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Post by redrum on Jul 26, 2020 7:20:09 GMT -5
Hi;
New to the forum and new to scooters, but I am a fairly good back yard mechanic. I was given a 89 SH50W that was not running and stored for years (maybe 10). I'd like to get it up and running just to tool around some private roads we have in the area. I did the following:
drained the fuel, added new, ethanol free
changed the petcock, and can suck vacuum and get the fuel to flow
changed the air cleaner foam (although I am trying to start it air cleaner removed
disassembled and cleaned the carb - float, needle valve, 2 jets, etc.
changed the spark plug, can confirm spark when removed, plug case against a frame bolt.
Initially it would "start" when I spray carb cleaner into the throat of the carb, but only runs a little bit (running on the carb cleaner). Now, I can confirm it is getting gas from tank, through petcock, into carb bowl (drop carb bowl, it's full with gas). I can get it to start without the ether, but it barely runs, bog, dies. After start, as it starts to bog, applying a bit of choke gets it to run a few extra seconds, but then it dies.
So, my question - I'd like to "give up" on this carb (unless someone has some insight), and buy an aftermarket carb. But, it's so confusing with so many carbs, and none specifically that identify it as compatible with the SH50W. At the very least, I'd like to find a carb rebuild kit.
Can anyone help me out here?
Thanks, Jim
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Post by redrum on Jul 27, 2020 8:26:37 GMT -5
anyone? I could use a little help, anyone that has had to go aftermarket before, just point me in the right direction, what to measure, what to expect to have to modify (throttle/choke connections, etc)
Jim
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Post by geoffh on Jul 27, 2020 14:52:03 GMT -5
Hi,welcome to vintage Yamaha tuning I have a 1988 project CG50 and I can feel your pain,you need to run the engine with the stock airbox fully fitted for these to run right,if it starts a runs a little your almost there the factory mixture screw setting is 1 and 3/4 out,strip the carb(again)and clean poke prod every hole and passageway to ensure that 10years of sitting has been removed.no easy answer on a replacement carb but your old one should be fine.keep at it
Geoff
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Post by redrum on Jul 28, 2020 6:26:44 GMT -5
Thank you for your reply Geoff. I don't want to give up but I am baffled. Also, I put a few $ into some parts so I'm "invested". I just received some foam for the air cleaner (old foam disintegrated) so I'll install and try to run with air cleaner in place. The carb does not have a miixture screw www.bikebandit.com/oem-parts/1989-yamaha-razz-sh50w/o/m146690#sch142071the only adjustment is the throttle stop screw. I took the carb apart again and poked every hole, especially the 2 jets, and they are all clear. It acts like it is still not getting gas, although after a squirt of choke cleaner it seems to run longer now than it did before, especially with choke full on. If I drop the bowl after taking the carb off, it is full of gas. If it were a lawnmower, weed wacker, chainsaw, etc at this point I would either get a carb rebuild kit or a new carb. I can't find either, that is why I came to the forum, looking for some advice from someone in my spot. You can't rule anything out, float, needle valve, jets, etc without being able to swap out. It baffles me that there must of been a ton of these out there, yet you can't find the single most prone to failure part available. Jim |
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Post by geoffh on Jul 28, 2020 15:02:43 GMT -5
Jim this may help,on that parts diagram the mixture screw is number26 idle speed is number23. 26 may be covered with a cap or years of grime,keep on asking.
Geoff
Take some photos of scoot engine and carb if you can.
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Post by aeroxbud on Jul 28, 2020 15:50:39 GMT -5
If it's been standing for 10 years you could have an air leak. This would make it hard to start.
Check the rubber mounting from the carb to the air box for splits of cracks.
Also check the crank seals for any signs of leaking.
If you get us a picture of the carb. We could probably recommend you something. The Dellorto carb is a good replacement. But there are various ways they mount.
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Post by redrum on Jul 29, 2020 7:10:47 GMT -5
Thank you both for your help. Geoff, on the mixture screw, my bad "oh, that screw". Its funny, on the carb diagram in the service manual it is not identified. Here are some pictures, but the most bizzarre thing happened this morning. In trying to take the carb off, the choke cylinder is stuck in the carb. It won't pull out, choke lever is stuck, and I am afraid of breaking something. I have had that carb off and on 10x and the choke and throttle assembly just slides right out. When I last tried to start it, the choke actuated fine. Oh well, something to keep playing with. Here are some pics Thank you again; Jim    |
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Post by redrum on Jul 29, 2020 7:12:09 GMT -5
I forgot to mention aeroxbud, all of the rubber/compliant material is in real good shape, hoses, the carb mount, etc.
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Post by redrum on Jul 29, 2020 7:45:18 GMT -5
ok, that was weird, pulled on the choke plunger harder than I would like to and it snapped free and came out. Here are some more picks of the carb. I don't have calipers at this location (cabin where the scooter is to roam), but I would say the ID of the carb (interface to engine) is 15/16" (2.4-2.5 cm) OD and the ID is about 3/4" (1.9 - 20.cm). More pics...    |
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Post by Steve B on Jul 29, 2020 9:38:59 GMT -5
Somebody should play the ultra sonic cleaner game.
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Post by geoffh on Jul 29, 2020 14:58:30 GMT -5
OK we have the same upright engine with very similar carbs mines autochoke but that seems all that's different,the later horizontal engines use a dellorto PHVA12 which is what most aftermarket carbs are based on,the carb slide is larger on these than yours but would fit to your existing air filter and inlet manifold.here,s a picture of my carb with the mixture screw set at factory.  Geoff |
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Post by redrum on Jul 29, 2020 15:01:40 GMT -5
she lives! It must have been the mixture adjustment, thanks Geoff.The service manual doesn't even address it. Either the previous owner had it messed up, or perhaps during my carb disassembly/reassembly I did not have it correct. Since I didn't even know it was there, that's possible. Another forgotten toy saved from the fate of eternal storage...  thanks again for those that took the time to take interest and reply. I needed the second set of eyes... Jim |
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Post by geoffh on Jul 29, 2020 15:07:58 GMT -5
That,s a result,it is a nice tidy scoot,you just have to name it and start a build thread to keep track of your service and probs as you go.
Geoff
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Post by aeroxbud on Jul 29, 2020 16:54:06 GMT -5
That's great. It looks a tidy scooter. Well worth saving.
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Post by redrum on Jul 29, 2020 18:26:55 GMT -5
That,s a result,it is a nice tidy scoot,you just have to name it and start a build thread to keep track of your service and probs as you go. Geoff Her name is Stella, thank you again. I think I want to find another one to fix for my wife  Jim |
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