Kinetic Analysis
New Member
Hey so I don't normally post and I know this could/should go in the technical forum, but I think this one is important. Many of you have notice by now that the RC390 is not, actually, Ready-To-Race. In fact it's not even ready for particularly hot weather. There are three problems that I had to solve on this bike that had nothing to do with performance and have not yet been addressed by the factory:
I can't be sure but I suspect that #3 contributes to a bunch of other engine problems. The good news is that for $750.00 there is now a fix. Assuming you don't ride much in very cold temps you can add one of these:
https://www.hsbkracing.com/parts-an...90-secondary-auxiliary-radiator-2015-to-2018/
If you have done the Spal puller fan modification you can retain the fan. I recommend keeping it even if you are racing since the fan is still going to come on as you enter the pits on a really hot day. Yesterday it was about 100F at Thunderhill. Data from the ODB says intake temp was about 113F while the coolant remained at 190F on the front straight at a GPS measured 105MPH top speed. That's about where it would be on my 1299 in the same conditions. In terms that most of you will understand: The dash now shows the temperature at the knee.
The modification is pretty straight forward. It's a bit of a pain in the ass to get everything fit, but the chance of screwing it up is low and you don't need special tools. It does eliminate the thermostat, so your bike will take longer to heat up and you might have some issues if you ride in really really cold weather. Also I have an aftermarket lower fairing so I wasn't able to make the attachment at the bottom of the radiator, but it still fit with no issues.
More pics...
https://photos.app.goo.gl/c28AZacJxJy5YmRK8
- The head gasket has issues, particularly on the early models
- The fan is a grenade
- The radiator is too small. Period.
I can't be sure but I suspect that #3 contributes to a bunch of other engine problems. The good news is that for $750.00 there is now a fix. Assuming you don't ride much in very cold temps you can add one of these:
https://www.hsbkracing.com/parts-an...90-secondary-auxiliary-radiator-2015-to-2018/
If you have done the Spal puller fan modification you can retain the fan. I recommend keeping it even if you are racing since the fan is still going to come on as you enter the pits on a really hot day. Yesterday it was about 100F at Thunderhill. Data from the ODB says intake temp was about 113F while the coolant remained at 190F on the front straight at a GPS measured 105MPH top speed. That's about where it would be on my 1299 in the same conditions. In terms that most of you will understand: The dash now shows the temperature at the knee.
The modification is pretty straight forward. It's a bit of a pain in the ass to get everything fit, but the chance of screwing it up is low and you don't need special tools. It does eliminate the thermostat, so your bike will take longer to heat up and you might have some issues if you ride in really really cold weather. Also I have an aftermarket lower fairing so I wasn't able to make the attachment at the bottom of the radiator, but it still fit with no issues.
More pics...
https://photos.app.goo.gl/c28AZacJxJy5YmRK8