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I wanted to make you guys aware of an issue we had with our 2021 GP1800R SVHO last week.
Greg was riding the ski and it lost power. Came home to do a compression test and cylinder #4 had 0 psi compression.
We pulled the intake manifold off in the process of removing the head only to find the ribbon disc missing from it's mounting location and instead it was bouncing around inside the intake manifold.
What happened is the rubber seal that held the ribbon came loose, got stuck between the intake valve and the seat and bent the valve. Easy fix! It could have been much worse, we were very lucky that no other damage occurred.
Later that week our friend Brock brought us his 2019 FX SVHO to install some upgrades, including the Riva ribbon delete kit and to our surprise his ribbon disc was cocked sideways and pushed into the intake manifold with hardly any pressure from one finger. This was a bone stock ski!!
I used to not recommend the ribbon delete on 2018 and newer skis because the ribbon is larger than prior years and flows more air. Now, due to these incidents, I highly recommend doing the ribbon delete on Stage 1+, Stage 2 and Stage 3 ski's.
On stock skis a quick fix would be to use a short self tapping screw and run it through the manifold into the ribbon on the opposite side of the ridge in the manifold.
If you look at this picture, you will see there is a ridge on one side that holds the ribbon in place. I don't like this design, if Yamaha would put a ridge on both sides it would securely hold the ribbon from dislodging and causing such issues.
Many of you guys that aren't getting the RPM that you should, your SVHO engine may already have a ribbon that's dislodged and blocking airflow. Check it asap!!!
Greg will be dropping a video this week about this issue and we will post it here.
Greg was riding the ski and it lost power. Came home to do a compression test and cylinder #4 had 0 psi compression.
We pulled the intake manifold off in the process of removing the head only to find the ribbon disc missing from it's mounting location and instead it was bouncing around inside the intake manifold.
What happened is the rubber seal that held the ribbon came loose, got stuck between the intake valve and the seat and bent the valve. Easy fix! It could have been much worse, we were very lucky that no other damage occurred.
Later that week our friend Brock brought us his 2019 FX SVHO to install some upgrades, including the Riva ribbon delete kit and to our surprise his ribbon disc was cocked sideways and pushed into the intake manifold with hardly any pressure from one finger. This was a bone stock ski!!
I used to not recommend the ribbon delete on 2018 and newer skis because the ribbon is larger than prior years and flows more air. Now, due to these incidents, I highly recommend doing the ribbon delete on Stage 1+, Stage 2 and Stage 3 ski's.
On stock skis a quick fix would be to use a short self tapping screw and run it through the manifold into the ribbon on the opposite side of the ridge in the manifold.
If you look at this picture, you will see there is a ridge on one side that holds the ribbon in place. I don't like this design, if Yamaha would put a ridge on both sides it would securely hold the ribbon from dislodging and causing such issues.
Many of you guys that aren't getting the RPM that you should, your SVHO engine may already have a ribbon that's dislodged and blocking airflow. Check it asap!!!
Greg will be dropping a video this week about this issue and we will post it here.
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