Bottom end assembly

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jack10525
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Bottom end assembly

Post by jack10525 »

As some may know from reading other posts I am in the process of rebuilding my motor all the way do to reinstalling the crank and bearings. Anyway the manual shows some special tools: crankshaft jig, bearing installer and, crankshaft installation tool. I've seen Eric Gorrs site and read the tips on installing cranks and bearings so do I still need to get these tools? Can I make them? Thanks for any help guys.
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Post by KDXGarage »

Have you considered sending the whole engine to RB Designs (assuming he does that sort of thing)?
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Post by canyncarvr »

As you can tell from the large number of responses..there isn't a lot of this done, and I'm one of us that hasn't.

Still..(I think this was sorta covered in another thread of yours)..I DO know some things about the process.

It may not be rocket science, but it's considerably beyond most folks. Sure...if you've done it a few times I'm sure the next time will be easier than the first time.

I'll bet'cha you could count the number of riders that split their own cases on a couple of hands..and the number that split and true their own cranks on one hand.

So..this amounts to an apology for not being able to give you any decent assistance..and a kudos to you for wanting to tackle the job yourself. You do need some sort of truing setup..some v-blocks at the very least I'm sure.

If you're a machinist type by nature and are generally familiar with the pressing and extraction of metal pieces (and have the equipment to do it) then you very well may do an excellent job.

If you are a shadetree mech of average+ ability with a decent set of handtools...sorry, but I wouldn't bet on a positive outcome.

Last I checked, FRP charged $150 just to split a KDX..and THAT is after you send'em the motor!! Maybe that included basic seals and a put-together..I don't know..but it's considerably more difficult than falling off a log.

But then....manual transmissions were always a mystery to me until I took one apart to replace some broken syncros. Quite an education. Worked fine when I was done, too! Glad I did it. Now I know there really isn't much to'em at all!

Good luck. If you DO end up doing it yourself it would be a treat to see a pic or two and a synoptic write-up of your learnin'!

And..as said before...RBD does do crankshaft work. I'd bet you any $$ you want it will be done fast and as perfect as humanly possible.

This just occurred to me: You might ask IdahoCharley about this...or ask him to maybe take a look at this thread. Seems he has a leg (or two ;) ) up on most riders when it comes to fixin' stuff. He may be able to shed some light on your questions for 'ya!

Cheers!
Last edited by canyncarvr on 06:41 pm Jul 12 2005, edited 1 time in total.

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Post by Indawoods »

I leave that stuff to the pro's.... mainly because I don't want to tear it back apart... and if I did it... that's probably what would happen! :lol:
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Post by jack10525 »

Haha small world, I did send my crank to RBD. He's gonna put in a new hotshot connecting rod and bearing and true it up. I just need to reassemble everything. Just about everything is gonna be brand new: bearings, seals, gaskets, connecting rod, piston, and rings. I'm just having a problem finding a couple of special tools. I guess I just have to go to a dealer and order them. And yeah if I can't do it myself I'll just take to a local shop (not a dealer) and have them assemble the bottom end. I gotta at least try though. After all it's only money. :mrgreen:
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Post by jack10525 »

Well I've started the bottom end assembly. Well I've only put the crank bearings in. But at least it's a start. The crankshaft still scares me. Oh by the way I sent the crank out to RB Designs to rebuild it with a hot shot connecting rod and bearing. They do good work. Turn around was quick too. :prayer: Wll I'll post pics in a bit.....
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Post by canyncarvr »

I remember reading in an Eric Gorr writeup about crankcase assy...that some pretty bad noises (snaps and cracks and pops) can happen when you squeeze the the parts together.

Obviously the crank should spin pretty much effortlessly when you're done.

Oh..don't know about the KDX...but some case bearings are touchy as to install depth...they are NOT pressed in until they bottom. Watch for grooves in the cases that are used for oil flow and such...don't cover'm up!

Looking forward to some pics!

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Post by jack10525 »

Well I got the engine back together and it actually STARTS!!! :prayer: It started on the first or second kick. I've still got some adjustments to make but it seems ok. So far no fluids have leaked out of the case but the drain line on the bottom of the carb had gas running out of it. Could that be a stuck float? I tapped it with a wrench to try and make it go down. Also the engine is pretty noisy. Is that normal? When I blip the throttle it sounds good though. Well if I find out how to post pics I will.
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Post by KDXGarage »

CONGRATULATIONS! I am glad to hear you got it all going again.
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Post by jack10525 »

Well I've found a few problems. I used MTL Fluid 80 weight gear oil for the gear box. I'm not sure if it's the oil or what but the clutch does not lock up. It feels like it's slipping. Also there is a vent or overflow on the carb float bowl that is leaking gas pretty good. Do you need to turn off the gas when the bike is not in use? Well at least it runs.... :mrgreen:
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Post by KDXGarage »

I don't know what to say on the clutch, but normally when the float bowl fills to a certain level, it shuts off the fuel flow into the carb. You don't really HAVE to turn off the gas when it is not in use, but if it is sitting at an angle, it can cause it to leak. There's a little tab near the floats that sets the level.
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Post by jack10525 »

Yeah I've had to adjust the float height on carbs before. I didn't adjust anything on this on except the idle speed. I guess I'll have to take it apart and check it out. Any idea what that tube is for at the bottom of the carbs float bowl? The manual doesn't really say much about it.
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Post by canyncarvr »

I don't know of a tube at the bottom of the float bowl. The Keihin PWK doesn't have tubes there. I'm missing something.......

re: oil

This is an oil that was used before? It's a gear oil for use in wet clutch apps?

Did the clutch slip before?

Clutches will slip for a number of reasons...a different oil used, the WRONG oil used, not presoaking new plates.

Did you put the washers both under and 'over' the basket? Well...the 'H' model anyway.

re: leaks

Stuck float, yeah...but more often a problem with buildup on the float needle seat or a bad float needle. If you commonly have old gas in the thing (don't ride for months at a time) I'd bet on the seat being bad. It's not replaceable (again, on the PWK). You can clean'm up, though.

Congrats on it running, anyway!!

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Post by jack10525 »

Well I've figured a few things out. I bought this bike broke so I don't really know how the clutch felt. Maybe the change in trans fluid made the clutch engage different. It's getting better though. As for the carb when I had the engine apart I just pulled it off and put it on a shelf. I figured it was fine the way it was. Well I pulled it back off and found out that all the screws on the bottom of the float bowl and the drain plug were really loose. I'm sure that's why it was leaking. I did check the float bowl seal and it looked ok. Maybe sometime down the rode I'll rebuild the carb. "Did you put the washers both under and 'over' the basket? Well...the 'H' model anyway." I'll have to check the manual for this. I followed it pretty closely but I can't remember how many washers they showed there. Well I'm gonna try and post a link to pics. Hopefully it works.....http://community.webshots.com/album/385788416SMQUMc
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Post by KDXer »

Way to go with the pics.... Thanks.... :supz:
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Post by m0rie »

Nice Pics.
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Post by jack10525 »

Well I think I have to rebuild the carb or at least clean it out. I'm starting to think the previous only had no idea what maintenance was. :butthead: It starts right up but idles way too high and the adjustment screw do nothing. Also the idle will increase and then the engine dies and will not start. I know it's from flooding because the plug is wet. If I dry it off it will start back up. As far as running, it's a little off. Kinda like the gas is not getting to the engine smoothly. So back to work I go..... :lol:
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Post by IdahoCharley »

Jack10525 - Good pictures. Check your throttle cable to be sure it has some slack in the cable. (If it does not have slack in it the the slide will be high resulting in a high idle and the idle screw will not work.) A lean condition when the engine is hot while also cause an high idle. Your write up seem to suggest that you may have one or more things contributing to the idle problem.

Concerning pictures.

(1) Looks like you took good care on the project - protecting the rod - cleaned outer cases, parts, etc, GOOD JOB

(2) I did notice in one picture that you had gasket surfaces protuded from your cases. Assuming that everything was matched up gasket surface wise: I would take a razor blade and cut the excess off close to the case. If you don't it has been my experience that chemical cleaners, soap or a commbination of whatever seems to seep into the gasket area and degrade it. Also an agressive power washer can "grab" an area of the gasket and possible cause a gasket surface leak.
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Post by fuzzy »

Good job on getting her running! :partyman:

However, I would be a little worried about crank alignment. This is the single most important thing when assembling a two cycle. Why does this differ from a four cycle? They usually don't split at the crank.

While I've always done all my won 2T work, I've always left this task to the builder. When assembling the cases you have to check the run-out of the crank. Just 'spinning freely' doesn't cut it. You may/may not find this out when you hit 11k w/ a load on the motor, and even then maybe only after the 10th time you do it. I've watched my kart engine builder assemble my cases 5 times before he was satifsfied, and he had probably built over 1000 motors of the same type.

I don't even have the ability(more so the equipment) to assemble my air-cooled, trannyless kart engines. I can assure you if you don't have the cases on these right they will toast a set of crank bearings(if not the crank itself) in less than one race. We do run 15k+ so it shows up sooner, but at the same time there is less margin of error during assembely when compared to a trannied MX motor.

Just food for thought...Hopefully you'll be OK :supz:

If you completely grenade your lower end...We want picsl! :butthead:
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Post by jack10525 »

IdahoCharley wrote:Jack10525 - Good pictures. Check your throttle cable to be sure it has some slack in the cable. (If it does not have slack in it the the slide will be high resulting in a high idle and the idle screw will not work.) A lean condition when the engine is hot while also cause an high idle. Your write up seem to suggest that you may have one or more things contributing to the idle problem.

Concerning pictures.

(1) Looks like you took good care on the project - protecting the rod - cleaned outer cases, parts, etc, GOOD JOB

(2) I did notice in one picture that you had gasket surfaces protuded from your cases. Assuming that everything was matched up gasket surface wise: I would take a razor blade and cut the excess off close to the case. If you don't it has been my experience that chemical cleaners, soap or a commbination of whatever seems to seep into the gasket area and degrade it. Also an agressive power washer can "grab" an area of the gasket and possible cause a gasket surface leak.
Thanks bro. Yeah I do have some gasket material hanging out. On the cllutch side the larger gasket that is just inboard of the clutch kind of slipped out in a small section. I didn't notice this until I came back from a quick test ride. I'm gonna have to replace that one but it's only like ten bucks and it's easy to get to. I'll take a razor and trim the rest down. As for the carb the cable has pletty of slack. I think one of the jets maybe clogged. I'll just tear it down and shoot it with some carb cleaner. I'm getting there slowly but surely.

Fuzzy,

Yeah if I blow it up I'll post pics. It cost me about $250 to do my engine myself. If it dies I'll just find a new one on ebay or something. Its only money..... :mrgreen:
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