I'm not sure if this is common knowledge but I haven't read it anywhere and ran into this problem a while ago (read: 2013).
My throttle slide guides were worn out but these parts cannot be ordered from Suzuki. They are simply missing from the drawings and not known in the Suzuki parts catalogue.
As mine were worn out I wanted to buy new ones. I looked around and found the same carburettors used on the GS500 on a BMW motorcycle.
(http://i93.photobucket.com/albums/l51/teamicecream/Photo08-10-13131434.jpg)
Contrary to Suzuki, BMW does have these things in their parts catalogue.
If you want new ones locate a BMW dealer and ask for these parts:
BMW article no.: 13 11 2343374 (throttle slide guide, german word is 'trager' aka 'carrier')
BMW article no.: 13 11 2343393 (o-ring for the bottom of the slide guide)
These parts can be found on at least this motorcycle:
Series: E169
Model: BMW F 650 97
build year/month: 1996/12
Note that if the guides are worn out your throttle slides are also worn. Install new slides together with the new guides or they may wear out rapidly again.
In 2013 I made a 3D printable model because I really needed new ones but had not found the BMW ones yet. You can find/order these from shapeways (http://shpws.me/GAFv). I've had several people ordering these 3D printed units and received no complaints. Perhaps if the BMW part is expensive at your place you could get them from shapeways.
The problem I had:
Engine holding back and cutting out on the highway. I took the caps from the carburettors and found this:
(http://i93.photobucket.com/albums/l51/teamicecream/Photo18-09-13121231.jpg)
(http://i93.photobucket.com/albums/l51/teamicecream/Photo18-09-13121236.jpg)
Some sort of plastic paste consisting of plastic grinded from the slide guides. Also found a broken needle.
And ofcourse the totally worn out slide guides you have already seen
(http://i93.photobucket.com/albums/l51/teamicecream/Photo08-10-13131434.jpg)
(http://i93.photobucket.com/albums/l51/teamicecream/Photo22-09-13115921.jpg)
Left; broken needle, middle a worn needle and at the right a brand new needle.
Suzuki micro fiche. Note that the slide guide is not shown
(http://i93.photobucket.com/albums/l51/teamicecream/gs500fiche.png)
The BMW fiche
(http://i93.photobucket.com/albums/l51/teamicecream/bmwfiche.png)
Number 5 the slide guide and number 6 the o-ring. Don't forget the o-ring or your bike will run poorly.
When you have acquired your new slide guides do not forcefully push them into the carburettors. Take a file or some sanding paper and grind down the little wings untill they slide into the carburettor with pretty much no resistance.
(http://i93.photobucket.com/albums/l51/teamicecream/vijlen.jpg)
Once again do not try to push them in with force, you will break the wings.
Keep in mind that the most important consequence of a worn slide guide is a worn emulsion tube, which will cause low rpm rich mixture problems that are not easily correctable via jetting (since in general the jetting circuits correspond to openings rather than rpm).
Regards,
Derek
The tabs on the slide guide should not be modified in order to get them to seat.
Regards,
Derek
Quote from: motolab on April 09, 2019, 08:49:20 AM
The tabs on the slide guide should not be modified in order to get them to seat.
Regards,
Derek
They should if they don't fit and mine didn't fit. I tried to force one in which broke off one of the tabs. Upon closer look at some original slide guides I noticed the tabs were modified as well. It is hard but brittle plastic. Just make sure it is a snug fit, if there is play the throttle needles and slide guides will not be happy.
Very interesting! Thanks for posting this info.
How many miles were on your GS500? You would think that if Suzuki does not offer the slides as a replaceable part, they must not consider it a part subject to wear? I have not heard of this problem before. What do you think caused your worn slide guides in the first place?
The tabs on the slide guides are not modified prior to installation. It may appear as though they are because part of the tab may abrade during installation.
Regards,
Derek
I have seen a few worn slide guides. Most of those were the result of not keeping airfilter clean and likely riding in dusty environments. The katana carbs of which I parted out several have had these which are same as the GS (cos its the same carb).
Anyway good info to have. The slide itself gets damaged more often, if you drop it onto a hard surface, it will break. Plus there is the wear from dust from a dirty air filter.
Cool.
Buddha.
Quote from: Bluesmudge on April 09, 2019, 12:03:54 PM
Very interesting! Thanks for posting this info.
How many miles were on your GS500? You would think that if Suzuki does not offer the slides as a replaceable part, they must not consider it a part subject to wear? I have not heard of this problem before. What do you think caused your worn slide guides in the first place?
I cant recall exactly. It was 60k or 80k kilometers. The slide guides wear because they are nothing more than plastic. They move a lot, the air pushes the throttle slides against the guide so they rub against each other whenever the slides move. Wearing them out at some point is inevitable.
I figure there might be a difference in the type of slide guide. I have a 25kw power limited GS500 (old Dutch regulation). The power is limited by the use of (original Suzuki/Mikuni) throttle slides with an extra hole in it. It stops them from fully going up because the hole kills the vacuum. Perhaps the smaller travel causes more wear at the bottom. Although they don't move more often and my other full power GS500 from 89 with half the mileage seems to have the same rate of wear.
At some point the guides wear out no matter what. It is in fact quite common, and is the case for all BST- and BDST-series carburetors. On the BST33, emulsion tube wear sets in when the surrounding plastic has worn flush with the depressions in the bottom corners of the guide (adjacent to where the slide bottoms, circled here in green on a new guide):
(http://media.moto-lab.com/images/other/Mikuni/Slide%20Guides/BST33/slide%20guide,%20new,%20green%20circles.jpg)
The below chart is from a '99 GS500E with stock air filter in place and 14.7K miles on the clock:
(http://media.moto-lab.com/images/Graphs/Suzuki/GS500E/'89-'00/Emami,%20E/02BASE100%25TH.jpg)
Red is WOT after having replaced the emulsion tubes and slide guides; blue is prior. You can clearly see the improvement in mixture uniformity from having replaced the emulsion tubes (which were worn because the slide guides were worn).
Regards,
Derek
Anyone know the specifications for that slide quide o-ring? Or link to the topic where to find it!
BMW article no.: 13 11 2343393 (o-ring for the bottom of the slide guide)
D. and ID. information, I would pick that o-ring from lockal dealer!
Appreciate you are not in the UK but the o-rings, and many other BST33 parts are available on this site.....
https://www.motobins.co.uk/ (https://www.motobins.co.uk/)
Thanks! Yeah, I'm at Finland actually. :cheers: Bst33 parts hardly available here! O-rings tho are available but I'll look for the dimensions or just order there! 30years old o rings have melted to the gap.. No leaks still!
Quote from: nurms on September 18, 2020, 11:36:04 AM
Thanks! Yeah, I'm at Finland actually. :cheers: Bst33 parts hardly available here! O-rings tho are available but I'll look for the dimensions or just order there! 30years old o rings have melted to the gap.. No leaks still!
They are just standard metric o-rings. If you have a local hardware store with a selection of orings, just match it up. It should fit the groove and protrude about 1/3 of the cross section thickness out of the groove.
These are out my carbs slide guides. I hadn't tossed the used parts yet. Remember, these are used and somewhat distorted / flattened. The cross section is probably showing a bit wider than a fresh oring. I'd use these measurements as a
"guide only" and find the closest standard sized. One usually sorts by cross section, then I.D.
(https://iili.io/2Iavzg.md.jpg) (https://freeimage.host/i/2Iavzg)
(https://iili.io/2IaSLJ.md.jpg) (https://freeimage.host/i/2IaSLJ)
(https://iili.io/2Ia8Xa.md.jpg) (https://freeimage.host/i/2Ia8Xa)
Great!
Thanks a lot! It is kinda odd that for example carburettor rebuild kit at my local store do not include that o-ring. I believe the tourmax kit has only the pilot screw o-ring and the float o-ring.
Quote from: Sporty on September 19, 2020, 04:32:37 AM
Quote from: nurms on September 18, 2020, 11:36:04 AM
Thanks! Yeah, I'm at Finland actually. :cheers: Bst33 parts hardly available here! O-rings tho are available but I'll look for the dimensions or just order there! 30years old o rings have melted to the gap.. No leaks still!
They are just standard metric o-rings. If you have a local hardware store with a selection of orings, just match it up. It should fit the groove and protrude about 1/3 of the cross section thickness out of the groove.
These are out my carbs slide guides. I hadn't tossed the used parts yet. Remember, these are used and somewhat distorted / flattened. The cross section is probably showing a bit wider than a fresh oring. I'd use these measurements as a "guide only" and find the closest standard sized. One usually sorts by cross section, then I.D.
(https://iili.io/2Iavzg.md.jpg) (https://freeimage.host/i/2Iavzg)
(https://iili.io/2IaSLJ.md.jpg) (https://freeimage.host/i/2IaSLJ)
(https://iili.io/2Ia8Xa.md.jpg) (https://freeimage.host/i/2Ia8Xa)
Do you know are these NBR o-rings? NBR should be somewhat resistant to gasoline but I think about trying Viton o-rings. Viton will handle gas for sure.