Etec 800 won't pull 7900

[ctd]

If you pull the plastic cap off the raves. You can zip tie them up to the frame ahead of them for testing purposes, bottom end will be dead but it will open up on top end . If it changes something I would dive into them. If it doesn’t I would put a fuel pressure gauge on and see if it drops off as your driving.

Exactly, the full open of the valve's needs to be verified first. The rpm they do this is 7600rpm, right were the complaint is.

My method is to use a track stand, remove the RAVE cap. Set the clickers to #1 for highest load & bring the rpm up so you can get a brief hi rpm load. You can see the valve's go through each of the three stages. If the sled has a bit of a non stock muffler the exhaust sound will change noticeably when the valve goes full open.

Testing this way you have to be careful to not press the throttle lever to quickly. The 800 E TEC ECU has two rev limit strategy's, one of them is if the engine accelerates to quick it will bog the engine & not allow the valves to open.

If you do this & verify the valves are opening there still could be a mechanical problem with the valves, such as a broken valve below the housing. You have to remove them & verify all is well.

After this then you need to verify loaded fuel pressure as 1100 stated, it's not hard to do.......your symptom's do not suggest a fuel issue. You still need to verify pressure is good under load if the RAVE's are working correctly.

Or you can continue guessing & poking .

 

[MK4TDI]

Exactly, the full open of the valve's needs to be verified first. The rpm they do this is 7600rpm, right were the complaint is.

My method is to use a track stand, remove the RAVE cap. Set the clickers to #1 for highest load & bring the rpm up so you can get a brief hi rpm load. You can see the valve's go through each of the three stages. If the sled has a bit of a non stock muffler the exhaust sound will change noticeably when the valve goes full open.

Testing this way you have to be careful to not press the throttle lever to quickly. The 800 E TEC ECU has two rev limit strategy's, one of them is if the engine accelerates to quick it will bog the engine & not allow the valves to open.

If you do this & verify the valves are opening there still could be a mechanical problem with the valves, such as a broken valve below the housing. You have to remove them & verify all is well.

After this then you need to verify loaded fuel pressure as 1100 stated, it's not hard to do.......your symptom's do not suggest a fuel issue. You still need to verify pressure is good under load if the RAVE's are working correctly.

Or you can continue guessing & poking .

The rave valve system was a stupid design on 800 Etecs, the French trying to reinvent the wheel basically. A lot of parts that are prone to failure, that's why I switched mine to run on cylinder pressure like they used to.

The new ones with the electronic servo seem to have solved most of the issues.

 

[ctd]

The rave valve system was a stupid design on 800 Etecs, the French trying to reinvent the wheel basically. A lot of parts that are prone to failure, that's why I switched mine to run on cylinder pressure like they used to.

The new ones with the electronic servo seem to have solved most of the issues.

I will disagree, many advantage's over the previous design of open or closed. Three very controlled stages independent of WOT or not, improved power curve(not just WOT), improved mileage, engine life, cleaner yada yada

There are a few failure points, if you take the time to understand how it works it is actually straight forward & easier for the non BUDS sledder to repair.

The servo motor is faster than 800 E TEC design, the main reason for it. The faster acceleration time of the 850 engine design required the RAVE's to move faster with precision. It's not bullet proof either, cable, servo, broken valves & leaky seals all give issue form time to time. Each time you work with them mechanically you should do a re sync, if you replace the servo it needs a re sync. This requires BUDS or the equivalent.

Technology is tough & the evolution of these 2 stokes has been amazing. There have been some bad designs & issues as it has moved along, I would "not" include the 800 E TEC RAVE as a bad design.