Worth Continuing..........

Well, after a buddy checked out My XJ650 Bobber project he decided he might like to build one also since all he builds, rides, and works on is Shovelhead rat bikes. He purchased one at the end of Sept for $35. It had sat out under a tree for about 12 years was what I was told. SO him being able to work on Bikes I figured he knew what he needed to do to get her running and street worthy.....WRONG!!! His way was throw some gas in new battery and crank until it started. He did get it started but ran like Crap. So I asked all the questions needed for a proper start and run first time with these. Almost every answer was a big NO. So I grabbed my tools went over and started with a Comp test and valve specs and this is what I got.
It has just under 8k miles by OD. It is a 1981 XJ650 Maxim

I am using Starret Machinists Feelers and calipers for measurements.

0 being I couldn't even fit a .001 between Lobe and shim.

#1 IN: .003/.076mm Y280

EX: 0 Y280

#2 IN: 0 Y280

EX: 0 Y280

#3 IN: .003/.076mm Y270

EX: .003/.076mm Y265

#4 IN: .008/.203mm Y265

EX: .008/.203mm Y270

Engine Compression in PSI Cold

#1=62 psi
#2=80 psi
#3=105 psi
#4=119 psi

A little Oil in Cyl changed nothing.

Now because of these Numbers is it worth to get these Valves in spec and continue with new comp test? or just have him pick up another engine?

 

If you can't fit a feeler gauge in at all then that valve is constantly open. No way it will generate any significant compression that way. Kudos for doing the wet test but with an open valve it doesn't tell you much about 1 or 2 other than it's still blowing air right back out the open valve-it does indicate the rings on 3 and 4 should be ok.

So YES put those valves in spec, give your buddy a good talking to about how to do what you already know how to do. For $35 he can rationally afford to put a few hundred or more into the bike and it would still be worth it.

Since it hasn't ran in forever it's hard to truly estimate it's overall condition, but you'll never know until you get those valves in spec. If you haven't already I would change the oil and clean anything that can be cleaned. The carbs obviously will need it too.

It wants to be save or it wouldn't have even run with those numbers, 1 wasn't igniting for sure and 2 is iffy-no wonder it sounded like it did.

 

Since the wet test changed nothing (as expected) and you have zero clearance valves on the two low compression cylinders, then I wholeheartedly agree with MM. Put the valves in spec and see what numbers it makes. As low as the mileage is, you might get lucky. It's worth a few shims to find out.

 

looks like If I'm correct here. I can have him change these shims from First to Second Number with a switch of 4 of them. Now the only ones that make me wonder are the ones that are at 0 Because there is No real base line for the 0 Clearance Valves. I used the chart for the How to you put up BigFitz.

AIRHEAD VALVE ADJUSTMENT with Pics

#1 IN: .003/.076mm Y280 - Y270 ( Use from #3 IN )

EX: 0 Y280 - Y265 ( Use from #3 EX )

#2 IN: 0 Y280 - Y270 ( Use from #4 EX )

EX: 0 Y280 - Y265 ( Use from #4 IN )

#3 IN: .003/.076mm Y270 - Y260

EX: .003/.076mm Y265 - Y250

#4 IN: .008/.203mm Y265 - Y260

EX: .008/.203mm Y270 - Y260

 

What you do for "zero clearance" valves is to swap in a thinner shim, usually two sizes smaller, then take a reading. Then use THAT reading to decide what you need to put in there.

 

With only that many miles on it, supposedly, how in the world could the clearances gotten that low? Something doesn't seem right.................

That being said, if you did the check properly, and those are indeed the numbers, then my next gut reaction is:

Heck, with that few miles on it, of course it's worth it....get the shims in spec, then recheck compression. I bet you end up with a real good bike.

Make SURE that you change the oil, and THOROUGHLY clean the carbs, etc.....

But.....if you can at least get the shims is spec and show good compression, I bet you'll be fine.

Many of us, myself included, have started with worse.

Dave F

 

BTW FItzy....my 650 seca is coming home this afternoon!

Dave F

 

All names and places have been changed to protect the Innocent.
The Story as I was told
( If you don't Like long Story's/History's STOP here )
Long story short it has been abused and passed around!

In a small town far and away there lived a little ole man who loved collecting anything with an engine running or not. From bikes, car's, truck's, lawn mower's, weed eater's, wood chipper's and so on. Well as the "Collection" grew larger his neighbor's started to complain about his collection. As the complaint's started to pile up with the city They being the city stepped in and told the little ole man to clean up or face fines fee's and such. The little ole man not wanting to throw perfectly good "Stuff" away started selling and giving his "Stuff" away. Now along comes "Bill" and "Bill" being a collector of Bikes and bike part's makes a deal and purchases a large amount of the "Stuff" the little Ole man had. Getting the little ole man out of trouble with the city and making a few dollar's. Now it so happen's 2 of these item's amongst all the "Stuff" was a 1981 Xj 650 maxim and a 1983 xj 650 maxim both running bikes at the time I was told. As time went on and the bikes sat outside with noone loving them the elements ravaged them over time. Now many year's later along comes "Bill's" son "Joe" who at the time was 15-16 started to eye ball the bikes sitting in the back 40 under the tree's. Now "joe" getting his license soon and wanting something to drive decided to get one of these 2 bikes up and running. "Joe" wanting to impress his dad and to have something to ride took it upon himself to drag the 2 bikes into an old work shed and pull them apart. now a short time went on and "joe" got frustrated with the project's lost interest in the bikes and found a new love in big lifted 4x4 truck's. Now some time has passed and "Bill" cleaning up some found said bikes in pieces year's later in one of the ole work shed's. Not caring much about "Jap rice burner's" ignored the bikes stuffed more things into the ole unused shed and put them out of mind. Now along comes "Pete" unemployed, bored ,and looking for something to do and something to make a few buck's on start's poking around and find's the 2 XJ's in pieces in the ole work shed. After asking "Bill" if it "was cool to do something with them" "Bill" had forgetting about them and not caring said "sure have at it". "Pete" seeing the 83 torn down cases cracked open and all turned to the 81 which had only the cylinders off decided that was the one to start on first. Now "Pete" being unenjoyed and almost broke used what he had to put the 81 back together. "Pete" to pay for things needed to put the 81 back to working order sold off part's of the 83 to pay for said item's. New gasket's, Oil, brushes, carb part's ETC. So after a time "Pete" get's the bike running but not very well and after some time throw's his hand's up and say's "F it" pushes the bike back under the old tree and moves on to other thing's. Some more time passes and along comes "Mr.Shovelhead" whom I have known for many many year's get's told of a project I'm working on and him being him "If it aint Harley it aint Sh*T" kind of additude comes over wanting to borrow a sheetmetal shear from me see's the XJ bobber and decides it's cool which surprises me. After a month or so goes by I get a call about his new project a 1981 XJ650 maxim. Turn's out "Bill" is one of the guy's he rides with and was talking about My Bobber project with. "Bill" informed "Mr.Shovelhead" he had one of those "sitting under a tree in his back 40" and would sell it to "Mr.Shovelhead" for a whole $35. And so now we are at this point with me jumping in to make sure it get's done right and to see her flying down the road soon!

I like a good story and history when it comes to thing's I'm working with or on. As I also was confused about the Mileage on the OD and the condition of the Bike. Now that I have the history nothing I will or "Mr.Shovelhead" find on this Bike will surprise Us.

 

>In a small town far and away there lived a little ole man who loved collecting anything with an engine running or not.....

Geez, every time I saw a name pop up in there, I was expecting to see MINE.

Dave F

 

Hahahaha!!!

Truth that Dave! You are surely not alone.


BTW that story could explain the super tight valves on a low OD in more than one way.