Evaluating potential bike for purchase that won’t start
 

Hi Everyone,

I’m new to the forum and am potentially trading my old chevy suburban for a 2001 superhawk. The bike in question turns over but doesn’t start. It’s been sitting, and while the owner is convinced it just needs a carb rebuild, I want to make sure it hasn’t catastrophically jumped time and sent valves into pistons. Would I be able to hear a disastrous clattering even when turning over if this had happened? Any quick and relatively painless ways to inspect the ccts or at least confirm that there are no bent valves?

Thanks,
-Ed

Good ol' compression gauge.

This. And if you spin it over & the pistons are hitting the valves, it's a pretty obnoxious clacking sound you certainly can't miss, at least on every one I've ever heard with that problem.

That wasn't my experience chaos. I heard nothing out of the ordinary whether spinning the motor on the starter or when running.

Yeah I imagine it's not universal depending on the extent of the damage but over the years I can think of 3 different bikes I've bought with "blown engines" and they all clacked loudly when I hit the starter and spun the engine, which I assumed was the valve coming into contact with the piston after skipping timing. I remember taking at least one of them apart and seeing a half moon beat into the top of the piston.

Either/or, if the valves are bent or the piston is cracked one would think that it have little or no compression.

I would say wing it and buy it. What you save in gas will pay for a whole motor on ebay if need be.

AV

Unless the seller is willing and the buyer is capable of doing a compression check on site before sale...approach the purchase as if it will need a new head installed (or old head serviced, repaired and reinstalled.)
Rear heads are easy to come across undamaged, front ones a little harder.

Im a bit anal when it comes to working on bikes...which is really good for my customers paying me to work on their bikes...but cause more $$$ to flow out of my wallet when it comes to working on my own bikes.

If a head is coming off a bike with 20,000 or more miles ...Im that guy that would pull poth heads and have them both serviced...new valves, seats cut, guides checked or replaced as needed, new seals, springs, cottors.. in the "In for a penny, in for a pound" deal..knowing that the job is done right, once and will not need a second repair attempt later.... Time for me is a more sparse commodity then some toy money.

In a pinch a rear head can be used in front, it just takes a little machine work and a blanking plate for the now unused CCT hole.The head would best be modified in a machine shop for the no hassle 100% sure bet mod. But reality is, it "could" be modified by a home mechanic with some moderately basic tools and general experience. Drill press, drills from 5mm for the holes to be tapped to much larger to drill out the head for the CCT to fit into, M6x1.0 tap. Again if the person doing the mod is not really confident in their past experience and tool usage, and has the tooling required on hand...that person would be $$$ ahead to find a local machine shop to bore the hole drill and tap the fastener holes and face the head surface the CCT will seat against. 1-1.5 hours is what Id guess a shop would charge.... Some places you might even get it done for trade....say buying the machinist lunch and a 6 pack if said machinist is looking for something "different " to do on his next break