Slow Jets

[kwatts]

I just finished tearing my carbs down for a rebuild. The bike seemed to me to run fine, but I wanted to go through the carbs since I had never done it before. My question is...I think I am supposed to have #35 slow jets, but instead all 4 carbs have #38 slow jets. I know there was a recall for low speed driveability improvements for the '85 Interstate and Aspencade, that entailed installing new slow jets. Does anybody know if these new jets that were installed due to the service bulletin happen to be size #38?

[Guest]

Honda service manual shows.....#35 slow jet

[bs175dths]

I do not know the answer to your question but wanted to mention this, there is a California Only set of carburetors and a 49 State set. First you will need to determine which carburetor set you have. The way these GL’s move around the country, you may have a California Only version in SD.
Also, while you are in there, often times folks are only concerned with the jets, ports and screw settings. Don’t forget to take a look at the top of the carburetor. The throttle slide needs to be able to GLIDE un and down the cylinder without restrictions. Often, sediment will accumulate on either the throttle piston side or the cylinder walls, (or both) and cause some resistance which translates to ‘slight hesitation just off idle’ or a’ bogging down’ when doing a roll on. Be careful not to damage the needle as any deformities will have an effect on performance. Also be careful with the diaphragm as they are easy to damage. When installing the throttle needle back into the carburetor body, make sure the diaphragm is correctly seated in it proper place before putting the top on. You do not want to pinch, crease or damage the diaphragm as this will affect performance. One final suggestion, lubricate the carburetor linkage. Before installing the carburetors on the bike, test each throttle needle for smooth upward movement and a distinctive ‘snap’ when closing. The same goes for the carburetor linkage. All the butterflies should open smoothly and when you release the linkage, they should ‘snap’ closed. Add a bit of lubricant at EACH enriching location (each carburetor has its own) as these should slide smoothly as well.

When we are ‘rebuilding’ carburetors we tend to neglect the linkage and the enriching circuit but oil will attract dirt which will cause resistance and the smoothness of operation slowly goes away.

BTW, work on one carburetor at a time as the rule of thumb is to not mix parts.

I did a carburetor rebuild on my brother’s ’82 CB750 Nighthawk and the ‘shop’ mixed parts. Two bowls were switched as well as two throttle slides, they damaged two choke butterflies and left out the accelerator pump o-ring. Done three years ago for $300.00 and he is pissed. I decided not to tell my brother the ‘other things’ I found as even after three years, he wanted to go back and ‘discuss’ the matter.

Good Luck.

-Ride On

[neoracer]

if its running fine with the 38's leave well enough alone,dont 2nd guess yourself

[BladeRunner]

Since we are on carbs, can anyone tell me if the diaphrams from a Sabre 750 or Magna 750 are the same as the 1200's? I have two of Randaks rebuild kits for my wings, but I also have a box of carb parts from the other two bikes. I haven't really compared them,but, this post got me thinking.... I have seen the price of those diaphrams hock: hock: Just wonder if I need them can I use those?

[kwatts]

bs175dths,
Thanks for the info & tips on the rebuild. I have the 49 State model.

I have done a little research into the Service Bulletins. #9 was just to replace the jet needles on the '85 Interstate & Aspencade (49 State). And #10, where they replaced the jet needles and the slow jets, only applied to the '84 Interstate & Aspencade (49 State) and the '85 (Calif) models.

So it appears that there was no Service Bulletin related requirement to change the slow jets to a #38. I have ordered the #35 slow jets that are apparently supposed to be in the carbs.

Neo,
I was thinking the same as you, if it aint broke don't fix it. But, the jets are inexpensive and I have everything torn apart anyway, and the jets will be here in about 5 days. Which is okay because there is still lots of snow on the ground and I am still waiting on Old Bike Barn for other parts to be sent that I ordered. It should be interesting to see if this changes anything during low speed driving. Hopefully it will be for the better!