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1987 Rebel 250
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170 Posts
Discussion Starter · #1 · (Edited)
Bought the bike with left (drivers side) cylinder disconnected from head, no air filter. Started up and ran great, drove it 32 miles home (I know that's not good).

Replaced exhaust collar, gasket, and air filter runs great.

Replaced starter clutch (Chinese junk), ran like garbage, put old starter clutch back in (but with new Chinese internals), runs great, but now occasionally makes a "barking" or "honking goose" noise on start up.

Right side exhaust came loose while riding, drive it about 10 miles home. Looked like some oil was bubbling and boiling out of the valve cover gasket. Fixed exhaust, went to bed.

Today: Put some "engine restorer" in the oil, starts rough and stalls when given gas. Rev it to get it moving in first, runs okayish. Still runs rough.

What happened? It used to run 100% flawlessly!

Burnt valves from loose exhaust?
Engine restorer messed something up?
Something went wrong with starter clutch installation?

Help me out fellas

EDIT: Just went for 30 min ride. Seemed better. Still a little hesitating and sounded like backfiring? Liveable, but could be better
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #3 · (Edited)
Have you checked compression? Have you checked for intake leaks? Are you sure the “engine restorer” is okay for the wet clutch?
That's a good point. I think I'll buy a compression gauge and test.

For intake leaks, I'm guessing to spray carb cleaner near intake and see if RPM changes?

I should have researched engine restore; I didn't even think about the wet clutch

EDIT: Engine restore is not to be used on wet clutches. It will glaze over plates. I'm so dumb. I'm gonna change the oil, and hopefully I didn't do too much damage.
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1987 Rebel 250
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170 Posts
Discussion Starter · #5 ·
It felt fine when I was riding it. I guess we'll see. I flushed it with "motor flush" (this time I researched to make sure it was okay) and I'm going to refill with Valvoline 10w40 for motorcycles. How bad of a job are clutch plate installs?

I bought new plugs, got the carb soaking in chem dip, going to do valve clearance, and I cleaned the tank with "The Works." Check out what the PO left inside..... not sure what they are lol

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1987 Rebel 250
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170 Posts
Discussion Starter · #9 ·
I'm using a similar one. 12,000 miles on it so far no issues. The splines are already aligned (at least mine were), so, just as the old one can slide off as a set... the new one goes on as a set, with patience & a little dexterity. 30-45 minute job total. Just remember to soak the whole thing in engine oil for at least 4 hours before assembling, I left mine overnight.
Any kind of engine oil? Or specifically a motorcycle safe oil? Thanks!
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #16 ·
Tire Automotive tire Tread Motor vehicle Synthetic rubber


DANG IT MAN! I just soak these new clutch plates for a few hours and only now realized that the jug says it has friction modifiers 🤬🤬😡😡😡🤬😡

I thought since it was a W 50 it would be safe. Apparently I should read things. Man I can't get this right. I guess I'll throw them in and see what happens
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #18 ·
100psi left cylinder

85psi right cylinder

This might be game over boys. I'm guessing burnt valve/worn rings/scored walls, or something awful like that. I think I'll get it running and either live with it or sell it.
 

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1987 Rebel 250
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Discussion Starter · #20 ·
I didn't realize the engine had to be warm and the throttle wide open--once I did that, I got 140psi on the left side! This is also after I adjusted the valve clearances.
 

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1987 Rebel 250
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Discussion Starter · #23 ·
You might try drying them off and then soaking them in a light organic solvent like gasoline. Finally soak in non-ec oil.

--garicao

"Life is uncertain. Eat dessert first."
So plain old 10w40 for cars is ok to use? The clutch feels great for now. I figure for $22, I'll just ride it till it goes out and then replace.
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #29 ·

· Registered
1987 Rebel 250
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170 Posts
Discussion Starter · #31 ·
a wet vs dry compression test can tell a lot..
squirt a tablespoon of 30w through the plug hole and check compression again..
higher wet figures are indicative of collapsed rings..

Leak down tester to test valve seal and percentage of leak past rings..
shade tree version.
Use a compressor that can regulate output pressure and plumb 5psi to 10psi into cylinder,, listen at exhaust and carb for hiss with cylinder at TDC when valves should be closed.. shouldn't hear anything..
hiss will at oil filler will always be heard, real loud indicates lots of blow-by.
How hard is a ring job versus a valve replacement? They both sound like major surgery 🥺
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #33 · (Edited)
proper valve job would entail grinding seat and replacement valve to match..
at the very least knurling valve guides or replacing them..

Rings could be as simple as freeing up collapsed rings and honing cylinders or replacing with new rings & pistons if they are scored.
Both are major procedures..
Ride it till it dies it is then 😂. Maybe I'll throw some engine restorer in the cylinder holes and call it a day.

Could I just buy a gently used top end and swap it over? How hard would that be?
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #36 ·
Will these $13 fleaBay valves work (just pricing things out in case it is the valves)?. The OEM set are hundreds, and this one is literally $13. But maybe it's made of monkeymetal.
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1987 Rebel 250
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Discussion Starter · #38 ·
basically 1st and 2nd gen Rebel valve specs are the same except Valve seat width is wider on 1st gen..
part numbers are different and 1st gen intake valve is listed as Unavailable

does your leak down test indicate valves are loosing compression?
Left dry: 145psi
Right dry: 115psi

Left wet: 175psi
Right wet: 145psi

Not good. I'm guessing a burnt exhaust valve on the right, and bad rings for both?

This might be it for me. Valve job and rings seem too much work for me to attempt (with kids, wife, job, etc) and too much to pay someone to do (I'm guessing at least $800).

I don't have a compressor so can't do leak down, but it seems like I'm screwed.
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #41 ·
I really doubt the valves are burnt.. Don't know why you feel they are without proof..
There are Used and New P&C sets for sale on eBay which will likely solve your compression problems.
That cylinder that's at 115 dry had the exhaust disconnected for years (by PO), so I assumed that since the psi remained low even after adding oil to the cylinder, that it just be more than the rings leaking, and that's it's probable (given the above) that the exhaust valve could be burnt. I'll be happy if I'm wrong. I really don't want to replace valves.

Partzilla has the gen1 and gen2 cylinders as different part numbers, so I thought those eBay kits wouldn't work. I was even thinking about going with the 280cc, but that seems like a gen2 part as well. I guess I could swap the top end to gen2 and that would work.

I'm very open to suggestions. Called tons of shops, and no one is willing to touch my bike......
 

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1987 Rebel 250
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170 Posts
Discussion Starter · #43 ·
imho you should disassemble the engine first to discover what is needed..
1st generation has different cam, lobes were ground differently and slightly higher rise which I believe is responsible for increased horse power over 2nd gen Rebel.. 2nd gen head is a downgrade

Differences in cylinders that I have noted 1st gen used 4 dowel pins and 3 stud gaskets

While the 2nd gen cylinder used only 2 dowel pins and no stud gaskets..

1st gen members who have ordered Head Gaskets have received 2nd gen gaskets.
Two of the head gasket holes are too small to use 2 of the dowel pins which can be discarded..

unproven Big Bore cylinder may be a waste of money and you won't hear from Elchico as he was able to get himself banned within 3 weeks of joining..
That was very helpful. I really appreciate it!

Can I ride the rest of the season with low compression? Or should I tear it down as soon as I can?
 
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