The new guy

[Devchev]

Hey all, I've just joined this forum yesterday. I'm really excited about it. I'm about to begin tearing my motor apart on my 79SF that I just picked up cause it stopped running on me. I'm just going to rebuild the whole top end. I know a lot about Harley-Davidson's, as I work as a service writter and rentals manager at a dealer for the last couple years, but I don't know a whole lot about metrics. Any pointers? Cautions? Things to watch out for or avoid?

Thanks a lot! Happy motoring

Dev

[jwhughes3]

welcome

Glad to see you join the madness...

There are permanent Tech Tips that may help in knowing both what to look for and history - go to Home page - Tech Tips...

We won't hold the Hardley stuff against you (much) but the main thing to know about these bikes is they don't make any bike like this anymore - pretty well designed and thought out to last...so if you are making changes consider how it may affect your longevity.


Other than that dive in. Search on what answers you need - this is an old forum so alot has been done different ways over the years..

And don't start any tire or oil threads!


John

[crazy steve]

Well, first thing is, these ain't Harleys...

While some things will be very similar (chassis, forks, brakes) in terms of design, the engine/trans is considerably different. These can be quite a bit more difficult to work on in some ways, and tuning is certainly more involved. Do get a service manual and get familar with the bike before you tear into it. Don't be in a big hurry to tear the motor down, as internal engine parts are difficult/impossible/expensive to find (no deep parts well here unfortunately). Luckily, these are generally pretty bulletproof for major problems, with most problems being fuel system/wiring related, with occasional trans issues. If the motor is toast, it will be far cheaper to find a good used replacement rather than do a rebuild.

Like John said, pretty much everything you need to know is here somewhere, so welcome.

And if you decide to do a brake upgrade, the HD 4-piston calipers are a fairly easy swap if you thin the stock rotors down; I'm sure you could get a 'deal' on some new take-offs...

[SFerinTEXAS]

I'm about to begin tearing my motor apart on my 79SF that I just picked up cause it stopped running on me.

Just curious what reasoning led you to this course of action. Maybe there is something others could learn.

[TopCatGr58]

Hey there Dev,

Yes, WHOA there fella!! These bikes/engines are getting harder and more expensive to find parts for, many are now Non-available from Yamaha since they only supported them for about 10 years! SO....tearing into the engine blindly could set you up for some really expensive processes.

Some questions about the bike you've just picked up, like how many miles on the clock? Unlike other bikes of it's era, these can go 100k miles or more!! Yes, that is no BS, they used flat crank and rod bearings instead of roller.

Next, have you done a compression test? The only aftermarket or oversize piston options are a big bore kit from WISECO. But your engine may not need that heavy of work.

The most common reasons why they stop running is due to electrical problems, and if it has the OEM glass fuses fuseblock, that's your first MOD/Repair to do. Next is the battery. If weak, can drop to below 10.5 volts during startup process, and that's not enough juice to fire the ignition module! Then there's the charging system, corrosion commonly causes problems with the reg/rect and the large ALT plugs BEHIND the fuseblock panel! ALL of the connections can get corroded, and doing a complete harness break down/apart of all connectors, cleaning, dielectric greasing can go a long way in eliminating electrical gremlins. Other electrical ignition problems are the Pickup coil wires, as well as the spark plug coils, the ballast resistor, and rarely the actual TCI unit.

The next most common problem is fuel/carbs. A search for carb 101 will reveal a fine thread by Wildkat that can show the process of cleaning the carbs properly! DO NOT SOAK them in a bucket of cleaner....will damage the butterfly shaft seals!!!!

SO....some simple troubleshooting can go a long way in AVOIDING very expensive and unneccessary engine work, as well as the trouble in trying to find parts!

As stated, find/download the service manuals, read thru the tech tips...ALL OF THEM, and then do some simple testing BEFORE you start tearing into the engine.

Curious...will YOU be doing the mech work, or will you be having some of the H-D mechs/techs working on it??

[SFerinTEXAS]

So much for my subtle approach. But Yeah, What TC said.

So again, Just curious what reasoning led you to this course of action.

[Devchev]

Thanks everybody for the advice! I appreciate it. I know parts are difficult to find... it's like finding parts for a Shovelhead.

T.C, duly noted. I'll check that stuff out. I will either be doing the work myself or having an aftermarket shop do some diag work to help me out (mostly to save time.. I work 45-50 hours a week).

SFerinTEXAS, it's blowing oil into the third cylinder. Thats mostly why it's not running I believe.

Here's my situation: I bought the bike, after inspecting it to the best of my ability and test riding it and listening to it run for a while. I rode it home from about 110 miles away and it clearly felt like it needed a carb sync. He also mentioned that to before I bought it. I know some guys that know how to do carb syncs and I'm not afraid to try it.

When I got home, it start popping very loudly out the right muffler, and I found oil coating the end of the muffler. I had it towed to the import bike dealer that next door to the harley shop and had them take a quick look at it (know some guys there, employee discount etc) just to see if they could give me a general idea. Well, they were useless, except they were able to put a copper insert into the third cylinder spark plug hole which I found stripped. They did a compression test on three of the four cylinders, But I do not know if they did one on the third cylinder once they repaired the spark plug threads. After replacing the spark plug caps and plugs, they were still unable to start the bike. I found excess amounts of oil on the third spark plug and could see a lot of carbon and oil in that cylinder, as well as oil coming from behind the header from the block on the third cylinder.

Piston rings? Valve stem seals? valve guide seals? Head gasket? Therefore my thought to rebuild at least the top end. The battery is brand new, and the charging system holds a charge very well. The turn signals are slow, but not when I get moving. But the starter is very strong and fast with no issues there (except maybe a slightly noisy starter clutch). It just won't start and is blowing oil into that cylinder.

OK. So... yeah. Besides that, I need to sync the carbs and clean them for sure.

Thoughts? I can get gasket kits from bike bandit for the full motor, I can get piston rings and get valve seals. If worse comes to worst... I'll get another motor and tie that down. I'm hoping I can save this motor.

I've heard many good things about these bikes. I don't hesitate to believe that they are a 100K mile bike. Mine has 57K.

Should I try an aftermarket "resto" shop? I found one north of me that is pretty reputable, and they specialize in older bikes.

-Dev

[Devchev]

crazy-steve, Harley-Davidson calipers will bolt onto my 79SF? If so, great. I may as well try to get some Sportster handlebars that are 3/4 inch into 1 inch diameter so I can use sportster mastercylinders... parts are plentiful. Just an idea. anythings possible.. haha

[Devchev]

also, I picked up a Clymer manual and have been studying it. It seems very detailed and well written. Tons of good photos and cautions and warnings and specs and everything. so yeah

[jwhughes3]

Dev

Dev - there are some torque inaccuracies in Clymers (search other threads) so Id trust the FSM for those.

If I remember the HD calipers arent direct bolt on but need an adapter but work. You'd need to search cuz I cant remember who did it.

Could be they swapped/ messed up wires in your plug fix? Maybe messed up pickup wires by accident (how i dont know just throwing it out).

John

[SFerinTEXAS]

What a story. Thanks.
Just off the top of my head i say

get a reliable compression test across all cylinders. (throttle has to be wide open for this) Got a new tester at AutoZone for $20

Raw fuel will soot up a cylinder and ergo will appear oil-like where ever it comes out. and cause backfiring in the exhaust.

these will run on 3 cylinders, not happy but will run

Your problem could be rings or a combination of other things .

If compression is good I would concentrate on ..........lots of things.
Good luck, hope you got a good deal on the buy

[CatatonicBug]

You can download a digital copy of the Clymers or the Yamaha manual from the link in my signature. There have been a few errors noted over the years in both of them, but yes, they make life a lot easier.

[natemoen]

I say, do the carb work before you even consider opening the engine. If you can get her running.then put a few hundred to a thousand miles on her and give the rings a chance to free up and reseat.

As to the hd calipers, they are not a direct bolt on but take adapter plate that crazysteve has dimensions for as well as turning the rotors down. Not many turn these rotors though, they are a hardened stainless steel rather than regular steel like others.

[crazy steve]

crazy-steve, Harley-Davidson calipers will bolt onto my 79SF? If so, great. I may as well try to get some Sportster handlebars that are 3/4 inch into 1 inch diameter so I can use sportster mastercylinders... parts are plentiful. Just an idea. anythings possible.. haha

Oops, sorry, missed the 'SF' in your post... Nope, nothing will fit on those weird front forks except the stock calipers. If you swap to standard forks/trees, then that opens up some possibilities. Here's the swap info for standard forks:http://www.xs11.com/forum/showthread...arley+calipers

As far as swapping to HD master cylinders, that opens a whole 'nother can of worms. You can't use the single-disc Sporty unit, you'd need the BT dual-disc M/C with it's bigger bore. Besides the 7/8 vs 1" handlebar thing, HD puts the brake light switch in the handlebar controls, not on the M/C like Yamaha does. To get a functioning brake light, you'd have to swap to HD controls and the differences in the control layout/wiring make this a tough swap as the turn signal wiring is much different. If you did a total rewire of the signals and used the HD 'turn module' you could do it, but otherwise no. I looked at this, but decided it was way more trouble than it was worth...

Who do you work for? Eastside? Or Downtown?

[TopCatGr58]

Hey Again Dev,

The gasket kit isn't really needed unless you need to do a top end job, most folks just use 3 bond or equivalent sealant in lieu of gaskets. And you can get a better deal on Partsnmore.com for the complete gasket set IF you need to get a headgasket. Whole set with headgasket for about $100.00, Yamaha gets $75.00+ for the head gasket alone. And you get the valve seals, and the valve guide O-rings.

Yes, you need to do some diagnostics, like checking to see if you are getting spark on the dead cylinder. The plug caps have built in resistors, the internal contacts corrode, along with just the wire where they screw onto it, remove the cap, check it's resistance...should be ~5k, then inspect plug wire...if green corrosion found, can trim back to good copper. If resistance too high, can just get replacement NGK from many sources, you don't really need the resistor since mostly found in resistor plugs now, and it's for radio interference control anyways, not for performance.

The early models carbs have brass floats, they get pinholes and leak/sink causing carb flooding. Also, float valve needles are metal on metal, get junk stuck between causing leaking/flooding. Can get newer styled rubber/viton tipped from Yamaha XV920 model, both screw in seat/valve that will fit the 1100 carbs. The valve alone won't work, too big gets stuck in seat!

57K miles is just a good break in level. There are some areas of maintanence that can cause costly damage if done wrong....so be sure to check out the cam chain tensioner adjustment procedure carefully and thoroughly. DO NOT REMOVE The tensioner body from the engine UNTIL you find and read the "GOT DEFEATED" thready by Trbig about what can happen when you remove the tensioner body.

Okay, as stated, a checklist of things for you/your mech/tech to check out would be a good thing. You may also want to PRINT out or provide the manuals and such for the techs, with specific warnings about certain steps or procedures. Crazy Steve lives in your area and can tell you more about the shops there, who would be reputable, BUT...most of us have found that working on these bikes ourselves was the best and most economical way to go, but we can understand the lack of time issue, and if your pockets are deep enough, then you can outsource your work for sure.

Also, had the bike been ridden much recently prior to you acquiring it, or had it been sitting for months/years? IF it had sat for years, then sticking rings is a strong possibility and just running it to reseat them can reduce lots of the oil in cylinder problem along with improving compression, reducing carbon buildup, etc.! Sorry this is running so long!

1.) Proper compression check...but still may not be full story if rings are stuck.
2.) Spark check on cylinders, resistance of plug coils WITHOUT caps on, resistance of caps, clean/replace as needed.
3.) Carbs cleaned thoroughly inside....removing all pilot/main jets, emulsion tubes, pilot/idle jet screws(MUCH CARE HERE...check for broken tips..see tech tips) Replace float/needle seats with the XV920 ones.
**Install in line fuel filters, possibly remove OCTY if you want simplicity, just ensure petcocks shut off works, but if carbs floats valves work, not as big a deal, just more insurance against fuel leaking from carbs getting into engine/oil!
4.) Change all fluids, even use some MMO in engine oil, would work better IF engine can be gotten to running first....just to normal temps, on center stand, NO DRIVING NO LOAD or heavy revving, run thru gears and work clutch, then drain, can help unstick rings as well as clean out old varnish from clutches and other parts.
5.) With specials, best brake performance upgrade is Stainless Steel braided lines.
6.) Still suggest checking and replacement of fuseblock to solid fuses.
7.) Valve lash/clearance check, adjust with replacement shims as needed prior to attempting any real carb tuning/synching. Cam chain tensioner adjustment. Also check intake boots for vac. leaks, around synch ports, and mating to head surface. They are double walled, outside cracks are usually just cosmetic.

The list can go on and on from here. Have fun, good luck, keep us posted.
T.C.