Old motor

[MikeScoot]

After finding a HUGE variation in compression between the pots on my #1 bike, I checked the compression on the spare (#2) bike. It was last registered in 2003, and I think it's safe to assume it hasn't really run since then.

Don't laugh, but it showed an encouraging 50PSI (dry) on BOTH POTS! Why do I think that's good? Well because they both have similar readings.

Have whacked some de-choker in and will check the result in the morning. I really wanted to get som Yamaha Ring Free but there seems to be none on the shelf in Australia. They can get some sent over from New Zealand but that will take a couple of weeks. So I used a ThreeBond product and also bought some Mercury Power Tune (engine cleaner).

Why am I writing all this drivel? lolol Cos nobody else would give a rats about this sort of thing.

Even if the compression doesn't come up much I'll swap it into the #1 bike (because it has MUCH tidier electrics that all seem to work, whereas #2's electrics look like a mad woman's breakfast and NOTHING works) and give it a try.

If all this fails I'm afraid I'll just have to offload both bikes in one way or another.

[kevin g]

When I was getting my '83 running I measured 150psi compression on both cylinders.  My front cylinder would not fire and it was traced to a clogged idle passage in the bottom of the float bowl.

[MikeScoot]

That's useful information, Kevin. Thanks. I'll pay particular attention to those idle passages.
Continued with painting this morning and just let the de-choker do its thing in the #2 engine. Then in the arvo I flushed the pots with WD40 and threw in some more de-choker. I'll do this again tomorrow if the compression hasn't come up.

Patience is a virtue. :-)

[MikeScoot]

I'm REALLY HAPPY right now! When I first tested the #2 engine it only had around 50PSI in both pots. I ran some Threebond cleaning stuff throuigh it, flushed with WD40 and repeated a couple of times.

Today I flushed it (twice) and checked then compression - 125 beautiful PSI!!! I'm really happy! Now to swap that motor into the #1 bike, which is infinitely tidier - especially since the electrics on #1 haven't been hacked to blazes.

Did I mention I was happy?  :-) :-) :-)

[Walt_M.]

Excellent result! Do yourself a favor while you have the engine out and check the valve clearance. it's kind of a pain to do it in place. It may be ok but you won't have to question when it was done.

[MikeScoot]

Cheers, Walt. Thanks. I'll do that right after I give the motor a really good clean.

Also, I checked with the head mechanic at the yocal Yammie dealership and they can do a shim job (if necc.) for about $100 if the motor is out.

(just written a big "check clearances" notice to myself) :-)

Cheers,
Mike

[injuhneer]

Can the folks in OZ get their hands on the AC Delco Top Engine cleaner? I have used it to break free the rings on chronically smoking Saturn engines. They are infamous for the oil rings getting stuck (no drain holes on the oil ring land). I figured the stuff was worth a shot and much cheaper than a ring replacement.

Another option is Marvel Mystery Oil.

[MikeScoot]

G'day Mike.

Thanks for the tip on the Delco stuff but I probably don't have much immediate need for it now because my other motor has free'd-up.

Of course it would still be good to have a ready spare motor so I won't give up on the crook motor, but I do suspect there's something seriously mechanically wrong with its rear piston or rings. I do have a 7mm endoscope (borescope?) on the way and it will be interesting to see if that is of any use in identifying the problem.

But now it's time to concentrate on cleaning and checking the good motor and getting it into the #1 bike.

Cheers

[kevin g]

Does your local shop still have the special tool that is used to hold the valve buckets down to remove the shims?  Otherwise the cams have to be removed which is not hard.  When I got my bike it had not run in years and I found the front cylinder did not have the cam timed properly.  I suspect that someone removed the cams to adjust the valves and did not get the cam back in correctly.

[MikeScoot]

More very useful info, Thanks Kevin.

This thing looks like it might have had a shim job just before it was put out of service because the clearances are all (bar one) right on their maximums. The one that isn't on the max. is still well within service specs. Happy about that 'cos I've saved a few bucks!

The Haynes manual seemed a bit vague on the flywheel positioning, either that or one of my cams is also out of it's correct position. Bit tired now after a long day of thorough engine cleaning, manual deciphering, swapping parts between bikes, running around town to get decent feelers etc. Will review the manual tonight and recheck the cams and clearances tomorrow morning. Time now to tidy up and get some tucker on the way.

[kevin g]

The manual is confusing on the cam positioning.  The indexing pins and other markings are all easy to identify.  The thing that seems odd is that one cylinder has the cam lobes facing in at TDC on the compression stroke and the other cylinder has the lobes facing out at TDC on compression.

[MikeScoot]

That's EXACTLY what I wasn't comfortable with.  :-) I checked again against the 1T mark for front and the 2T mark for the rear and it all made sense. Remounted the rear exhaust 'Y' piece and spent most of the afternoon and early evening trying to wrangle the engine back in without disturbing the 'Y' piece. Knocked it hard a couple of times but it seems OK. Fingers crossed.
Tricky getting the engine lined up for that first long stud at the back! Within about 5mm but it's dark outside now and the mozzies are thick!
Time for a few beers! :-)

[MikeScoot]

Happy to be able to report that my 11H motor is running quite well! IT'S ALIVE!!!

[Walt_M.]

That's good news, another step forward.

[MikeScoot]

:-) and the cooling system all seems to work as it should too. Gauge works and the fan kicks in when it should.

[WGuaire]

:-) and the cooling system all seems to work as it should too. Gauge works and the fan kicks in when it should.

My was doing that. But, the temp would rise as I drove. The thermostat was not opening to let the coolant flow.
I used an automotive thermostat for a 1993 Nissan Sentra 1.6L engine. $6 and change.

[MikeScoot]

I'm pretty sure the coolant is cycled through the radiator at all times and that the thermostat simply controls when to activate the fan.  The temperature sending unit measures temperature and sends an appropriate signal to the temp. gauge on the dash.

[WGuaire]

The coolant flows when the thermostat gets heated, then it opens to let coolant flow. The temp sensor for the fan is separate.

http://ridersofvision.net/rovforum/index.php?topic=15953.msg147491#msg147491

[jefferson]

There is a coolant bypass hose so yes the coolant flows through the radiator all the time. It is not enough to cool the motor though so the thermostat opens for more flow when then temp gets there.

[MikeScoot]

Sorry. My mistake. I thought you were talking about the thermostatic switch.