Top End Rebuild - XJ650

Right, so I bought low mileage cylinders online, they had one picture from underneath and at an angle you couldn't see the YICS ports. They said it was from a 1980 xj650 maxim with low miles.

Anyhow, they had YICS ports so it couldn't have been from a 1980 engine. I contacted the seller for a refund and return shipping label.

 

Was it eBay? If so, you'll be able to recover the $. If it was a private sale, I hope they make good on it for you.

Dave

 

Yeah, they are sending me return shipping label.

Also. Can I use a smaller bored engine cylinders and have them bored over to 650?

 

If you're thinking of the 550, that's a YICS engine. You MUST stay with the 1980-1981 xj650 stuff for yours unless you do a major transplant.

Depending on what you do, there are some internal differences even between the years of the 650 engines. I can't remember what they are, but Len could tell you.... Seems I recall something about differences in the gearing or something......

 

Ah, well it is YICs, so I can't use it anyway.

Okeydokey.

I picked up a complete exhaust ... for *rattling off* $89.95 off of ebay. It has the original crossover tube, and everything. One header pipe has a dent, and the crossover tube does have a small one as well. Besides that they're solid metal, and I'm pleased.

Ok.

So I was using this tool. http://www.jbtoolsales.com/lisle-36050-valve-keeper-remover-and-installer-kit/#oid=1002_1 To do a valve stem seal job on the head. I ended up having a little bit of difficulty, but I finally got it down. I finished my cylinder 1 and 2 exhaust valve, and then I noticed these ringish, dents where the tool made a lip. It is possible to just dremel smooth out that lip?? Or did I ruin the head. I've used these tools before, but I've always had the head with springs that stick out, and aren't recessed. The valve shim buckets won't fit in the hole.

Thanks!

 

Idk what tool that is but you should invest in the c-clamp style compressor (or make one). It has a bucket that will fit on top of the valve seat. The actual bike buckets should have been identified with its location upon removal. Bath the bucket in new oil then slowly rotate it around the hole until it drop. A bit of heat to expand the head might work too. They're a tight fit. Hope this help.

Gary H.

 

There is a clear ridge that formed because the tool may have slipped while hammering it. I've used the C-Clamp ones, but this one is much similar, and easier to use. They work with both valves springs exposed and hidden in the head.

Anyhow, would dremeling that ridge away affect the head / valves in any way?

 

Idk. Maybe another member will chime in. There may be other techniques other than the dremel.

Gary H.

 

If you are going to knock the ridge down with anything, use emery cloth covered in a light coating of oil to help trap the filings. You may be able to use a hardened peice of tool steel to push the ridge enough to let the shim buckets fit. In either case be very careful and work slowly.

My personal preference would be to disassemble, remove the ridge with the workpeice far away from the head to avoid contamination, and reassemble with a different holding tool.

 

Well I messed it up. I tried to knock the ridge down, and I did. I was able to get the bucket in, but it doesn't want to slide up and down correctly.

I think I'm going to call it quits with this head. For price of shipping on a set of cylinders from a 82' seca. ( compatible motors cylinders with the 1980 ) I was able to add a head for only $10, and because I was over $75, shipping was free.




The cylinder bores look really clean.

I need to get a new dowel pin, and gasket though for it.

The listing said the bore was 63mm. I'm hoping it was not bored over a size, but it is possible. I'll ask for the pistons too if it was, and if not I'll request a return label on just the cylinders. We'll find out though. They said the bike was running with unknown miles.

EDIT: I decided to go ahead and purchase those pistons anyway. They're off the same bike. If they're overbored, then I just bought overbored pistons to go with it. Sadly I'll still need rings, but I'll be able to find out.

 

Well, these cylinders were a go.

They were the best one out of them all. (Out of an 82 seca.)

I messed up while installing them. I broke a fin. I tried using epoxy and it looked like it was supposed to be there. Tomorrow night I am going to pick up jb weld and completely secure it. Slowly grind any small ridges and make it look like it originally did. I feel like an idiot.

Tomorrow I am also finishing the head. Lapping valves, and then I'll put everything back together.

Pistons were a pain the butt to do alone. End gaps were fine out of the box as well.

It is coming alone nicely, I am hoping to throw this puppy into the bike and finish the small wiring harness this week.

Sunday evening is my last day at work at a car dealership ( I am a lot boy ). - I was offered a position at the motorcycle dealership ( about two weeks ago ) I got the cylinders honed at the first time around. They're offering me a way to work into a small engine mechanic position by providing the necessary certifications online. It will be interesting!

 

Ok.

So everything has been put back together... I cleaned the carbs at work.. ( we have this awesome sonic machine ).

I'm having a problem with the idle however... and the idle screw isn't quite doing what I want it to..

Let me just make sure I am understanding this right.. turning the screw clockwise will increase the idle, and counterclockwise will decrease idle.

When I start the bike it wants to jump immediately to 5000-6000 rpms.

 

Are the carbs synced yet?

Sounds like a vacuum leak though---

 

Did you throw the whole rack of carbs in the sonic solution? Or did you disassemble the carbs and only put the metal parts in the cleaner? 35 year old rubber isn't rubber anymore. It's that flamed up, ridden through hell stuff you described earlier, kinda similar to plastic. Plastic doesn't seal well, especially after sonic cleaner starts slowly disintegrating it...

I'm with Dave. Carbs sound out of sync and possibly leaking air. Take your time, do a good bench sync, put em back on the bike, and use an unlit propane torch around the butterfly shafts and intake manifolds to see if you have a leak.

 

I disassembled the carbs. The sonic cleaner solution is essentially soap and is rubber friendly. Therefore it wouldn't hurt any rubber to begin with. The reason I took it apart was to clean the fuel circuit.

 

The whole carb is a fuel circuit---

 

Haha.. anyway - I seem to have this annoying squeak that just will not go away. I can't find the source of it. I double and triple checked vacuum leaks and even manifold bolts but it just won't stop squeaking. No idea why. I'm kind of stumped on this one.

Also - redoing the bench syncing seemed to have helped the idle. I must have incorrectly done it the first time.

 

you still have to do a running sync after you get it running. just sayin'

FU

 

I understand that. Here is my problem however.

If I have a squeaky noise, be it exhaust leak / intake leak. It doesn't make sense to do a running sync until I have completely solved the issue. I seems that the high reving was due to an incorrectly set bench sync. The butterfly valves were open too much, and resyncing helped.

 

Use a length of vacuum hose against your ear liek a stethoscope (put an ear plug in the other ear) and work your way around with the other end to listen for where the squeak is coming from. That will narrow it down. Using propane is another option. Work an unlit torch around the intake side of the engine until the idle speed increases; that will find your leak.

 

Float levels in spec? Carbs clunking?

 

Ok solved the problem... the new intake manifold gasket was leaking. Replaced with a spare I had and no more squeak.

Was doing a vacuum sync today. Was going well, but I seemed to have a chain rattle / tap noise.

What is the proper procedure to tighten the chain?

Anyhow, my bike ended up dying and wouldn't restart. I wondered if it was because of the battery, because the spark looked weak.. but my genius charger said I was between 25%-50% power on the battery. Swapped coils with a good spare and had same problem. It looks really small and hard to see.

So I decided to try to see if I can turn the bike over by hand.. I can't seem to turn it counterclockwise, but clockwise works fine.

 

If your battery is that low, it ain't gonna start

 

Alright.. I'll charge it and try again tomorrow.

 

Ok .. Ok...

So this morning the bike didn't want to turn over more past 1/4 turn clockwise and counterclockwise.

I'm wondering if the rattling was from the tensioner failing... and my timing jumped causing me to bend a valve.... would explain why I couldn't get it to start again, and why I can't turn it over past 1/4 turn.

Luckily I have a spare head with all 8 valves from another 1980 head. Worst comes to worse, I can steal from a 1982 head that I have as well.

It is worth taking out the cams, resetting the timing.. looking into the tensior and making sure it is correct. Putting it back in and testing with a compression test. However I'm not feeling good with this one.

... 1 head gasket please!

 

first, I would pull the valve cover and check the cam timing and chain tension. then go from there.

FU

 

Neat thread. I'm learning a lot vicariously.

 

How much lower would an engine with a bent valve have for compression?

 

A bent valve won't close all the way. You should do a leakdown test to see if the valves are sealing. A compression test won't tell you if the valve is bent or not.

 

Ok.

So compression test came up

1 & 4 -> 120
3 & 4 - 90-100

Which would make me think I incorrectly did my shim adjustment incorrectly. I need to double check and will get NEW feeler gauges. My original ones were questionable, and I should have bought new ones.. but I didn't. Ok - double checking that.

So, I redid the timing and tensioner, all was supposed to be good. I had the valve cover off, and was playing with it a little bit, I started to watch the timing jump again. I would do 1-2 second bursts and at one point it wouldn't start anymore. Timing jumped to where it locked previously.

Thinking back, it was kind of a similar situation to what happened the first time...

Possibly the timing was jumping enough to not start, and not kiss valves.. but by continuously trying to start - the chain jumped until the crankshaft locked.

OK OK -- enough speculation..

Leakdown test needed. Now I need to order one.

 

Did you replace the chain?

 

No I didn't.

 

That may be why it keeps jumping time. The camchain tensioner can only go so far. Did you clean and reset the tensioner when you had the head off?

 

I did reset it..

Ok.. I noted this when putting cams in again... I can turn the engine clockwise just fine.. but I try to turn counterclockwise and the chain seems to bunch up.. and get sucked downwards until the crankshaft locks...

I had only one cam in when testing this.

 

Would an automatic cam chain tensioner bolt up in place of the manual one?

 

If you only had one cam in, there's no way that the chain could have stayed taut enough TO turn backward.

 

Yes.

 

Slow down. You're moving at a rabbit's pace but not accomplishing what's necessary. I've re-read this entire thread and imo most of the problems you're having are coupled with potential "pilot errors". A lot of the help you seek has been given. If all the components are within spec and are correctly assembled that engine will turn/run proper. Press the refresh button and follow the advice given. You can swap parts all day long but if the result doesn't change...well you know. We're all here to help and learn from each other.

Gary H.

 

Woh there, I just haven't told the full story. Has nothing to do with me asking a few different questions. Sometimes I have to wait for parts / tools to come in before I can accomplish the first bit of advice. While I'm waiting to I will continue to ask questions and play around with it.

I asked about the tensioner because the chain shouldn't be worn and stretched. It was working just fine a few weeks ago. It wouldn't wildy stretch in the span of 2 weeks and very little run time.
More likely it would be the tensioner that failed. I asked if an automatic tensioner would bolt up and work.. because I have one.

As for the leakdown tester, amazon refuses to send a drone to my house with one. I had to wait a few days. Now that I have the tester I can post results.

However, for the time being until I got a leakdown tester I tested the compression, and Hogfiddle noted that it won't tell me if I have a bent valve / not sealing. Anyhow, actuating the starter button I could watch the timing jump. I removed the cams and waited for the leakdown tester to arrive, no point of resetting timing one more time to check the shims to just double check one last time.

I did however play a tad with the chain to see if I could figure out what was happening. Hog noted that I the chain wouldn't stay taut to turn counterclockwise and thinking about it that made sense.

Since the cams were out, all the valves will be closed, and I can plug in a leakdown tester without having to move the engine to tdc of each cylinder.

Amazon package arrived and an otc leakdown tester was in it.

The results

1,4 were at about 2% leakage
2 was at 4-5% leakage
3 was the problem with well above 10% leakage on the intake valve.

There is my problem. This is what I need to fix. Head off, replace valve, head back on. Redo / check shims. since new valves in 3 will have been fitted.

 

Without more of the "full story" it appeared you were chasing a ghost. I've done this successfully a couple times and currently doing a case break (primary guide replacement) which will include rebuilding the top end. Just trying to help. Good luck with the build.

Gary H.

 

I don't think that's quite what I said.....

 

A compression test simply tells you your compression amounts.

A leak-down tester helps you determine if and where the compression loss is. By maintaining a constant supply of compressed air, you have the ability to listen for where the air is escaping . If you hear it at the carbs, you have an intake valve leak. If you hear it at the mufflers, you have an exhaust valve leak. If you hear it at the oil filler, you likely have either piston/rings leak, valve stem leak.

Neither will tell if a valve is bent or not .... They will only indicate whether valves are sealing or not ( if its determined that the leak is at a valve) then it's up to you to determine why

 

I'm sorry, it was K-moe who said that originally. One page ago.

Everyone has been a huge help.. I've just been getting you all mixed up.

 

Don't worry... We're not mixed up

 

Thought I would put in a good word. I am doing a similar rebuild here. I like this thread it has been reassuring. In my small shop I have a small utility drill press, one that can be bought on craigs often for 50 -75 dollars. It is very handy to drill out broken bolts and for simple drilling. But I bought it for another reason. With a small 3/8 ths extension mounted into the chuck, and with a wooden base to place the head on at the right angle, I found it works great as a light weight arbor press. And that means you can use it to disassemble and reassemble your valve train. I used an old socket that fits in the lifter bore and cut half of it off so I can get my fingers and a magnet to pull out and put in the valve keepers. I left half of the socket at the end for stability. The amount I cut off was about an inch. I also note that inserting the keepers it was made much easier if I coated the keepers in a grease to allow it to be pushed on, then rotated to the backside and then the second keeper pushed on and and stay before I release the spring. I am sure many of you have that same type of small drill press. The wooden "head holder" is made so that I have been able to do a maxim x head (20 valves) as well as a Suzuki a Honda and of course a Yamaha XJ.

 

I've considered buying a used Seca that has some problems and found this discussion while searching for clues as to how much work it will need.

I've read through the thread and I'm not sure it's conclusive regarding "Typical" cylinder head oil leakage on early Secas. It sounds like it could be a relatively minor or it might be a huge ($$$$) problem.

As I said earlier, I've been looking for a restorable UJM (Universal Japanese Motorcycle) from the late 70s to mid 80s and came across an 82 XJ650R that looked like it might have potential. The bike has been sitting for years and has several problems that are related to its non-use, I believe.

The bike has about 18k miles and looks to have been generally well cared for, but has just been sitting too long.

The fork seals are leaking. The cam chain is a little noisy. The engine does not smoke, or have other engine noises, though. There is oil contamination on the front calipers (may be the leaking forks OR a leaking caliper).

None of these things concern me too much and are typical of a bike that hasn't gotten much use, but there is one more problem that has me worried. The cylinder head gasket appears to be leaking oil on the left side. Reading this thread makes me leary of purchasing it, since it sounds like a top end rebuild or worse could be in this bike's future.

To those of you who've owned and repaired these bikes: Should I assume the worse (head rebuild and cam chain replacement -- along with machine work) or do these early)?

Thanks for your input.

 

@mrgem: We guesstimate a amount between $600-$800 to fully restore and make road worthy any one of the xj series bikes. This amount does not include missing or beyond repair damaged parts. It also does not include tools. At 18k miles the bike shouldn't have any major problems. A compression test will tell if the engine is in decent shape. The oil leak may not be the head gasket but the valve cover gasket and or the cam chain tensioner gasket. The brakes and forks will get rebuilt during the restoration process.

Gary H.

 

800 ain't bad...

 

+The knowledge of this forum...PRICELESS!

Gary H.

 

This is about how much I'll be into my Seca after purchase price. ~$1500 doesn't seem all that bad to me. /shrug