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1977 LM 1 running lean on right side

J

Jonathan

Just got it firing!
Joined
Sep 20, 2011
Messages
15
Hi all,
So I have a 77 LM1 that was punched out too 1000cc and dual plugged. The bike runs a lot hotter on the right side. Upon starting and warming up it is most noticeable. The pilot jets are 64 and the mains are 145. I can sync the carbs with my carbomate and get it tick over at 1000rpm nicely. Idle mixture screws are out 1-1/2 turns. manifold have new gaskets and rubber sleeves are new on the dellortos. What do you suppose it is?
 
Have the carbs been rebuilt? Have you performed a compression test? or a leak down test? Even though components are new, check for them not sealing and extra air getting in. Spray the intact tract with a wd40 or similar and see if RPM changes.

It is not uncommon for one side to be running a little hotter than the other. Can't really check temperatures unless you can get an IR thermometer to check exhaust temps at the headers.
 
Thanks John
The carbs are rebuilt but as you point out I’ll look for leaks and perform the compression and leak down. Just out of curiosity why is it normal for one side to potentially run hotter? Compression should be in the 175 psi neighborhood? Leak down pump 60 PSI in?
 
As above ..... I had to fiddle with the pick ups ( Dyna magic box and 5 ohm coils ) individually to get both pots firing at the correct time .
There are marks on the flywheel that can be seen thru the bell housing for each pot . I just used a timing light and fiddled the pick ups until I had both right . Also make sure the advance mechanism is working correctly while your at it .
That would have been 15 years ago and I haven't touched them since..........love that Dyna ;)
 
Thanks for the info MC. I do have a Dyna 111 installed. When I bought the Lemans 1, the previous owner had dual plugged it but never installed the dual coils. The small spark plugs were installed but never activated. I finished the twin plug install with the correct coils and then was told that I needed to retard the ignition because of the twin plugs. It’s been a while and I just can’t remember how by how much. I’m assuming with the Dyna that if you’ve got one pot set correctly then the other is automatically correct no?
 
Jonathan said:
I’m assuming with the Dyna that if you’ve got one pot set correctly then the other is automatically correct no?
Click to expand...
The answer is no. You get one side correct, then you have to adjust the pickup for the other. Sometime you have to go back and forth with some rotation of the "distributor" and then go after the pickups again. It can take some time to set them up, but once set they stay in time. I wish I could tell you the number of degrees to retard, but timing will be close to TDC as the flame front from dual plugs progresses rapidly.
 
Thanks John,
Good to know. That may be the problem. Will look into it today
 
So today I got into the timing and low and behold the static timing was seriously advanced on the right side. I never got to the left side. As a start I set the flywheel directly on the mark between fully advanced and TDC, hooked my buzzer light up to the red wire on the coil and where I turned the ignition on the light and buzzer came on. Here's the problem ....when I loosen the distributor housing and turn it all the way to the left and then the right the light never goes out and I can only get it to go out by exceeding the housing allowable degree's adjustment by turning the crank from the alternator bolt. This surprised me. Each sensor has a line on it as does the rotor pick up. I would have thought that lining them up would have put me in the ballpark but that wasn't the case either. Anybody ever experience this before?
 
Jonathan said:
So today I got into the timing and low and behold the static timing was seriously advanced on the right side. I never got to the left side. As a start I set the flywheel directly on the mark between fully advanced and TDC, hooked my buzzer light up to the red wire on the coil and where I turned the ignition on the light and buzzer came on. Here's the problem ....when I loosen the distributor housing and turn it all the way to the left and then the right the light never goes out and I can only get it to go out by exceeding the housing allowable degree's adjustment by turning the crank from the alternator bolt. This surprised me. Each sensor has a line on it as does the rotor pick up. I would have thought that lining them up would have put me in the ballpark but that wasn't the case either. Anybody ever experience this before?
Click to expand...
You have Hall Effect sensors. They trigger as the magnet on the rotor passes. The lines just are there as a start point. You need to ditch that buzzer light and time by when the spark plug fires. Do a web search on Dyna III ignition and you may just find the instructions for setting it up.
 
Hmmm I did go to Dana’s support site and downloaded the Dyna 111 instruction and they do tell you to use the light attached to the coil. Apparently the air gap between the rotor and sensors is unimportant so long as they don’t touch. I need to check that as well. So with the plugs out and grounded, with the ignition on, the plugs will fire simply by turning the crank at the alternator bolt?
 
Well I got it done today. Interestingly my flywheel had no markings other than dashes. I hooked up a degree wheel and confirmed what was what. To John Z’s point I did it by actual visual spark and then checked with an induction scope. Right on the money and now running great and evenly. Thanks for everyone’s help
 
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