Finding 3rd carb body

[Oro]

Hi and thanks again. This is me but my dad JK is right here.

I mis-spoke, the CALIPERS were missing, those were the rotors on the bike when acquired. I think they are original as they seem to have ~15k miles on them matching the odo. The bike has matching vins on the steering head. But they appear to be pre-81 per comments above.

9-digit stamped: 4RO-004582
17-Digit decal (pic above) is hard to read but last digits are the same.

I understand that 81 was the transition from make-unique VINs to standardized 17 digit ones, so both are valid (and argue for 81).

The engine is stamped 2HY7-021578, which indicates not an original motor, correct? I can't find exact decoders online for the nums.

Not particularly worried about a frankenbike - I'm more used to encountering "Frankenguns" as I used to do some gun collectnig and 'smithing. Dad used to race a Yamaha SC500 - there's a pic on the wall here somewhere. oh, here it is. This is c. 1974. One tricky bike. Anyway, I am more knowledgeable about Hondas as I've owned and restored several from 76 to 87. He worked in Kawasaki dealership in the 70s and knows Kaws and Yamahas much better but not this model I had a similar 83 CB1000C until stolen a few years ago, so a similar bike the the special but not far from the standard, obviously. I had a to a similar resto on it about 10/12 years ago and it was a joy when done.

The bike was in the same hands 99 to recently, and the previous owner didn't mention any major surgery on his part, so parts swapping must have happened before that.

I also agree this is the right palce! I have some experience with auto/bike forums - I have even been a mod at two (actively one now - planetisuzoo). Before I join a forum I read it a bit and make sure it has the right vibe people plus technical knowledge. Frankly I was surprised the "single model" forum like this was so vibrant because usually it's not. Impressive.

[Oro]

The original color is a ruby red; the sidecovers were there and all intact. The tank's a mess and in the works. He has found an original seat in great shape and matching color.

[Bax]

Hi Oro, First welcome to the club. Seems I'm a bit late to the party on the carbs. Noticed a few indicators to help ID the carb array vintage. 80&81 models were shipped with the BS34-iii bodies. These bodies had SS float frame with rubber floats. -iii also had dual float vents to the bowl in the carb mouth and stamped steel diaphragm covers which 1&4 were polished. Looking at the pics you provided it seems that the diaphragm covers are all cast Aluminum, single bowl vent, and brass floats. I'm not sure on the 78E if the idle stop for the carburetor array was positioned top back for 78 only (I seem to remember 79 models as well) but later models, 80 up, it was front lower. Seems like a carb array from 78 is most likely.
---Bax

[cajun31]

Oro... the rotors are probably from the same source as the carbs. The originals for the frame you have were slotted. Motoman was spot on concerning the motor. You at least now have enough info to know what you are looking at and how to proceed, acquire the right parts etc... Keep us posted on your progress and everyone loves pictures on this site so keep those coming.

[JohnKa]

Any way to do a static timing? I have a bib on the #2 carb on EBay. And two new floats coming

[JohnKa]

That photo I posted is a 1932. Dodge Brothers Touring Car I brought back to life

[Bonz]

Oro, the motor in that frame pictured is either a 78,79 or 80 model. The engine model lettering/numbering is stamped into top of case on the clutch side(right) above oil filler plug. Coding will start with a 2H7(IIRC). If motor were original, the motor coding would match the frame coding.

Hi Brant, I think I see the stub for the kick starter coming out of the case. Unless someone did a retrofit of a kickstarter would that mean it’s a 78 or 79 and not an 80?

[cajun31]

Any way to do a static timing? I have a bib on the #2 carb on EBay. And two new floats coming

when you say static timing... not sure what you are asking or what makes you ask.

[Bax]

OroJohnKa In case you didn’t have this already, here is a link to the service manuals with all the models supplementals included. Setting up timing will differ depending on the model year of the engine.

link is getting broken in this forum, need to click his personal site then his motorcycle then other motorcycles and select Yamaha.


Bax

[Oro]

Not saying we aren't making progress, it's just sometimes in a non-linear direction.

ere is a link to the service manuals with all the models supplementals included. Setting up timing will differ depending on the model year of the engine.

Dad bought a copy of the service manual and we have the link. Timing appears to be off and are checking that again. By "static" he means engine not running (e.g., during assembly) - vs dynamic timing when running for fine-tuning on some systems.

Heads on the bench now and some valves are bent - he had rebuilt it so the timing was wrong. I'm going to go through the manual now and check. The print manual he has says "XS1100 78-80." Are the heads in any way different 78-79-80-81? I will look in the manual now and see if it gives different stating timing procedures. EDIT: no it does not, just has one procedure for setting the cams.





This is the manual he used/I am reading now.

[Bax]

On the timing issue. Seems there is a mismatch of year parts on the bike. The 78E had mechanical advance and the later models did the advance electronically with the ignition box. If you have a later ignition box with the early mech pickup on the engine that's probably a likely cause of timing being off (need to check part numbers on ignition box). Other common issues that can indicate timing/spark not being right: Conductor broken in the insulation on the loop back wires for the pickups. Vacuum leaks or wrong port connected on the vac advance unit. Advance unit(s) does not rotate freely.

---Bax

[DiverRay]

Static timing is all the same. Be sure you have the crank with #1, Left side as you sit on the bike, at TDC. Pointer on the left crank should be at T, IIRC. Then set the cams BEFORE putting the head back on, #1 cam at TDC, both valves closed. Pay attention to the rotation direction on the engine! it's "backwards" of most engines.
Remember, you CANNOT rotate the cams with both cams installed, you will bend valves. I like to set up the crank at TDC, put in the intake cam, and then the exhaust. Use the marks on the cam to get close and no problems.

[cajun31]

this comes from the maintenance section... it involves adjusting valve clearance but is a good pictorial of what Ray is telling you to look for. Valve Adjustment Pictorial - XS11.club Forums

[Oro]

The carbs are as found. But who knows. I noticed one float bowl was different (it was 2g heavier). Have another body coming for one that has pitting, and got a float to match. Will get back on that soon.

The motor has a mechanical vacuum advance mechanism on the left side of the crankshaft, and then there's this control module on the rear fender.

P/n says

Type TID14-01
2h7-10

The "2H7" at least matches the engine, but the engine again is:

2H702 1573

So I don't know if it's significant the engine appears to be 2H7-02 (with mech. advance) , and the module 2H7-10?

[DiverRay]

That is the proper TCI module for the engine. Big thing is check the wires on the pickup coils and make sure they aren't bad before you install everything. Pull on the wires and look for the insulation to deform into an hour glass shape. If it does not, your good. If it does, you will need to replace or repair the wires. When re-installing do NOT crimp the wires in the factory clamps!!! Just crimp slightly to keep the wires away from the spinning parts. The tight crimp is why the wires break, a factory defect from day one. If allowed to slide a bit, they will go for a LONG time.