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PostPosted: Sun Jul 20, 2008 11:02 am 
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Joined: Nov 2, 2006
Country: USA
State/Province: CA
City: Santa Rosa
thanks.
I hope to get to the valve adjustment this afternoon.

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 Post subject:
PostPosted: Sun Aug 03, 2008 5:35 pm 
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Joined: Nov 2, 2006
Country: USA
State/Province: CA
City: Santa Rosa
My partner and I adjusted the valves and tightened the head bolts and nuts. I now hear the valves tapping, they're not real loud, but I didn't hear them before the adj. We adjusted them to 0.003 inch and the work was done on a cold engine.

We also replaced the spark plugs. They have a lot of carbon on them. Indicating a too rich mixture?

My bike has always idled a little rough, not real rough, but just enough to notice it. I assumed that was from the PO letting it sit for a year. About once every 6 weeks or so it will die when given gas from a dead stop. I've run through one tank of gas with the recommended amount of seafoam, but since the valve adj the idle seems just a little worse.

Thoughts, comments?

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PostPosted: Fri Aug 08, 2008 10:52 am 
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Joined: Dec 5, 2004
Country: USA
State/Province: MN
City: Fergus Falls
.003" is .076 mm. Your valves are probably just a little too loose still which is causing the ticking.

For the rough running, you might want to pull the carb and check how clean it is. There are a few posts around here on how to do that.

The plugs should also be a tan color. You could check your air filter and make sure it is clean, and also clean out the carb. Put in a fresh set of plugs and see what happens.

Tom O.

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 Post subject:
PostPosted: Sun Aug 10, 2008 10:22 am 
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Joined: Nov 2, 2006
Country: USA
State/Province: CA
City: Santa Rosa
Thanks Tom.

I checked the new plugs last night. After only 100 miles they have carbon beginning for form.

I also checked the air filter. It is not very dirty, but when I opened up the air cleaner compartment, the bracket [Rebel manual calls it the setting plate] just fell out. Because the bracket wasn't in correctly, the air filter was not held correctly in place to the opening in the side of the air cleaner housing.

Would that cause or contribute to the plugs fouling with carbon?

I have thought about pulling the carb, but I thought I would run a couple of tanks of gas with the appropriate amount of Seafoam before I pull the carb.

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 Post subject:
PostPosted: Mon Aug 11, 2008 1:22 pm 
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Joined: Dec 5, 2004
Country: USA
State/Province: MN
City: Fergus Falls
Seafoam can do good things, but it isn't a miracle worker.
I'd still pull the carb and do a full work-over on it.

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 Post subject:
PostPosted: Wed Aug 13, 2008 9:12 am 
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Joined: Nov 2, 2006
Country: USA
State/Province: CA
City: Santa Rosa
Thanks Tom.
If I pull the carb and get it back together in one try I'll be a miracle worker. :D

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Courage is being scared to death... and saddling up anyway.
Bravery is being the only one who knows you're afraid.


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 Post subject:
PostPosted: Tue Apr 07, 2009 10:42 pm 
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Joined: Jan 4, 2009
Motorcycle: '85 Honda Rebel 250
Rebel: 250
Country: USA
State/Province: IL
City: Carbondale
So this may be a dumb question, but I'm not really sure what I'm accomplishing by adjusting the valves. I'm thinking that the distance the valves travel effects the amount of fuel/air mixture drawn in with each stroke (is this correct?). Apart from getting rid of the clicking sound people complain of (which either I'm not hearing or I don't know what to listen for), what does the adjustment do? Does it have any affect on fuel efficiency? Is it typical to notice improved performance after an adjustment? My bike is an '85 with just under 4k miles on it (original owner didn't ride it much...) so I assume it's never been adjusted. I plan to do the scheduled adjustment next month though I haven't noticed any clicking or problems, and am just curious what I'll actually be fixing when I do the adjustment.

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 Post subject:
PostPosted: Tue Apr 07, 2009 11:31 pm 
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Joined: Oct 16, 2005
Motorcycle: 2014 CB500XA
Rebel: None
Country: USA
State/Province: AZ
City: Green Valley
You have the basics, but, if the gap is too small the valve closes late. A tad less and it doesn't close completely or sticks. So you have hot burning gases escaping during the explosive stroke. This results in burned valves and probably a valve seat regrind/valve replacement situation.

Right is best, but if you are going to err, it is safer to err on the "a tad loose" side.

What is scary, is that I know a few folks who intentionally run their valves tight for the small performance gain.

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 Post subject:
PostPosted: Thu May 14, 2009 1:18 pm 
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Joined: May 17, 2008
Motorcycle: Suzuki V-Strom DL650K9
Rebel: None
Country: USA
State/Province: KY
City: Louisville
Ok, SOOOO... I decided to perform the valve lash adjustment this morning on my 08' Rebel 250. Over the past year I have read everything I could on the Rebel250.com website with regards to this task.

Surprisingly, this was easier than I thought it would be. All the little engine parts were so much smaller than I expected. It was like working on a toy. Very cute.

After reading everything I could on the site over the past year, I didn't even have to refer back here during the process. The only thing I used were tools and my 2008 CMX250C service manual.

The manual lists 0.002-0.004 inch. I chose to go the middle of the road with 0.003. Before I loosened the tappet lock nuts I checked the gap on the valves. (.002 fit), (.003 fit), (.004 fit), (.005 NO fit). They were all 0.004 which is in spec but I decided that it was probably heading in the loose direction so I adjusted them to down to 0.003.

Interestingly enough I did not have the right tools for the job, that is, I did not have a proper box, offset wrench for the tappet lock nut or a tool for the tappet itself. I had to use a 9mm socket and ratchet. There is no way to secure the tappet while tightening the lock nut so I resorted to an old fashioned, time tested method.

I used the 0.004 gauge to get the tappet in position so that when I locked the nut down, the tappet would roll into spec at 0.003. Granted, it took a couple of tries on each one but not necessarily a painful procedure and it went quickly.

In the end I was able to adjust the tappets so that the 0.003 would slide in and feel a slight drag where the 0.004 would not want to slide in. I adjusted all four the exact same way, and tightened the tappet lock nuts down with my trusty beam type torque wrench. 7 ft-lb. The valve cover, exactly the same 7 ft-lb. I didn't Mike Lance anything.

Total procedure time about 1.5 hours including seat and tank.

I took her out for a test ride and I didn't see any real difference in performance. I warmed the bike up well before I hit the road to make sure I would see the actual performance of it. It operated pretty much the same as it did before.

Typically with my 220 lbs on it, it never was a super champ at getting up to 70+ unless I had the wind at my back. 67+/- into the wind provided it was not a stiff breeze; the winds are calm today and out of the southwest at maybe 5 mph. These are about the same results I achieved after the valve adjustments and I did hit 75 with the wind at my back. These are GPS measurements, not the speedo.

I will call this is a success. It still would be nice if this bike would hit at least 70 on command.

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 Post subject:
PostPosted: Thu May 28, 2009 12:47 pm 
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Joined: May 26, 2009
Country: USA
State/Province: TX
City: Tyler
Well i have been thinking about adjusting the valves on my bike but for one, ive never gone into the inside of one of these small engines. Have done so to many chevy engines but not a mini honda. My bike has almost 10k miles on it right now and i dont know for sure but i would say, just since when i got the bike there was no fuel filter on it, and didnt look like it had too many regular services, that the PO did not adjust the valves in its lifetime. Soooo lets just say that they have never been adjusted at 10k. Is it time to adjust them??? I dont really want to take something apart if its not really necessary. I dont notice any noise coming from the valves, although there is a light clicking at the motor i just assume thats what this guy is supposed to sound like. It performs just fine so i dont see the need to adjust them but id like some input from some here who know about the regular sounds of this bike and what mine is up to.


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 Post subject:
PostPosted: Thu May 28, 2009 1:09 pm 
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Joined: Sep 9, 2004
Motorcycle: Suzuki Gsf1250
Rebel: 450
Country: Canada
State/Province: NB
City: Rusagonis
sarends wrote:
Is it time to adjust them??? ... I dont notice any noise coming from the valves, although there is a light clicking at the motor I just assume thats what this guy is supposed to sound like..


Yes, its time. And there is always the chance that your valves are wearing tighter rather than looser. (It DOES happen sometimes), and while loose valves are noisy and steal power, tight valves can be lethal. So, yeah, do it. If you've been inside older Chev engines, you'll feel right at home.
brent


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 Post subject:
PostPosted: Thu May 28, 2009 1:40 pm 
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Joined: May 26, 2009
Country: USA
State/Province: TX
City: Tyler
Well then i guess ill head up the road to my buddys garage to borrow some feeler gauges. This article here explains it all really i just didnt want to get into if i didnt need to but it never hurts. I use to adjust the valves on my old camaro every week sometimes 2 or 3 times a week. Just cause i could and i liked to hear it purrrrrr. Well that cat had a little more than a purrrr, more like a tiger growllllllllllllllll!! :lol:


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 Post subject:
PostPosted: Sun May 31, 2009 1:28 pm 
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Joined: May 26, 2009
Country: USA
State/Province: TX
City: Tyler
Well i went to go get some feeler guages and happened on a buddy who has been working in motorcycle shops for about 20 years and he looked over my bike, and said hes been listening to it for the last few weeks and he suggests that i dont adjust the valves on it. He said its running toooo smoothly to adjust the valves. I have to agree with him cause it does sound good right now. I think il wait on the valve adjustment for a bit.


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 Post subject:
PostPosted: Wed Jul 22, 2009 6:56 pm 
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Joined: Jul 21, 2009
THANK YOU TOM!!!

I just adjusted the valves on my bike and your guide was a tremendous help!!! I had the Cylmers book, but with very few pictures it didn't make to much sense..

And as for the adjustment, all I can say is, WOW! It's like a different bike. It's an '86 rebel 250 with 8100 miles, and I'm going to guess the valves have never been adjusted cause when I first got the head off, the rockers were loose enough to fit a .006" feeler with almost no resistance.

Again, I love this forum, thanks for all your help guys!!!

Matt


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 Post subject: Get a LARGE screwdriver!!!
PostPosted: Wed Nov 11, 2009 6:11 pm 
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Joined: Oct 11, 2009
Just want to mention that to get the crankshaft cap and timing cap off the engine with minimal damage and cussin', you need a VERY LARGE flathead screwdriver. The head has to be both wide and thick.

I bent many a coin and banged up my caps pretty good with some medium sized screwdrivers.
Then I got smart and went to Sears, got a 3/8" Screwdriver:
http://www.sears.com/shc/s/p_10153_1260 ... rewdrivers

And it is SO easy when you have the right tool.


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 Post subject:
PostPosted: Wed Nov 11, 2009 8:45 pm 
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Joined: Oct 16, 2005
Motorcycle: 2014 CB500XA
Rebel: None
Country: USA
State/Province: AZ
City: Green Valley
A silver dollar works pretty well, too.

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 Post subject: Better advice than the manual
PostPosted: Sun Jul 11, 2010 9:32 pm 
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Joined: Sep 1, 2009
Country: USA
State/Province: NJ
thanks for the clear color photos! Made this much easier than it could have gone-


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 Post subject:
PostPosted: Wed Aug 25, 2010 3:31 pm 
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Joined: Aug 24, 2010
After reading this thread, I adjusted the valves on my son's newly aquired 2005 Nighthawk 250.

I did a couple of time saving tricks that seemed to have worked well.

Instead of pulling the crankbolt plug and turning the engine with a wrench, I shifted to top gear and just rolled it on the floor to turn the engine.

I didn't pulle the flywheel indicator plug either. I turned the engine over until the notch on the cam was facing forward or back and adjusted the cylinder at TDC.

Motor is now very quiet.

My owner's manual doesn't give a range of valve adjustement, only .003".


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 Post subject:
PostPosted: Thu Aug 26, 2010 7:48 pm 
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Joined: Aug 24, 2010
Motorcycle: CMX
Rebel: 250
Country: USA
State/Province: OH
City: Cleveland (Willoughby)
jsonder wrote:
A silver dollar works pretty well, too.


Great tip!!

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 Post subject:
PostPosted: Thu Aug 26, 2010 8:31 pm 
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Joined: Feb 23, 2009
Motorcycle: Rebel 250 plus a few others
Rebel: 250
Country: Canada
State/Province: NB
City: Fredericton
Quietness is not the goal of valve adjustment. .003 is the goal. Too quiet is worse than too noisy since it indicates tight clearance. You are correct that the precise position of the crank is not too crucial as long as the cam follower is definitely on the round part of the cam and not a lift section.

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