Rotor Holding Tool

[M. Hausknecht]

Really bad engine damage this last weekend at WERA Roebling Road event means I need to take my motor apart, completely. Motor is out of chassis and head is off. Missing an inch long piece of Wiseco piston top ring land on intake side of #1 cylinder. Squish areas are all beat up from what looks like two small bits of piston ring.  Yamaha rotor generator holding tool (90890-04166, YM 04166) is tough to find and scary expensive. I can probably use an impact wrench to get the nut off but that won't work for reassembly. Whatcha using to hold the generator rotor stationary on the 07?

[mossrider]

Strap wrench and impact and let her buck

[D.A.]

I haven’t needed to remove my rotor but based on the factory service manual, the tool looks like a plain old strap wrench, just as @mossrider said.

Amazing that Yamaha wants $200+ for it!

[Triple Jim]

Oil filter wrench maybe?

[AP996]

I just used one of my normal ratchet straps, wrapped it round the rotor and secured one end, worked fine. Sounds like it’s going to get expensive.

[M. Hausknecht]

Regular strap wrench it is. Thanks guys. I need new pistons, probably oversized so I can eliminate a shallow, narrow groove in the #1 cylinder wall. I'm going to try to save the head, ported by Zoran, by cleaning up the squish areas by hand. I'm hoping I'll see only a small, if any,  increase in chamber volume being the squish area and all. Maybe try a little thinner head gasket. The valves look ok, although I haven't removed them yet, so I'm hoping the seats aren't damaged.   

[M. Hausknecht]

For those following along, the nut holding the generator rotor to the crankshaft was easily removed with an impact wrench. I just held the rotor with a gloved hand. Same for the clutch nut. By the time I'm ready for reassembly, I'll have all of the appropriate tools.

A word to the wise: never get rid of functional tools, even when you're "sure" you'll never need them again. Until recently,  I last worked extensively on motorcycles in 2003. I got rid of all my motorcycle engine related tools, several years ago. Now, I'm buying them all over again. Sheesh.

[AP996]

Do you know what the cause of the damage was?

[M. Hausknecht]

Best guess after corresponding with professionals is detonation. Not sure why only one cylinder. I have an a-Racer Super 2 ECU and I wasn't involved with the engine build or tuning (ECU is totally adjustable for mixture and spark advance by gear). Need to check fuel pump intake screen, and injector for that cylinder. I need to get the ECU tune redone in any event because I'm going to 13:1 pistons from 12.5:1.

 

[AP996]

7 hours ago, M. Hausknecht said:

Best guess after corresponding with professionals is detonation. Not sure why only one cylinder. I have an a-Racer Super 2 ECU and I wasn't involved with the engine build or tuning (ECU is totally adjustable for mixture and spark advance by gear). Need to check fuel pump intake screen, and injector for that cylinder. I need to get the ECU tune redone in any event because I'm going to 13:1 pistons from 12.5:1.

 

Are you running the same fuel map on both cylinders? I only ask as it’s #1 cylinder that’s been detonating and that might lend weight as to why Yamaha’s stock fuelling is a little richer on #1 cylinder.

[M. Hausknecht]

 

12 hours ago, AP996 said:

Are you running the same fuel map on both cylinders? I only ask as it’s #1 cylinder that’s been detonating and that might lend weight as to why Yamaha’s stock fuelling is a little richer on #1 cylinder.

Dunno yet. I wasn't involved with building or tuning the motor. While I'm awaiting a rotor puller I need for further disassembly, I'm going to dig into the details of the bike's existing tune today. There is only a single O2 sensor. Thanks for reminding me that #1 should be getting a smidgen more fuel.