Author Topic: picked up an intersting freebie over the weekend (Read 3002 times)

wadarush · « **on:** November 04, 2007, 07:02:11 PM »

A friend of a friend called it quits on a little 1985 xr80 after blowing the engine, fixing it, piecing it all back together, and discovering that something wasn't assembled right in the clutch and kickstarter.
I took it off his hands yesterday along with two spare engines. This should be a fun little project. I don't want to put too much into it though as I'm hoping I can turn it around a make a little money off it.

Just today I took the engine out and tore it apart but haven't reached the tranny internals to figure out the kick start issue... it would only catch on the rare kick of the lever.

Any enthusiasts know the where-abouts of an online repair manual for this xr80?
It's such an odd looking little bike but I bet it's a blast to ride!

wadarush · « **Reply #1 on:** November 05, 2007, 03:33:59 AM »

side note....
This is a Honda and it has a single overhead camshaft.
But I don't blame the moderator for bumping the post to the other bikes section.

bryanj · « **Reply #2 on:** November 05, 2007, 04:24:06 AM »

Never seen one in real life here in UK but looks identical to 125 single so have a look for manual for that

Terry in Australia · « **Reply #3 on:** November 05, 2007, 04:32:28 AM »

I had an XR80 given to me years ago that someone pulled out of the rubbish dump, I then passed it on to a friend for his kid, but I don't think he ever got it finished.

They're not a bad little bike, but the flood of cheap Chinese dirt bikes here has killed off any desire to restore little bikes like the XR80. Cheers, Terry.

mattcb350f · « **Reply #4 on:** November 05, 2007, 08:22:43 AM »

Those XR80's are great little bikes, good find!
My guess is that if the PO wasn't inside the tranny than the problem is likely in the clutch area. Never had my XL80 apart though to know how the kicker works. BTW the exhaust on your bike is off a XL80S, see the indent by the airbox...thats for the dual "bone" shock set up on the XL80S.
Also just noticed the support stablizer bar for the rear drum is missing. Don't want to jam on the brakes without that little piece in place...

I don't know of an online manual but clymer's is pretty good if you get your hands on one.
The manual will cover the 75cc to 100cc bikes, those engines are roughly the same. The 125cc's on the other hand are a different bread of engine.
Matt.

wadarush · « **Reply #5 on:** November 05, 2007, 09:12:05 AM »

Yeah the PO had the engine and tranny apart so I'll be dissmanteling everything to build it properly. I've already spotted plenty of missing, stripped, or broken bolts... even the crank end that attaches the clutch has been roughed up and is questionably useable. I've been able to locate all the missing parts off evilbay so far and nothing has been over $10, score!!!
Interesting that the exhuast is off another model. As long as it works and the little thing runs well that's all I'm concerned about. No restoration here just an attempt to make a quick buck. Anyone looking for a christmas present for their kid?

wadarush · « **Reply #6 on:** November 05, 2007, 06:38:49 PM »

I made a little more progress tonight. Continued disassembling the motor and tinkered with the kick starter. From what I can tell, without the manual or parts catalouge (I have the Clymer manual coming in the mail, thanks for the suggestion), it looks as if a few spacers are missing to keep the kick start gear inline with the tranny gear. I'll see soon enough.

mattcb350f - I think I found the stablizer bar for the rear drum brake that you were talking about... check it out

It's tucked away neatly and attached to the swing arm. Is this different than the model you were thinking of?

lastly, upon inspection of the crank it looks as if the PO has even put new bearings on the crank and piston rod. It's a pity he messed up the thread on it though... whoops guess the camera didn't focus well enough

mattcb350f · « **Reply #7 on:** November 05, 2007, 07:20:50 PM »

So that's what they look like inside

..the ol' missing washer issue, I've seen this before...but it was my own fault

That's a different stabalizer bar than on my XL, I just didn't see it at first. The XL's have the bar running up to the front of the swingarm like on the CB's.

Matt.

wadarush · « **Reply #8 on:** December 19, 2007, 03:36:18 PM »

Here is the update on this turd...

Got everything back together correctly: Kick start now functions properly, all stripped out bolts and spark plug hole (by the PO, of course) have been drilled and helicoiled. (Do you know how hard it is to find a 10mm by 1 pitch helicoil? I do now!!)
Set points and timed ignition... with a torn apart flashlight! I've never had to time something that didn't have a battery to power the points.

aaaannnnddddd the stupid thing still won't run. Turns out i've got no compression... I have a whopping 30psi (with oil in the cylinders) when I should have 170psi. So I performed a leak test and it sounds like the valves aren't seating right because I can hear the compressed air coming out the exhaust and intake... bummer huh.

Here's my question for anyone who's "in the know". A buddy from work suggested that if the valve seats and guides aren't to bad that I can "seat" them by hand at home. He suggested that I put some valve grinding compound on the valve seat and rotate the valves back and forth in hopes of sanding them down. I just want this stupid thing to run... would anyone suggest using this method?

Terry in Australia · « **Reply #9 on:** December 19, 2007, 03:58:39 PM »

Yeah mate, that's called "lapping in the valves" and is very easy. Go buy a suction cup type lapping stick (about 5 bucks at a auto parts store) and some valve grinding paste, and lap them in. Best way to test for seal (before you reassemble the engine again) is to invert the head and pour some gas into the combustion chamber and if it holds the level for an hour or so, it's good. Cheers, Terry.

750goes · « **Reply #10 on:** December 19, 2007, 04:18:55 PM »

ditto what Terry mentioned

you may have to lap the valves more than once to get a good fit

what are the rings like - within specs are the compression rings the right way up

is the bore gumbooted

mgmuellner · « **Reply #11 on:** December 20, 2007, 06:48:46 AM »

I had an xr80 as a kid & must have nearly killed myself a million times on that thing - that was a ton of fun! I bought a couple z50's which was my first bike & will hopefully find a xr80 too.

wadarush · « **Reply #12 on:** December 20, 2007, 03:36:53 PM »

Quote from: dgfischer on December 19, 2007, 04:56:11 PM

Check your valve clearances before you tear it apart. If the valves are too tight, it will cause compression to leak past the partially opened valve.
DG

I have valves adjusted, timing correct, ignition timing correct, points gapped properly, there's gas and oil in it... yaddah yaddah

Quote from: mgmuellner on December 20, 2007, 06:48:46 AM

I had an xr80 as a kid & must have nearly killed myself a million times on that thing - that was a ton of fun! I bought a couple z50's which was my first bike & will hopefully find a xr80 too.

Yeah I agree that this bike would be a ton of fun... IF IT WOULD RUN!
I made a sincere attempt last night but to no avail. Burt Monroe (the fastest indian) would have been proud of my doings last night... haha.
I tore the top end apart and found a couple things wrong with the valve train.
There was a chunk of jb weld stuck in the valve spring, who knows where that came from. Secondly the exhaust valve was bent slightly but enough to see a sliver of daylight past the seat.

So... my remedy was to find the exact high side of the valve, stuck it in a vice and gave it a whack with a flat body hammer. It did the trick! The valve was able to seat properly. To make sure of it I "lapped the valves" but with a twist. I stuck my die grinder on the end of each valve and with valve grinding compound on the seat, I went to town.
Now the engine seems to have proper compression but I haven't been able to measure it accurately yet.

All this aside I'm apparently missing some minute detail because the little turd still wont start!

750goes · « **Reply #13 on:** December 20, 2007, 03:49:15 PM »

give it a shot of aerostart - straight down the carb throat when cranking...

you got a good spark too ??

wadarush · « **Reply #14 on:** December 20, 2007, 04:17:48 PM »

Quote from: 750goes on December 20, 2007, 03:49:15 PM

give it a shot of aerostart - straight down the carb throat when cranking...

you got a good spark too ??

Cranking? Hahaha... you mean kicking. That adds to this whole mess.

754 · « **Reply #15 on:** December 20, 2007, 10:09:23 PM »

Well seeing as you staightened the valve with a hammer, and then ground lines into them with the die-grinder.. may as well order in new ones!!

BTW lapping uses a back and forth motion.. for a reason..

Terry in Australia · « **Reply #16 on:** December 20, 2007, 11:39:05 PM »

What is the reason mate? I've always lapped my valves in, in the traditional fashion, but never really understood why I couldn't use a drill attached to the lapping stick? (truth is, I did on my Suzuki GS1000S engine a couple of years ago, and it's fine, but I'd like to know why I shouldn't?)

750goes · « **Reply #17 on:** December 21, 2007, 01:38:26 AM »

Terry, I would think that constant turning in one direction only, (unless you have a reversible drill), could wear the valve seating angle into a possible wrongly aligned/angled (though not intentioned) position...if you put more pressure on one side and not flush with the job... then where are you - up the proverbial creek......I would think the hand action is the slower but safer course..with less chance of major catastrophy......crikey that was a mouthful.......

However with good control on the drill at slower speeds and no real agression (let the compound do the work) , the drill will get the job done faster....

"thats called fence sitting"

Terry in Australia · « **Reply #18 on:** December 21, 2007, 03:03:07 AM »

Well "sat" Charlie, but considering that the valve stem is stting in the valve guide which is acting like a "bushing", it shouldn't be able to oscillate, and anyway, a drill turning the valve at a relatively slow speed would reduce any "oscillation" compared to the traditional method.

Personally, I reckon that the only reason we use a "back and forth" method is for economy of effort, i.e., we cut going one way, and then back the other. My cousin had a valve dressing machine in his bike shop, and a valve seat cutter too, and guess what? They only cut one way. Cheers, Terry.

wadarush · « **Reply #19 on:** December 21, 2007, 04:39:47 AM »

Quote from: 754 on December 20, 2007, 10:09:23 PM

Well seeing as you staightened the valve with a hammer, and then ground lines into them with the die-grinder.. may as well order in new ones!!

BTW lapping uses a back and forth motion.. for a reason..

Yeah, I know I deserved that one...
This project is all in the name of good fun and not spending any money though.
As soon as I find a 10mm by 1 pitch spark plug adapter for my compression gauge we'll see how accurate my mighty hammer was,

Terry in Australia · « **Reply #20 on:** December 21, 2007, 09:47:11 AM »

Mate, you gotta change your avatar pic, you're creeping me out!

wadarush · « **Reply #21 on:** December 21, 2007, 02:58:28 PM »

Quote from: Terry in Australia on December 21, 2007, 09:47:11 AM

Mate, you gotta change your avatar pic, you're creeping me out!

Creepy? That's not creepy, look at that pretty smile

Terry in Australia · « **Reply #22 on:** December 21, 2007, 04:40:36 PM »

Looks like Charlie Manson, with hair..............

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Author Topic: picked up an intersting freebie over the weekend (Read 3002 times)