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1999 XR100 coming back from the dead

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I was asked by a friend if I would look at his 99 XR 100.  From what I can gather, the bike either lost or was low on compression.  Being accustomed to working on 2 strokes, he decided to put in a new piston and rings.  Once apart, he felt he was in over his head, and stopped... that was 10 years ago.  Some where along the line a neighbor / friend tried to put it back together...

 

When he brought it to me, I was expecting to see a whole bike...  No I got just the motor in a crate. The rest of the bike is scattered throughout different boxes which he is tracking down. When I looked at the motor, I saw the valve cover and the side covers were off. RTV silicone had oozed out from the base of the cylinder and from the base of the head... hmmmm  Upon further inspection I could see the timing was was off as well.

 

OK, based on what I'm looking at, I'm not going to trust anyone's work on this little motor, so let the tear down begin.  Pull the cam and timing gear. pull the head, wow no head gasket, just RTV silicone...  nice.  Pull the cylinder, OK, here is the original base gasket, with more RTV silicone. Well they did put on a new piston and rings, but...  the rings were not in the correct order, and they were upside down.  Next I look at the cylinder... all it needs is a bit of scotch brite and its good to go.  I then look at the head... The exhaust seems to be really sooty, and with a lot of carbon buildup, while the intake side is clean.  I pour some oil into the combustion area of the head to check for leaks... sure enough the exhaust valve is leaking. I removed the valve, chucked it into my drill and gave it a spin it, yep its bent.  I checked the rod bearing, and there is zero up and down play, so for now I'm assuming the bottom end it good to go.  I did put the piston rings in the correct order, with the number facing up.  So until I get new parts, I'm at a somewhat of a stand still...

 

So far, I need a proper top end gasket set, and an exhaust valve.  I ordered a top end gasket set as soon as I saw the condition of the motor, and I just ordered an exhaust valve.  I'm still a little leery as to why the valve was damaged.  Was it the previous mechanic who mistimed the engine and was turning it over, or did the timing chain stretched and it jumped time. Did anyone ever check the timing chain tension... NO...  Once the valve arrives, I'll lap both valves to ensure a proper seal and reassemble the engine.  When its back together, and the valves adjusted, I'll check the tension of the timing chain and will then make a decision about whether or not it needs to be replaced

 

I'll update with pics as soon as the parts start to arrive. 

Edited by eprovenzano

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The more I think about i, I think I'm going to change out the timing chain.  There is an underlying cause as to why the valve got bent.  Was it the so called mechanic who worked on the bike, or did the timing chain jump a tooth and allow the piston to hit the valve?  The bike is 15 years old, and I'm sure was ridden hard... so to be prudent I think I change out the timing chain.  At least I'll be comfortable turning it back over to the owner knowing it should be good to go for quite a long time.

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I've been doing some research in regards to the timing (cam) chain replacement. Someone please correct me if I'm wrong... All. Need to do is pull the flywheel and fish out the chain,,and fish the new one back on... Will I need to replace a seal or anything else? I don't have a flywheel took, but the local shop will pull it for a few $$$.

The new exhaust valve has arrived and I'll lap the valves while I wait for the new timing (cam) chain to arrive

Edited by eprovenzano

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You can buy a puller that will work for almost any bike on eBay for $55. This is the one I have: http://www.ebay.com/itm/NEW-10-PIECE-ROTOR-FLYWHEEL-DRIVER-PULLER-KIT-SET-ATV-MOTORCYCLE-DIRT-BIKE-/201082436299?hash=item2ed1727acb&item=201082436299&pt=Motors_Automotive_Tools&vxp=mtr

 

I can't say if it's simply a case of swapping out the cam chain or if there are seals that need to be replaced. There is an oil seal on the parts diagram, Honda part 91202-436-004 it's $5 from Dillon Brothers http://www.partsfish.com/oemparts/a/hon/506bf494f870023420a2a376/alternator IMHO, just buy it and replace it if it's not too difficult.

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Thanks Smacaroni, I purchased a flywheel puller, and pulled the flywheel last night.  (It was really on there, I don't believe its ever been off. This was a case where the proper tool for the job was needed.  If I tried to use a standard auto puller, I would have damaged the flywheel.)  I then removed the stator, and could see changing out the chain was very easy to do.  It took all of 5 min to fish the old timing chain out, and replace it with a new one.  

 

I replaced the exhaust valve, and lapped the valves to get a proper seal.  I then did my redneck valve seal testing...  I set the head upside down, and poured oil onto the combustion area to check for leaks.  The intake valve is perfect, no leaks...  while the exhaust valve had a very very small leak.  I'll pull the valve and lap the valve a little more. With the engine dismantled lets fix it right the 1st time...  there's no rush to get it done...  I just want it done right...  I pulled the clutch side cover to inspect the clutch and inner workings... all looks good... (it just needs a good cleaning.)  I set the cleaned up cylinder back onto the engine (yes I used a new gasket :goofy: ) so little by little it's going back together.  

Edited by eprovenzano

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The owner stopped by and brought the rest of the bike.  As I showed him what I've done so far and explained to him what I've found and what's been done. He said "I remember someone telling me that the timing chain could have stretched and a valve could be bent."  As I went through the bucket of parts and bolts, I realized the only thing missing (at least at this point) is the timimg chain adjuster.  So I'll at least be able to finish assembling the engine and adjust the valves while I wait for my next parts order (timimg chain adjuster) to arrive.  

 

I took a quick look at the frame...  Steering stem bearing are shot, the right side case has taken several chain related hits...  I'll have to fab something to seal and protect the flywheel and stator.  The best one was when I grabbed the throttle and gave it a twist... nothing... the slide in the carb was stuck...  I tried to pull it up and it was not moving... I poured some oil on top of the slide and after 15 min. it freed up...  I can hardly wait to see the inside of the carb... I'm sure its clean...  NOT!!!  I'm planning on completely dissembling the carb, and cleaning every nook and cranny...  The gas tank still has 10 year old gas in it...  I think I've got my work cut out for me...  

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The head has been installed, the cam and timing gear are in and timed. The new timing chain is definitely apparent when trying to install the cam gear.  Not a lot of room to work... and new spark plug has been installed.  Next is to adjust the valves and tighten the flywheel nut.  The flywheel nut and the timing chain adjuster were missing, I picked up a 12mm nut at the local auto parts store and the timing chain adjuster was ordered via ebay.

 

Not much left on the little motor, then I'll turn my attention to the carb and frame.  

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Buy a 1 gallon can of carb/part cleaner. I like Berryman's, but I've used GUNK in the past with good results as well. GUNK is a little bit more harsh on your skin, IMHO, but it works the same. Buy some velcro and a bottle of Gorrilla glue.

Glue the pile/soft side of the velcro to the lid of the can. You'll need to weigh down the velcro because Gorilla Glue expands like crazy and will just act as a shock absorber if allowed to expand.

Once the glue is dry, drop your parts in,  slap an orbital sander on the velcro and turn it on. Voila! Cheap ultrasonic carb cleaner.

Edited by Smacaroni
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That's an awesome idea...
 

I went to set the valves, but decided to recheck my timing as the "T" mark was difficult to see on the flywheel.  I used some scotch brite and WD40 on the Flywheel to ensure I was hitting the mark.  I'm glad I double checked my work, as I was off a tooth.  I corrected the timing, set the valves and button up the motor.

 

I did pull the carb and as expected there was still a little bit of old gas left in it... Is the inside of a carb supposed to be brown??? Yea it was pretty nasty. The pilot jet was clogged, the main was clogged as well but I was able to clean it with a little wire. Yea this carb needs a good soaking.

Is it Ok to drunk the carb? Will dunking the carb harm any of the rubber bits?  

 

 

We're coming down the home stretch on this rebuild...  
 

Edited by eprovenzano

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For best results, scrub the outside of the carb with a brush under running water.

Then dismantle the carb completely. Or as far as you can, some times the screws that hold the butterfly style carbs in place (and possibly the choke flap in the XR100 case) are stamped so they can not be removed without excessive amounts of force. Exception: carbs with plastic slide guides, even if the screws are lock-tited in place, use a soldering iron to heat the screw and then remove or drill them out. For instance, the TM30? not sure of the number, on the TT-R225 has one exactly like this. The GS500 carb bank I took apart the other weekend had a O-ring under the slide guide too which would no longer work once soaked in carb cleaner even if they were not plastic.

 

When you get to the mixture screw, turn it in while counting the 1/2 turns (easy since most are flat head). When lightly seated, stop. Write down the number, say 5 1/2 means 2 and 1/4 full turns. Now back it out the whole way.

Remove all rubber and plastic pieces. Parts cleaner will damage these in a hurry. Remember, plastic is usually a petroleum by-product and as such, will be dissolved by the parts cleaner that dissolves petroleum. 

Put the metal components in the parts tray and soak it in parts cleaner for 15 minutes - sometimes more. I had a XR100 pilot jet soaking for months - I had a spare and I wanted to see if it would ever unclog. It did, just took a long time.

Pull the pieces out, blow out all orifices with compressed air - wire is a bad idea you'll end up changing an orifice size and won't be able to get the bike to run right. Maybe not today, maybe not tomorrow, but someday.

Then rinse all the pieces off with water and allow to dry thoroughly.

Now replace any broken or cracked rubber. I find most O-rings in the plumbing section until I bought a huge assortment for $20. Just match them up visually, it'll be fine.

Reassemble including putting in the mixture screw back the same all the way in, back out X number of turns.

 

See this pictorial, sure it's flat slide, but almost all carbs share the same process, even complex multi-barrel automotive carbs.

http://articles.superhunky.com/4/21

 

Good luck.

Edited by Smacaroni

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I used a can of spray carb cleaner I had on the self and a lot if elbow grease... I scrubbed every nook and cranny of the carb. The main jet cleaned up easily, but the pilot was a bitch... I did finally get it open.. It and several and the main are and currently soaking in cleaner.

I popped open the air filter to check it's condition.... Not good. If you touch it, it crumbles in your hand.. So I'll be ordering a new air filter as well

I was checking my notes to make sure all is well when I realized I set the valves to .02" and not .002". Oh well that's an easy fix especially with the engine still on my work bench

Edited by eprovenzano

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I was checking my notes to make sure all is well when I realized I set the valves to .02" and not .002". Oh well that's an easy fix especially with the engine still on my work bench

 

I was going through my feeler gauges last list, the smallest I have is .004"...  I have to stop at the parts store and get the proper feeler gauge.

Edited by eprovenzano

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I reset the valves, buttoned up a few more items, reinstalled the engine in the frame, put in some fresh gas and started to kick. After 5 kicks it started to sputter, kick again it would run for a second... After 10 kicks she comes to life.. Adjust the idle and she purrs like a kitten... The owner still needs to drop of the exhaust, and I still have a few things to do, install sprocket, chain, recheck all bolts, adjust the clutch, and ensure the brakes are in good condition.

But I'm happy to hear the bike come to life... The owner is amazed it's running again. Soon I'll be turning it over to him and I'll be out looking for my next project.

I'll post some pics just before I turn it back over to the owner.

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Here is a current pic... I spent some time wet sanding the fenders. I'm not done but it looks a lot better.

397EE6D7-3932-462C-A9E0-D9F86BB6BA6C_zps

The bike now starts on the 1st kick. I can't wait to finish this little project and give it a proper thrashing

Edited by eprovenzano

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Amazed it runs OK with out an exhaust. Not that it can't but that it's not so over lean that it won't run.

Good work.

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The owner dropped off the exhaust. I mounted it and also the chain and sprockets. I fired it up (2nd kick) and took it around the block. The bike runs great, but the brakes leave a lot to be desired... I guess I've grown accustomed to ktm disk brakes... I want to go over my work and recheck everything before I turn it back over to the owner I should have it ready in a day or two

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once ur done wet sanding hit fenders w heat gun...just lightly melt top layer of plastic for nice shine and takes the scratch marks out of plastic..just be careful take a light touch with heat gun or u get a melty distorted fender....good job on the xr looks great...next step drink coffee sit back and enjoy your great work

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I took it for a quick spin... yea I'm used to more "modern" brakes, (brakes on a KTM's are really good) but this little bike is a hoot...  I was checking it over and realized I left out the anti splash piece out of the carb... DAMN...  this is why I like to wait a day or two and go back and recheck my work.

 

Thanks 75nova420, this was a fun little project.  This was the true definition of a basket case   :jawdrop: ...  Even my wife can't believe what I've been able to do with the old XR based on the parts and pieces that I started with... I did hit the fenders with a heat gun, but so far its no bringing the shine back up... I'm still experimenting with that though... this was my 1st attempt at restoring the plastic, and yes the plastic was really bad with deep scratch and gouges.  It looks much better but it still needs a little more polishing...  I mounted the exhaust, but is needs to be repaired as it leaks (a lot).  The owner said he would take care of that.  

 

I plan to finish it up tonight.  If all goes as planned, this project will be replaced with a 07 TTR125 that looks like its been put through hell... That's if the price is right, and I think I can bring it back to life...  I could be a nice little bike for my wife. If she doesn't want to ride it, I'll flip it and make a few $$. I think I've found my newest hobby... repairing bikes.  My wife makes fun of me for spending soooo much time in the garage... well I look at it this way... she knows where I am and what I'm doing...  I'm not spending money on things that I shouldn't be doing... the little bit of money I do make I put into my bike fund, so I don't have to listen to her complain about all the money I spend on my bikes....  It's a win / win for everyone...

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I have a motor cycle fund that gets a little bit of money from each paycheck for the same reason, keeps me sane and sometimes I make a little bit of money in the process.

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