"D-Plate" caused detonation ?

[lmski]

Anyone heard of engine damage caused by detonation (using pump gas, stock carbs and settings) after a D-plate has been installed. Supposedly, Yamaha claims this will happen at roughly 6500 rpm on a 1200cc engine.

[Bryan Glynn]

The only way I can see that as possible is from the lower temps from the lack of the cat, causing a denser air mixture and thus a lean mixture in some cases. I believe the non-us versions of the ski come with the D-plate, but are also jetted slightly differently. Maybe that's why?

[lmski]

Do you think this is a serious potential problem, and if so, what should be done to prevent it? This is a family machine and not ridden that aggresively.

[Bryan Glynn]

Personally, no, I think it may only effect a tiny percentage of people - I know a ton including a guy here with many hours of D-plate riding without incident.

[dav_dman]

at 6500 rpm you're givin' it some good throttle, engaging the hi speed adjusters, so richen them an 1/8 and don't worry about it.

correct me if im wrong , Bryan.

[Bryan Glynn]

two words...tamper caps.

[VOODOO]

Many peeps on the Riva-Yamaha forum are using D plates without a problem. I have heard of Yamaha claiming lean running problems though. The euro spec boats with D plates do have richer jetting.

[Philip]

if you are going to replace the cat with a d plate this then gives you the opportunity to change the carb jetting - the stock jetting is on the lean side because unburnt gas is not a good thing for a Cat - it will literally catch fire