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Another Newb Afoot

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Hey guys, I'm totally new to the CRF side of Honda and found myself with an '05 450X. For the last several years, I have been messing w Honda trikes (250Rs and 350x) and it's been an experience working on these older (ancient) machines. I have found that there isn't much you can't do with tools, a shop manual and the right attitude.

 

So...here I am w a (fairly) modern liquid thumper. I found it listed in a small town a few hours from me and the price was right. The seller needed cash and was honest about the fact that he couldn't keep it running. He has had it for several years and never really had time to ride it.

 

When we met for me to look at it, he had to jump it to get it to fire...no big deal...dead battery I thought. I rode it for about 3 minutes before it died and I couldn't kick it back to life. We tried to jump it for a while and never could keep it running. That's when he started tuning it.

 

He simply twisted the carb in the boots to access the fuel screw and that's when I noticed that it didn't even have an insulator band on the venturi side of the carb! Obviously the filter side was too loose as well. (I do realize that I may be looking at a top-end and possibly a new bore...maybe even a valve job because of this extremely lean condition.)

 

I asked him to quit jacking w it and I offered him half of his asking price...eventually he took it. I guess he didn't feel like loading it back up and driving it 2.5hrs back home...or just glad to get rid of it.

 

After I got it home, I started tearing it apart.( Yes, I do have both the Honda service manual and the owners manual.) I found that throttle cable was way out of adjustment, the fuel screw didn't have an o-ring or a washer and the pipe was loose to the head. Actually the header nuts were rusted solid (not tight to the flange), and the studs screwed right out. Oh...and no gasket either. Several items contributing to a VERY lean state.

 

I did check valve and decomp clearance and all were right in the middle of tolerance. Actually, decomp was a little high...so I brought it back to .014. Compression on my Bosch tester was low at 53 psi...low I know. Rings could be shot.

 

So...I ordered all the parts that I could think of and left town for work (my job takes me away from home for a few days a week). My plan is to attack it Friday evening and all my parts should beat me home.

 

I also ordered a fuel screw from JD Jetting (love being able to turn them by hand).

 

So...my hope is that after I clean the carb, put in a (correct) fuel screw, actually tighten the carb in the boots, SECURELY fit the pipe to the head (and replace all exhaust gaskets) that I will have a running CRF450X for $600 plus $100 in parts.

 

I'm no stranger to turning wrenches and dealing with previous owner screw ups and neglect, but I'm really hoping this one turns out to be ok. My 10 yo son switched from quads to a CRF80 last year and dad needs a two-wheeled machine to keep up!

 

Other than the possibility of major major piston/cylinder/valve damage, what am I overlooking?

 

Thanks fellas.

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Couple things come to mind given that it doesn't sound like it's been taken care of well:

1. New cam chain if your not already getting one.

2. I would consider taking the carb apart mid-body to clean it.   You can get gaskets from JD Jetting.

3. Make sure you carefully inspect the slide seal, or just replace it.

4. I would replace the emulsion tube in the carb.  Doesn't sound like its been used a lot, so it may be fine, but on a bike that old they are usually worn.  It's about an $8 part and may save you taking the carb apart again.

5. New fluids of course.  I'd coolant looks bad, consider running a vinegar and water mix through it, then flushing it with plenty of distilled water.

6. Chassis wise, I would pull and grease both axels, check the lower shock bearing, and all the knuckle bearings, and the swing arm bearings.  Also I would coat the chain adjusters with some anti-seize.

7. Replace the oil in the forks.

1-5 are pretty much a must to get it running right.    6/7 you might want to wait for some down time.   Bearings can be a bear to replace if things are seized up.

Jim.

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Thanks for the reply Jim.
I hadn't planned on replacing the cam chain, but that is probably a great idea. I have a Shindy carb kit on the way (but I always use genuine Keihin jets...so they are on order as well). I will try to find an emulsion tube too.

Yes, once I get it fired and warmed up...I will change the oil and tranny fluid. The coolant looked ok when I drained it, so I didn't bother w a flush before refilling it.

The new battery turns it over just fine...that's a bonus that I wasn't expecting. Fork rebuild will have to wait as there is no sign of seal damage yet.

I do have a question about decomp clearance though. The manual is extremely confusing in addressing this. I was using the "one feeler gauge" method and I think I may have messed it up. My right exhaust clearance is .008, so I left it alone and used my .014 to set the decomp gap. Could I possibly be inadvertently closing the right exhaust gap slightly without a feller holding the lifter up and setting the decomp? Maybe I need to try the "two feeler gauge" method. I only mention it because it may (slight chance) that this is why my compression reading is a little low. I may be creating a artificially tight decomp doing it the way I did. Thoughts?

Thanks again.

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<< Could I possibly be inadvertently closing the right exhaust gap slightly without a feller holding the lifter up and setting the decomp? Maybe I need to try the "two feeler gauge" method. >>

Yes and the manual is confusing.   If everything is in spec, the total gap on the decomp is .025"  (valve lash of .011 and .014 for decompressor). 

If your using the single gauge method, first measure the valve lash.    Let's say your a little tight and sitting at .010.   You add .014 to that, and you'd want the decompressor set with a single gauge of .024

If you were using two gauges, you'd first find the gauge that gives you a slight drag for the valve lash (in this case .010), leave it in, and then use a .014 gauge to adjust the decompressor.

Works either way.   Where you want to end up is .014 + actual valve lash.

Jim.

Edited by Jim Dettman

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Thanks again for taking the time Jim. In your scenario above, I just don't see how you get the same decomp clearance using the two methods. Sorry...it's just not sinking in.

 

In your one gauge example, wouldn't you wind up with .034 in total clearance and not .024? The valve lash of .010 in addition to .024 of decomp clearance?

 

It seems to me that the single gauge method performed as written would yield a greater decomp clearance (0.10 greater in this example) than if you performed the two gauge method.

 

Please help me see what I'm missing...because that is usually the case. ;-). I am now certain that I have my decomp set wrong judging from my own confusion over this. I will be home this evening and plan on sorting it out then.

 

Thanks again.

 

 

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<<In your one gauge example, wouldn't you wind up with .034 in total clearance and not .024? The valve lash of .010 in addition to .024 of decomp clearance?>>

No.   Your total target clearance in that case is .024 (.010 valve + .014 decompressor).   You always want .014 on top of your valve lash.  

Let's use another example; say your even tighter and your valve lash is .009 (which is out of spec).    Using the two gauge method, you'd use .009 to take up the space for the valve lash, and a .014 gauge for the decompressor adjustment.   Total clearance is now .023

If you used the single gauge method, you'd use a .023 gauge to adjust the decompressor. 

Jim.  

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Thanks Jim...that helped a lot.

 

Well, I think I have finally gotten all of the gremlins (that I could find) out of this thing and now have a pretty solid rider. One thing I can say without a shadow of a doubt is...there is very little real estate inside of the frame! I don't want to have to pull that carb again any time soon.

 

To date, I have:

Changed all fluids

Cleaned and rebuilt the carb w Keihin jets (had to pull it again due to bad float level)

New tires

New throttle cables

New chain and sprockets

New rotors (both were badly warped)

Rebuilt both calipers and master cylinders

Set decomp

New pipe (old one was pushed back into the frame and badly dented and rusted)

New exhaust gaskets

 

So far so good. This winter I will change all of the bearings and bushings and rebuild the forks.

 

Very pleased. And holy cow this thing has a lot of power!

IMG_2011.thumb.JPG.e7bd3161f2be5bec910d86c23b372da6.JPG

 

 

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Good job all the way around! After you get used to it and want a lot more power, do the usual mods everyone does and it will really wake it up.

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Thank a lot...I feel extremely lucky that nothing major (or even close) had to be done...yet.

I'm a firm believer in baby steps when it comes to things like this. This 450X is the first dirt bike that I've had in a looooong time, so it is more than plenty for quite some time. Maybe some day I will do the usual mods, but for now...I'm happy as a clam!

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