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Discussion Starter · #1 ·
Hi,

This post is to collect the thoughts I had posted on the introduction thread. To recap real quick,
1. I own a 77 Bonnie T140V.
2. She's not running right now.
3. She was running well over the summer, topping 105mph.
4. She started running rough as it got colder.
5. I let her sit over winter and now she won't start.
6. I checked compression and it was around 90psi both cylinders.
7. I checked the compression once more, after squirting a little oil through the spark plug hole. This time it yielded 115psi, 108psi, 104psi and then 95psi consistently in the left cylinder. The right cylinder consistently yielded around 95psi.
8. I am going to drain the gas tank and carbs, balance the carbs, replace the Pb-H2SO4 battery with a gel cell battery and give it a shot.
9. I am baffled as to what else to do other than a top end rebuild which will take time and wits, I'm sure.
10. Please help!
 

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I think you need to locate the reason/s for the troubles you describe.
Battery Voltage? (on load, headlight on)
Ignition timing/good spark.
When it was running, was the exhaust smokey?
What colour are the plugs?
Is it wet-sumping? Oil loss?
 

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Before you pull the top end off, go through the maintenance section of the service manual, page by page, and do everything in the section in the order it's shown in the book. DO NOT SKIP ANY STEPS; do the FULL maintenance.

Flush out all old gas in the tank, too.

THEN try the bike out again.
 

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Discussion Starter · #4 ·
Re:

Before it stopped running, the left cylinder was smokey. It does leak a little oil, but it has always had enough oil. Not sure what you mean by wet sumping.. I thought it was a dry sump with oil in the frame.
 

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GPZ is right , do the prescribed maintenance, if it started running rough in the fall chances are it requires a good tuneup but letting it sit over winter without preparing it probably means carbs are varnished up & need a good cleaning. With todays gas going bad as quick as it does possibly draining tank & carbs & using fresh gas will get it to run. 95 lbs is a bit low but more than enough compression to start & run bike. Start with the gas to see if it runs then go thru whole procedure to get it running right.
 

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There are many causes of `wet sumping`.
This condition results from wear/failure of engine components. Generally, oil escapes into the sump.
A check that I did, was to leave the bike on the centre stand (not at an angle) for a day...remove the crankcase filter (the angled sump drain), catch the oil that escapes in a container. If the quantity is more than 100ml, you`ve got problems.
Causes/remedies: [engine in the frame]
A quick oil pump check, remove the plugs and oil filler cap. Kick it over several times and ensure oil is returning to the reservoir.
Check that the oil-pressure release valve is not stuck open. Remove it, disassemble it and clean it.
If the oil pump seems inefficient, check the ball-valves are seating properly and not stuck.
Check/clean all oil filters.
Other than that you need to check the valves/guides, piston rings/bores head gasket, etc.
There are probably other things, but off the top of my head this is what I did.
 

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As I understand it, wet sumping is when the sump fills with oil. The oil pump is actually two pumps in one housing. One side provides oil pressure to feed the engine, the other side scavenges the oil from the bottom of the crackcase and returns it to the oil tank. It could be the oil pump isn't scavenging properly or it could be leaking past a check ball and draining back into the sump if it does it when sitting.
 

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Not sure what you mean by the FSM, but get yourself a Haynes manual, pop open a favorite beverage, and read it through.
 

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Discussion Starter · #10 ·
Re:

Not sure what you mean by the FSM, but get yourself a Haynes manual, pop open a favorite beverage, and read it through.
http://cgi.ebay.com/ebaymotors/Triu...30335817399QQptZMotorsQ5fManualsQ5fLiterature

That's the FSM, as issued to the dealers. In your (all the gurus on here) opinion, which is better: Haynes or the FSM (Factory Service Manual)?

I reckon Haynes has better pictures.. Thoughts? I'm going to buy one or the other within 24 hours, but not both (although I probably should).:cool:
 

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Eliza, If you can swing it, do get both books. Like the old saying goes, "Two heads are better than one". If I where only going to get one than I'd favor getting the Service Manual because of the good parts assembly diagrams. Good Luck
 
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