1988 SB50 Resurrection

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AMPsocal
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Re: 1988 SB50 Resurrection

Post by AMPsocal » Sun Sep 24, 2017 1:56 pm

Ok some Updates: The bike is running super good. Slightly warm at WOT for extended periods of time (5 to 10 minutes with up-hill pulls included) at 370-400F Cylinder head temp. Have not seen any signs soft seizing and the plug reading looks good (dark tan to light brown in color). I changed out the expansion pipe and put a PG short copy and the power delivery is way smoother and quiter. When running the expansion pipe the power came on fast and a bit violent. Have about 100 miles on it and started running into an issue with the coupling holding the carb to the manifold. The coupling keeps slipping off the manifold side no matter how tight the clamp is. I may try to remove the chrome plating on the manifold as it becomes real slippery when fuel gets on it. Have any of you guys ran into this? I have read a few post with manifolds coming loose or loose couplings, but no definitive answers on how it was resolved. Just needed a little reassurance before i removed the chrome plating on the manifold where the coupling attaches. Thanks for all the sound advice so far in to the future. :thumbwink:

https://youtu.be/XMnkeiTsO_U
Last edited by AMPsocal on Sun Sep 24, 2017 3:08 pm, edited 1 time in total.
2010 Honda SH150i
1988 Honda SB50e

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eclark5483
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Re: 1988 SB50 Resurrection

Post by eclark5483 » Sun Sep 24, 2017 2:09 pm

I had the coupler problem as well, very irritating to be driving 40mph down the road and it pops off. What I ended up doing is using a 1" radiator hose from the auto parts store and making a makeshift coupler out of that. It ain't pretty, but it works. The hose is NOT made for fuel, but it does work and I have seen no wear on it inside from gas. The old coupler would never stay on no matter how tight I got the clamps. I even tried copper spray inside.
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Re: 1988 SB50 Resurrection

Post by bonesv » Sun Sep 24, 2017 3:12 pm

AMPsocal wrote:Ok some Updates: The bike is running super good. Slightly warm at WOT for extended periods of time (5 to 10 minutes with up-hill pulls included) at 370-400F Cylinder head temp. Have not seen any signs soft seizing and the plug reading looks good (dark tan to light brown in color). I changed out the expansion pipe and put a PG short copy and the power delivery is way smoother and quiter. When running the expansion pipe the power came on fast and a bit violent. Have about 100 miles on it and started running into an issue with the coupling holding the carb to the manifold. The coupling keeps slipping off the manifold side no matter how tight the clamp is. I may try to remove the chrome plating on the manifold as it becomes real slippery when fuel gets on it. Have any of you guys ran into this? I have read a few post with manifolds coming loose or loose couplings, but no definitive answers on how it was resolved. Just needed a little reassurance before i removed the chrome plating on the manifold where the coupling attaches. Thanks for all the sound advice so far in to the future. :thumbwink:

https://youtu.be/XMnkeiTsO_U
viewtopic.php?f=8&t=12740&p=103989&hili ... el#p103989
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AMPsocal
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Re: 1988 SB50 Resurrection

Post by AMPsocal » Sun Sep 24, 2017 4:02 pm

Thanks BONESV! I spent close to 45 minutes searching and never found that post. To admit i was doing a google search the first 30 minutes.

I found the problem, the coupler was on backwards. The Coupler has a bigger internal rib on one side. This should be mounted on the manifold side vice the carb side. This made for a more solid coupling to the manifold. Leaving the smaller internal rib of coupling to the carb side and less weight/hanging load. Plus the groove/notch on the carb is smaller as well. I never noticed this when i originally installed the carb. DOH! I was blaming bogus parts when it was the installers (My own) fault. :coolcruise:
2010 Honda SH150i
1988 Honda SB50e

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sum_azn_kid
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Re: 1988 SB50 Resurrection

Post by sum_azn_kid » Mon Nov 06, 2017 6:22 pm

Swap out that stock frontend now that your bike has some power. When I had those stock brakes and forks with my 72 it was pretty sketchy. After frontend swap felt a lot better
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AMPsocal
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Re: 1988 SB50 Resurrection

Post by AMPsocal » Wed Dec 27, 2017 8:31 pm

Belated Merry Christmas All.

I got silly question how often do you all foul out plugs? Does it happen often? The reason i am asking is i took a 3 month break from the scooter and when i tried to start it it the other day and she would no fire up. The bike had run just fine (little hot on the top end WOT runs, up to 400 degrees) before i parked it the garage a few months back. its getting the plug wet and has spark, but the spark looks weak and the plug electrode and porcelain are sooty black. I understand i have a bit of carburetor tuning to do. I am just asking while waiting on some new spark plugs to arrive.

Side not i took off the expansion pipe and installed the PG short copy, since the response with the expansion pipe was to snappy and looping out was a real possibility. The PG short mellowed out the power and is substantially quieter. I am also exchanging the Malossi shock right now since the one i picked up did not fit. I guess i needed the offset version since tire clearance is just a bit over 1/8" from stock shock (SB50E) to tire. So until i fix the springy rear end i haven't exceeded 35 MPH, but i know there is a whole lot more once i do the gears and carb/veri tuning. Then after all that i can start working on the front end and brake upgrade.

Again Thank you all for the inspiring feedback, Oh and a Happy New Years to all!
2010 Honda SH150i
1988 Honda SB50e

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