Topic: 550F Tune Up Time *Updated 4/20...please read*

[Scott S]

 Put about 120 miles on the Old Girl today. Still running great. I got to watch the odometer click over to 7,500 miles!
 I was able to get to 100 miles on the nose before hitting reserve. With a good bit of 5th gear cruising, I got 30.9 mpg. Still not as much as I would like, but much better than the 26 it was getting. No more fouled plugs, so far. Such a sweet bike to ride.

[jonda500]

My 500 always goes onto reserve at almost exactly 100 miles, but the best my 550F has done is 96 miles - it doesn't have great compression though 120 90 90 70!

Edit: NOTE- My 550F curently has the smaller 14 litre tank on it, which is handy for comparing it with my 500- when I get my larger tank up and running I will obviously get further!

[reddyvv]

I get 95-105.

[Tews19]

Same here. I've mentioned this for a few years. I think it's funny when I read people stating they get 55-60mpg.

[becken]

I've always gone 140 to 150 miles before going on reserve ever since new. Hondaman has some good tips in the FAQ section under " thoughts of Hondaman"  for the 500/550 series of bikes. The advance spring and emulsion tube modifications made a big difference in the low to mid range operation, although I'm still going 140 to 150 miles before hitting reserve. My bike is stock other than a K&N air filter and the Hondaman transistorized ignition.

[jonda500]

This is confusing - so 100 miles before going onto reserve is normal for the 14 litre tank, but with a 550F tank that would be pretty bad I guess. -I reckon my 550F should get almost 140-150 miles too when I replace the 500 tank that's on it now with my larger 550 tank.

[Scott S]

 The best I've ever gotten with the "middleweights" was with a '71 CB500. That bike regularly got 38-42 mpg and would hit ~125 miles before reserve.

 The 550 that's being rebuilt for my STF2 bike only returned 26 mpg. It, coincidentally, was a '76 model. I know that there is NOTHING that should differentiate the '76 model from previous years, but I've heard others say that their '76 model has always suffered poor fuel mileage. Now, granted, that engine was tired and had started fouling #3 plug.....hence the current rebuild.

 I had a '78 550K with a 562cc engine, ported head, CB650 cam, etc., and it would get an easy 34-36 mpg riding it however I wanted to.

 The '76 550F in this thread has seen a BEST of 31-32 mpg after finding the upside down jet. It's been tuned to death; valves are right, timing is right, compression is good, etc., etc. Bone stock bike and carbs except for the drop in UNI filter and a Pamco.

 I'll soon have another '76 550K on the road to compare. Same deal: bone stock engine, carbs, exhaust, etc., with a drop in UNI and a Pamco.

[Deltarider]

I'll soon have another '76 550K on the road to compare

If the 087A carbs are on that bike, I'm curious to know what differences there are to the former 022A carbs that were on the 550K and 550K1. According to my documents the 087A should have different airscrews, knowing the same that are in the 069A carbs on the 'F' models, but sofar I have seen no confirmation of this. What else could have been different that Honda gave those carbs a different number (087A and not 022A)? Needle position maybe? It's a mystery.
If you ever go in there and have the feeling the carbs weren't opened before, please take notes.

[Scott S]

 Just went through the carbs. You can see the air screws here:

[Deltarider]

Thanks, they look like the crossdrilled airscrews used on the CB550K(0) and CB550K1 and not like the solid ones that were on the 'F' models. Why the Parts List (http://www.honda4fun.com/pdf_parts_list/pdf_spac550/CB550-K0-K1-K2/CB550-K0-K1-K2_04.pdf) on page C10 mentions the CB550K2 has the 'F' model airscrews, I really don't know. Is it a mistake perhaps?
Yet there could be another reason why Honda gave these carbs a different number, knowing 087A. The only thing I can think of is that maybe the needle position differed from the 022A carbs that were on the CB550K(0) and K1. Now, don't go in there just for that but if you are, take a note of in what position you found them. Mystery of 087A remains to be solved. Anyone who has these 087A carbs in 'unmolested' form, is invited to shed some light.
BTW, for the brass parts shown in your picture it is not that important to keep them separate in containers 1,2,3 and 4. For needles and needle jets it is however.