My new Carbtune from Morgan...

[chuckycheese]

Well, I finally gave in and got one...it's a very nice instrument (but it should be for $113 dollars), so here goes....

It works great and tells me whats going on but I can adjust the two inner carbs with no problems, the outer ones are difficult...and when I work on them, the inner ones are screwed up. One of the tricks I learned was to go slow and wait for the engine to settle down....but I'm still having a hard time.

Do any of you Morgan Carb-tune gurus have any advice. By the way, my bike ran pretty darn good before I attempted this but the initial reading was waaaaaaaaaay off the mark so I'm looking forward to a 'cool ride' after I get it figured out. Thanks for you advice, as always!!:-D

[chef1366]

I know you probably know you tune them all to #3 since it doesn't have any adjustment.
I had the same problem the first time with mecury sticks. Adjust one and another one changes. Be patient and make sure you have a couple of fans blowing on your headers.
Do you have the adjustment tool or are you trying to do the cylinder a tad lower to make up for the tightening of the lock nut? (Like me. Actually I've gotten pretty good at it.)

[earlfor]

I always adjust the carb that is the farthest out. Cylinder order is immaterial.
I dont try to adjust any one carb all the way to match #3 with the first few rounds of adjustment. Rather, I bring 1,2 and 4 into the general range of #3 in small increments. Once close, then I shoot for a perfect matchup.

An example of how I do it is
If cylinder 4 was the farthest value away from the control value of #3. I would adjust 4 until either it matched #3 or until it resulted in an out of synch value greater on 1 or 2 than I had on 4. usually, adjusting any cylinder will at a point result in another cylinder having a greater out of synch value than the one you started adjusting. You dont get all the way there at once on any one cylinder, you're going back and forth randomly in small increments, gradually drawing them all closer together. (I'm probably making myself about as clear as mud here. LOL )

Until I get all cylinders very close, I dont bother with the locking nuts. I let everything sit loose so I can quickly go back and forth. Once close, I fingertight all nuts leaving them loose enough to adjust, but not so loose as to move freely.


E.

[denydog]

I just did mine yesterday. It is confusing to me, but it seems to help if I try to keep a couple of things in mind.

#3 is not adjustable.
Turning an adjustment screw clockwise increases vacuum.
#4 adjusts off #3
#2 adjusts off #3
#1 adjusts off #2, so if you adjust #2, it will throw off #1 (So I like to get # 2 close before doing #1)

I hope I got that right, and it makes sense. But like earlfor, I end up going back and forth a few times.

[Steve]

Denydog,

The findings you report are EXACTLY what the book calls for. \\/

Also remember that, if you are doing a complete tune-up, carb sync is the LAST item on the agenda.
1. compression check - to verify basic integrity
2. valve clearance - if too tight, might affect compression readings
3. ignition timing - '80 and up bikes don't have points, so are not adjustable
4. carb sync - done last, especially if you have changed valve clearance. If you have changed a shim or two, you will have affected how the cylinder fills, so it will draw a bit more vacuum and throw off the balance.

Carb sync will make it run smoother, but I think it has the greatest affect at- and just-off-idle. I have run the engine at higher speeds with the gauges attached, but only on the centerstand, not out on the road. (Throttle settings will be different on the road.) I have seen the balance change a bit as the engine speed went up, but it was never very far off. It is my (humble) opinion that if you are running at 25% throttle, you might have two carbs at 25%, one at 23% and one at 28%. Yeah, they are a bit off, but not too bad. But, if you drop down to idle settings, one will be at 1%, two at 3% and one at 6%. Can you see how rough it might run? 8-[ The difference is not so noticeable at speed, but it really shows up at idle and the lower throttle settings used around town.


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[earlfor]

I have been told this doesnt work, but It works perfectly for me. :-)
Believe me or not, your choice. ehehe

Once I have the carbs synched at idle range, I throttle up to the rpm level I primarily use the bike at. Out on the road, that is around the 4k 4500 rpm range. I note the synch values at that rpm. I then do a final "finish" synch to match everything up exactly at 4K-4500 rpm. The bike then runs absolutely smooth as glass in that range. Idle will usually be slightly rougher, but I dont spend much time in idle range, so thats fine with me.

E.

Denydog,

The findings you report are EXACTLY what the book calls for. \\/

Also remember that, if you are doing a complete tune-up, carb sync is the LAST item on the agenda.
1. compression check - to verify basic integrity
2. valve clearance - if too tight, might affect compression readings
3. ignition timing - '80 and up bikes don't have points, so are not adjustable
4. carb sync - done last, especially if you have changed valve clearance. If you have changed a shim or two, you will have affected how the cylinder fills, so it will draw a bit more vacuum and throw off the balance.

Carb sync will make it run smoother, but I think it has the greatest affect at- and just-off-idle. I have run the engine at higher speeds with the gauges attached, but only on the centerstand, not out on the road. (Throttle settings will be different on the road.) I have seen the balance change a bit as the engine speed went up, but it was never very far off. It is my (humble) opinion that if you are running at 25% throttle, you might have two carbs at 25%, one at 23% and one at 28%. Yeah, they are a bit off, but not too bad. But, if you drop down to idle settings, one will be at 1%, two at 3% and one at 6%. Can you see how rough it might run? 8-[ The difference is not so noticeable at speed, but it really shows up at idle and the lower throttle settings used around town.


.

[Steve]

The only problem that I see with that is that, with no load (on the centerstand), the throttle setting will be different that it will be out on the road. On the stand, you might be open about 5%, out on the road it might be 20%, so you still won't have it quite perfect unless you drive it with the gauges attached so you can check it.

I am glad it works for you. :-D Sounds like too much work for me. 8-[


.

[chuckycheese]

Thanks!

Thank you all for the excellent responses and advice. I understood, perfectly, what each of you wrote. It sounds like my impatience is probably my biggest problem (which it often is). I'll try again this morning and go about it as you've suggested!:-D

[chuckycheese]

Update

Armed with the new confidence I got from you guys, I went out and had it synched in about 20 minutes!\\/I thought, by far, the hardest part was tightening the nuts without screwing up the setting. I do have the Motion Pro tool....it seems like it would be very hard to do without it. I didn't get it absolutely perfect, but it's really close.

Thanks, to all, again!!:-D

[earlfor]

Thats great! Cheers! It gets easier after a few times with the Carbtune. :-)

E.

Armed with the new confidence I got from you guys, I went out and had it synched in about 20 minutes!\\/I thought, by far, the hardest part was tightening the nuts without screwing up the setting. I do have the Motion Pro tool....it seems like it would be very hard to do without it. I didn't get it absolutely perfect, but it's really close.

Thanks, to all, again!!:-D

[chuckycheese]

Thanks, again!

Thats great! Cheers! It gets easier after a few times with the Carbtune. :-)

E.

Yes, it seems that like so many other jobs, it will be easier next time. I took your advice and adjusted the one first that was further out of balance and it really seemed to simplify the procedure a great deal!:-D

[tconroy]

I just did mine today and it took about 15 minutes to get them perfect.I synced them at 1750 rpm per clymers manual and then took it up to 4000 and saw hardly any difference.there is hardly any vibration at any rpm and it pulls a lot harder.I had diffculty keeping it idleing evenly for some reason,probably cause I didnt let it warm up enough butI did use fans anyway, and a long fuel line.I Put the outside carbs at 2 cf's higher than the inside carbs cause of stock exhaust and also what the book say's.It looks good when you get them all lined up like there suppose to be.Once i got the tank back on the fuel line had air in it and the prime would not work till I purged the air out.You can do this by unscrewing one of the bowl drain plugs and then turning the prime on to refill it and get the air out of the line.