4 bent valves and more!

[John]

The valves in the 80-81 are larger in diameter than those of the 78-79. They won't work unless you have them ground down to the proper size. The pistons and rings are the same on all models.

[caferacer]

thanks jhon iwas wondering were can i git a good price on valves and cam chain with the link this will be the 2nd time in 2 years i have to rebuild this head do to the tensioner this time i started it and it claterd i re ajusted the tensioner hoping for the best and just cranked with no compresion last year i replaced all the intake valves this time hard telling it cost 800. last time ??????

[TopCatGr58]

A bit more research before throwing $$ at it!

Hey CafeRacer,

I don't know exactly what you're expecting from those used pistons?? As John said, the valves are smaller than the ones in your 80. You could swap the entire head and use the 79 head, but you'll have the smaller valves.

As was stated in your earlier thread, NEW YAMAHA standard or oversized pistons are not available anymore. You can still get Standard sized rings, but what wears in the engine is the cylinders! And IF you have too much wear, then you would need to bore the cylinders, and your OEM pistons and rings won't work.

Going to the Big Bore Kit is about the only way to rejuvenate the cylinders and pistons. But if you had decent compression prior to the valve mishap, then you probably don't need to spend $$ on the pistons or rings, just fix the head and valves and ride!

Sorry you don't or aren't able to do the heavy wrenching on your bike! I know I couldn't afford to have one if I didn't know how to work on it! Just hate seeing you have to spend so much$$ on it. IF I lived near you I'd offer to help you work on it to save you hundreds of $$ on labor! What you've already spent, you could have outfitted yourself/garage with a decent set of tools necessary for performing most wrenching tasks!
T.C.

[andreashweiss]

Have some decent used parts in case they are needed. Solution one complete 78e engine 40,000 miles $350.00 ,solution two head off above engine $125.00 , solution three, bottom of above engine minus head,middle gear,starter,clutch,pickup coils,altinater,engine sidecovers,$125.00 I have shipped lower engine before via UPS in big rubbermaid container weighes approx 125 pounds and goes for approx $1.00 pound rubbermaid container costs approx $20.00 . Prefer not to sell pieces off head rather keep it complete. Also have cam chains,primary chains,cams (off 81) all used. andreas

[caferacer]

if i would buy the 79 head with the smaller valves but keep my 80 carbs etc what would i git pwer loss or gain and the reson im looking at rins and pistons i am having blow by coming from my crnk case brether and my oil cap if i take it off runing

[TopCatGr58]

Well,

Without a prior compression check, it's hard to say much about your blowby symptoms Doing a valve job can accelerate the affect due to increased sealing of valves putting more pressure against the rings possibly pushing more past them! Some air flow from the vent is normal, just due to the pumping action of the pistons.

The carbs are really not a factor, just not as adjustable/tunable as the earlier series, but are fully interchangeable. The 78 engine was the fastest XS11, and it had the smaller valves, but it also had slightly different profiled cams! If you get the cams with the head, you probably won't experience any power loss, and might get a very slight boost? There was a recent thread about using the earlier cams in the later heads and vice versa.

Again, if your shop that did your valve job last year did a compression test, and it was good, then you probably don't have a true blowby problem, so you could still get by with just the valve job.
T.C.

[caferacer]

thanks t.c i hope someday i eil be as good with these bikes as you if i can figure out how i would love to post of my xs most people around here cant beleve it was a full dressed tour bike when i got it from the bone yard and one more question were can i fiend the cam chain with the removable link

[caferacer]

andreas can you let me know is the head good so it can be bolted on or what dos it need and what would shiping be to illinois 62401

[TopCatGr58]

If you'll go to the MAIN PAGE of the FORUM, and then scroll down to the Forum How To section, you'll find a thread about how to post photos!

Parts-n-more has the cam chain and link. It's not a link like a drive chain with a pressure clip, you'll need to peen over the ends of the link once installed.
T.C.

[mro]

The pistons and rings are the same on all models.

Pistons not the same.

78/79 9.2 to one compression
80/81 9.0 to one compression

Notice difference by looking at top of piston.
Diameter and height same
different part numbers too
______________

78/79 piston will work in an 80/81 if you replace all of them and vice-a-versa..............


mro

[andreashweiss]

The 78e engine is complete and has no issues. I would be taking the head off of it if you want it. Will be a decent used head that will only be taken apart enough to take it off the engine. It came from a previous owner that serviced it properly and after he passed away his kid sold it to me. The service records showed regular oil changes cam chain and valve adjustments. Price for the head includes shipping to you anywhere in USA. andreashweiss@yahoo.com