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Old 01-10-2013, 10:53 PM   #6706
crobox
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Location: Taos, NM
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I have a decision to make about this engine, but it involves knowledge that I don't have. So I am hoping some of you guys who understand these engines better than I do can chime in...

I have read enough of this thread to understand some of the issues at play, but I just don't have the experience to be sure of the right way to go.....

As some of you may have noticed, I am rebuilding my 1986 XL. The build thread is here. Because I am doing so much to the bike, I figured I would go ahead and re-do the top end, just so I knew I was starting with a fresh engine. Instead of opening my engine first and sending the jug to be re-bored, I purchased on eBay a freshly bored cylinder with a matching Wiseco 101mm piston (with rings and wrist-pin). These items arrived yesterday.



Also yesterday I pulled apart the top end of my bike, and I found the existing cylinder walls to be in apparently very good condition. You can see the hone marks very clearly. There is some very mild vertical scoring at the forward part of the bore. You can see the scoring, but I can barely feel it.




I didn't quite realize until reading the paperwork for the Wiseco piston that it is a higher compression piston (11:1) My main concern associated with installing the new items is: Am I going to need to change the cam??? Or anything else major? To be honest I do not really want to get into changing a bunch of other engine components just to match this piston. (By the way I am at stock jetting, but I live at 7000 feet... so I will be a little richer than "stock".)

I'm not worried about having purchased the jug and piston, like "Oh I bought it, I really should use it." I can just re-sell it, no big deal.

So my quandary is: leave it alone and put the head back on (after a valve job, which it is definitely going to get)?
Or install the new jug and piston?

I need some guidance about which way to go. What do you guys think?

Thanks,
Christian
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Previous Bikes: Honda XL250R (2 of them), Honda XL600R, Kawasaki KLR600, BMW K1100LT, BMW R60/6, BMW K75, Husqvarna 430XC
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Old 01-11-2013, 04:23 AM   #6707
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Quote:
Originally Posted by crobox View Post
I have a decision to make about this engine, but it involves knowledge that I don't have. So I am hoping some of you guys who understand these engines better than I do can chime in...

I have read enough of this thread to understand some of the issues at play, but I just don't have the experience to be sure of the right way to go.....

As some of you may have noticed, I am rebuilding my 1986 XL. The build thread is here. Because I am doing so much to the bike, I figured I would go ahead and re-do the top end, just so I knew I was starting with a fresh engine. Instead of opening my engine first and sending the jug to be re-bored, I purchased on eBay a freshly bored cylinder with a matching Wiseco 101mm piston (with rings and wrist-pin). These items arrived yesterday.



Also yesterday I pulled apart the top end of my bike, and I found the existing cylinder walls to be in apparently very good condition. You can see the hone marks very clearly. There is some very mild vertical scoring at the forward part of the bore. You can see the scoring, but I can barely feel it.




I didn't quite realize until reading the paperwork for the Wiseco piston that it is a higher compression piston (11:1) My main concern associated with installing the new items is: Am I going to need to change the cam??? Or anything else major? To be honest I do not really want to get into changing a bunch of other engine components just to match this piston. (By the way I am at stock jetting, but I live at 7000 feet... so I will be a little richer than "stock".)

I'm not worried about having purchased the jug and piston, like "Oh I bought it, I really should use it." I can just re-sell it, no big deal.

So my quandary is: leave it alone and put the head back on (after a valve job, which it is definitely going to get)?
Or install the new jug and piston?
I need some guidance about which way to go. What do you guys think?

Thanks,
Christian
Your cylinder on your bike looks like a worn cylinder that was rehoned and got new rings(and piston???)....

Wiseco piston rated compression they list is wrong, that will be a 10.5 to 1 slug at best.

I would use the ebay cylinder and Wiseco piston if the piston to wall clearance is correct.

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Old 01-11-2013, 07:41 AM   #6708
crobox
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Quote:
Originally Posted by MentalGuru View Post

Wiseco piston rated compression they list is wrong, that will be a 10.5 to 1 slug at best.
Thanks.... Yes I remember reading that the compression is slightly over-rated. But will I have problems the Wiseco piston and the stock cam? I'm pretty sure the best gasoline I can get around here is 91.
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Previous Bikes: Honda XL250R (2 of them), Honda XL600R, Kawasaki KLR600, BMW K1100LT, BMW R60/6, BMW K75, Husqvarna 430XC
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Old 01-11-2013, 10:21 AM   #6709
davek181
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I ran Wiseco 102.4 11:1 in my XL for several years and over 20,000 miles with stock cam and it worked great. No pinging on premium fuel and ran great. I calculated the compression ratio when I installed it and it came out to be about 10.3 to 1 actual.

The only reason I took it out is that I broke a crankshaft and ended up putting in a XR crank in it instead and couldn't use the XL piston anymore. I did end up using a 102mm overbore XR piston with my new (used) crank, also with stock cam. It also runs great that way.

I talked with the guys at XR's only and anyone else that would listen to me about the advantages/disadvantages of a stock cam and concluded for my riding needs I really would be happier with the stock grind and resultant low and midrange performance.
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Old 01-11-2013, 10:34 AM   #6710
crobox
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Thanks so much, DaveK.

That is pretty much the info I was hoping to hear.

The building consensus has me pretty convinced to stick in the Wiseco and new cylinder. Besides, it will be interesting to further pull apart the stuff I've got now and inspect the piston.

Cheers,
Christian
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Previous Bikes: Honda XL250R (2 of them), Honda XL600R, Kawasaki KLR600, BMW K1100LT, BMW R60/6, BMW K75, Husqvarna 430XC
Click HERE for my Cummins 4BT International Scout build thread www.christianristow.com
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Old 01-11-2013, 12:38 PM   #6711
davek181
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How many miles on the bike? You may get comments from other well meaning people that you should do the cam chain and guides, cylinder head refurbish with all new new guides and valve and rocker, etc. All of this can be very true depending upon mileage and intended usage. If you are going to ride cross country and want no troubles then, maybe yes. if you are going to use it like I do where I use it for my summer commuting with occasional adventures where I rarely get more than a couple of hundred miles from home, then you can be a little less demanding on overall condition.

I replaced my cam chain and transmission and crank bearings last time I had it apart involuntarily for crankshaft failure due to the fact that it had 40,000 miles on it then. I also changed a couple of gear ratios then too, just beacause I was there and could easily at that time. If the crank had not failed I would still be riding it with no worries.
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Old 01-11-2013, 08:35 PM   #6712
crobox
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The bike shows 28,000 miles on the odometer... but I have only put about 200 miles on it myself, and I don't know anything about the bike's history before me. And, I am reasonably sure someone has freshened up this engine somewhat recently. Everything inside looks very clean.

Here is the piston, which I exposed today...



Pretty much every part of this engine that I uncover looks clean and within spec.

I am fairly certain that I my game plan is to go ahead and use the new Wiseco piston and bored cylinder, have the valves and seats ground, do new valve stem seals and gaskets, and call it a day. The camshaft and rockers look practically brand new and the cam lobes are nowhere near the service limit, so I think I will leave all that stuff alone. I haven't measured the valve stems yet but I'm keeping my fingers crossed that they're good. I'll do that tomorrow... Or Monday.

Cheers,
Christian
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Previous Bikes: Honda XL250R (2 of them), Honda XL600R, Kawasaki KLR600, BMW K1100LT, BMW R60/6, BMW K75, Husqvarna 430XC
Click HERE for my Cummins 4BT International Scout build thread www.christianristow.com
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Old 01-11-2013, 08:54 PM   #6713
davek181
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Sounds like you are on the right path, freshen it up a little and big bore too. You will love it. Maybe the prior owner redid the valves too.

Hints of the day: Use genuine Honda gaskets and seals for best results. You can reuse the rocker cover gasket. Be really careful on cylinder head bolt retorque, the threads are a little weak, go to the low side of the specs. They can be heli-coiled if they do pull, I got some extra long ones for mine when that happened and it worked great.
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Old 01-13-2013, 06:36 AM   #6714
Edouard_Bracame
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XL 600 LM Rebuild engine



Rebuild Engine reinstalled in the frame, the seat is missing but I have to replace the cover as it is torned, You can see as well both auxiliary tanks installed on the rear fender(for the beer...;-)))...)



New Wiseco piston installed 97.50mm, the XL 600 LM has the same bore diameter then the XR600.



The Engine during the rebuild the play at the connecting rod was still within limit, so no need to install a Copper bushing.

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Old 01-13-2013, 11:47 AM   #6715
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WoWWW !




Quote:
Originally Posted by Edouard_Bracame View Post


Rebuild Engine reinstalled in the frame


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Old 01-13-2013, 11:54 AM   #6716
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My wife.

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Old 01-13-2013, 11:59 AM   #6717
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Érd, Hungary

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Old 01-13-2013, 12:02 PM   #6718
joexr
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Old 01-13-2013, 01:53 PM   #6719
m2h
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Originally Posted by Stretchah View Post
M2h, I hope it's not the same issue, but, it may be worth checking out to be on the safe side. Like Brucifer said I was lucky the chunk of seat didn't come off and cause more damage. The related issues I was having was that it would randomly die on rides too and was a pig to start when comp was low. When it was high I needed decomp to get over TDC and when low I could kick it sitting down without .

Something else to look for perhaps is when I took the carb boots off I noticed that I had black soot in the bell mouth of one of the carbs where the valve wasn't closing and the exhaust gases were blowing through.
I'll keep my fingers crossed it's an easier fix for you :)

On the upside I took the cylinder off and its very smooth and no damage at all, so, going to get a hone and new rings Dropping the head and Barrel into the shop on Saturday, so ,will keep you updated on progress, can't wait to get her back on the road
Thanks for the reply, i havn't been able to do anything to the blke for a while but now xmas/new year madness has settled i'm on to it. Will have to start checking valve clearances and decomp etc. first but its a bit strange because when i did get it going it ran really sweet so i'm abit baffled. Glad to see your bore was ok , one less thing to worry about
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Old 01-13-2013, 07:32 PM   #6720
bnjgriffin
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Quote:
Originally Posted by Moparmanpete View Post
Ok so I just got done ajusting alittle more added some SEA FOAM and she starts great and idles smooth and revs pretty good.
I am a happy man and there is peace on earth (that I must disturb with my shananagns)
My foot is sore but managable after all the kicking the past couple of days, can't be good , I must be getting XLed
We'll see how it starts cold.


Thanks for the help guys Much appreciated


Pete

Hey Pete,
If you have a California Carb, there is a couple of great photos back on page 163 from cynicwanderer which show what ports should be open or plugged. Hope that helps.

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