FJR Owners Forum banner

throttle body sync issues

2K views 8 replies 6 participants last post by  Skidney 
#1 ·
okay so the other day i got my morgan tbs in the mail and i tried to sync it and ran into some issues (gen1 2005)

so my first question is do i first set the 3rd cyclinder to 25cm and adjust the rest then or don't touch it people seem to have different opinions about this

i got them mostly synced up but cylinder 4 i can screw it all the way in and out without it really changing it drops but it doesn't go up. cylinder 1 is all the way in for it to line up but it's a bit of a given that the screws shouldn't be all the way in or out. what causes this exactly?

what i did ran the engine till it was warm about 2bars then turned it off then removed the rubber tabs on the nipples and hooked up the throttle body sync since 4 was the lowest i adjusted that one first once i saw the screw could be turned all the way in without changing anything i went to 1 and 2

i wouldn't be surprised if the tb is dirty or the injectors got some blow back from when the engine skipped timing

cheers
 
#2 ·
Bring the bike is older and perhaps higher mileage... vacuum passages and sync screws can get crudded up a bit, so you can remove all the screws, squirt some solvent down those holes and clean up the tips of the screws.... consult the parts diagram, note there is spring, teeny brass washer and a teeny o-ring around the shaft of the screw... you don't want to be going crazy and losing any of those parts, especially the o-ring, otherwise you're ordering a new screw assembly (~$7).


What I normally do is set #3 to at least 3/4 turn out maybe 7/8. Ignore all the vacuum readings too many variables to nail that down, but you should be "close" and that counts in this case, and only #3, again. Ignore what it is, condition of your aged engine, valve clearances, etc. influences it.... Sync all other cylinders to #3, and if you have one totally closed yet not synced, back out #3 a tad more and re-do. If you're out more than one turn, note the spring that holds it is losing tension to hold the screw from turning due to vibration.
Next valve check, you may find larger differences in clearance to #3 and the offender, but that's not absolutely necessarily true either. In any case, if you adjust all clearances to be equal across cylinders, your sync should become a narrower differential between cylinders.... in theory.

The other thing is, it does not matter which one is the reference screw, if another one lets you get all the others in line, then sync to that.
Note all this applies to Gen1/2, not Gen3+.
Injector cleaning may not be necessary but never hurts, not sure it has a very large effect on sync as the intake draw should be similar anyway. Let's say worst case one is clogged, not firing, then that likely does if one cylinder is not working at all, engine not smooth. Rather than trying injector cleaners, send them off to a cleaning service who can test and tell you the flow rates.
 
  • Like
Reactions: Skidney
#3 · (Edited)
Bring the bike is older and perhaps higher mileage... vacuum passages and sync screws can get crudded up a bit, so you can remove all the screws, squirt some solvent down those holes and clean up the tips of the screws.... consult the parts diagram, note there is spring, teeny brass washer and a teeny o-ring around the shaft of the screw... you don't want to be going crazy and losing any of those parts, especially the o-ring, otherwise you're ordering a new screw assembly (~$7).

What I normally do is set #3 to at least 3/4 turn out maybe 7/8. Ignore all the vacuum readings too many variables to nail that down, but you should be "close" and that counts in this case, and only #3, again. Ignore what it is, condition of your aged engine, valve clearances, etc. influences it.... Sync all other cylinders to #3, and if you have one totally closed yet not synced, back out #3 a tad more and re-do. If you're out more than one turn, note the spring that holds it is losing tension to hold the screw from turning due to vibration.
Next valve check, you may find larger differences in clearance to #3 and the offender, but that's not absolutely necessarily true either. In any case, if you adjust all clearances to be equal across cylinders, your sync should become a narrower differential between cylinders.... in theory.

The other thing is, it does not matter which one is the reference screw, if another one lets you get all the others in line, then sync to that.
Note all this applies to Gen1/2, not Gen3+.
Injector cleaning may not be necessary but never hurts, not sure it has a very large effect on sync as the intake draw should be similar anyway. Let's say worst case one is clogged, not firing, then that likely does if one cylinder is not working at all, engine not smooth. Rather than trying injector cleaners, send them off to a cleaning service who can test and tell you the flow rates.
getting them tested sounds like the more expensive option in this case about taking them apart the only thing im really worried about is the o-rings on the injector needing to be replaced and i have no clue where to get those im going to clean out the passages as good as possible and then set the 3rd one like you said and i'll go from there.
what kind of solvent would you use in the passages to clean them out?
cheers
 
#5 ·
What fjrlee says...
I'd focus on the sync and not worry about the injectors right now. If you use name brand Top Tier fuel or that containing polyetheramine/Techron, injectors are likely fine. High milers can take/sent the injectors to a cleaning/flow test service. Can always use an injector cleaner in a tank or two if you think it's a concern. The o-rings are likely fine.
 
#6 · (Edited)
Personally, I treat every 3 or 4 full tanks when filled with Lucas fuel treatment, probably a bit excessive but it seems to smooth things out a bit, my take Is that it certainly shouldn’t hurt anything. I do this on everything I own, as long as I remember to do it,which is questionable theses days.

I walked to the front of my garage this past Saturday to get my bottle of Lucas to treat the tank of my now full garden tractor and came back with a rag and checked the engine oil. And then off I went to mow grass never adding a drop of Lucas ������

This old age thing is not for the weak or faint of heart, some day I fully expect my wife to have to retrieve me from the local town 15mi away on my tractor having mowed all the grass to get there,,,,,,, if she can remember who I am ��
 
  • Like
Reactions: slowdave
#9 ·
Thanks RaYzerman!!!!

Thanks so much RaYzerman. I was doing a sync yesterday, preparing for a trip from North Carolina to Colorado, and I was having issues finding the "Master" throttle body. Everything I had read stated the screw was painted white. However, all of mine were unpainted. I was having trouble getting things to sync and was scared to start adjusting until I knew which one was the master.

Fortunately for me I found your reply to this post. You saved the day. Got everything synced up and no more handle bar buzz.

Thanks so much. Really appreciate your detailed response.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top