OK you certified wrench turners...

[mro]

bearings

Not gong to be able to check rod bearings thru pan. Can get to 2 and 3 thru pan but not enough room to check em.

If your going to check the bearings, doing so by trying to "wiggle em by hand" will only let you know if one is "real bad".

Should check w/plastigauge.

Don't do this w/o manual........
Splitting cases not that hard, but takes some time. After you get the bottom case off, all the bearings are easy to get to. Check mains while in there.

The case bolt holes are numbered. I take a piece of card board and pop holes in it to hold bolts as I remove em (One piece for top, another for bottom, felt pen number card board holes). Place other parts that go together in plastic bags.

[Originally posted by Geezer[/I]
Piston slap sounds like a rattle at and idle and usually goes away at higher RPM.

Can sorta sound like a rod knock, but not (sorry....hard to explain noise) and can get Louder under load. Sound may seem to originate from other than cylinders.

Should be noticeable scratches on piston with corresponding scratches on cylinder wall. Will just get worse longer engine is run.

On the one engine I repaired for this, #3 cylinder was just with in spec and so was the piston, but there were the scratches. (think one bolt was coming loose on rod cap) Was just going to hone cylinder and stick in new piston/rod/rings/bearing (bearing was in spec too). But then felt uncomfortable about cylinder, so replaced cylinder and pistons etc. from a parts bike. Good as new.


mro
btw
my 80G might be developing "piston slap" and sorta sounds like what Geezer describes, but going to ride it till bad and then do like I did to other one.

[trbig]

There doesn't seem to be any problems with clearance for the valves, and they are shimmed to the XJ specs which actually would open them further. The problem (If that's what it is) is the carbon around the edges of the piston where the combustion looks to be not quite as complete as the center, and the carbon that has built up around the top of the cylinder.... The small space that is left between the cylinder and the head after the piston gets to TDC (Maybe 1/8th inch??)
I have almost always run Marvel mystery oil through this, thinking that it was cleaning it (That's what it claims anyway) Looks like next time, I may try the Seafoam and seee what happens. I always the the MMO would help keep everything in the top end lubed and make the motor last longer. That seems to be my problem alot of the time.... thinkin'!

As for the oil... I have used Roteela 20-50 exclusively.

Thanks for your input. I will check the filter and pan for shavings when I can see again... lol. <<<< I hope that's a hell of a lot funnier for you than me! If I don't see any, I'm going to wheel grind the carbon off, slap it back together and see what happens for now.
Tod

[mro]

I have almost always run Marvel mystery oil through this, thinking that it was cleaning it (That's what it claims anyway) Looks like next time, I may try the Seafoam and seee what happens. I always the the MMO would help keep everything in the top end lubed and make the motor last longer. That seems to be my problem alot of the time.... thinkin'!

Engine last longer.........planned maintenance, and don't ride it like I do mine.

All those additives and such............aren’t worth the money, do regular maintenance, clean/fix when needed. (IMPHO)


mro

[HobbyMan]

I have only noticed a difference using things like marvel mystery oil and sea foam when you put them full strength in direct contact with the carbon and grime and letting them set for a while. I really don't think running them through the gas tank makes that much of a difference. Any other "walmart" addatives definitely don't do anything drastic. They are all probably made out of the same stuff. To get the best out of MMO or sea foam, I have found that if you let it soak for a while, it makes a difference. If you haven't seen my thread documenting this what a difference
And yes, regualr maintainance is the key.

[trbig]

There is a product made for 2-stroke motors.. can't think of the name right now, but you spray it directly into the throat of the carbs with the engine running. It is kind of foamyAfter the can is empty, you kill it and you let it sit a while. Then start it and run a bit... it too will smoke up the entire yard... block.. neighborhood, and possibly county!.. lol. It will smoke for a good 30 minutes, but it works great at breaking all that carbon apart... may find it and see if there's any warning on using it on 4 strokes. I use it on my 4 cyl. outboard, and it keeps everything cleaned up in it.

My eye feels a little better today, but I have to go in this morning and let them look at it again... see if they want to scrape and gouge on it some more. The medicine they gave me is keeping one eye dilated though (My dominant eye).. so kinda tough. Maybe be able to at least drain the oil and take the filter out and look at it later.

Tod

[Do Lee]

If the carbon build-up is hitting the top of the heads or the valves due to the larger XJ valves or even the valves hitting the top of the piston ypu should see a shiny area where the peices touch. If its a deep knock, hammering sound I would check crank and rod bearings. If it a loud tapping noise I would check valves, cams, guides & cam chain.

I've used Evinrude Engine Tuner. Works great breaking up the carbon, varnish build-up and crud. I use it to clean the passages in the carberators. Works as a spray on and spray in carb. with engine running. Does not damage rubber parts. It costs about $8.00 a can.

[trbig]

If the carbon build-up is hitting the top of the heads or the valves due to the larger XJ valves or even the valves hitting the top of the piston ypu should see a shiny area where the peices touch.

As stated before, there seems to be NO problems with valves hitting anything. There is a small lip of carbon on the cylinder wall at the very top of the cylinder, and a buildup on the edges of the piston. IF it's hitting, this is where it will be.

If it a loud tapping noise I would check valves, cams, guides & cam chain.

Again... as stated before, everything including cams cam bearings, valve adjustment, and timing chain with guides have been checked. Everything has been checked so far, and all that really remains to be ruled out is the crank and rod bearings. I will check those by looking for shavings in the oil... possibly tonight. Doc didn't dig into my eye any more today, so I may be able to pull off a Popeye, and do it one-eyed tonight.

That does sound like the right stuff in the can though. Carbon is the killer of a 2-stroke... so I try to use it at least once a year. I don't see why you couldn't use it in a 4 stroke. It does make a better smoke bomb than anything you can get for the 4th of July though!! lol

Tod

[DiverRay]

Tod,
If you do have a LOT of carbon buildup on the pistons/heads, that can be the "knock" you hear when hot. The carbon WILL get hot and glow, setting off the fuel/air mix BEFORE the plug fires. This will cause problems and knocking in the engine.
I use Berryman's B12 Chemtool for cleaning out the carbon. It is very close to Seafoam, and works as well, I think. If the engine is apart, put a rag over the area to be cleaned and pour the chemtool on the rag. After about 5 minutes, you should be able to just wip the carbon off. If the engine is still together, warm it up, and then remove spark plugs and pour some down two of the holes that are near TDC. after about 10 minutes, turn engine 180 and repeate on second 2 cylinders.
Let set another 10 minutes, turn over SLOWLY 2 crank revolutions, reinstall plugs and fire.
You won't get as much smoke as MMO, but it WILL clean the inside of the combustion chamber.
Ray

[planedick]

Me too....

I have a "what I consider" a very noisy top end. I have been down all the usual avenues of remedy to no avail. I have looked in the cylinders with a bore-scope and there isn't any carbon deposits as you have, nice & clean with orange tint. I have since given up and just decided it is a noisy engine and just rode the hell out of it. After putting 16000 hard miles on it, it hasn't gotten any worse nor has it lost any compression. I have found that the valve clearance is a little on the tight side, but not enough to cause problems so I let it be. I figure for the money I have in this bike, I won't be too upset if it goes up in smoke. Besides with all the gurues here and so many scources for parts, it will be a long time before it is out of style. Besides all that, being 66 this month the darn bike will probably outlast me. LOL

[trbig]

Well...

It appears to be good news.... sort of. Every one of the rods seems to have absolutely NO play in them... and after draining the oil and removing the filter, I see not even the slightest HINT of any metal flakes, copper tint, or anything else that would point to a bearing going out. I guess this may be a good lesson for anyone else. If you hear a knocking... and your compression is good.. and nothing in your oil... try sea-foam or or some Berrymans first before tearing into it. It could save you alot of time, effort, and even an eye! lol.

Does anyone see a problem with making my own base gasket out of rolled gasket material? Is the thickness of this absolutely critical at this point? I think what I have and what was on there are very close, but didn't know if the crush thickness is something that has to be right on. I am just going to re-use the head gasket, since this motor isn't going to be expected to survive another year.. hopefully a few more months of sporadic (Winter coming on) riding. Otherwise, I'll have to order 2 gasket sets.. one for this motor.. and then another for the other motor. JUST the head gasket at my local shop is 100 bucks.. so the 78 bucks for the complete set online is by far the best buy. And TC... I plan on torquing this head to a little more than 14 pounds this time around!

Tod

[mro]

Gasket Recycle

If the used gasket is in good shape, spray it with Copper Coat (think that's what it's called)

Will help fill in imperfections and seal better. Have had no problems with engines I used it on in the past.

Should be available at local auto part store.




mro

[trbig]

The base gasket is destroyed. That's what makes the cylinders so hard to take off... the base gasket is stuck to both machined parts... (Cylinder base and motor block) and it gets torn apart in the process. The head gasket looks fine.
I was only concerened with the actual THICKNESS of the base gasket. I didn't know if a few thousandths would change the piston stroke in the cylinders enough to matter.

Tod

[Geezer]

A thicker base gasket would lower the compression a little but there wouldn't be any other effects.

Geezer

[trbig]

Maybe I'll just put an extra thick gasket on and leave the carbon alone.... lol


Tod

[chopwatchagot]

Make sure the new base gasket isn't too THIN or your valves WILL be hitting the pistons. Also I read in I think the Clymer's manual(?) that you shouldn't remove that ring of carbon around the top of the cylinder unless you are doing a complete overhaul. Supposedly to do so will adversely affect oil consumption