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Topic-icon ‘76 R90S. Electrical issues.

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2 months 2 weeks ago #6122 by mikethebike
Replied by mikethebike on topic ‘76 R90S. Electrical issues.
Thanks for the cable tip!
Still not quite done yet, nipples still en route LOL.
M

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1 month 4 weeks ago #6324 by mikethebike
Replied by mikethebike on topic ‘76 R90S. Electrical issues.
Quick update,
The cable nipples arrived. I had to strip the tank coating that had been applied by some one trying to mask what would have been a rusty tank after the bike sat for 30 years. When I finally got the silver junk out I had solid lumps of coating 1/2” thick from the forward end of the tank. It took a week of pea gravel and a bicycle chain to break it all out. I used the German product sold by Boxer 2 Valve. I now have a tank that looks original inside, as the coating is the same red as original.
After10 days I added fuel, gave it some choke and after 30 yrs she fired up in the 3 rd attempt.
Now I have an issue with the left carb leaking fuel. I took the bowl off, held the float closed and fuel came out if the accelerator jet. I haven’t had time to examine the circuit of the Dellorto’s yet so I’m not sure what’s happening.
It did sound sweet though.
More new to follow.
Michael

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1 month 4 weeks ago - 1 month 4 weeks ago #6337 by Wobbly
Replied by Wobbly on topic ‘76 R90S. Electrical issues.
Congrats on the start up !!

I don't even rate as a Dellorto amateur, but I can type fairly well. :P

Your carbs are probably not actually "leaking", but rather having fuel come out of the overflow and falling to the ground. The overflow protects the engine should you leave the petcock in the ON position, so that raw fuel doesn't run into the engine, dilute the engine oil and thus cause severe engine damage. This is a very likely scenario whenever the fuel tank is positioned above the carbs, simply due to the weight of the fuel.

Lots of carbs use a viton (rubber) tip on the float needle, which after decades takes "set". Replacing BOTH float needles will insure a better seal AND raise the float level back up to a more desirable level. Or it could be a bit of trash (tiny chunks of old fuel line most likely) washed down and holding the float needle open. I'd replace the float needles just on general principal either way.

Hope this helps.

Don't hide 'em, Ride 'em !!
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Last edit: 1 month 4 weeks ago by Wobbly.

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1 month 2 weeks ago #6409 by mikethebike
Replied by mikethebike on topic ‘76 R90S. Electrical issues.
Thanks Wobbly,
I was just siting here searching for a new L/H carb as I found a hairline crack in the connection to the cylinder head. I think you are right on the needles, I'll order new float needles tonight.
Im having a lot of trouble getting this bike timed, but it may also be that i cant get a good idle yet to use the strobe properly.
What ca you expect from something that sat around for 35 yrs.
More to follow.
Thanks again.
M

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1 month 2 weeks ago - 1 month 2 weeks ago #6414 by Wobbly
Replied by Wobbly on topic ‘76 R90S. Electrical issues.
Here's the biggest mistake owners can make....

Whatever is going on on one side, is just miles away from happening to the other. So if you have one bad inlet hose, you need to replace BOTH. If you got one bad float, then you need to replace BOTH. If you suspect one bad.... well, you get the picture. ;)

In short, most owners expect their bike to idle and run correctly. But what that really "boils down to" is running the same on both cylinders. How can an engine run the same on both sides without having identical parts on both sides ? I know this is not your game plan or method, but the way you worded your response left that door open, and it's a very sore point for me.

But you'd be surprised how many owners work on one carb for months, can't get the bike to run right, finally throw in the towel, and then agree to pay me $80/hr to simply go through both carbs and install identical parts into what should be identical carbs. And then they scream because I replaced new parts with new parts. Well, what did they expect ? With carb parts, the identifying part numbers are on the bag !! Only the person removing the parts from the bag gets to check those numbers.

End of rant ! :lol:

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Last edit: 1 month 2 weeks ago by Wobbly.

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1 month 1 week ago #6445 by mikethebike
Replied by mikethebike on topic ‘76 R90S. Electrical issues.
LOL.
You'll be very pleased to know that I did in fact purchase 2 new valves and floats from Bevel Heaven. I hope to have them by tomorrow. The crack on the engine side of the carb wasn't all the way thru. I dremmeled it out and used JB Weld. It looks OK. Also the crack was about 1/2 way along the plastic spigot on the head tube so it should allow an air in. Only putting the back on will tell.
I'm using a Motion Pro carb balancer so I should be able to get the two set up properly.
But if anyone has a PHM 38 B body gathering dust, I'd be interested in it.
Michael

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