R90S Rebuild Rush Before Airhead Rally

[Cigars&Scotch]

A little back story before we start.
I p/u a 1977 R90S Bitsa bike from a fellow ADV rider here on the board. Its a bitsa bike because it uses a 1977 R100RS frame and a 1976 R90/6 block and has been turned into a R90S. The bike actually was built for Rocky Mayer. Yea that one, the one that make those seats.
When I got the bike , she ran pretty good but I did have an issue with the idle and carburation. I rode it that way for most of last summer with intentions of doing some overhaul during the winter

The first thing was the Lester wheels. They are ok, but I wanted some nice wire wheels. I went out in search for some wheels on fleabay and IBMWR. I purchased 2 sets of wheels and picked out the best from the set. Off they went to our buddy Woody.


Here they are before




And after Woody did his magic.



While at Woddy's I asked him to replace the bearing with a set of seal bearings. The tapered rollers are good, but since I did not know the history of the wheels that I got, might as well upgrade instead of replace.




Woody did a fantastic job. He clear coated the hubs and used SS spokes and nipples. He also used heavier spokes in the rear to deal with my fat ass.

Here they are mounted.



And the rear



Looks pretty cool huh!!!!

[Cigars&Scotch]

OK next upgrade.

Remember that fat ass . Well I called our buddy over a Wilburs for a set of rear shocks. I talked to him and told hiw what I wanted to do and he recommended the Ecoline shocks. One they look original and have modern valving and where the right price. I waited about a month for them to come in from the fatherland and put them on. A direct replacement, nice. No messing with, just 2 bolts off and on.

They feel alot better then the old ones and still look stock. Once the bike is all setup, I will play with the preload and fine tune it.

[Cigars&Scotch]

Next upgrade:

Cylinder Heads

The heads on the bike were suppose to have been rebuilt not to long ago by Ozzi out in Cal. My intentions were to have them gone over and then dual plugged. I have a friend with a 90 GSPD that had the same treatment and really woke the bike up after.


Living in NJ, I am pretty close to Rubber Chicken Racing and its head proprieter, Tom Cutter. I gave Tom a call and set up a date to drop off the heads to have him do his magic on them. The reason I chose Tom was that I liked the idea of welding on Alum washers on the new plug port so you can use the same spark plug top and bottom.

I dropped them off at his house/work shop. He took a look at them and ask for some back ground on them. I told him about the recent rebuild and asked him to go over it and do the plugging.

Got a call from the man about a month later. He said that the plugging was done. Then he told me that the right head had the exhaust seat spinning. He said when they cleaning the head, bead blasting I guess, they saw the seat spin. They heated the head up and the seat fell out. That aint what suppose to happen folks. That explains the trouble I was having with the idle and carbs. I cound never get the bike to run on the left cylinder by it self. The right had no problems. Also the left was way off in the mixture screws compared to the right. I should have done a leak down test on the bike. Tom said that there was no way I was going to get a stable idle with the left cylinder leaking at the exhaust seat. Live and learn.

I told him to replace both seats and the valves, just in case. So I basically had a complete rebuild oh the heads.

View of the head with new seat



New plug head with alum washers welded on so you can use same plugs




Different view



Intake side



Exhaust side



Top view




Pretty huh?

Well 4 plugs are not going to get fired with the same coils. I spoke to Tom about it. He recommended either Accel or the Dyna coils.

I contacted Motorrad Elektrik for a set of Dynas and mounting brackets. I told him that I had a Dyna III ignition and dual plug setup. He sent me the green coils, brackets and 4 wires. Installing the coils was a no brainer. Remove the old Bosch coils and mount the new Dynas with the brackets to the existing screw holes. Then wire the same way as you took them of.




They tell me that they fire all the time. Meaning that it is a wasted spark system. So they fire on compression and exhaust.

I was thinking of running a wire from each coil to both cylinders. That way if a coil craps out for what ever reason, you can still run on the other coil and 2 cylinders.

Any body have any experience with that?

[Cigars&Scotch]

Dang head cold is getting to me.

MORE TO COME.

[Cigars&Scotch]

So what do you put under the nice head with the 2 wires cominng out of it?

A Siedenbock 1000cc kit, what else.

Besides the fact that it took a month getting hear from Germany and put me 2 wks behind my build schedule, it is a gorgeous kit.

Here is the old and the new



For another $50, I had them install the SS tubes on the cylinders.



Also the kit uses a O ring on the base while the OEM did not.



Piston difference






Inside the piston



Work end

[Cigars&Scotch]

So what do I get for all those Franklins?

You get bigger pistons and a Nikasil cylinder. The pistons are teflon coated, that is the black stuff you see. The old 900cc pistons weigh 614 grams and the 1000cc pistons weigh 596 grams. So you save 18 grams in mass on a larger piston. So thats like .5 oz at the end of the rods.







The rings are sent to you in a trifold envelope with instructions on how and where to place the 3 rings.





The best part oi is that the rings actually say TOP on them. And you know I still screwed up the oil ring. Damn Dayquill!!

The way I install rings is to use some old feeler gauges and use them to slide the rings down to there proper grove.







TDA!!

The oil ring has a spring the is seperate from the ring and rides inside a channel inside the ring. Not at all like the stock setup.

The second ring has a lip on the outside



The third ring is the normal ring. Note the words on the ring making it almost fool proof.

[Cigars&Scotch]

Well everything was going great till I opened the other ring package. It looked a little beat up. Probably got smashed by the cylinder during its month long journey. The oil ring was in 2 peices. I don't think they come that way.




You think the end gap might be a little much? DON'T EVEN THINK ABOUT JB WELD!!!!

Sent Meyer an email to see if I can get a replacement sent out.

So the project shifts gears to other things tmr until I get a replacement.

[datchew]

Awesome. Great pictures.
This job is coming down to the wire for the spring fling.

[honcho]

can't wait to read more, and see your bike in 3 weeks.

[fixer]

ballpark price on those Wilburs Econoline shocks?