viscosity and the 50 weight should not be a factor until the engine approaches operating temperature. On the other hand, you didn't have an issue until you changed the oil, which logically points to the oil causing the problem.

It will be interesting to see if changing to a lower viscosity corrects the issue.

 

[Columbia]

My 998 doesn't like to be cold. It rumbles almost painfully for the first 2 minutes. I use the oil the manual recommends. Warming it up before putting in gear reduces the shudder considerably. A few miles and the engine is hot and the juddering is gone.
Scared me the first few times it happened. Now I ignore it an ride on.

 

[Mikey]

When it comes to 2 stroke engines, I am a firm believer in warming them up before a ride. And really, after this post I may just do the same with the Spyder. After all, that oil is shared with the trans, and both the engine and the trans work on oil pressure; sooo, it would not hurt a thing to let it warm up while putting on the gear for a ride!!