If you like our site, please consider joining our club!
By joining you will help ensure that we can continue to provide this service
JOIN HERE!

New to this site

The place to discuss the R 90 S as well as the R90S Worldnet archives!
jstewart
Posts: 30
Joined: Wed Jun 09, 2021 3:30 pm

Re: New to this site

Post by jstewart »

srankin I don't want to ruffle any feathers here. Should I be posting on another forum??

User avatar
srankin
Posts: 1052
Joined: Fri Jul 14, 2017 8:45 pm
Location: Spencerport, NY USA
Been thanked: 12 times

Re: New to this site

Post by srankin »

Don't worry about what forum to post on, LOL, just be aware, they're some rabid R90S fanatics out there who believe strongly in the purity of the R90S bike.

No one but me has mentioned it so, maybe I am a jerk? LOL

Better fit would be the "Classics" part of the forums. Enjoy the riding happy Fourth of July. St.
Owner of a 84, R80RT and 78, R100RS

MikeL46
Posts: 151
Joined: Fri Jan 01, 2016 1:58 pm

Re: New to this site

Post by MikeL46 »

In the Muscle Car world vehicles like that are called clones. Not a real XYZ, but exactly like an XYZ.

I like the term and nobody is offended by the desire to emulate a cherished design.

Mike
67 R50/2 w/R100 engine/trans and Ural Sidecar
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar

jstewart
Posts: 30
Joined: Wed Jun 09, 2021 3:30 pm

Re: New to this site

Post by jstewart »

Have not been on here for a while so some updates:
1. 1000cc Siedelbrock kit finally came in.
2. 38mm carbs are here.
3. Conversion back to R90s bars or the nearest thing we could find is complete.
4. Conversion back to R90s switchgear and choke lever is done.
5. New ignition for dual plugs is here as well as coils.
6. Transmission thrust clearance was corrected as well as bearings replaced.
7. Crank clearances and thrust were checked and crank re-assembled in cases.
8. Rods were checked and were less than 1 gram of each other.
9. Rod bearings were replaced.
10.Heads were sent off for dual plugging, flow testing, new OEM seats for methanol fuel.
11.44mm intake valves installed in heads.
12.re-use 40mm exhaust valves with new seats.
13. Checked crank & lightened flywheel balance & they were perfect from previous owner.

The holdup has been getting parts particularly the OEM valve seats from Germany.

User avatar
cbclemmens
Posts: 213
Joined: Sun Apr 25, 2021 2:21 pm
Location: Apollo, PA
Been thanked: 4 times

Re: New to this site

Post by cbclemmens »

You can calculate the compression ratio by measuring the compression with a regular compression gauge and dividing by atmospheric pressure (14.7 psi). For example, my R 75/5 has 160 psi compression, i.e. 160/14.7 = 10.88:1.

Craig

User avatar
schrader7032
Posts: 9004
Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX
Has thanked: 2 times
Been thanked: 28 times

Re: New to this site

Post by schrader7032 »

Seems like a lot of compression on that R75/5!! I've been using a rule of thumb for computing things like that. Starting the compression ratio, such as 9.0:1 for the R75/5, I add 1.0 for the atmosphere then multiply by 14.7. So a 9.0:1 compression ratio is about 147 psi compression. If you have the compression results, one can work backwards.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

jstewart
Posts: 30
Joined: Wed Jun 09, 2021 3:30 pm

Re: New to this site

Post by jstewart »

Have not been on here for a while but the project at Guenther Wuest's shop is nearing completion. The biggest problem was getting the OEM 44 mm intake and the 40 mm exhaust seats for methanol gas. This took nearly 2 months from Germany. The bike is running and Guenther is putting break in miles on it weather permitting. First problem that showed up was the EME ignition did not have a tach drive for the electric tach. No caution from EME that the less expensive 3 curve EME did not work with the electric drive tach the more expensive EME module was installed and another problem cropped up. The tach will go to 4000 RPM and stops there. Hooked up another tach and it does the same thing. Haven't solved this one yet but I am sure Guenther will. The second problem cropped up after the first 50 mile ride. The rear gear seal was installed backwards and it was leaking fluid. A new seal installed properly resolved this issue so the only issue remaining is the tach reading correctly the entire RPM range.

User avatar
srankin
Posts: 1052
Joined: Fri Jul 14, 2017 8:45 pm
Location: Spencerport, NY USA
Been thanked: 12 times

Re: New to this site

Post by srankin »

It is very nice to see you are making positive progress on the build. Glitches do happen on occasion and you look like you are in good hands to get them solved. I bet you are chomping at the bit to get on and ride the bike yourself?

Thanks for keeping us up to date and don't forget to send pictures from time to time. St.
Owner of a 84, R80RT and 78, R100RS

jstewart
Posts: 30
Joined: Wed Jun 09, 2021 3:30 pm

Re: New to this site

Post by jstewart »

Srankin I sure am but is has turned bitter cold here and I can wait. Still no answer on the tach problem but Guenther has been busy on other projects. He did tell me after break in that it was a strong running motor (he ought to know since he owns 2 stock R90S bikes). He said it pulls the front wheel easily from a 1st gear roll. The final compression ratio is 10.2/1 and there is no sign of detonation with the dual plug heads and 336 cams he installed. Contrary to most info I have read on R90S sites there is no lack of low end power/torque with the 336 cams and the 1000CC piston kit with the higher compression ratio. You never see any actual test dyno numbers on either stock or modified R90S or R100 bikes but I am going to put this one on the dyno and see. We have a good dyno operator and dyno room here in Louisville. Should be interesting to see the HP & TQ curves on this project this spring. 8-)

jstewart
Posts: 30
Joined: Wed Jun 09, 2021 3:30 pm

Re: New to this site

Post by jstewart »

Tach problem fixed. Guenther took it apart and found several components on the board had failed. Cold here and the weather is to bad to ride so I am going to take the trailer to pick up my bike on Sunday. I had forgotten this but the R90S bikes that were raced in superbike in the 1970's were actually 1000cc bikes. BMW won at Daytona in 1976 I believe and took the SB title that same year with these highly modified bikes. :D

Post Reply