2013 January 07: Re: Repaired Speedometer for I-Convert
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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.
Hi Gordon,
Sorry for the delay in getting back on this topic. I haven't touched the Convert since I washed it right after the last oil mess occurred before Christmas. As per your suggestion, I do plan to swap breather boxes with my Ambassador as a first step. I'm doubtful this will help anything, but we'll see.
While I definitely understand (at least some of) the differences between a race bike needing a bigger breather and a Convert running down the interstate, to some extent it is only a matter of degree. I've got an 850 engine instead of a 1000 engine; the Convert spins ~10% higher at any given speed due to losses (total guess here, but it must work harder to overcome hydraulic losses not present in direct-drive systems); and things seem fine at 70 MPH but oil starts a spewing big time when I go up from there and start running higher speeds.
Indeed, it might be the breather. If not that, I'm going to pull the cylinders and have a look at the cylinders/rings/pistons. I hope something jumps out at me but I fear everything will seem great. A replacement breather or a few dollars on replacement gaskets is a whole lot easier than re-engineering a breather. I don't want to have to do that unless I can't figure any other way out of this.
One thing is for certain, there is a fix for this. I can flog my Ambassador at high speed for miles without any ill effect. I've very little use for the Convert if I cannot do the same.
Insert marketing slogan here: I demand performance!
I'm not sure when I'll have the chance to swap and test, but you haven't heard the last on this oily topic. :>
Regards,
Gregory Bender
Gordon's reply to Gregory:
Hey Greg, the silence was deafening, I thought maybe I ticked you off! I even went back and re-read what I sent to make sure it wasn't insulting, I sure didn't mean it that way, but maybe I wrote a little short in my haste. I think you're right, the breather swap does sound kinda futile, but wouldn't it be nice if it were that easy? I also agree about the Convert running harder due to the slush box but the standard breather normally works just fine in Converts too. I think the big diff between a race bike and a street bike is the amount of time the race bike is at full throttle, and the amount of time spent near maximum rpms. And this is typically relentless without any relax time to catch up until the race is over, which is a minimum of 10 miles and usually more. There's obviously some throttle modulation going on, but there is almost no steady state operation, which is what street bikes frequently encounter, for example running at high speed down the interstate. I think cylinder pressure is highest at full throttle, and I think blow-by would increase with higher cylinder pressure. Then you've got the idea of rings sealing at higher rpms, which is a whole ‘nother thing. In the end, who knows, surely not me. I still have my suspicions. I looked for flutter diagnosis and found this which mentions measuring blowby.
Maybe simply comparing blowby with your Amb engine would be interesting. I think I told you all about my experience with my first race bike, the track oiler. And the shattered piston rings. The local guy that knows these things told me it was caused by ring flutter, at some higher rpm the rings no longer held tight to the cylinder walls and vibrated themselves to death. I ran them until they shattered, at which point it was *really* a track oiler and could no longer be run. They were Venolia pistons in iron sleeves.
It's good you demand performance. If something doesn't do what I want it to do, it's verging on useless. Worse, it causes me grief.
Gordon
Gregory's reply to Gordon:
Hi Gordon,
Oh, no. You didn't tick me off at all...not in the slightest. We left to visit family right before Christmas and didn't get back until New Year's Eve. So, I was busy prepping for and then busy making up afterward (no good deed shall go unpunished, or something like that).
I've not made any progress yet and likely not for a little while. Maybe this weekend??? We'll see.
I really enjoy the Convert - a lot - up until it blows oil on everything. I've thought about selling it for that reason alone, but cannot in good conscience not disclose that information up front. So, I might as well fix it myself and then be able to enjoy it.
Regards,
Gregory Bender