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1987 Rebel 250
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Discussion Starter · #1 ·
Is it practical to put a 13t, 12t, or smaller on the front of a 87' 250 CMX? I don't need to go above 55 ever. I spent most of my time joy-riding in the country at 30-35. I don't plan to ever go on the interstate.

I'm getting mileage may suffer and I'll have to shift through gears really fast?
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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If you're just putting around town & on back roads. Then I that the factory sprockets are probably best. But I've always gone larger front & smaller back sprockets. I like the more mellow sound. To me the original gearing sounds too hyper at speed. But... you said never above 55mph. Still, I'm normally into 2nd as I get through an intersection.
 
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1987 Rebel 250
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Discussion Starter · #3 ·
So, my bike maxes out at about 65mph in 4th gear; if I shift into 5th, the rpms go down, but I don't go faster.

Would installing a smaller front sprocket then make sense? Maybe I'd get more acceleration + be able to make use of 5th?
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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Something is obviously wrong. With an 87 you should easily be able to hit 80 mph with the stock gearing.
I wish I had time the other day to take it for a test ride. I'll have to schedule a time to ride over there again.
 
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What is your current front and rear sprocket size?
 
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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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14:33 is stock.
 
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If it won't accelerate well, and the gearing is stock, something isn't right.
 
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1987 Rebel 250
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Discussion Starter · #9 ·
I just confirmed that the gearing is 14/33

It is a bit slow, but it seems to run ok. With me being 145lbs, the bike 30lbs lighter than stock, and this being an 87, you'd think it would have no problem getting up to speed.

I figure since I don't use 55+ anyways, if I reduce my front gear to 12 or so, maybe I'll top out at 55 but have better acceleration.

I cleaned the carb and tank, I'm not sure what else could be going on performance-wise. New plugs, new air element, exhaust is tight, mix screw 2.25 turns out, new clutch. It does pop a little bit, which Emil told me was too lean. If I choke it more than 1/4 way though, it just dies. Not going to lie though, going 65mph feels terrifying on this bike.
 

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Going to a smaller front sprocket isn't going to fix what's wrong with the bike. I can't definitively tell you what's wrong, but dirty carbs are the leading cause of poor engine performance.

Are you new to riding? If not, why is 65 mph on a Rebel terrifying to you?
 

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1987 Rebel 250
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Discussion Starter · #11 ·
I may soak the carbs for another few days and see how that goes.

I've been riding for about 15 years. I used to get up to 100mph with my Vulcan 500, but the Rebel in comparison feels squirrelly and vibrates a ton at high speed lol. The Rebel has sweet spots where there's no vibration (e.g., 3rd gear 40mph and 4th @ 50mph), but most of the time the vibration is nuts. Maybe my last cruiser was just exceptionally smooth. It could just be that this bike has had a hard life, and it's worn out.
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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The engine mounts are normally the primary cause of a strong vibration. 1987 means 35 year old mounts. Time & weather does a lot to rubber. I've replaced many engine mounts & loved the resulting smoothness. I actually had 1 engine vibrate so bad that the gas in the float bowl seemed to be getting aerated causing issues. After fixing the mounts, these issues with how it ran dissapeared.
 
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1987 Rebel 250
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Discussion Starter · #13 ·
The engine mounts are normally the primary cause of a strong vibration. 1987 means 35 year old mounts. Time & weather does a lot to rubber. I've replaced many engine mounts & loved the resulting smoothness. I actually had 1 engine vibrate so bad that the gas in the float bowl seemed to be getting aerated causing issues. After fixing the mounts, these issues with how it ran dissapeared.
Sounds like I need to order the mounts! I'm hoping I can find a source besides Partshilla.....

Is just the front mount rubber?
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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The 1987 has three engine mounts that I know of. The top engine mount which is below the gas tank, between the intake manifold. And then you've got the front and the back.
I'm going to go look at my 1987 engine for sure....Yes 3.
 
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Discussion Starter · #15 ·
The 1987 has three engine mounts that I know of. The top engine mount which is below the gas tank, between the intake manifold. And then you've got the front and the back.
I'm going to go look at my 1987 engine for sure....Yes 3.
But only one has rubber? Partzilla only lists the front mount as having rubber

White Font Line Parallel Screenshot
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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I just took the engine out of my 87. You'd think that I could remember whether it had more, but I can't. I just love the disconnects in my mind that come as time goes on!
But on the plus side... I never hold a grudge. I forget those things too!
 
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1987 Rebel 250
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Discussion Starter · #17 ·
I just got the carb soaking. Is there a way to soak that top umbrella thing that has the springy needle? I didn't soak that, since there's no obvious way to me to get the rubber off
 

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1987 Rebel 250
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Discussion Starter · #18 ·
I also just realized that my pilot screw didn't have an o-ring. I wonder if that could have caused issues (i.e., the number of turns out would be different with and without o-ring, possibly causing me to run lean)
 

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You can remove the needle from the slide diaphragm (umbrella thingy) assembly and soak it, but the rest of it shouldn't be soaked in Chem Dip. Done a bunch of carbs, and only had one where the slide/diaphragm needed cleaning. Soapy water and a soft toothbrush or cloth can be used to clean the rubber diaphragm and carb spray on the metal slide.

Dimensions for the a/f/pilot screw washer and O-ring are here: Are all carburetor float gaskets the same? | Honda Rebel 250 & 450 Forum (hondarebelforum.com)
 
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Discussion Starter · #20 ·
You can remove the needle from the slide diaphragm (umbrella thingy) assembly and soak it, but the rest of it shouldn't be soaked in Chem Dip. Done a bunch of carbs, and only had one where the slide/diaphragm needed cleaning. Soapy water and a soft toothbrush or cloth can be used to clean the rubber diaphragm and carb spray on the metal slide.

Dimensions for the a/f/pilot screw washer and O-ring are here: Are all carburetor float gaskets the same? | Honda Rebel 250 & 450 Forum (hondarebelforum.com)
Interesting, I don't have an o-ring or washer for my pilot screw. I probably lost it with last rebuild. I'm guessing eBay for o-ring, but what about washer? Hardware store?
 
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