Jump to content
Sign in to follow this  

'93 XR650L top end overhaul

Recommended Posts

First a little background. Bought bike Aug 2010. It only has 9800 miles. It ran fine until one day it would not start. It did smoke/burn oil when I let off of the throttle. Found the no start to be because of only 30 psi compression. It went up to 90 psi after adding a little oil in spark plug hole.

I have took the top end apart taking some photo’s as I went. Here is what I have found so far. Let me know what you think.

Valves: 1 intake and 1 exhaust seat leaking and other 2 very small seep leak. Looked like 1 intake valve guide leaked. Should I just replace all valves and guides since it is a ’93 or should I just have the valve seats ground so they do not leak?

Decompression pin: I think it is stuck down? My manual shows it sticking out a lot. Since it was sticking out just a little I push it down, thinking it would spring back up, and it stayed there. The manual also states not to loose it, like it will fall out.

Cam/ timing chain. The cam lopes are in limits. Cam looks good. I think the timing chain is stretched. Look at photo’s, what do you think? The timing chain rides high on cam gear. When I pulled up on chain at gear it did move up a little. Also someone stated on this site that when the hole in timing chain tensioner is not straight up then the chain is stretched. Mine is about 30 deg from top (see photo).

Head: It looks like it got hot at one time or do you just think that is blow by?

Piston: it looks good. It is stamped MN9 on side it has a stamp HF1. This is the standard Honda piston correct?

Piston rings: worn—out of limits. Top ring end gap is .057in. (4X limit) and second ring end gag is .051in (more then 2X limit).

Cylinder: it looks good and only has one small scratch that I can fill. I plan to have the cylinder checked for out of round and check cylinder to piston cap. If good just have cylinder hone and new set of rings.

I’m not planning on any power upgrades just repair and fix anything that is worn so I will not need to go back into it for a long time. This should keep the cost down also. Is it best to go back in with Honda parts or should I use something else?

SN851379.jpg

SN851391-2.jpg

SN851390-1.jpg

SN851389-1.jpg

SN851388-1.jpg

SN851383-1.jpg

SN851382-1.jpg

SN851381-1.jpg

SN851380-1.jpg

SN851379-1.jpg

SN851393-1.jpg

Share this post


Link to post
Share on other sites

The machine shop said the cylinder is out of round. Told me I need a .020 larger piston. All I can find is .040 or 101mm. Does anyone make a piston between std and this?

Per my Honda parts list they list them as 0.25 and 0.50 oversize's. Is this a misprint or are they that large?

Also Wiseco only list pistons from '96 and up. They should fit the '93-'95 also correct since it is the same engine?

Edited by sae267839
add more

Share this post


Link to post
Share on other sites

Well if the bores still the stock size then you need the 0.25 Piston or first oversize..If it's already at 0.25 then you need the 0.50..

I'll need to check a parts fiche,,back shortly..

Honda lists the same Pistons for both your bike and the 01-06 models

Part numbers are

13101-MAN-690..Standard

13102-MAN-690..0.25 oversize

13103-MAN-690..0.50 oversize

Make sure you get the correct one for the bore..ask the rebore guy what size that should be.

Edited by Horri

Share this post


Link to post
Share on other sites

Horri, I have talked to a couple people and the manual is in MM and I was thinking IN. So the first oversize is 100.25MM or 0.010in over and second is 100.5MM or 0.020in over. Do you agree with this?

Share this post


Link to post
Share on other sites
Horri, I have talked to a couple people and the manual is in MM and I was thinking IN. So the first oversize is 100.25MM or 0.010in over and second is 100.5MM or 0.020in over. Do you agree with this?

Sounds sort of right..Best ask at the engineers..I'm no expert on rebores or converting mm to in or inch to mm..

Share this post


Link to post
Share on other sites

Make sure you get the correct one for the bore..ask the rebore guy what size that should be.

The shop will rebore after I get a piston so it can be bored to the piston size and within spec's.

Share this post


Link to post
Share on other sites
The shop will rebore after I get a piston so it can be bored to the piston size and within spec's.

Yep ,,well I don't know what Piston you have in there so I can't tell you what Piston you need..The rebore bloke should have measured the internal diameter of the bore or the width of your current Piston and told you what Piston to get...I'm not going to advise buying one when I don't know enough about what's there at present..

Going by whoever saying you need the 0.20 Piston then I'd say he means first oversize is what you want,,that'd be Honda p/n 13102-MN9-305 or 13102-MAN-690..which are both the same Pistons but with superseeded part numbers which is the 0.25 oversize..

If it's wrong don't blame me.

Edited by Horri

Share this post


Link to post
Share on other sites

Currently it is the STD piston in bike. I think the first oversize is only 100.25MM or .010in over. So I'll go with the second oversize 100.50MM or .020in.

Share this post


Link to post
Share on other sites

Go with the second .50 mm over piston........the chain is stretched badly,replace it.........

Take the head in and have them check the valves....if grinding them makes the margin too thin have them replaced and cut the seats.if you are replacing guides put in new valves at the same time,both wear.........also be aware that when they press the guides out there are o-rings under the guides that need replacing or it`ll smoke big time out the tailpipe.....

Check the cam gears closely,you`ll likely find the lower gear worn.....replace both gears if worn......

Check the rod small end for wear.....and also pull the oil pump apart and check for bad scoring......

That decomp pin should not stick down,there is a small spring under that and it may be broken....

Replace the oil seal in the clutch cover that the end of the crank goes into...it can wear and harden and that passageway supplies oil to the crank,rod and lubricates the piston pin with the flyoff of oil from the bigend bearing..........

ummmmm.......i think that`s the important stuff:smirk:

Oh.......are the rockers still good????????

B

Share this post


Link to post
Share on other sites

hi OP, Brian.

Hope Im not hijacking too much, but speaking of clutch cover crank seals, looking at mine real close this time(Im about to start rebuilding the engine again) my seal has a slight out of roundness or mark...

but the crankshaft slips nice and tight and the rubber itself is still pliable, its not cracked but I want to be sure...

would this seal be found at a bearing and seal shop? is it honda specific?

Ive already mad my big order and this would set me back anothr 3 weeks or so...

Any comments appreciated!

christian

P.S. Sorry for the hijack

Share this post


Link to post
Share on other sites
hi OP, Brian.

Hope Im not hijacking too much, but speaking of clutch cover crank seals, looking at mine real close this time(Im about to start rebuilding the engine again) my seal has a slight out of roundness or mark...

but the crankshaft slips nice and tight and the rubber itself is still pliable, its not cracked but I want to be sure...

would this seal be found at a bearing and seal shop? is it honda specific?

Ive already mad my big order and this would set me back anothr 3 weeks or so...

Any comments appreciated!

christian

P.S. Sorry for the hijack

Well......i can`t say if it`s available aftermarket..........but if the crank does not have the runout at that end within limits and the seal is worn out of round,you could have a leak at that seal......

If it`s soft and fits the crank tight.........i wouldn`t be too worried about it,depending on what you mean by "out of round".

B

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×