Author Topic: XL600, good resources?  (Read 3386 times)

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Offline Dunk

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XL600, good resources?
« on: October 28, 2018, 01:03:06 PM »
I picked up an 85 XL600 this weekend. Not beat to hell but PO was not especially mechanical so it's a bit neglected. He has started it before I arrived and it started second kick for him while somewhat warm. It's been a while since I had a Thumper (an '82 XT550, years ago) but this one is hard to start for sure. Both decompression cables are stretched and/or out of adjustment, as are all the other cables. I got a manual and need to go through all the basics. PO says he had the carbs rebuilt, but I noticed one of them dripping around the fuel bowl. I also read the stator on these is a common problem and a weak or failing stator will make them hard to start. Apparently a "Ricky Stator" is the hot ticket? I was unable to find specs on that compared to stock or any other replacement stators.

Anyone know anything about these old thumpers? Good forum? Source for parts?

In any event I'm looking forward to getting this thing squared away and doing some trail riding. Hopefully it's a minor project not a major one. Might end up being a good daily rider as I worry a lot about riding either of my CB750s in traffic since I was hit by a car. A newer less valuable and more easily replaceable bike seems more sensible.

Offline Dunk

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Re: XL600, good resources?
« Reply #1 on: October 29, 2018, 08:38:31 PM »
I checked the stator spark coil and ignition coil and they're out of spec. Also low battery voltage and small battery with wrong connections which could affect the CDI. Ordered new stator, ignition coil, spark plug cap, spark plug, battery, CDI was cheap enough so got that too. Should take care of the weak areas of this bike and get it running. Wiring has been hacked in a few spots, I have plenty of bullet connectors and such so I'll patch that up properly and clean connections while I wait for parts.

Measurements:
Ignition coil primary resistance: .31 ohms
Ignition coil secondary resistance 2962 ohms
  through cap: 8282 ohms
Cap resistance: 5240 ohms
Stator ignition coil resistance: (0 on ohms scale) on auto: .3822 Kohms
battery: 6.x volts, loose connections


Offline Dunk

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Re: XL600, good resources?
« Reply #2 on: November 03, 2018, 06:20:15 PM »
I replaced all those electrical bits and still no love other than the occasional sputter and die. While I had the air box loose I sprayed the carb air bleeds with cleaner, can't hurt. After a bunch of kicking I opened drain screw on the primary carb and only got nothing, but did get fuel out of the secondary carb. Pulled the bow on teh primary and it has a little nasty at the bottom but was nearly empty. Sprayed jets while bowl was off. Float level was set to virtually empty. Set to 20mm and it fired up after a few kicks, idled smooth and seemed to run nice. Went for a quick rip down the street and back and it would lean out bad and misfire or die out when the secondary carb opened, ran well if I kept it under 1/4 to 1/3 throttle.. Pulled the secondary bowl and found a similar situation, fuel level way too low, float was set at over 25mm. Unfortunately I broke the rubber tip of the needle off so now it's back to waiting on parts. I'll be traveling for work in a week, for a week, so I expect I'll get the parts just in time to leave.

In any event, that's what I get for trusting a PO rebuilt the carbs. Also have a new chain, sprockets, slipper, and misc other bits ordered. Maintenance has been neglected on this thing but it's time to get caught up. Hopefully it's just a little project of all the neglected maintenance and doesn't turn into a restoration. It's weird to think of "restoring" anything from the 80s, still seems brand new to me.

Offline Dunk

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Re: XL600, good resources?
« Reply #3 on: November 18, 2018, 06:03:19 PM »
Doesn't seem to be any interest but I figure I should update this... The starting issue turned out to be carb bowls on the wrong carbs. There is a jet in the primary carb for the choke to work, the secondary carb bowl does not have this passage drilled. This explains the occasional firing for a second or two but able to start when hot. I got that sorted along with more cleaning of the carbs, replaced chain and sprockets. Found worn countershaft drive teeth. Ordered a wider sprocket made to remedy this or extend countershaft life by engaging more spline depth. Countershafts are NLA, but a newer XR650 countershaft bolts in. The new shaft is different with more splines on the output side and the factory sprockets have deeper spline engagement. That's the long term fix if I decide to go through the engine. Thinking a longer stroke XR crank and big bore for 650+ cc, but I'd leave that for if I get to that point.

Apparently it's easy to swap modern cartridge forks with longer travel on, from an XR650 or XL400, or longer travel standard forks from an XR600. Swingarm is a bolt on for a longer XR swingarm and bolt on XR shock just need to make a mount for the remote reservoir, just need some work thinning the XL wheel and with spacers to keep the cush drive. Also options for a rear disc. Brakes are weak on this thing for street riding, not sure how much that'll matter once I get knobbies on it. Need to ride it some and figure out if I want to keep but improve the factory suspension or go with XR parts. Not sure how much value these have to the restoration crowd but I do know when they come up for sale around here they go quick. Any modifications I do I'll probably keep to bolt on swap back to factory as I suspect value will be stable or increase over time so a cafe hackjob equivalent would be bad.

Offline seanbarney41

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Re: XL600, good resources?
« Reply #4 on: November 18, 2018, 06:56:16 PM »
I replaced a broken countershaft in an xr400 a couple years ago...don't be afraid.  It was an easy one weekend job if you have all your parts lined up.  Very easy to work on engine and extremely well engineered and I would expect the 600 to be the same.
If it works good, it looks good...

Offline Dunk

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Re: XL600, good resources?
« Reply #5 on: June 22, 2019, 03:15:14 PM »
I found the source of my carb problems, the middle/lower rubber boot to head bolt was too short and stripped out resulting in a variable vacuum leak. Got a longer factory bolt which fortunately bit into good threads and sealed it up along with new rubber oring gaskets for the boots and spacer. I also got a Dynojet kit and put that in along with a full and proper rebuild of the carbs and a larger idle jet. It runs much better now, and starts easier. Still a little finicky if it stalls somewhere between cold and operating temp, but I think that's the nature of these bikes. Cold starts are within a few kicks, still learning what it wants for choke with the bigger idle jet (not much), and hot starts are 1-2 kicks. Always must be cleared with decompression lever and a few kicks if stalled, and seems to be good practice for a one kick start if it was running within a few minutes.

I picked up an extra pair of wheels and put D606 tires on them along with a rear sprocket with a few more teeth. Also got 98 XR600 forks, which are cartridge forks a couple inches longer, and another XL600 top triple which I'll have bored out to fit the larger diameter XR600 forks and retain stock gauge and key mounting along with the fork lock. Got an XR swingarm too, which is aluminum and a bit longer. It's narrower and will requiring cutting down the XL brake and making spacers to fit. Still looking for an XR600 shock. The XR suspension will be my a winter project, for now I want to enjoy it this season and have a baseline to compare to.

Last weekend I put the knobbies on and went for a ride 75 miles mostly off road. I lost the tail light and license plate. Thought I was fortunate to find an original taillight and license plate bracket on eBay but it doesn't fit the aftermarket DC plastics. I could make it work I guess, but I'll put it for sale for someone who is restoring one. I ordered an aftermarket XR600 fender with tail light, and a dual sport light and license plate bracket for it. This should be more compact, lightweight, and less likely to break or fall off than some of the other options I was considering. I believe the fender will fit with minimal modification. I enjoyed the 75 mile ride and can't wait to get the replacement light and license bracket to get back out. I did bottom out the suspension a few times on whoops. The XR parts should make a big improvement when I get around to it.


Offline Dunk

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Re: XL600, good resources?
« Reply #6 on: March 29, 2020, 07:12:29 PM »
I haven't been very present on the forums lately, mostly distracted with old dual sports though of course I'm still riding my K1. My K5 developed a noise before the holidays, I'm thinking it's time for primary chains and tensioner and a full inspection and freshening up. Unfortunately I haven't got around to it as I've been busy with dual sports this winter.

So the XL600 got new rejetted. Appreciably richer on primary and secondary carbs helped, leaner on the slow jet to ease starting as it was way big from the previous owner. I still need to fine tune jetting as when letting off from WOT a bit there is a stumble and surge. I think jetting is pretty close, but need to raise needles so I'll do that next time it's convenient.

I focused on suspension work recently. I swapped the 37mm XL600 forks for a set of 43mm '97 XR650L forks which are longer and of cartridge design. More travel is more good. I rebuild those with springs appropriate for my weight, new seals, and synthetic 5w fork oil. To mount the original XL600 gauges to the top triple I had a local welding shop weld new tabs on the top triple. Some longer hoses, cables, misc. brackets, and so forth and the front bolts right on. It's a big improvement and looks clean and like it could have come from the factory that way.

For the rear I swapped an '87 XR600 aluminum swingarm. it is longer and a bit lighter than the steel XL600 swingarm. The XR600 and newer XR650L dual sport do not have cush drive hubs though for less wear and smooth operation on pavement. As the aluminum XR600 swingarm is narrower, to retain the XL600 cush drive hub I machined about 3/8" off the brake plate outer "nose", ground down the brake stay pin to fit, and clearanced the groove on the brake plate for the brake stay pin on the swingarm. I also had a shorter spacer made for the left side of the rear wheel. On the XR600 swingarm, just about all of the shorter width is removed from the left (drive) side, so the wheel ended up not centered to the frame. I had to lace the wheel offset to make up the rest of the difference and get the wheel centered. All said and done, it fits and all is well. For now I put the old XL600 shock back in, but it's very inadequate compared to the new modern front suspension, though the swingarm gives a bit more height from the extra length. I have an XR600 shock I will rebuild and install though. I also replaced a damaged clutch cover and upgraded the oil pump to an improved version for a 2020 XR650L along with new drive and driven gears, which are one tooth more on drive and one tooth less on driven for more oil pump RPM and oil volume.

All said I'm really digging the old XL and getting back into riding off road. I also picked up a matching '86 XL350 for the boss back in November. We did all the basics and it runs great, but it's too heavy for her to pick up on her own when she drops it and while she can start it normally, she cannot start it after it has flooded from dropping it. This means we need a lighter dual sport for her. In my Craigslist perusing I stumbled across a street legal 1977 Yamaha IT400 (two stroke) which was converted several years ago in CA. I used to have an '82 IT465 and regret selling the bike, but it's impossible to get them street legal here. I jumped on the IT400 since it had a street legal title, did the usual stuff plus a top end, and had a little fun with it but despite being lighter than the XL350, at 40 HP and the twitchy nature of a two stroke it's not suitable for the boss. I'm keeping my eyes open for an '85 XL250, for fun to add to the stable since apparently I'm now collecting 1985 model year XL Honda's. The 250cc-600cc RFVC bikes are all basically a 600. Minimal chassis and suspension changes and same engine but smaller bore or stroke so they're all heavy. The boss asserts that we're a Honda family, so we've been looking for an XL200 for her,  a 3 year production bike which is older tech engine and lower output but significantly lighter and still modern monoshock suspension that can take all the upgrades I did to my XL600. Finding one with a title is a struggle!

Offline kap384@telus.net

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Re: XL600, good resources?
« Reply #7 on: April 03, 2020, 11:47:22 PM »
Awesome to see the old thumper back up and running!  Good investigative work on the carbs.  Nice suspension upgrades.
« Last Edit: April 03, 2020, 11:51:36 PM by kap384 »
1965 Honda CB450K0
1972 Honda CT70K1
1975 Honda MR50
1975 Honda CB400F Supersport
1977 Honda CB750F2 Supersport
1978 Honda XL100
1979 Honda CBX Supersport
1982 Honda VF750S Sabre - Adventure Bike modified
1983 Honda CX650T
1995 Honda VFR750
2016 Honda CRF1000L Africa Twin
2015 KTM 200 XC-W
1963 Suzuki T10
My 1977 CB750F restoration - http://forums.sohc4.net/index.php?topic=66779.0
My 1975 CB400F restoration -
http://forums.sohc4.net/index.php?topic=145196.msg1651779#msg1651779
'More Stock Than Not' thread - http://forums.sohc4.net/index.php?topic=90807.500
My CT70 Resurrection - http://forums.sohc4.net/index.php?topic=145221.0
Best Motorcycle Tool Ever - https://www.engduro.com

Offline Dunk

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Re: XL600, good resources?
« Reply #8 on: October 04, 2022, 06:39:45 PM »
More XL600 fun. Haven't rode this bike in over a year. It started burning more oil than the two stroke IT, which I looped and bent the frame on... Oops, knew there was a reason I stopped riding big two strokes. I'll fix the IT eventually but the XL600 is underway. It had an XR600 engine (82mm stroke x 97mm bore), nifty since the XL600 was an 80mm stroke and 100mm bore. I got an XL600 jug and bored it to 101mm for a new piston to use with the longer stroke XR crank. 641cc. Cool.

One of the chain guard bolt holes on the cases was busted, so I found an '85 XL600 case to use. Small end of the rod was all wallowed out, new rod and such. Some fancy new transmission bits. Lower ratio 1st and 2nd, higher overdrive 5th. Should be pretty slick, all sleeper like as if anyone cared about that on a dirt bike. It'll make my inner purist feel good that some other purist might think it's an original engine at a glance.

The XL350 got an XR swingarm and shock and the the taller forks from the XL600. I haven't been off road but a few rides with my neighbor who picked up an XL600 this summer, but the XL350 is my daily rider if it's raining in the morning. Neighbor got an '83 XL600 which apparently has bigger carbs I rebuilt for him. I found a set of the bigger carbs for my XL/XR/whatever it is now but I'll have to port the head as the intake ports are smaller on later bikes. Fun project. Should be done some time this winter, a fun ride for snow I guess.

Offline 70CB750

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Re: XL600, good resources?
« Reply #9 on: October 05, 2022, 04:47:15 PM »
Following.

We moved to USA in 97 and I was without a bike till 2011. In that period of time I was imagining getting KLR.  For some reason the one big cylinder seemed the perfect thing - plus the fact that Kawasaki makes it for like 30 years now.

But the K0 found me first  ;D
« Last Edit: October 06, 2022, 02:48:00 AM by 70CB750 »
Prokop
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Offline andy750

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Re: XL600, good resources?
« Reply #10 on: October 06, 2022, 03:27:52 AM »
Cant go wrong with a big thumper - got my 2006 XR650 back in 2015. And then this year went modern with the T700.
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline grcamna2

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Re: XL600, good resources?
« Reply #11 on: October 06, 2022, 09:57:35 AM »
subscribed  8)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Dunk

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Re: XL600, good resources?
« Reply #12 on: October 11, 2022, 07:10:17 PM »
Little work on this while I wait on parts. Removed bearings from the new numbers correct '85 XL600 cases and blasted them. Decided to try walnut shells, while cleanup is easier I'm not impressed with abrasiveness. Removed loose paint easy, gave up after a while on removing all paint. Might paint as they are or might use fine glass beads. Still waiting on parts, since it's potentially the last NOS XR600 countershaft I'd prefer to run all new bushings in even though everything measures within wear limits.

KLR is a good bike. All the big three 600-650cc thumpers are solid bikes. Low performance compared to some of the latest dual sports, but they keep making them because they're simple, reliable, and perform well all around. New XR650L is basically a 30 lbs heavier XL600 that's down 10 HP to be emissions legal, my buddy has been trying to find a new one, put a deposit on one and got in line since they sell as fast as they make them.

Offline grcamna2

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Re: XL600, good resources?
« Reply #13 on: October 11, 2022, 08:10:01 PM »
I really like the XL600R Dunk and I'm closely following this build of yours  8)
What exactly is your plan for the engine build;will you be keeping the XL crankshaft for it's shorter rod and high-rev capacity? or don't you like revving the engine up to make the power and prefer the 'tractor-pull' torque of the XR600 longer stroke ?  I'm very interested in this rebuild  ;)

I would like to get one and set it up with lower street suspension & wheels.
« Last Edit: October 11, 2022, 08:15:14 PM by grcamna2 »
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline BenelliSEI

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Re: XL600, good resources?
« Reply #14 on: October 12, 2022, 05:22:37 AM »
I really like the XL600R Dunk and I'm closely following this build of yours  8)
What exactly is your plan for the engine build;will you be keeping the XL crankshaft for it's shorter rod and high-rev capacity? or don't you like revving the engine up to make the power and prefer the 'tractor-pull' torque of the XR600 longer stroke ?  I'm very interested in this rebuild  ;)

I would like to get one and set it up with lower street suspension & wheels.

Consider an Ascot? I’ve often thought they would look much better with the front lowered a bit, and a headlight and instruments from a cb750! This one is for sale locally for about US$1200..... Mmmmm.

Offline RAFster122s

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Re: XL600, good resources?
« Reply #15 on: October 12, 2022, 08:08:05 AM »
Scottly has an Ascot…
David- back in the desert SW!

Offline grcamna2

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Re: XL600, good resources?
« Reply #16 on: October 12, 2022, 09:40:42 AM »
I really like the XL600R Dunk and I'm closely following this build of yours  8)
What exactly is your plan for the engine build;will you be keeping the XL crankshaft for it's shorter rod and high-rev capacity? or don't you like revving the engine up to make the power and prefer the 'tractor-pull' torque of the XR600 longer stroke ?  I'm very interested in this rebuild  ;)

I would like to get one and set it up with lower street suspension & wheels.

Consider an Ascot? I’ve often thought they would look much better with the front lowered a bit, and a headlight and instruments from a cb750! This one is for sale locally for about US$1200..... Mmmmm.

Yes John  :) That one does look very good.  8)

They had a problem with the starter gear and how it stressed-out the left engine cover:it would wear the hole for the gear shaft just enough to jamb the starter gear and cause hard starting.I know there's a modification that a person sells which installs a good bearing into the sidecover which fixes that problem.
« Last Edit: October 12, 2022, 09:43:21 AM by grcamna2 »
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Dunk

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Re: XL600, good resources?
« Reply #17 on: October 15, 2022, 05:10:01 PM »
I really like the XL600R Dunk and I'm closely following this build of yours  8)
What exactly is your plan for the engine build;will you be keeping the XL crankshaft for it's shorter rod and high-rev capacity? or don't you like revving the engine up to make the power and prefer the 'tractor-pull' torque of the XR600 longer stroke ?  I'm very interested in this rebuild  ;)

I would like to get one and set it up with lower street suspension & wheels.

The engine in the XL600 when I got it was from an '87 XR600, so I only have the longer stroke XR600 crank (80mm). I had the local Honda dealer rebuild the crank with a new rod since the small end had wear. It is getting an XL600 jug bored to 101mm and a Wossner piston which should put compression at about 9.3:1. Keeping it low compression to potentially running lower octane fuel, or at least not having issues with detonation when it gets hot on tight single track. My '85 XL350 runs very hot and even with 93 octane will knock at times in extended slow riding on tight trails. Tried checking the oil one time when it was hot after a ride, the crankcase gets so hot it blistered my fingers on the dipstick. I have a newer XR250 clutch cover and and XR400 oil cooler to use on that one eventually.

IIRC this will be 641cc. The '87 XR600 engine already had plenty of torque and didn't particularly care what gear it's in. Pick the wrong gear for a hill climb and it'll lug through it just fine. Should do even better with more displacement. These engines are notorious for destroying countershaft splines from the factory style thin sprockets, a wide spline sprocket is mandatory. I wanted the taller 5th gear regardless for lower highway RPM, but given the torque of this engine a wide ratio trans may let me drop a few teeth on the rear sprocket to get even lower highway RPM and maintain the same low speed performance. I'm keeping the stock XR600 cam for low end torque. For comparison, the XL350 has a 6 speed transmission and you're always shifting, it's easy to stall and it is not a happy sounding engine if you're in the wrong gear.

No more progress on the build so far. Waiting on new dowels for the cases and a bushing for the trans. I broke in the cam on the new engine for the woman's Thunderbird yesterday and spent much of today doing maintenance on my daily rider CB750. In that regard the XL600 is a fun commuter bike. Hard to not pull the front wheel up when getting on it, and super convenient to take fun cuts along the way. I wouldn't supermoto one but these can make a fun commuter with 80/20 tires and still be serviceable for light off road. After I got it I got a second set of wheels and kept the 80/20 tires on the original wheels and put DOT knobbies on the second set. The idea was swap the more street friendly tires to not wear out the knobbies, but that got old after about two wheels swaps. I just learned to love changing tires (I don't really love changing tires), and air up to 22 psi for street riding vs the 8/15 or whatever I run off road.

This is a tall bike from the factory. Mine is taller as I swapped XR650L cartridge forks on the front, really make the ride nicer and a big improvement off road from a larger diameter fork that flexes less. The XR600 swingarm I swapped is almost 2" longer, adding more height, and I have an XR600 shock to use that'll make it even taller. I'm 6'4" so not a bit deal. My neighbor that recently got an XL600 is short and it's a tall bike for him, he doesn't want it any taller. It's a hard engine to start, harder if it's uncomfortably tall.

Offline grcamna2

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Re: XL600, good resources?
« Reply #18 on: October 15, 2022, 06:37:45 PM »
I really like the XL600R Dunk and I'm closely following this build of yours  8)
What exactly is your plan for the engine build;will you be keeping the XL crankshaft for it's shorter rod and high-rev capacity? or don't you like revving the engine up to make the power and prefer the 'tractor-pull' torque of the XR600 longer stroke ?  I'm very interested in this rebuild  ;)

I would like to get one and set it up with lower street suspension & wheels.

The engine in the XL600 when I got it was from an '87 XR600, so I only have the longer stroke XR600 crank (80mm). I had the local Honda dealer rebuild the crank with a new rod since the small end had wear. It is getting an XL600 jug bored to 101mm and a Wossner piston which should put compression at about 9.3:1. Keeping it low compression to potentially running lower octane fuel, or at least not having issues with detonation when it gets hot on tight single track. My '85 XL350 runs very hot and even with 93 octane will knock at times in extended slow riding on tight trails. Tried checking the oil one time when it was hot after a ride, the crankcase gets so hot it blistered my fingers on the dipstick. I have a newer XR250 clutch cover and and XR400 oil cooler to use on that one eventually.

IIRC this will be 641cc. The '87 XR600 engine already had plenty of torque and didn't particularly care what gear it's in. Pick the wrong gear for a hill climb and it'll lug through it just fine. Should do even better with more displacement. These engines are notorious for destroying countershaft splines from the factory style thin sprockets, a wide spline sprocket is mandatory. I wanted the taller 5th gear regardless for lower highway RPM, but given the torque of this engine a wide ratio trans may let me drop a few teeth on the rear sprocket to get even lower highway RPM and maintain the same low speed performance. I'm keeping the stock XR600 cam for low end torque. For comparison, the XL350 has a 6 speed transmission and you're always shifting, it's easy to stall and it is not a happy sounding engine if you're in the wrong gear.

No more progress on the build so far. Waiting on new dowels for the cases and a bushing for the trans. I broke in the cam on the new engine for the woman's Thunderbird yesterday and spent much of today doing maintenance on my daily rider CB750. In that regard the XL600 is a fun commuter bike. Hard to not pull the front wheel up when getting on it, and super convenient to take fun cuts along the way. I wouldn't supermoto one but these can make a fun commuter with 80/20 tires and still be serviceable for light off road. After I got it I got a second set of wheels and kept the 80/20 tires on the original wheels and put DOT knobbies on the second set. The idea was swap the more street friendly tires to not wear out the knobbies, but that got old after about two wheels swaps. I just learned to love changing tires (I don't really love changing tires), and air up to 22 psi for street riding vs the 8/15 or whatever I run off road.

This is a tall bike from the factory. Mine is taller as I swapped XR650L cartridge forks on the front, really make the ride nicer and a big improvement off road from a larger diameter fork that flexes less. The XR600 swingarm I swapped is almost 2" longer, adding more height, and I have an XR600 shock to use that'll make it even taller. I'm 6'4" so not a bit deal. My neighbor that recently got an XL600 is short and it's a tall bike for him, he doesn't want it any taller. It's a hard engine to start, harder if it's uncomfortably tall.

Your bike has an 87' XR600 engine:cases,trans,primary drive,etc. All 87 XR600 ?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Dunk

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Re: XL600, good resources?
« Reply #19 on: October 16, 2022, 05:29:22 PM »
It was all '87 XR600 engine, but the guts will be going into '85 XL600 cases since one of the case guard bosses was cracked on the XR cases and the XL cases were cheap enough. The cylinder is from an unknown year XL600, I got that for the 101mm piston since the XL had a factory 100mm bore while the XR is 97mm. Less to bore and the XR sleeve would likely be getting thin at 4mm over.

Primary drive/basket/etc will be XR600 bits. I had considered changing the basket and crank gear to XRL parts for the 2.029:1 primary ratio instead of the XR/XL 2.188 but it really doesn't matter since you can accomplish the same thing with sprockets and my XR basket is is good condition.

The transmission primary shaft I'm using is from a European model, maybe an NX or something else obscure. I got this shaft for the 12t 1st gear instead of the 13t XR/XL ratio and because it was a kickstart model so doesn't have extra length or oiling holes for the starter idler gear... Drops right in.

Offline grcamna2

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Re: XL600, good resources?
« Reply #20 on: October 16, 2022, 06:40:38 PM »
It was all '87 XR600 engine, but the guts will be going into '85 XL600 cases since one of the case guard bosses was cracked on the XR cases and the XL cases were cheap enough. The cylinder is from an unknown year XL600, I got that for the 101mm piston since the XL had a factory 100mm bore while the XR is 97mm. Less to bore and the XR sleeve would likely be getting thin at 4mm over.

Primary drive/basket/etc will be XR600 bits. I had considered changing the basket and crank gear to XRL parts for the 2.029:1 primary ratio instead of the XR/XL 2.188 but it really doesn't matter since you can accomplish the same thing with sprockets and my XR basket is is good condition.

The transmission primary shaft I'm using is from a European model, maybe an NX or something else obscure. I got this shaft for the 12t 1st gear instead of the 13t XR/XL ratio and because it was a kickstart model so doesn't have extra length or oiling holes for the starter idler gear... Drops right in.

Good info on this,especially the trans. primary/mainshaft from the Euro model;it never hurts to have a Lo 1st gear for carefully navigating certain terrain.
I know many folks don't like kickstart but I do,even on a large thumper like that;I hope your compression release is working spot-on  :D
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Dunk

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Re: XL600, good resources?
« Reply #21 on: October 20, 2022, 05:09:23 PM »
The XL has both an automatic and manual decompression. It can be a bear to start if you don't follow the procedure to clear the cylinder, and finicky even then when inbetween cold and hot. Some science stuff people smarter than me understand but once a piston gets bigger than 4" or so it becomes difficult to distribute the air fuel mixture so it'll ignite easily, or some such.

No more progress on the XL, but head parts came in. It'll get new guides, valves, springs, etc.

Attached chart of the gearing differences. I'm currently running 15/48 sprockets. I'm hoping with the gearing change and extra displacement I can go to stock 15/45 sprockets to drop 600 highway RPM and keep the same or better low end grunt. It's all sugar sand around here and DOT knobbies only hook up so good, so it'll probably work out.
« Last Edit: October 20, 2022, 05:13:59 PM by Dunk »

Offline Dunk

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Re: XL600, good resources?
« Reply #22 on: April 30, 2023, 02:32:36 PM »
Now a 641cc with the lower 1st/2nd swap and taller NX 5th. Head is sketchy, valve job didn't come out like I wanted and the center cam journal is trashed but it runs and feels pretty torquey going up and down the street in the rain. Running the small '85 XL carbs that came on the bike but rebuilding a pair of early XL big carbs. Head was port matched to the big carbs. Should be fun. Long term I found a NOS XL600 cam since the center journal is bad, and will have to find another early XL/XR head with a good center journal. If this janky head holds up for this summer I'll be happy.


Offline grcamna2

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Re: XL600, good resources?
« Reply #23 on: April 30, 2023, 02:57:16 PM »
Looking good Dunk.  8)
Have you been riding it in to work ?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Dunk

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Re: XL600, good resources?
« Reply #24 on: April 30, 2023, 03:23:48 PM »
Not yet, just got it running today. Tempted to ride it tomorrow since it looks like the rain will continue, but hesitant given the mediocre top end and I've got maybe a mile on it so far. I'll probably get some miles on it around the neighborhood and the sand pit around the corner before I commute with it again.

Bummer is my XL350 had a loss of compression and no longer runs. I was commuting on that whenever it rained, but now I gotta tear that engine apart too. Another early dual carb RFVC with even more limited parts availability than the 600... Repop XL350 rods are readily available with the small pin but nobody makes pistons. Repop XR350 pistons with the larger pin are readily available but you can't get rods for them. No idea if it's top or bottom end but I suspect that 350 will turn into a full tear down and rebuild like the XL600.

My buddy send me for sale listings of cool old bikes and cars regularly. I used to see them as cool old cars I might snatch up if I liked. Now I even them as projects I don't have time for. Even the nice looking ones, or especially the nice looking ones, will need major work. Too many irons in the fire.