1988 SB50 Resurrection

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AMPsocal
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1988 SB50 Resurrection

Post by AMPsocal »

Hello all,

Hope all is well out there. first time poster long time lurker. As the title states i am bringing a SB50E back to life. I have acquired a newer AF16 engine and a few other go fast parts to make this scoot more road worthy. I am currently fabing the motor mount which will stretch and lower the motor 1 inch for the stock location. Once i have the motor installed is when i will need some advice. I already have a 50MM CMR big bore kit and a OKO 28MM carb and manifold standing-by, but would like to run the engine stock for a few months till the wife got use to the extra speed.
Do you guys keep the factory oil pump or go premix? I am asking since i am missing components to the oil pump system. This would include but not limited to the control cable, hoses (which all need to be replaced anyways) and the oil tank which is cracked and leaks. I looks more cost effective if i premix the same for the dirt bikes and go kart. But i don't know if this may have a detrimental affect on the longevity to the engine. Plus is there anything to be done to the oil pump when i install the BBK? Well thank you all in advance for all the advice and tips. OH I wanted to give Glenn at Glenn's cycle supply a shout out for the parts i picked up from him (SYM DD rear hub, wheel and Michelin S

http://s32.photobucket.com/user/evolfor ... ed%20Stuff

Sorry, fixed the link. new to posting photo's and photobucket.
Last edited by AMPsocal on Wed Nov 23, 2016 10:15 am, edited 4 times in total.
2010 Honda SH150i
1988 Honda SB50e
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eclark5483
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Re: 1988 SB50 Resurrection

Post by eclark5483 »

Run 32:1 premix, ditch the pump. And when you pull the old engine, definitely interested in the old intake and reeds if you're looking to sell them.
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Re: 1988 SB50 Resurrection

Post by noiseguy »

Biggest issue with pump remove is blocking up the volume on the bottom end. You can fill it with a metal slug, or grind teeth off the pump so it no longer rotates.
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Re: 1988 SB50 Resurrection

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Ok all, made a bit of progress. I have added a few pictures to the Bucket. Looks like i will have to modify the motor mount a bit. First I have to notch the bottom and angle cut the rear of the mount. This will facilitate the continued the use of the stock kick stand and provide the clearance for the motor to sit in the proper position at rest. This will also add the necessary distance for correct suspension travel. If any of this looks wrong, please let me know so i can make the correct adjustments. Again thank you all for the continued advice and support. This site is my motivation to get this project going and hopefully finished in a timely manner (2-3 months).

OK, made more progress with that mount. i chopped off the bottom half of the square tubing i added and that was a perfect fit. The square tubing is 2" .120 wall mild steel.

[img][IMG]http://i32.photobucket.com/albums/d16/e ... yppjds.jpg[/img][/img]
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Re: 1988 SB50 Resurrection

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I have a few more questions, I just ordered a PG oil pump delete and a few other small items from Scooterswapshop. This should get me up and running for the mean time. The question i had was about the electric choke on the stock AF-18E carburetor. The one i received had the wires cut off at the solenoid and i just don't have enough wire to reattach. If i omit this feature will it have any adverse affect on the performance, besides cold start? Second question is tire balancing? I am seeing a lot of conflicting information on this topic, but my plan has this scooter topping out around 50MPH. Again thank you for all the replies and support past and present.
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Re: 1988 SB50 Resurrection

Post by Meatball »

All I do to balance scoot wheels is line up the yellow or red dot on the tire to the valve stem. Not all tires manufacturers have dots tho.
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Re: 1988 SB50 Resurrection

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Ok, Slow going with the scoot, but i have since painted the engine mount/hanger. installed the CMR 90cc BBK, PG oil pump delete plug. Drilled and tapped the fuel pump pulse port to 1/16 NPT and installed a areoquip 1/16 pipe plug. I got the rear tire (Michelin S1 3.00-10) mounted. i plan to hang everything back on the bike this week to finish fabing the upper shock mount. Does anyone have a recommendation on the rear shock absorber? the stock SB50E shock seems very springy with no amount of rebound control. I figure i mine as well install something good so i will not have to readdress this in the future. I have added a few photos in the photobucket link above, but nothing real good yet. Again thank you for the motivation and help with this long standing project.
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Re: 1988 SB50 Resurrection

Post by benji »

You should pick up a new bystarter (choke solenoid) there easy to install and it'll be a bear to start w/o choke.
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Re: 1988 SB50 Resurrection

Post by noiseguy »

AMPsocal wrote:I have a few more questions, I just ordered a PG oil pump delete and a few other small items from Scooterswapshop. This should get me up and running for the mean time. The question i had was about the electric choke on the stock AF-18E carburetor. The one i received had the wires cut off at the solenoid and i just don't have enough wire to reattach. If i omit this feature will it have any adverse affect on the performance, besides cold start? Second question is tire balancing? I am seeing a lot of conflicting information on this topic, but my plan has this scooter topping out around 50MPH. Again thank you for all the replies and support past and present.
On bystarter: Dead bystarter means you're always in "enriched" mode. You will want to replace this.

On wheels: You can balance them yourself pretty easily, so why not do it if it concerns you. Or do it if it's an issue.
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Re: 1988 SB50 Resurrection

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The Flu took me out for almost 2 weeks, but back to work now. I got a few more items from the Philippines, but the fit and quality is less then expected. both the expansion pipe and PG copy did not fit very well. I will have to cut and re-weld the flanges so the rest of the pipe will align correctly. The pipe mounting/support points will also have to be redone. I have installed the BBK, but had to modify the fins on the cylinder to fit the shroud. I figured the shroud cost more then the BBK, so modifying the cylinder fins was the appropriate action. I just trimed down two fins that protruded out 3/8". So not much was actually removed (maybe 3% of total fin area). I plan to make the new upper shock mount this week. I will be making some tabs to secure the upper shock mount. The upper mount itself will be located 3 1/2 -4" rearwards of the original shock mounting stud to maintain the stock shock angle and distant from eye to eye. The only concern i have is the clearance to the fuel tank, which is within 3/4" of the shock. I don't think it will contact, but this does not account for any deflection which may occur under high load situations (pot holes and big driveway transitions).
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Re: 1988 SB50 Resurrection

Post by Meatball »

Meatball wrote:All I do to balance scoot wheels is line up the yellow or red dot on the tire to the valve stem. Not all tires manufacturers have dots tho.
UPDATE: The method I mentioned above has worked OK up until recently. Swapping tires/rims on different scoots left me a terrible front end wobble. I thought it was a bent rim, bubbled tire, folded tube, etc...turns out it was badly out of balance. No position of the tire to rim would cure it. I had to balance the tire by hand by spinning the tire/rim while on its axle many times. Using chalk to mark the 12o'clock spot every time it came to rest. this gave me the location to put some weights. Now when spun, it comes to rest at random locations as there is no longer a "heavy" spot to rest at the bottom. Wobble was 100% eliminated and it cost less than $10.

http://www.harborfreight.com/catalogsea ... re+weights
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Re: 1988 SB50 Resurrection

Post by noiseguy »

Meatball wrote: I had to balance the tire by hand by spinning the tire/rim while on its axle many times. Using chalk to mark the 12o'clock spot every time it came to rest. this gave me the location to put some weights. Now when spun, it comes to rest at random locations as there is no longer a "heavy" spot to rest at the bottom. Wobble was 100% eliminated and it cost less than $10.
That's how it's done, though can't say I've ever had to actually do it myself... How much weight did it require?
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Re: 1988 SB50 Resurrection

Post by Meatball »

noiseguy wrote:How much weight did it require?
I actually used some scrap lead strips I had laying around the shop. Final weight I used is unknown but it seemed to require more than I anticipated. Rather large chunk. I just kept taping larger pieces on until balance was achieved, then epoxied and re-painted after it cured.

I have never had to do this to a rear rim. Never even checked one for balance since Ive never had a bumpy one. Maybe most of the weight being in the rear renders any balance issues undetectable? Plausible theory.
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Re: 1988 SB50 Resurrection

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Ok, made some progress. I got the shock mount in and welded. The stock SA50 carb installed and the bike fired up. I wired the AF16 coil and starter harness spliced in to the SB50e harness. The interesting point is the wires matched color to the coil, except for the starter which is red/white on the AF16 harness and the SB50e harness is white. I hacked up the factory throttle cable to work till the one i ordered arrives. I also ordered a Mallosi shock and a new battery.

Now the issue i am having is keeping it running/idling. I rode it around the yard for a few minutes and the oil pump plug popped out and stalled out. I reinstalled the plug, but the bike now has a difficult time to maintain idle and the applied throttle bogs for a few seconds before it peeps up again (no idle when throttle is let off). Not sure what to do, but i am going to wait for the parts before i starting troubleshooting and the breaking in process. I also had to revert to the expansion pipe since the knock off PG pipe does not fit without major adjustment. :( Regardless this thing is beast with this 50mm bore!
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Re: 1988 SB50 Resurrection

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Update: I had to get a new CT manifold, since i messed up the first one. Got the 30mm OKO carburetor installed. Needle jet e-clip in the middle position and she seems to run real good. The cylinder temps on low speed break in 15-20 MPH are at 220-260 F range. With a few up hill runs getting towards 300 F MAX at 15 MPH. I have the premix at 32:1 so 4oz (burris HiRev Castor)to 1 gallon of gas which seems real smokey to me, but i can change the ratio a bit after break/wear-in. i have ran just over 2 gallons through the engine. So i think i am almost ready to do some WOT testing along with carburetor tuning. What are your guys suggestions? more break-in time? if so how much more?

On a side note: There seems to be an exponential amount of vibration with the engine once up to 25 MPH (have not gone beyond 25 MPH) is this normal? should i go faster and see if the vibration get worst? just need some reassurance before proceeding on. Again Thank You all for the assistance and motivation. I will hopefully start recording this stuff and put it up on youtube once i find time to figure out the movie/video editor software.

https://youtu.be/XMnkeiTsO_U
Last edited by AMPsocal on Sun Sep 24, 2017 3:07 pm, edited 1 time in total.
2010 Honda SH150i
1988 Honda SB50e
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