Gregory Bender

2012 December 20: Repaired Speedometer for I-Convert

Updated:

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This entry is extracted from a series of email exchanges between myself, Charlie Mullendore of Antietam Classic Cycle and Gordon Kline of MG Cycle. Both Charlie and Gordon were very supportive and helpful.

I road 200 miles on the Convert today...to grab an excellent Carne Asada Burrito up in Prescott. Most excellent! I dressed warm and had my hippo hands installed (it was below freezing at my house this morning - not very common here). No trouble with the roads...though I did need to be careful of a few icy spots up in the mountains.

Performance report:

  1. Speedometer held together nicely.
  2. No leaks from the rear drive.
  3. No leaks from the engine UNTIL I was running 75 - 90 MPH on the interstate coming back home. Clearly engine oil, clearly overwhelming the breather, clearly all over the motorcycle. Seems I can run 65 - 70 MPH without any trouble. Pump it up to modern freeway speeds and I start pumping oil. Ugh.

Ideas?

Regards,

Gregory Bender

Charlie's reply to Gregory:

Hmmm. No ideas here other than fitting a breather box with a larger volume.

Charlie

Gregory' reply to Charlie:

Hi Charlie,

I've got to do something. Man am I frustrated that oil gets on everything: over and over again.

When I chatted with Andrew Gray, he had a bigger air box made for his endurance racer. I don't have the details, but I know larger air box volume and ensuring exits to atmosphere were *bigger* than the inlet and return combined were a couple of his design points. There isn't a lot of space up under the Tonti gas tank (voltage regulator, wiring, etc.). But, my coils are placed in my battery box, so that gives me some more room. Perhaps I can fit a long-ish tube under the main frame tube and do something that way. I am not looking forward to this as it is all a shot in the dark.

Perhaps I should try the Bunn breather before anything else. Would should be easier to try and Rick Duarte seems to have good luck with it. Hmmm....

Regards,

Gregory Bender

Gordon's reply to Gregory:

I'm thinking it's got to be something with your cylinder to ring seal, it's just not normal for that to happen without something being wrong in there. Since you mentioned one cyl was replated, my suspicion lies there. It's possible that at the higher rpms your rings start fluttering and they lose their seal. Your compression test wouldn't show that problem, nor would a leak down test. If the rings flutter enough, they'll crack and the problem will be more consistent, and the static tests would probably show it. Alternatively, I'd go back to the idea that the breather box is somehow faulty, especially the check valve, and I suspect this because of my experience with the doubled up check valves causing the same oil blowing problem.

I'd start by swapping in a known good breather box just cuz it's easy. You've got nothing to lose in trying that other than your time.

For what it's worth, those are my thoughts. I'm sure it sounds like a broken record, but what else can it be?

Gordon

Gordon's reply to Gregory:

One last opinion before I go out and clear snow: There's a big difference between a race bike needing a bigger breather and a Convert running down the interstate. Your 'vert shouldn't need any more than just the standard box, unless there's something wrong.

Gordon


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