Early or late?

[BA80]

It's time to swap engines in Ol'Okie. It's never been the same since being super overheated climbing Pikes Peak a few years back.

Trying to decide weather to go back with the early ( 78 - 79 ) engine like I have now or to go with the later engine ( 80 - 81 ).

The early engine seems much quicker after 3500 rpm but the late engine is a little smoother power and better low end.

I have both I could use and both have their pros and cons. I'm leaning towards the early model. I like the quick power.

[JeffH]

Which motor do you think is better, stronger, more reliable?

Big question would be where are you going where you need to maybe be quicker?
Just using the E/F motor may not get you anything in the long run. Quicker is maybe a 'feel good' thing that may or may not happen with a 40 year old motor.
Do you know the history on either of the motors? To me that would probably be deciding factor in picking which motor.

And yeah, your motor got pretty hot on Pikes Peak waiting in that long uphill queue at the toll booth. 90 degrees. No breeze. For an hour I think it was. My 11 was getting a bit unhappy too. Your Oil probably close to giving up the ghost from the excessive temp. Plus living where you do your driving speeds are considerably more than average.

Jeff

[DiverRay]

Plus getting good fuel! Grain alcohol is for drinking, NOT internal combustion engines. That said, I'd still go with an early engine. I've never noticed the "new" engine being any smoother than the early.

[Radioguylogs]

I ride both versions regularly, and I notice the exact same things as Greg.

The SF engine is noticeably faster.

The SG engine starts more quickly, idles more smoothly, and has more power at lower RPMs.

I always want to enjoy the throttle every chance I get, and so I get more enjoyment of of the quicker engine.

I'd pick the early engine if it were me.

[motoman]

For you and your riding style Greg, stick with the earlier model engine. Cam timing advance and losing that through the use of the 4RO set-up would also save from having to change those components, TCI etc. So, there ya' go.....get r' done buddy.

[MPittma100]

Early or Late

The one that checks out the best is the one to use. After 40 years in service, early or late matters little.

[skids]

I ride both versions regularly, and I notice the exact same things as Greg.

The SF engine is noticeably faster.

The SG engine starts more quickly, idles more smoothly, and has more power at lower RPMs.

I always want to enjoy the throttle every chance I get, and so I get more enjoyment of of the quicker engine.

I'd pick the early engine if it were me.

I'm with Mike. Peaky torque gives you more of a charge! If you are thinking long interstate type rides, the 81 can give the best fuel economy with the later carbs and exhaust. The best low-end torque that I felt was with one of my 78's with a Jardine 4-1 pipe.

[BA80]

Thanks for the input y'all. Sorry I didn't reply earlier but most of the time I can't get on here. It just says " site not found". I wish the powers that be would fix that.

Some of the most respected friends and acquaintances have answered.

The early engine I have is in an SF with a bent frame that came from Bob Falter's man cave in Iowa. It shows about 50K on the clock and has been VERY WELL taken care of since the bike was crashed.

The late engine is from an SG I bought from a person here in town that does fantastic restorations on bikes and cars. His collection of vintage Yamahas is impressive. IIRC it only showed about 20K on the clock when I got it. I sold it to JWHughes and he pretty much stripped it but for the engine, wheels, and harness. Bohn Frazier got the harness to fix the electrical problems on his SG.

I had removed the head because #1 and #4 plugs were frozen and broke off and I needed it off to get them out. That head went away on another bike I sold several years ago. The cylinders are in VERY good shape but I would need to overhaul a head for it.

I'll need to do 2nd gear in both just to be sure.

I think I just talked myself into the SF engine. I like the way the F engines run, especially with the E timing components I have in mine now.

As far as exhaust and carbs, either way I'll be staying with the early carbs. Much more dependable and greater adjustability. I'll also be staying with the Mac system I modified the mufflers on. That less restrictive setup really woke up my current engine. Back pressure is great for 2 strokes but not so much with the 4 strokes. Did a lot of research on that.

[dpotter58]

There are no "powers that be". It's the wild wild west!!!

[motoman]

IMO, you've talked yourself into the best choice Greg.

[DiverRay]

There are no "powers that be". It's the wild wild west!!!

dpotter58, the site is run from the EAST Coast. The problem is life has gotten to those that know how this site runs. I'm a "hardware guy", so I can do a LITTLE on the software side, but running something like this is well beyond anything I can do.
I really hope that someone can find a way to fix the site, as like a LOT of people it is my only way into the xs world. I do NOT do faceplant, as I've been hacked twice within two weeks. As someone who had to keep passwords at high levels, I know it wasn't that kind of problem....

[BA80]

Face plant. Ha ha ha.

I Facebook a lot. It's the only way I can stay in touch with my kids and other family scattered all over the map.

I've been hacked a few times but I've always been able to recover my account and change the password. Haven't had any issues in quite some time now.

There are a lot of FB xsives that would love to join but can't because self registration is closed and emails seem to be ignored. Almost like .com is committing suicide.

[motoman]

Face plant...…...BTDT, as you well know

[3Phase]

Face plant...…...BTDT, as you well know

Heh, Basefook sux, I haven't used it for well over a year.

You've got a good selection there, Greg and if you have genuine "E" mechanical and vacuum advance parts you're stylin' for the early engine.


The mechanical advance weight assembly has a tendency wear loose on the shaft and flies around under the timing cover like a Wham-O Water Wiggle.

The large bearing for the pick-up coil plate and vacuum advance gets grungy and 'notchy' too and you lode gas mileage when it sticks. The dust seal on the back side of the bearing pops off so you can clean and lube it and it's not toohard to put the shield back on. Almost every assembly I've seen has that fine red iron oxide powder all over the underside of the bearing/housing. Bleh.

The later '81 engines with the 4RO TCI don't have the maintenance/wear problem with the mechanical advance but they still need the vacuum advance.

The XJ11 got rid of both and went all-electric with its... 'unique' ... yeah, I'll go with 'unique' 10M TCI and the MAP (?) sensor on the frame. FWIW my XJ's still running fine with zero maintenance. I might clean the carburetors sometime before the end of the year just for grins but it still starts with one kick on the kicker so leaving it alone is a good plan.

The carburetors aren't as important if they're set up right. I went 'round the mulberry bush about that with Planedick until I gave him a set of '80G carbs and we put them on his ''78 E "Pathfinder". It ran great until he lost it one day but that had nothing to do with the carbs.

[BA80]

SCOTT!!!!! You ARE still alive.

You should have surfaced last July and made the trip up North with me. Had a great time.

You did get a bike that will stay running for a long trip by now I hope. Ha ha. No more Hardley making it.