Low compression and low power, cheapest fix?

[XSokieSPECIAL]

If you run lean you can damage a motor

An ENGINE Steve!!

Your washing machine runs on a MOTOR, your scoot and your cage runs on an ENGINE!!

Just sayin'

You think maybe there is some holes burnt in the pistons from running lean?

If you've got access to a scope BossMaverick you might want to scope those cylinders, Or just pull the head and see.

That would cause a great deal of blow by and loss of compression/power.

[Ken Talbot]

Geez Ken, been waiting since 2004 for the "more to come" part!!!

Well, that Special turned into a Winter Project that winter. You know, the one with the small big-bore kit, stripped to the frame, all the powder coated parts, etc, etc. The project got 'stalled' the year I broke my shoulder, and I just haven't got it restarted - yet!

TMSAISTI

[BossMaverick]

If it turns out to need rings/cylinders you can find a pistons/rings and cyliinders set that came from a running bike on e-bay. With patients you can get them cheap. Less than $50 shipped.

If I go with this option, shoudn't I still get new rings for the pistons so I'm not fighting the same battle later on?

How much is too much to pay for a used engine without compression numbers? I located one 500 miles away and he's asking $200 but it's the same mileage as mine and he can't do a compression test as its already out of the parted out bike. All he can tell me is that it ran before being parted. I'm leaning towards not getting this engine since it would cost about $400 with travel expenses to get it.

I might have a lead on an engine locally from a '81 or '82 custom. I won't be able to find out if he still has it until the shop is open Monday or Tuesday. Would those engine years be a "drop in" engine or would I also have to switch ignitions, carbs, etc? Knowing who this person is, I'm already guessing he will want way too much money for it (one of those he has it and I need it so the price goes from cheap to costing an arm, leg, and kidney).

[trbig]

Just be patient and watch around on Craigslist. The prices you're quoting for an engine will buy you a whole new bike... and then think of all the parts you can either have, or make your money back selling.

I see a listing in Townsend, Montana where they're parting one out.. did you contact them?

Right now is a good time of year to be looking.. until about the end of Feb. You aren't going for a ride any time real soon anyway, so be patient and watch for a good deal.


Tod

[BossMaverick]

Townsend was the one engine for $200, Montana is a big state. Thanks for reminding me about being patient. I've had the urge to ride for about a week now and everytime I look at my bike the urge gets worse. Dang snow, ice, and negative temperatures...

[XSokieSPECIAL]

I've had the urge to ride for about a week now and everytime I look at my bike the urge gets worse. Dang snow, ice, and negative temperatures...

Like I keep telling my sons " move down below the arctic circle".

But, looking outside it looks kinda like a Montana winter here in Oklahoma right now.

[DGXSER]

Know the feeling Ken. I have this project bike and have almost finished it up. Then the carbs flooded the engine crankcase with gas!

So now I need to recheck the fuel tank cleaning I did, and pull the carbs back off, add in line filters like I should have , and dang it is friggin cold in the garage for doing all that right now!!

[Crazcnuk]

Problem with buying a used engine is that it may be no better than what you have. Unless you can find one with reliable test numbers, it's a game of Russian Roulette.

On the up side, if you decide to tear into yours, you likely do not have to touch the bottom end. (I assume you've had no strange issues or noises?)

What you need are:

1) Rings. (Wait until you get it apart to measure so you know what you need.)
2) Gasket set @ $80 on Ebay
3) Cam chain (optional but recommended)
4) Piston retainer rings (also optional)


You will need access to tools to measure your bores, and a cylinder hone is handy. You can also get a hand lapping tool for under $10. I used a c-clamp with a modified socket to take the valve springs off/on.

Watch our other thread as to what Hastings has for rings. Hoepfully they will have ones that work for cheap.

The top end just involves pulling the head and barrels off. Can be done in the bike, w/o too much trouble. Plenty of threads about getting the barrels off.

[motorhead]

[QUOTE=XSokieSPECIAL;250555]An ENGINE Steve!!

Your washing machine runs on a MOTOR, your scoot and your cage runs on an ENGINE!!

I used to have this argument .Google it ,it has become kinda generic....motor=engine.
I know it used to be!
electric= motor
internal combustion = engine
I say motor, cause it sounds cooler

[motorhead]

Bossmaverick your getting good advice on doing your own topend ,Then you know what you have .Plus you'll have the satisfaction of saying you did it .I Think you should pull topend before ordering parts .Depending on cylinder damage you may need an overbore with new pistons .Look carefully at your old stuff and diagnoise what happened to damage what you have .If you aren't that familier, show the pistons to an area racer .They usually have experience with what "lean" looks like.Holes in top of piston ,lifted upper ring land .You can tell by looking .If lean is what caused it .You'd better go back thru carbs ,petcocks,lines ,filter on petcocks in tank.Make sure on mainjet .It's better to be a little rich initially and slowly jet down till you like the way your plugs look .Just trying to help .

[XSokieSPECIAL]

[QUOTE=motorhead;250619]

An ENGINE Steve!!

Your washing machine runs on a MOTOR, your scoot and your cage runs on an ENGINE!!

I used to have this argument .Google it ,it has become kinda generic....motor=engine.
I know it used to be!
electric= motor
internal combustion = engine
I say motor, cause it sounds cooler

Ok man,

I guess if we called them all engines then a motor boat would have to be an engine boat, and a motor head would have to be an engine head!

And that wouldn't LOOK cool.

[red bandit]

My suggestion was merely the cheapest fix. If you go this route the specs should be checked before you install. If the specs are there no need to put new rings in, cheapest fix. Used parts, engines, bikes are a gamble. Ask questions from seller first. If they seem to avoid your question, don't buy. Be patient. In the last few months I've bought a mostly there parts bike w/ good running engine for $100, (2 hr drive) and a cylinder/pistons set (diff. seller) delivered for $20 in very good condition. Be patient. And like they said, see what you need first. Sometimes you can find a complete bike for what this route (plus gaskets) would cost. Be patient, be patient, be patient.

[trbig]

Nothing new, but I have to disagree with Crazcnuk. If a motor is having that much blow-by and tired enough that it has very little compression, just rings isn't going to do you any good.

As a piston goes up, the rod is at an angle and forces a lot of pressure sideways against the cylinder wall. Over time, this makes the cylinders egg-shaped and also puts a lot of wear on the piston skirt. Simply throwing round rings into an egg shape isn't going to make it re-seal. So after spending nearly $200 on rings and nearly another $100 on gaskets, you'll still have the same problem. And if the top end is that worn out, you better be prepared to replace crank and rod bearings also.

With the longevity of these motors, if you can find one with 40k miles or less on them for cheap, it should be fine... even if the previous guy was terrible about changing oil.

Also, even if a motor is out, more than likely the starter is still on it... or easily thrown back on. Get a battery, ground the negative to the motor and hit the positive. Pull the spark plugs out first of course, but you can still check the compression. If it doesn't have at least 100 pounds, cold and dry there, or if one of the cylinders is way off the others, I'd walk away.

Tod

[rpgoerlich]

A couple deals out there:
78XS11 $250
FREE 79' YAMAHA XS 1100
XS11 starters

[Crazcnuk]

Again, TR, you're assuming the worst, before you get in there. I did say MEASURE did I not?

Yes, you will have to measure everything, and you may even need a set of barrels, but they are not that expensive.

With a 30yr old bike how DO you know when one has low miles (for sure)?

My theory is, if you're thinking of replacing, anyway, take it apart and look. IF you find it doesn't need much, awesome, if it needs too much, then by all means look for some other solution.