ST1100 Needle Holder - Canada Type?

[jrp]

Anyone know why the needle holder is different in the Canadian market? Just curious. Snide remarks are welcomed.

 

[paulcb]

It's a more friendly design.

 

[kiltman]

Sorry

 

[Upt' North]

Is it designed to hold a "Joint"?
Upt'North.

 

[bdalameda]

I noticed this too. I can only surmise it has to do with the throttle response. Vacuum is bled from the intake tract through a hole in the slide and up into the diaphragm, and the larger the openings in the slide the faster the slide will open to respond to throttle movement. It looks like the part has cutouts in it that may uncover holes in the slide that will allow higher vacuum flow. On other CV carbs I have modified to improve performance I have enlarged the hole in the slide to increase throttle response. I think this must be why these are different - I could be wrong.

 

[CYYJ]

From looking at the illustration above, it appears that the "Canada type" part is adjustable (it has indentations in the side to allow it to be turned by hand), and the "other" part is not adjustable.

I don't know if the parts catalog illustration above is taken from a worldwide publication, or a parts catalog that is specific to North America. If it is a North America specific publication - in other words, the catalog applies to ST1100 models that were sold only in Canada and the USA - then the part that is different, the "odd part out", is probably the American part (the default part). Likely it is not adjustable in order to comply with American emissions regulations.

To prove or disprove this theory, we need to find an illustration from a European parts catalog that shows what the European ST1100 model part for the same year of manufacture looks like.

Michael

 

[jrp]

From looking at the illustration above, it appears that the "Canada type" part is adjustable (it has indentations in the side to allow it to be turned by hand), and the "other" part is not adjustable.

I don't know if the parts catalog illustration above is taken from a worldwide publication, or a parts catalog that is specific to North America. If it is a North America specific publication - in other words, the catalog applies to ST1100 models that were sold only in Canada and the USA - then the part that is different, the "odd part out", is probably the American part (the default part). Likely it is not adjustable in order to comply with American emissions regulations.

To prove or disprove this theory, we need to find an illustration from a European parts catalog that shows what the European ST1100 model part for the same year of manufacture looks like.

Michael

The diagram is from the North America-specific ST1100 service manual.

I highly doubt that the indentations are to allow turning by hand as the holder locates deep in the carburetor slide and it is impossible to get your fingers in there (see attached picture).

I also suspect that it has something to do with U.S. emissions rules. It would be interesting to know what the European models have.

bdalameda's explanation makes sense to me; would a slower rising slide reduce emissions? I don't know.

Jeff

EDIT: I'd like to get my hands on a set of the Canada-type holders to see what the performance difference is like.

 

[afrymoyer]

I can't find anything in all my notes. I do know that different Keihin model numbers were used in different countries. I helped a guy tune his carbs from overseas (England I think). The factory jetting was very odd and very much surprised me what Honda had done.

The needle holder is a "locking cam" design in our US models and it appears that way for the Canadian. I wonder too, if the vacuum pistons/slides are the same part number or something different. Mystery....

 

[jrp]

So I got my hands on one of these "Canada type" needle holders. They are quite a bit smaller than the U.S. ones:








However, I can not get it to fit into the collar in the bottom of the slide:





Here is what the collar looks like removed from the slide:





If any of our Canadian brethren (or anyone else whose carbs have this type of needle holder) happens to have their carbs currently out of their bike, it would be greatly appreciated if you would post a picture of the collar at the bottom of the slide so that I can see the difference.

Thanks,
Jeff

 

[jrp]

Seems the Canadian slide has a difference part number and the parts list doesn't specify a collar. The image of the slide doesn't have the cutouts on the bottom for the collar tabs as mine does. I suspect that the Canadian-type needle holder only fits these slides.

 

[jrp]

I think I found a pic of the inside bottom of the Candian slide:



Which is obviously different from the US market slide: