Bing 64 Throttle Butterfly Installation Confusion

Hi Tim,

Thank you for bringing this to our attention!

We must state that Loctite 603 is required according to the Heavy Maintenance Manual (HMM), as we cannot deviate from the official manual instructions.

However, the Loctite 603 procedure was recently introduced into the HMM, whereas the Rotax-Owner video you referenced predates this change.

That said, we spoke with a certified Rotax overhaul shop, and they are still using the peening method (as shown in the video) without Loctite. Additionally, we inspected a brand-new certified carburetor from stock and found that it was still peened from the factory without Loctite.

This raises the possibility that the manual contains an error, and we will follow up on this to clarify.

One thing is certain, once Loctite 603 is applied to these screws, they cannot be removed without drilling them out. With the peening method, all that’s required is filing down the damaged threads, making removal much easier (harder to install but easier to remove). This has been the standard procedure for over 30 years.

We will follow up with further clarification soon. If the HMM procedure is confirmed to be correct and Loctite 603 is required, we will update the video accordingly.

I've always peened mine. Why? Because if the Loctite fails or the way it was applied wasn't great then that screw comes out then it's headed for a cylinder to be a ping pong ball. I peen mine over better than Bing (all mine have to have the threads ground down) and in 25 years have never had one come loose. I do a lot of carbs every year. Many of Bings screws will come out if you heat the rod that the brass butterfly is mounted in. Once in a while I have to grind down the threaded side of the screw to get them out, but I found using a butane torch to heat that area allows the metal rod holes to expand enough to just unscrew them.

My philosophy is better safe than sorry.

p.s. guys,

If the screw is hard to unscrew stop before you break it off then you have another big problem.

I have a pair of carbs to do this Sunday.

Rotax Owner,

I've never used Loctite 603. If you heat it up with a little butane torch will they unscrew?

From what I've read heat will help break it loose. Kind of like other Loctite products.

FWIW.  The Rotax maintenance manual heavy instructions for the Bing 64 are, I believe, installation instructions for rebuilding/reconstructing the carburetor.  Whereas the new carburetor that you examined has a factory installed throttle butterfly.  That was installed in the fabrication of the carburetor as opposed to the rebuild/reconstruction instructions in the Rotax maintenance manual heavy.

Thus the two methods differ, as the equipment available for the initial fabrication supports manufacturers installation at the Bing factory. Whereas the factory equipment available for the maintenance of the carburetor is not expected to be available for maintenance unless the heavy maintenance is being done by Bing at the Bing factory.

Tim

Hi all

There is no requirement to remove the butterfly before overhaul.  It is part of overhaul and not inspection.  I am not in favor of Loctite on the screws.  Using heat, you need to get it to 400F (205C)  to let it break free, there is a risk of other damage if you are not careful.  The carb has been running with fuel and everything must be removed first and cleaned to prevent more serious issues.

Just because you can find the information in the heavy manual, one should consider if they are really up to the work.  Just my opinion.

Cheers