Orlin,
Thank you soooooooooooooooo much!
You've made my month!
Does the engine have to be sagged/loosened?
I'll give a back story....
I've been collecting/wrenching on bikes for a long time now, and anyone who knows me, knows that if it has two wheels and a motor, I want it!
Back in October I got a phone call from my brother-in-law. He was in town (well, state) helping his brother, Mark, and family make his final arrangements. He'd fought for years, but the cancer had spread, and he wasn't given long.
I was told Mark had a couple bikes, that none of his kids wanted to mess with, and if I could come with the trailer, they were mine, free of charge. All he could tell me was that they were bigger old Yamaha's.
I arrived in short order.
What I left with was a trailer, an an SUV, FULL of two Ventures, all parts, and some spares. I was told one had been a parts bike for the other, and that one had been running recently.
I noticed that the right rear plug had a pressure gauge hanging out of it ( I got the gauge and a brand new sync tool as well). But he said it had run, free is free, and I saw the look in Marks eyes that was one of dispair for never having got to ride either of them, sadness to see them go, but a little hope that something would be made of them.
Tinkering around, within a week, I had the primary bike running, still on the trailer. I sent a video to Mark, whom I was told was ELATED to see it, really raised his spirits.
There was a problem though, that right rear cylinder WOULD NOT fire. Spark, check. Compression, check. Fuel, well it was getting the same start fluid the others were.
I did notice that the throttle slide wasn't opening as it should though. A quick hand-over-the mouth of the carb revealed very little vacuum.
Hmmm, maybe there's a clog in the intake boot.
Pulled the carbs. Nope, no clog. NOT GOOD.
Rolled motor over with carbs off, and watched in horror as the valves didn't budge a bit.
Pulled cam cover and found that the cam was snapped, right under the carrier.
Both valves compressed easily, though one just wouldn't seat fully. We're talking just barely not seating (grain of sand type clearance).
Could I slap a cam in it? Yeah, but I already have a leaky valve. It could very well possibly be bent (not sure if this is an interference engine). Replacing the cam would mean messing with all the valve shims which will be worn all different. And most importantly, what shape is that piston in if that valve's been stuck open, or cam snapped and allowed that valve to slap the piston just enough to crack it.
I'd rather pull the head, check the piston, replace with a used head who's cams/valves match, and are known to be good.
Its been too cold lately to work on it, but it's looking like a thaw is on the way, and I was hoping to pull that head and have it replaced by late April. If not a whole lot sooner.
I see now, it's very do-able.
I really want this bike tip top by Late spring, early summer.
Thanks again for all your help!